JP7542816B2 - Fluorene compound and method for producing same - Google Patents

Description

The present invention relates to a novel fluorene compound.

High-energy light such as ultraviolet light (ultraviolet or UV) is effectively used in applications such as sterilization, chemical analysis, resin curing, and white light-emitting diodes (LEDs). Mercury has traditionally been used as a source of ultraviolet light, but due to its harmfulness to the human body, development of new light-emitting materials to replace mercury is underway, and near-ultraviolet LEDs with a wavelength of 365 nm using gallium nitride (GaN) have already been put to practical use. However, devices using inorganic light-emitting materials tend to be complicated in their manufacturing process, so there is a demand for organic light-emitting materials that can be easily or efficiently produced by methods such as coating. Compounds with a fluorene skeleton are known as such organic light-emitting materials.

Non-patent documents 1 to 4 disclose the luminescence properties of 9,9-bis(4-methylbenzyl)fluorene (BMBF).

Patent Document 1 also discloses an illuminant containing a fluorene compound represented by the following formula (1), in which the hydrocarbon group represented by X in formula (1) that may have a substituent is a group represented by the following formula (X1):

(In the formula, X may be the same or different and represent a hydrogen atom, a hydroxyl group, a carboxyl group, an alkoxycarbonyl group, an amino group, a substituted amino group, a halogen atom, or a hydrocarbon group which may have a substituent; R ¹ may be the same or different and represent a substituent; and k may be the same or different and represent an integer of 0 to 4.)

(In the formula, A represents an alkylene group or an alkylidene group, m represents 0 or 1, Z represents an arene ring, ^R2 represents a substituent, and n represents an integer of 0 or more).

JP 2018-145391 A

Abstracts of the 97th Annual Meeting of the Chemical Society of Japan (2017), 3PA-017, "Crystal Structure and Luminescence Properties of Fluorene Derivatives", Chemical Society of Japan Poster at the 97th Annual Meeting of the Chemical Society of Japan (2017), 3PA-017 "Crystal Structure and Luminescence Properties of Fluorene Derivatives" Proceedings of the Society of Polymer Science, Vol. 66, No. 1, 66th (2017) Annual Meeting of the Society of Polymer Science, 1Pc071 "Preparation and Light-Emitting Properties of Polysilsesquioxane Thin Films Hybridized with Fluorene", Society of Polymer Science, Japan Poster for the 66th (2017) Annual Meeting of the Society of Polymer Science, 1Pc071 "Preparation and Light-Emitting Properties of Polysilsesquioxane Thin Films Hybridized with Fluorene"

Non-patent documents 1 and 2 disclose that 9,9-bis(4-methylbenzyl)fluorene (BMBF) has an emission peak at a wavelength of 322 nm in the solid state at room temperature and emits ultraviolet light with a narrow half-width (or high monochromaticity). Non-patent documents 3 and 4 disclose that the emission quantum efficiency of BMBF is 7.6% in the solid state and 18.8% in a dichloromethane solution, and that a hybrid thin film formed by mixing polyphenylsilsesquioxane (PPSQ) prepared from phenyltrimethoxysilane and BMBF has an emission quantum efficiency of 18.2%, about three times that of the solid state, possibly due to suppression of concentration quenching.

However, although the fluorene compounds described in Non-Patent Documents 1 to 4 can emit ultraviolet light with short wavelengths and high monochromaticity even in a room temperature environment, their luminescence quantum efficiency is still insufficient. In particular, for practical use as photoelectric conversion elements such as ultraviolet light-emitting organic EL elements, high luminescence quantum efficiency is required in the solid state of the ultraviolet light-emitting material, and therefore further improvement in luminescence quantum efficiency is expected.

On the other hand, in Patent Document 1, aryl groups and the like are exemplified as the substituent represented by ^R1 , and specifically, C _6-10 aryl groups such as phenyl groups are described.

However, Patent Document 1 describes that an alkyl group is particularly preferable as the substituent represented by ^R1 , and discloses that the substitution number k of ^R1 is more preferably 0. Furthermore, Patent Document 1 not only does not describe any specific fluorene compound having a substitution number k of 1 or more, but also does not specifically prepare such a fluorene compound in the examples.

Therefore, an object of the present invention is to provide a fluorene compound capable of emitting light with high luminescence quantum efficiency (quantum efficiency or quantum yield), a method for producing the same, and uses thereof.

As a result of intensive research to achieve the above object, the inventors discovered that a specific fluorene compound exhibits extremely high luminescence quantum efficiency compared to conventional compounds, and thus completed the present invention.

That is, the novel fluorene compound of the present invention is represented by the following formula (1).

(In the formula, Z ^1a and Z ^1b each independently represent an arene ring, Z ^2a and Z ^2b each independently represent an arene ring, R ^1a , R ^1b , R ^2a , R ^2b , R ^3a and R ^3b each independently represent a substituent, A ^1a and A ^1b each independently represent a linear or branched alkylene group, k1 and k2 each independently represent an integer of 0 or more, m1 and m2 each independently represent an integer of 0 to 4, n1 and n2 each independently represent an integer of 0 to 4, p1 and p2 each independently represent an integer of 0 or more, m1+n1 and m2+n2 each independently represent an integer of 0 to 4, and at least one of m1 and m2 is an integer of 1 or more).

In the formula (1), Z ^1a and Z ^1b may be a C _6-12 arene ring, Z ^2a and Z ^2b may be a C _6-12 arene ring, A ^1a and A ^1b may be a linear or branched C _1-6 alkylene group, and m1 and m2 may be an integer of 0 to 2.

In the formula (1), Z ^1a and Z ^1b may be a benzene ring, a naphthalene ring or a biphenyl ring, Z ^2a and Z ^2b may be a benzene ring, a naphthalene ring or a biphenyl ring, A ^1a and A ^1b may be a linear or branched C _1-4 alkylene group, and m1 and m2 may be 1.

The fluorene compound may have an emission spectrum in a solid state that includes at least one emission peak having a maximum wavelength λ _em,max of about 350 to 450 nm and a half-width of about 60 nm or less, and has an emission quantum efficiency of about 40% or more, preferably about 50% or more. The fluorene compound may be a light-emitting material and/or a sensitizer.

The present invention may include a step of coupling reacting a compound represented by the following formula (2) with a compound represented by the following formula (3); or a step of reacting a compound represented by the following formula (4) with a compound represented by the following formula (5).

(In the formula, X ^1a and X ^1b each independently represent a group capable of forming a carbon-carbon bond by a coupling reaction; Z ^2a , Z ^2b , R ^2a , R ^2b , R ^3a , R ^3b , A ^1a , A ^1b , m1, m2, n1, n2, p1 and p2 are the same as in formula (1); m1+n1 and m2+n2 each independently represent an integer of 0 to 4, and at least one of m1 and m2 is an integer of 1 or more.)

(In the formula, ^X2 represents a group capable of forming a carbon-carbon bond together with ^X1a and/or ^X1b by a coupling reaction, ^Z1 is the same as ^Z1a and/or ^Z1b in formula (1), ^R1 is the same as ^R1a and/or ^R1b in formula (1), and k is the same as k1 and/or k2 in formula (1)).

(In the formula, Z ^1a , Z ^1b , R ^1a , R ^1b , R ^2a , R ^2b , k1, k2, m1, m2, n1 and n2 are the same as those in the formula (1), m1+n1 and m2+n2 each independently represent an integer of 0 to 4, and at least one of m1 and m2 is an integer of 1 or more.)

(In the formula, ^X3 represents a halogen atom, ^Z2 is the same as ^Z2a and/or ^Z2b in the formula (1), ^R3 is the same as ^R3a and/or ^R3b in the formula (1), ^A1 is the same as ^A1a and/or ^A1b in the formula (1), and p is the same as p1 and/or p2 in the formula (1)).

The present invention also includes a method for exciting the fluorene compound to emit light, and a luminescent composition containing the fluorene compound. The luminescent composition may be a coating agent. The present invention also includes a method for irradiating a coating film formed from the luminescent composition with light and detecting the light emitted from the coating film with a detection device having at least a detector, preferably a detection device having a spectrometer and a detector. Furthermore, the present invention also includes a light-emitting element containing the fluorene compound.

In this specification and claims, the number of carbon atoms may be indicated as _C1 , _C6 , _C10 , etc. For example, an alkyl group having one carbon atom is indicated as a " _C1 alkyl" and an aryl group having 6 to 10 carbon atoms is indicated as a " _C6-10 aryl."

In addition, in this specification and claims, "solid state" means a solidified state in which the fluidity is lost and the substance is not dispersed in a dispersion medium or matrix such as a resin.

The fluorene compound of the present invention has a specific chemical structure and can emit light with high luminescence quantum efficiency (quantum efficiency or quantum yield). In addition, the fluorene compound can exhibit high luminescence quantum efficiency even in a solid state where the luminescence quantum efficiency is likely to decrease. Furthermore, the fluorene compound can emit ultraviolet light or visible light that has a short wavelength and is highly monochromatic (or has a narrow peak width in the emission spectrum) in a room temperature environment.

FIG. 1 shows the measurement results of the excitation spectrum (solid line) and emission spectrum (dashed line) of the BEPF-Ph obtained in Example 1 in a solid state. FIG. 2 shows the measurement results of the excitation spectrum (solid line) and emission spectrum (dashed line) of the BMPF-Ph obtained in Example 2 in a solid state. FIG. 3 shows the measurement results of the excitation spectrum (solid line) and emission spectrum (dashed line) of the BEPF obtained in Reference Example 1 in a solid state. FIG. 4 shows the measurement results of the excitation spectrum (solid line) and emission spectrum (dashed line) of the BMPF obtained in Reference Example 2 in a solid state. FIG. 5 shows the measurement results of the excitation spectrum (solid line) and emission spectrum (dashed line) in the solid state of BEPF-Si obtained in Reference Example 3. FIG. 6 shows the measurement results of the excitation spectrum (solid line) and emission spectrum (dashed line) in the solid state of BMPF-Si obtained in Reference Example 4. FIG. 7 shows the results of measuring the excitation spectrum (solid line) and emission spectrum (dashed line) of the BMPF-tBu obtained in Reference Example 5 in a solid state. FIG. 8 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) of BEPF-Ph obtained in Example 1 in a dichloromethane solution state. FIG. 9 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) of BMPF-Ph obtained in Example 2 in a dichloromethane solution state. FIG. 10 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) of the BEPF obtained in Reference Example 1 in a dichloromethane solution state. FIG. 11 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) of the BMPF obtained in Reference Example 2 in a dichloromethane solution state. FIG. 12 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) of the BEPF-Si obtained in Reference Example 3 in a dichloromethane solution state. FIG. 13 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) of the BMPF-Si obtained in Reference Example 4 in a dichloromethane solution state. FIG. 14 shows the measurement results of the excitation spectrum (solid line) and emission spectrum (dashed line) of BMPF-tBu obtained in Reference Example 5 in a dichloromethane solution state. FIG. 15 shows the measurement results of the excitation spectrum (solid line) and emission spectrum (dashed line) in the solid state of BEPF-Np obtained in Example 3. FIG. 16 shows the measurement results of the excitation spectrum (solid line) and emission spectrum (dashed line) in the solid state of BEPF-BPh obtained in Example 4. FIG. 17 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) of the BEPF-Np obtained in Example 3 in a dichloromethane solution state. FIG. 18 shows the measurement results of the excitation spectrum (solid line) and emission spectrum (dashed line) of BEPF-BPh obtained in Example 4 in a dichloromethane solution state. FIG. 19 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-Ph/PS (mass ratio) = 1/1 obtained in Example 1. FIG. 20 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-Ph/PS (mass ratio) = 1/10 obtained in Example 1. FIG. 21 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-Ph/PC (mass ratio) = 1/1 obtained in Example 1. FIG. 22 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-Ph/PC (mass ratio) = 1/10 obtained in Example 1. FIG. 23 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-Ph/PMMA (mass ratio) = 1/1 obtained in Example 1. FIG. 24 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-Ph/PMMA (mass ratio) = 1/10 obtained in Example 1. FIG. 25 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-Ph/PPSQ (mass ratio) = 1/1 obtained in Example 1. FIG. 26 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-Ph/PPSQ (mass ratio) = 1/10 obtained in Example 1. FIG. 27 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BMPF-Ph/PS (mass ratio) = 1/1 obtained in Example 2. FIG. 28 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BMPF-Ph/PS (mass ratio) = 1/10 obtained in Example 2. FIG. 29 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BMPF-Ph/PC (mass ratio) = 1/1 obtained in Example 2. FIG. 30 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating state of BMPF-Ph/PC (mass ratio) = 1/10 obtained in Example 2. FIG. 31 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BMPF-Ph/PMMA (mass ratio) = 1/1 obtained in Example 2. FIG. 32 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BMPF-Ph/PMMA (mass ratio) = 1/10 obtained in Example 2. FIG. 33 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating state of BMPF-Ph/PPSQ (mass ratio) = 1/1 obtained in Example 2. FIG. 34 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BMPF-Ph/PPSQ (mass ratio) = 1/10 obtained in Example 2. FIG. 35 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-Np/PS (mass ratio) = 1/10 obtained in Example 3. FIG. 36 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-Np/PC (mass ratio) = 1/10 obtained in Example 3. FIG. 37 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-Np/PMMA (mass ratio) = 1/10 obtained in Example 3. FIG. 38 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-Np/PPSQ (mass ratio) = 1/10 obtained in Example 3. FIG. 39 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-BPh/PS (mass ratio) = 1/10 obtained in Example 4. FIG. 40 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-BPh/PC (mass ratio) = 1/10 obtained in Example 4. FIG. 41 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-BPh/PMMA (mass ratio) = 1/10 obtained in Example 4. FIG. 42 shows the measurement results of the excitation spectrum (solid line) and the emission spectrum (dashed line) in the coating film state of BEPF-BPh/PPSQ (mass ratio) = 1/10 obtained in Example 4. FIG. 43 shows the results of single crystal X-ray structure analysis of BEPF-Ph obtained in Example 1. FIG. 44 shows the results of single crystal X-ray structure analysis of BEPF-Np obtained in Example 3. FIG. 45 shows the results of single crystal X-ray structure analysis of BEPF-BPh obtained in Example 4.

[Fluorene Compounds]
The novel fluorene compound of the present invention is represented by the following formula (1).

(In the formula, Z ^1a and Z ^1b each independently represent an arene ring, Z ^2a and Z ^2b each independently represent an arene ring, R ^1a , R ^1b , R ^2a , R ^2b , R ^3a and R ^3b each independently represent a substituent, A ^1a and A ^1b each independently represent a linear or branched alkylene group, k1 and k2 each independently represent an integer of 0 or more, m1 and m2 each independently represent an integer of 0 to 4, n1 and n2 each independently represent an integer of 0 to 4, p1 and p2 each independently represent an integer of 0 or more, m1+n1 and m2+n2 each independently represent an integer of 1 to 4, and at least one of m1 and m2 is an integer of 1 or more).

In the formula (1), examples of the arene ring (aromatic hydrocarbon ring) represented by ^Z1a and ^Z1b include a monocyclic arene ring such as a benzene ring, a polycyclic arene ring, etc. Examples of the polycyclic arene ring include a condensed polycyclic arene ring (condensed polycyclic aromatic hydrocarbon ring) and a ring-assembled arene ring (ring-assembled polycyclic aromatic hydrocarbon ring).

Examples of the fused polycyclic arene ring include fused bicyclic to tetracyclic arene rings such as fused bicyclic arene rings and fused tricyclic arene rings. Examples of the fused bicyclic arene ring include fused bicyclic _C10-16 arene rings such as naphthalene ring and indene ring. Examples of the fused tricyclic arene ring include fused tricyclic _C14-20 arene rings such as anthracene ring and phenanthrene ring.

Examples of ring-assembled arene rings include biarene rings such as biphenyl rings, phenylnaphthalene rings, and binaphthyl rings; and terarene rings such as terphenyl rings.

In this specification and claims, the term "ring assembly arene ring" refers to two or more ring systems (arene ring systems) directly connected by single bonds or double bonds, and the number of bonds directly connecting the rings is one less than the number of ring systems. For example, as described above, phenylnaphthalene rings and binaphthyl rings are included in ring assembly arene rings even if they have a fused polycyclic arene ring skeleton, and are clearly distinguished from "fused polycyclic arene rings" such as naphthalene rings (non-ring assembly arene rings).

Preferred rings Z ^1a and Z ^1b include C _6-14 arene rings, more preferably C _6-12 arene rings such as benzene rings, naphthalene rings, and biphenyl rings, which show high luminescence quantum efficiency even in a solid state susceptible to concentration quenching, and have a narrow half-width of λ _em,max in the emission spectrum, and are more preferably C _6-10 arene rings such as benzene rings and naphthalene rings, and are particularly preferably benzene rings. In addition, when rings Z ^1a and Z ^1b are benzene rings, they are also preferred in that they have excellent ultraviolet luminescence properties, and ultraviolet light having a wavelength of, for example, about 350 to 400 nm can be easily obtained. On the other hand, from the viewpoint of precisely adjusting the wavelength of the light obtained to the long wavelength side (visible light side), rings Z ^1a and Z ^1b are preferably polycyclic arene rings. Among the polycyclic arene rings, a condensed polycyclic arene ring such as a naphthalene ring is preferred in that it can further improve the luminescence quantum efficiency in a solution state such as a dichloromethane solution, and a ring assembly arene ring such as a biphenyl ring is preferred in that it can further improve the luminescence quantum efficiency in a coating state mixed with a binder component described later, etc. Therefore, by selecting the types of rings Z ^1a and Z ^1b , a highly efficient luminescent material can be prepared depending on the purpose (application).

The types of rings Z ^1a and Z ^1b may be different from each other, but are usually the same. When m1 and/or m2 are 2 or more, the types of the two or more rings Z ^1a and/or Z ^1b may be the same or different from each other.

In addition, the rings Z ^1a and/or Z ^1b may be substituted at any of the 1- to 4-positions and the 5- to 8-positions of the fluorene skeleton. When m1 and m2 are 1, the preferred substitution positions (or bonding positions) are those which are symmetrical on the paper in the above formula (1), such as the 1,8-positions, the 2,7-positions, the 3,6-positions, and the 4,5-positions, and the 2,7-positions are particularly preferred.

When rings Z ^1a and Z ^1b are naphthalene rings, the bonding position with the fluorene skeleton in rings Z ^1a and Z ^1b is, for example, the 1- or 2-position of the naphthalene ring, preferably the 2-position; when rings Z 1a and Z ^1b are biphenyl rings, the bonding position with the fluorene skeleton in rings Z ^1a and Z 1b is, for example, the 2-, 3- or 4-position of the biphenyl ring, preferably the 4-position.

Examples of the substituents represented by R ^1a and R ^1b include a hydrocarbon group (or group [-R ^A ]), a halogen atom, a hydroxyl group, a group [-OR ^A ] (wherein R ^A represents the above-mentioned hydrocarbon group), a hydroxy(poly)alkoxy group, a thiol group (mercapto group), a group [-SR ^A ] (wherein R ^A represents the above-mentioned hydrocarbon group), an acyl group, a carboxyl group, an alkoxycarbonyl group, an amino group, a substituted amino group, a cyano group, a nitro group, etc. In this specification and the claims, the term "(poly)alkoxy group" is used to include both an alkoxy group and a polyalkoxy group.

Examples of the hydrocarbon group (or group [-R ^A ]) include an alkyl group, a cycloalkyl group, an aryl group, and a group in which two or more of these hydrocarbon groups are combined (or bonded).

Examples of the alkyl group include linear or branched C1-20 alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-hexyl, n-octyl, ₂ -ethylhexyl, n-decyl, and n-dodecyl groups. Linear or branched _C1-12 alkyl groups are preferred, and linear or branched _C1-6 alkyl groups are more preferred.

Examples of the cycloalkyl group include a C _5-10 cycloalkyl group such as a cyclopentyl group and a cyclohexyl group, and a C _5-8 cycloalkyl group is preferred.

Examples of the aryl group include C _6-14 aryl groups such as phenyl, 1-naphthyl, 2-naphthyl and other naphthyl groups, biphenylyl, anthryl, phenanthryl and other groups. Preferred are C _6-10 aryl groups.

Examples of groups in which two or more types of hydrocarbon groups are combined (bonded) include alkylaryl groups and aralkyl groups. Examples of alkylaryl groups include mono- or di-C _1-6 alkyl C _6-10 aryl groups such as methylphenyl group (tolyl group) and dimethylphenyl group (xylyl group). Examples of aralkyl groups include C _6-10 aryl C _1-6 alkyl groups such as phenylmethyl group (benzyl group) and 2-phenylethyl group (phenethyl group).

Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

Examples of the group [-OR ^A ] include groups corresponding to the hydrocarbon group represented by R ^A , such as an alkoxy group, a cycloalkyloxy group, an aryloxy group, and an aralkyloxy group.

Examples of the alkoxy group include alkoxy groups corresponding to the alkyl groups exemplified in the section on R ^A above, such as linear or branched C _1-10 alkoxy groups such as a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, an isobutoxy group, an s-butoxy group, and a t-butoxy group.

Examples of the cycloalkyloxy group include cycloalkyloxy groups corresponding to the cycloalkyl groups exemplified in the section on R ^A above, for example, C _5-10 cycloalkyloxy groups such as cyclohexyloxy group.

Examples of the aryloxy group include aryloxy groups corresponding to the aryl groups exemplified in the above section on R ^A , for example, C _6-10 aryloxy groups such as a phenoxy group.

Examples of the aralkyloxy group include aralkyloxy groups corresponding to the aralkyl groups exemplified in the section on R ^A above, for example, C _6-10 aryl-C _1-4 alkyloxy groups such as benzyloxy group.

Examples of the hydroxy(poly)alkoxy group include hydroxy(poly)C _2-6 alkoxy groups such as a 2-hydroxyethoxy group, a 2-hydroxypropoxy group, and a 2-(2-hydroxyethoxy)ethoxy group.

Examples of the group [-SR ^A ] include groups corresponding to the hydrocarbon group represented by R ^A , such as an alkylthio group, a cycloalkylthio group, an arylthio group, and an aralkylthio group.

Examples of the alkylthio group include alkylthio groups corresponding to the alkyl groups exemplified in the section on R ^A above, such as C _1-10 alkylthio groups such as methylthio, ethylthio, propylthio, n-butylthio and t-butylthio.

Examples of the cycloalkylthio group include cycloalkylthio groups corresponding to the cycloalkyl groups exemplified in the section on R ^A above, for example, C _5-10 cycloalkylthio groups such as cyclohexylthio groups.

Examples of the arylthio group include arylthio groups corresponding to the aryl groups exemplified in the above section on R ^A , for example, C _6-10 arylthio groups such as phenylthio groups (or thiophenoxy groups).

Examples of the aralkylthio group include aralkylthio groups corresponding to the aralkyl groups exemplified in the section on R ^A above, for example, C _6-10 aryl-C _1-4 alkylthio groups such as a benzylthio group.

Examples of the acyl group include C _1-6 acyl groups such as an acetyl group.

Examples of the alkoxycarbonyl group include C _1-6 alkoxy-carbonyl groups such as methoxycarbonyl groups.

Examples of the substituted amino group include mono- or di-alkylamino groups, mono- or di-acylamino groups, etc. Examples of the mono- or di-alkylamino group include mono- or di-C _1-4 alkylamino groups such as dimethylamino group, etc. Examples of the mono- or di-acylamino group include mono- or di-(C _1-6 acyl)amino groups such as diacetylamino group, etc.

These groups R ^1a and R ^1b may be used alone or in combination of two or more. When the groups R ^1a and R ^1b are cyclic hydrocarbon groups such as aryl groups, they may form a ring assembly such as a ring assembly arene ring together with the rings Z ^1a and Z ^1b .

When the number of substitutions k1 or k2 is 1 or more, preferred groups R ^1a and R ^1b include hydrocarbon groups such as alkyl groups and aryl groups, hydroxyl groups, hydroxy(poly)alkoxy groups, and carboxyl groups. The alkyl group is more preferably a linear or branched C _1-6 alkyl group such as a methyl group, the aryl group is more preferably a C _6-10 aryl group such as a phenyl group, and the hydroxy(poly)alkoxy group is more preferably a hydroxy(mono- to deca)C _2-4 alkoxy group such as a 2-hydroxyethoxy group. Of these groups R ^1a and R ^1b , C _1-4 alkyl groups such as a methyl group, hydroxyl groups, and carboxyl groups are preferred.

The substitution numbers k1 and k2 of the groups R ^1a and R ^1b may be selected depending on the types of the rings Z ^1a and Z ^1b , and can be selected, for example, from integers of about 0 to 7. Preferred ranges are, in the following stepwise order, integers of 0 to 6, integers of 0 to 5, integers of 0 to 4, integers of 0 to 3, and integers of 0 to 2, and more preferably 0 or 1, and particularly preferably 0.

The two substitution numbers k1 and k2 may be different from each other, but are usually the same. When the substitution number k1 or k2 is 2 or more, the types of the two or more groups R ^1a or R ^1b substituted on the same ring Z ^1a and Z ^1b may be the same or different from each other. In addition, the types of the groups R ^1a and R ^1b substituted on different rings Z ^1a and Z ^1b may be different from each other, but are usually the same. The substitution positions of the groups R ^1a and R ^1b are not particularly limited, and may be selected according to the types of the rings Z ^1a and Z ^1b .

The numbers of substitutions m1 and m2 in the group [-Z ^1a -(R ^1a ) _k1 ] and the group [-Z ^1b -(R ^1b ) _k2 ] (hereinafter also referred to as Z ^1- containing groups) are, for example, integers of about 1 to 3, preferably 1 or 2, and more preferably 1. m1 and m2 may be different from each other, but are usually often the same. At least one of m1 and m2 is an integer of 1 or more, preferably both are integers of 1 or more, and more preferably both are 1.

In addition, when m1 or m2 is 2 or more, the types of two or more Z ^1- containing groups substituted on the same benzene ring among the two benzene rings forming the fluorene skeleton may be the same or different. In addition, the types of Z ¹ -containing groups substituted on different benzene rings among the two benzene rings forming the fluorene skeleton, that is, the group [-Z ^1a -(R ^1a ) _k1 ] and the group [-Z ^1b -(R ^1b ) _k2 ] may be the same or different, and are usually the same.

R ^2a and R ^2b may be any substituent other than the ^Z1- containing group, and representative examples include a hydrocarbon group such as an alkyl group (excluding aryl groups), a halogen atom such as a fluorine atom, a chlorine atom, or a bromine atom, and a cyano group. Examples of the alkyl group include a linear or branched C _1-6 alkyl group such as a methyl group, an ethyl group, or a t-butyl group. When the number of substitutions n1 and/or n2 is 1 or more, preferred R ^2a and R ^2b are a linear or branched C _1-4 alkyl group such as a methyl group.

The substitution numbers n1 and n2 of R ^2a and R ^2b are, for example, integers of about 0 to 3, preferably integers of 0 to 2, more preferably 0 or 1, and particularly 0. n1 and n2 may be different from each other, but are usually the same. When n1 or n2 is 2 or more, the types of R ^2a or R ^2b substituted on the same benzene ring among the two benzene rings forming the fluorene skeleton may be the same or different. In addition, the types of R 2a and R ^{2b substituted on different benzene rings among the two benzene rings forming the fluorene skeleton may be the same or different from each other, and are usually the same. In addition, the substitution positions of R 2a and R 2b are not} particularly limited, and may be substituted at ^positions other than the substitution position of the Z ¹ -containing group.

m1+n1 and m2+n2 are, for example, integers of about 1 to 3, preferably 1 or 2, and more preferably 1. m1+n1 and m2+n2 may be different from each other, but are usually the same.

Examples of the linear or branched alkylene groups represented by A ^1a and A ^1b include linear or branched C _1-6 alkylene groups such as methylene, ethylene, methylmethylene (ethylidene), propylene, 1,3-propane-diyl, 2,2-propane-diyl, and 1,4-butane-diyl. The types of the two alkylene groups A ^1a and A ^1b may be different from each other, but are usually the same in many cases. Preferred alkylene groups A ^1a and A ^1b include linear or branched C _1-4 alkylene groups, more preferably linear or branched C _1-3 alkylene groups, and among these, C _1-2 alkylene groups such as methylene and ethylene groups are preferred, and in particular, ethylene groups are preferred from the viewpoint of ease of improving the luminescence quantum efficiency.

Examples of the arene ring represented by Z ^2a and Z ^2b include the same arene rings as those exemplified in the above sections for Z ^1a and Z ^1b .

Preferred rings Z ^2a and Z ^2b include C _6-14 arene rings, more preferably C _6-12 arene rings such as benzene ring, naphthalene ring and biphenyl ring, further preferably C _6-10 arene rings such as benzene ring and naphthalene ring, particularly preferably a benzene ring.

The rings ^Z2a and ^Z2b may be different from each other, but are usually the same. The bonding positions of the rings ^Z2a and ^Z2b to the alkylene groups ^A1a and ^A1b are not particularly limited.

Examples of the substituents represented by R ^3a and R ^3b include the same groups as the substituents exemplified in the section on R ^1a and R ^1b .

When the number of substitutions p1 or p2 is 1 or more, preferred groups R ^3a and R ^3b include an alkyl group, an aryl group, a hydroxyl group, a hydroxy(poly)alkoxy group, and a carboxyl group. The alkyl group is more preferably a linear or branched C _1-6 alkyl group such as a methyl group, the aryl group is more preferably a C _6-10 aryl group such as a phenyl group, and the hydroxy(poly)alkoxy group is more preferably a hydroxy(mono- to deca)C _2-4 alkoxy group such as a 2-hydroxyethoxy group. Of these groups R ^3a and R ^3b , a C _1-4 alkyl group such as a methyl group, a hydroxyl group, and a carboxyl group are preferred.

The substitution numbers p1 and p2 of the groups ^R3a and ^R3b may be selected depending on the types of the rings ^Z2a and ^Z2b , and can be selected, for example, from integers of about 0 to 7. Preferred ranges are, in the following stepwise order, integers of 0 to 6, integers of 0 to 5, integers of 0 to 4, integers of 0 to 3, and integers of 0 to 2, and more preferably 0 or 1, and particularly preferably 0.

The two substitution numbers p1 and p2 may be different from each other, but are usually the same. When the substitution number p1 or p2 is 2 or more, the types of the two or more groups R ^3a or R ^3b substituted on the same rings Z ^2a and Z ^2b may be the same or different from each other. In addition, the types of the groups R ^3a and R ^3b substituted on different rings Z ^2a and Z ^2b may be different from each other, but are usually the same.

The substitution positions of the groups R ^3a and R ^3b are not particularly limited and may be selected depending on the types of the rings Z ^2a and Z ^2b , and when Z ^2a and Z ^2b are benzene rings, they are, for example, 3-position, 4-position, 3,4-position, 3,5-position, 3,4,5-position, preferably 4-position, 3,4-position, and more preferably 4-position, relative to the phenyl groups bonded to the groups A ^1a and A ^1b . For example, when Z ^2a and Z ^2b are naphthalene rings, the substitution positions of the groups R ^3a and R ^3b are often, for example, 1,5-position, 2,6-position, preferably 2,6-position, relative to the 1-naphthyl group or 2-naphthyl group bonded to the groups A ^1a and A ^1b .

Typical examples of fluorene compounds represented by the formula (1) include 9,9-bis(arylalkyl)-diarylfluorenes, such as 9,9-bis(arylalkyl)-2,7-diphenylfluorene, 9,9-bis(arylalkyl)-2,7-di(condensed polycyclic aryl)fluorene, and 9,9-bis(arylalkyl)-2,7-di(ring assembly polycyclic aryl)fluorene.

Examples of the 9,9-bis(arylalkyl)-2,7-diphenylfluorene include 9,9-bis(C _6-10 aryl C _1-2 alkyl)-2,7-diphenylfluorene such as 9,9-bis(phenylmethyl)-2,7-diphenylfluorene and 9,9-bis(2-phenylethyl)-2,7-diphenylfluorene.

Examples of the 9,9-bis(arylalkyl)-2,7-di(condensed polycyclic aryl)fluorene include 9,9-bis(C 6-10 aryl C 1-2 alkyl)-2,7-di(condensed polycyclic C _10-14 aryl)fluorenes such as 9,9-bis(phenylmethyl)-2,7-di(2-naphthyl)fluorene, 9,9-bis(2-phenylethyl)-2,7-di(2-naphthyl)fluorene, and 9,9-bis( _2- phenylethyl)-2,7-di(1 _- naphthyl)fluorene.

Examples of the 9,9-bis(arylalkyl)-2,7-di ring assembly polycyclic arylfluorene include 9,9-bis(phenylmethyl)-2,7-di(4-biphenylyl)fluorene [or 9,9-bis(phenylmethyl)-2,7-di(4-phenylphenyl)fluorene], 9,9-bis(phenylethyl)-2,7-di(4-biphenylyl)fluorene, 9,9-bis(phenylethyl)-2,7-di(3-biphenylyl)fluorene, 9,9-bis(phenylethyl)-2,7-di(3-biphenylyl)fluorene, and 9,9-bis(phenylethyl)-2,7-di(2-biphenylyl)fluorene, such as 9,9-bis(C _6-10 aryl C _1-2 alkyl)-2,7-di(ring assembly polycyclic C _12-18 aryl)fluorene.

Among these fluorene compounds represented by formula (1), 9,9-bis(arylalkyl)-2,7-diphenylfluorene and 9,9-bis(arylalkyl)-2,7-di(condensed polycyclic aryl)fluorene are preferred because they exhibit high luminescence quantum efficiency even in a solid state susceptible to the effects of concentration quenching and have a narrow half-width of λ _em,max in the emission spectrum. Among these, 9,9-bis(arylalkyl)-2,7-diphenylfluorene is more preferred because of excellent ultraviolet luminescence properties, and 9,9-bis(C _6-10 aryl C _1-2 alkyl)-2,7-diphenylfluorene such as 9,9-bis(2-phenylethyl)-2,7-diphenylfluorene and 9,9-bis(2-phenylethyl)-2,7-diphenylfluorene are even more preferred.

On the other hand, from the viewpoint of precisely adjusting the wavelength of the obtained light to the long wavelength side (visible light side), 9,9-bis(arylalkyl)-2,7-di(polycyclic aryl)fluorene such as 9,9-bis(arylalkyl)-2,7-di(fused polycyclic aryl)fluorene and 9,9-bis(arylalkyl)-2,7-di(ring assembly polycyclic aryl)fluorene are preferred, and from the viewpoint of further improving the luminescence quantum efficiency in a solution state, 9,9-bis(arylalkyl)-2,7-di(fused polycyclic aryl)fluorene is more preferred, and among them, 9,9-bis( _C6-10 aryl C ... 9,9-bis(arylalkyl)-2,7-diring assembly _polycyclic arylfluorene is more preferred in terms of further improving the luminescence quantum efficiency in a coated film state, and 9,9-bis( _{C6-10 arylC1-2} alkyl)-2,7-di(biphenylyl)fluorene is particularly preferred.

(Method for producing fluorene compound)
The method for producing the fluorene compound represented by the formula (1) is not particularly limited, and the fluorene compound may be produced by a conventional method, for example, by subjecting a compound represented by the following formula (2) and a compound represented by the following formula (3) to a coupling reaction (or cross-coupling reaction) according to the following reaction formula (hereinafter, also referred to as the first method).

(In the formula, X ^1a and X ^1b each independently represent a reactive group capable of forming a carbon-carbon bond by a coupling reaction; X ² represents a reactive group capable of forming a carbon-carbon bond together with the reactive group X ^1a and/or X ^1b by a coupling reaction; Z ¹ is the same as Z ^1a and/or Z ^1b in the formula (1), R ¹ is the same as R ^1a and/or R ^1b in the formula (1), and k is the same as k1 and/or k2 in the formula (1), including preferred embodiments thereof; Z ^1a , Z ^1b , Z ^2a , Z ^2b , R ^1a , R ^1b , R ^2a , R ^2b , R ^3a , R ^3b , A ^1a , A ^1b , k1, k2, m1, m2, n1, n2, p1, p2, m1+n1 and m2+n2 are the same as those in formula (1) above, including preferred embodiments.

The coupling reaction is not particularly limited, and examples thereof include conventional coupling reactions, such as coupling reactions using a palladium catalyst (or a palladium(0) catalyst) such as the Suzuki-Miyaura coupling reaction, the Migita-Kosugi-Stille coupling reaction, the Negishi coupling reaction, and the Hiyama coupling reaction, and coupling reactions using a nickel catalyst (or a nickel(0) catalyst) such as the Kumada-Tamao-Corriu coupling reaction. Of these coupling reactions, the Suzuki-Miyaura coupling reaction is often used.

The reactive groups X ^1a and X ^1b , as well as X ² , can be appropriately selected depending on the type of the coupling reaction. When synthesis is performed by the Suzuki-Miyaura coupling reaction, one of the reactive groups, for example, the groups X ^1a and X ^1b , can be a halogen atom or a fluorinated alkane sulfonyloxy group. Examples of the halogen atom can be an iodine atom, a bromine atom, a chlorine atom, and the like. Examples of the fluorinated alkane sulfonyloxy group can be a fluorinated C _1-4 alkane sulfonyloxy group such as a trifluoromethanesulfonyloxy group (or a group [-OTf]).

These one-reactive groups may be used alone or in combination of two or more. Among these one-reactive groups, a halogen atom is preferred, an iodine atom and a bromine atom are more preferred, and a bromine atom is usually used more frequently.

In the Suzuki-Miyaura coupling reaction, examples of the other reactive group capable of coupling with the one reactive group, for example, group ^X2 , include, for example, a boronic acid group (dihydroxyboryl group or group [-B(OH) ₂ ]), a boronic acid ester group, etc. Examples of the boronic acid ester group include dialkoxyboryl groups such as a dimethoxyboryl group, a diisopropoxyboryl group, and a dibutoxyboryl group; and cyclic boronic acid ester groups such as a pinacolatoboryl group (or group [-Bpin]), a 1,3,2-dioxaborinane-2-yl group, and a 5,5-dimethyl-1,3,2-dioxaborinane-2-yl group.

These other reactive groups may be used alone or in combination of two or more. Of the other reactive groups, the group [-B(OH) ₂ ] is usually used frequently.

The groups ^X1a and ^X1b and the group ^X2 may be any reactive groups as long as they are a pair of reactive groups capable of undergoing a coupling reaction with each other. The groups ^X1a and ^X1b may be the other reactive group such as a boronic acid group, and the group ^X2 may be one of the reactive groups such as a halogen atom. However, usually, the groups ^X1a and ^X1b are the one reactive group such as a halogen atom, and the group ^X2 is often the other reactive group such as a boronic acid group.

Examples of the compound represented by the formula (2) include 9,9-bis(C _6-10 aryl C _1-2 alkyl)-dihalofluorenes such as 9,9-bis(phenylmethyl)-2,7-dibromofluorene and 9,9-bis(2-phenylethyl)-2,7-dibromofluorene.

The compound represented by formula (2) may be prepared, for example, by the method described in Patent Document 1 or JP-A-2009-96782, that is, by reacting a 9H-fluorene such as 2,7-dibromofluorene, which is unsubstituted at the 9-position, with a base catalyst such as potassium t-butoxide to generate a fluorene anion having an anion at the 9-position of the fluorene skeleton, and then reacting this fluorene anion with a haloalkylarenes such as 4-(2-bromoethyl)benzene.

Examples of the compound represented by formula (3) include phenylboronic acid; naphthaleneboronic acids such as 2-naphthaleneboronic acid and 1-naphthaleneboronic acid; and biphenylboronic acids such as 4-biphenylboronic acid. The compound represented by formula (3) can be a commercially available product.

The ratio of the compound represented by formula (2) to the compound represented by formula (3) may be, for example, the former/latter (molar ratio) = about 1/2 to 1/10, and the preferred ranges are 1/2.2 to 1/8, 1/2.5 to 1/5, and 1/2.7 to 1/3.3 in the following stepwise order.

When synthesizing by the Suzuki-Miyaura coupling reaction, the reaction is usually carried out in the presence of a palladium catalyst. Examples of palladium catalysts include conventional coupling catalysts such as palladium (0) catalysts and palladium (II) catalysts.

Examples of the palladium(0) catalyst include palladium(0)-phosphine complexes such as tetrakis(triphenylphosphine)palladium(0) [or Pd(PPh ₃ ) ₄ ] and bis(tri-t-butylphosphine)palladium(0) [or Pd(P(t-Bu) ₃ ) ₂ ].

Examples of the palladium (II) catalyst include palladium (II)-phosphine complexes such as [1,2-bis(diphenylphosphino)ethane]palladium (II) dichloride [or PdCl ₂ (dppe)], [1,3-bis(diphenylphosphino)propane]palladium (II) dichloride [or PdCl ₂ (dppp)], [1,1'-bis(diphenylphosphino)ferrocene]palladium (II) dichloride [or PdCl ₂ (dppf)], bis(triphenylphosphine)palladium (II) dichloride [or PdCl ₂ (PPh ₃ ) ₂ ], and bis(tri-o-tolylphosphine)palladium (II) dichloride [or PdCl ₂ (P(o-tolyl) ₃ ) ₂ ]. When a palladium (II) catalyst is used, the reaction is initiated by reduction to a zero-valent complex by a reducing compound in the reaction system, such as a phosphine, an amine, or an organometallic reagent.

The palladium catalyst may be prepared in situ by adding a catalyst precursor such as tris(dibenzylideneacetone)dipalladium(0) chloroform complex [or Pd ₂ (dba) _{3.CHCl 3} ] and a ligand such as a phosphine or a carbene.

These catalysts can be used alone or in combination of two or more. Among these catalysts, palladium(0)-phosphine complexes such as Pd(PPh ₃ ) ₄ are usually used. The ratio of the catalyst may be, for example, about 0.01 to 0.1 moles, and preferably 0.02 to 0.04 moles, calculated as metal, per mole of the compound represented by the formula (2).

The Suzuki-Miyaura coupling reaction may be carried out in the presence of a base. Examples of bases include metal carbonates or hydrogen carbonates, metal hydroxides, metal fluorides, metal phosphates, metal organic acid salts, and metal alkoxides.

Examples of metal carbonates or bicarbonates include alkali metal carbonates or bicarbonates such as sodium carbonate, potassium carbonate, cesium carbonate, and sodium bicarbonate, as well as thallium (I) carbonate.

Examples of metal hydroxides include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and cesium hydroxide, alkaline earth metal hydroxides such as barium hydroxide, and thallium(I) hydroxide.

Examples of metal fluorides include alkali metal fluorides such as potassium fluoride and cesium fluoride.

Examples of metal phosphates include alkali metal phosphates such as tripotassium phosphate.

Examples of metal organic acid salts include alkali metal acetates such as potassium acetate.

Examples of metal alkoxides include alkali metal alkoxides such as sodium methoxide, sodium ethoxide, and potassium t-butoxide.

These bases can be used alone or in combination of two or more. Usually, metal carbonates such as potassium carbonate are often used. The ratio of the base to 1 mole of the compound represented by formula (2) may be, for example, about 0.01 to 100 moles, preferably 0.1 to 50 moles, and more preferably 1 to 25 moles.

The coupling reaction may be carried out in the presence or absence of a phase transfer catalyst. Examples of phase transfer catalysts include tetraalkylammonium halides such as tetrabutylammonium bromide (TBAB) and trioctylmethylammonium chloride. These phase transfer catalysts may be used alone or in combination of two or more. Of these phase transfer catalysts, TBAB is usually used.

The coupling reaction may be carried out in the absence or presence of a solvent inert to the reaction. Examples of the solvent include water; alcohols such as methanol and ethanol; ethers such as cyclic ethers and chain ethers; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; nitriles such as acetonitrile and benzonitrile; amides such as N,N-dimethylformamide, dimethylacetamide, and N-methyl-2-pyrrolidone; sulfoxides such as dimethyl sulfoxide; and hydrocarbons such as aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons.

Examples of cyclic ethers include dioxane and tetrahydrofuran. Examples of chain ethers include diethyl ether and diisopropyl ether.

Examples of aliphatic hydrocarbons include hexane and dodecane. Examples of alicyclic hydrocarbons include cyclohexane. Examples of aromatic hydrocarbons include toluene and xylene.

These solvents can be used alone or in combination of two or more. Among these solvents, a mixture of water and aromatic hydrocarbons such as toluene is usually used.

The coupling reaction may be carried out under an inert gas atmosphere, for example, nitrogen or a rare gas such as helium or argon. The reaction temperature is, for example, 50 to 200°C, preferably 90 to 150°C. The reaction time is not particularly limited and may be, for example, about 1 to 24 hours, specifically 1 to 10 hours.

After the reaction is completed, the reaction mixture may be separated and purified, if necessary, by conventional separation and purification methods, such as washing, extraction, dehydration, concentration, decantation, reprecipitation, chromatography, or a combination of these.

The fluorene compound represented by formula (1) may also be produced by the second method shown in the following reaction scheme.

(In the formula, ^X3 represents a halogen atom; ^Z2 is the same as ^Z2a and/or ^Z2b in said formula (1), ^R3 is the same as ^R3a and/or ^R3b in said formula (1), and p is the same as p1 and/or p2 in said formula (1), including preferred embodiments; ^Z1a , ^Z1b , ^Z2a , Z2b, ^R1a , ^R1b , ^R2a , ^R2b , ^R3a , ^R3b , ^{A1a, A1b , k1} , k2, m1, m2, n1, n2, p1, p2, m1+n1 and m2+n2 are the same as those in said formula (1), including preferred embodiments.)

In the second method, a compound represented by the formula (4) (or a 9H-fluorene having a ^Z1 -containing group in advance and unsubstituted at the 9-position) is reacted with a compound represented by the formula (5) corresponding to the groups [ ^-A1a - ^Z2a- ( ^R3a ) _p1 ] and [ ^-A1b - ^Z2b- ( ^R3b ) _p2 ] (hereinafter, these are also referred to as ^Z2- containing groups); that is, the order of introduction of the ^Z1- containing group and the ^Z2- containing group is different from that in the first method.

Examples of the halogen atom represented by ^X3 include a chlorine atom, a bromine atom, and an iodine atom.

Examples of the compound represented by formula (4) include 9H-fluorenes having a ^Z1 -containing group and unsubstituted at the 9-position, such as 2,7-diphenylfluorene, etc. The compound represented by formula (4) may be a commercially available product, or may be prepared by a method in which a compound unsubstituted at the 9-position of the fluorene skeleton is used in place of the compound represented by formula (2) in the first method.

The second method corresponds to using a compound represented by formula (4) as a 9H-fluorene having no substitution at the 9-position in the preparation method of the compound represented by formula (2), and can be prepared in accordance with the methods described in Patent Document 1 and JP-A-2009-96782.

(Characteristics of fluorene compounds)
Since the fluorene compound of the present invention has a specific molecular structure, when excited by external energy such as light energy or electrical energy, it can emit short wavelength light such as ultraviolet light or visible light with extremely high luminescence quantum efficiency, for example, ultraviolet light with a wavelength of about 350 to 400 nm, visible light with a wavelength of about 400 to 450 nm, etc. In particular, the luminescence quantum efficiency in the solid state, which was previously low, can be significantly improved.

The present invention also includes a method of exciting the fluorene compound represented by formula (1) with the external energy or the like to emit light, since it can emit light efficiently with a high luminescence quantum efficiency. The light generated by this emission may be ultraviolet light and/or visible light emitted by the fluorene compound itself emitting light, for example, light having an emission peak or half-width in the emission spectrum of the fluorene compound in each state (solid state, solution state, or coating state) described later, or may be light generated from a light-emitting material to which energy has been imparted by using the fluorene compound as a sensitizer, as described later.

Therefore, the luminescence quantum efficiency of the fluorene compound represented by formula (1) may be, for example, about 25% or more, specifically about 30% or more, in a solid state at a temperature of 25°C, with preferred ranges being 40% or more, 50% or more, 60% or more, and more preferably 65% or more, in the following stepwise ranges. The luminescence quantum efficiency may be, for example, about 20 to 100% in a solid state at a temperature of 25°C, with preferred ranges being 25 to 90%, 35 to 80%, 45 to 75%, 55 to 70%, and more preferably 60 to 70%.

In addition, the fluorene compound represented by the formula (1) can emit light with relatively high monochromaticity and short wavelength. Therefore, the fluorene compound represented by the formula (1) may have at least one emission peak having a maximum wavelength λ _em,max in the range of, for example, about 300 to 450 nm in the emission (fluorescence or phosphorescence) spectrum in a solid state at a temperature of 25° C., and preferably has at least one emission peak (or absorption band) having a maximum wavelength λ _em,max in the range of 330 to 420 nm, 340 to 410 nm, 350 to 400 nm, 355 to 395 nm, 360 to 390 nm, more preferably 365 to 385 nm, particularly 370 to 380 nm in the following stepwise manner. When rings Z ^1a and Z ^1b are polycyclic arene rings, they may have at least one emission peak (or absorption band) having a maximum wavelength λ _em,max in the range of, for example, about 390 to 420 nm, preferably 400 to 410 nm.

In the emission spectrum in the solid state, the half width of the emission peak (or absorption band) having the maximum wavelength λ _em,max may be, for example, 100 nm or less, or about 1 to 80 nm, and preferred ranges are as follows, in the following stepwise order: 10 to 70 nm, 15 to 60 nm, 18 to 50 nm, 20 to 45 nm, more preferably 22 to 40 nm, and particularly preferably 25 to 35 nm.

The fluorene compound represented by the formula (1) may have at least one emission or absorption peak having a maximum wavelength λ _ex,max in the range of, for example, about 250 to 450 nm, specifically about 300 to 400 nm, in its excitation spectrum (or absorption spectrum) in a solid state at a temperature of 25° C., and preferably has at least one emission or absorption peak having a maximum wavelength λ _ex ,max in the following stepwise ranges: 320 to 390 nm, 330 to 380 nm, 340 to 370 nm, 345 to 365 nm, and 350 to 360 nm.

The solid state may be, for example, single crystal, polycrystal, or amorphous, and is usually polycrystal.

The fluorene compound represented by formula (1) can emit light with high quantum efficiency even in a solution state. Therefore, the luminescence quantum efficiency of the fluorene compound represented by formula (1) may be, for example, about 30% or more in a dichloromethane solution state at a temperature of 25°C, and the preferred ranges are 40% or more, 50% or more, 60% or more, 65% or more, 70% or more, and more preferably 75% or more in the following stepwise manner. The luminescence quantum efficiency may be, for example, about 20 to 100% in a dichloromethane solution state at a temperature of 25°C, and the preferred ranges are 25 to 95%, 35 to 90%, 45 to 85%, 55 to 80%, and more preferably 65 to 75% in the following stepwise manner.

The fluorene compound represented by the formula (1) may have at least one emission peak having a maximum wavelength λ _em,max in the range of about 300 to 450 nm in its emission (fluorescence or phosphorescence) spectrum in a dichloromethane solution at a temperature of 25° C., and preferably has at least one emission peak having a maximum wavelength λ _em ,max in the ranges of 320 to 420 nm, 340 to 400 nm, 350 to 390 nm, 355 to 385 nm, and more preferably 360 to 380 nm in the following stepwise manner. When rings Z ^1a and Z ^1b are polycyclic arene rings, the fluorene compound may have at least one emission peak (or absorption band) having a maximum wavelength λ _em,max in the range of about 370 to 410 nm, preferably 380 to 400 nm.

In the emission spectrum in a dichloromethane solution state, the half-width of the emission peak (or absorption band) having the maximum wavelength λ _em,max can be selected, for example, from the range of 100 nm or less, or about 1 to 80 nm, and preferred ranges are as follows, in the following stepwise order: 10 to 70 nm, 20 to 60 nm, 25 to 55 nm, 30 to 50 nm, and more preferably 35 to 45 nm.

The fluorene compound represented by the formula (1) may have at least one emission or absorption peak having a maximum wavelength λ _ex,max in the range of, for example, about 270 to 400 nm in its excitation spectrum (or absorption spectrum) in a dichloromethane solution at a temperature of 25° C., and preferably has at least one emission or absorption peak having a maximum wavelength λ _ex,max in the following stepwise ranges: 280 to 390 nm, 290 to 380 nm, 300 to 375 nm, 310 to 360 nm, 320 to 350 nm, 325 to 345 nm, and 330 to 340 nm.

In the measurement of the luminescence quantum efficiency, emission spectrum, and excitation spectrum in the dichloromethane solution state, the concentration of the fluorene compound is not particularly limited as long as it is sufficiently diluted to such an extent that the effects of concentration quenching and the like are not significantly observed, and may be, for example, about 1×10 ⁻³ to 5×10 ⁻³ g/L, or about 1×10 ⁻⁶ to 10×10 ⁻⁶ mol/L.

In this specification and claims, the emission spectrum, excitation spectrum, and luminescence quantum efficiency can be measured by the methods described in the Examples below.

In addition, since the fluorene compound represented by the formula (1) exhibits high luminescence quantum efficiency, it can also act as a sensitizer capable of sensitizing a photosensitive substance. The photosensitive substance (or responsive substance) is not particularly limited as long as it is a substance that is responsive to light, and examples thereof include photopolymerization initiators and luminescent materials (or luminescent compounds), and typically, luminescent materials are often used.

The luminescent material (or luminescent compound) may be a fluorescent material or a phosphorescent material. The luminescent material is not particularly limited as long as it can provide energy from an excited sensitizer (exciton or excited species), that is, as long as it has an excitation energy (band gap) lower than the energy transferable from the exciton, and any conventional luminescent material (or visible light emitting material) can be used.

Perhaps because the fluorene compound represented by the formula (1) can impart a relatively high amount of energy, the light-emitting material can be easily or effectively sensitized, and can emit light brighter with high luminescence quantum efficiency (high luminescence intensity or brightness). This effectively improves the quality (or efficiency) of light-emitting elements (or photoelectric conversion elements) such as light-emitting diodes.

(Light-emitting composition)
The luminescent composition (or ultraviolet light emitting composition) of the present invention contains at least the fluorene compound represented by the formula (1) as a luminescent material and/or a sensitizer. When the fluorene compound represented by the formula (1) is contained as a sensitizer, other luminescent materials are usually contained. The fluorene compound represented by the formula (1) can be used alone or in combination of two or more kinds. Such a luminescent composition can be used in various forms or applications, for example, a coating agent such as a paint or ink composition.

The luminescent composition may or may not further contain a binder component, as necessary, in addition to the fluorene compound represented by formula (1). As the binder component, for example, a conventional resin (or polymer compound) can be used, and it can be roughly classified into a thermoplastic resin and a curable resin (thermo- or photo-curable resin).

Examples of thermoplastic resins include olefin resins; (meth)acrylic resins; styrene resins; vinyl resins, such as vinyl chloride resins and vinyl alcohol resins; fluororesins; polycarbonate resins; thermoplastic polyester resins, such as polyalkylene arylates, polyarylates, and liquid crystal polyesters, such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamide resins, such as aliphatic polyamides, such as polyamide 6 and polyamide 66, and semi-aromatic polyamides, such as polyamide 6T and polyamide MXD; polyacetal resins, such as polyamide 6T and polyamide MXD; tar-based resins; polyphenylene ether-based resins; polyphenylene sulfide-based resins; polysulfone-based resins, such as polysulfone and polyethersulfone; polyetherketone-based resins, such as polyetherketone, polyetheretherketone, polyetherketoneetherketoneketone; thermoplastic polyimide-based resins, such as polyetherimide-based resins and polyamideimide-based resins; thermoplastic elastomers; cellulose-based resins, such as cellulose ester-based resins such as triacetyl cellulose, and cellulose ether-based resins such as ethyl cellulose.

Examples of curable resins (thermosetting resins or photocurable resins) include epoxy resins; urethane resins; thermosetting polyester resins, such as alkyd resins, unsaturated polyester resins, diallyl phthalate resins, and vinyl ester resins; phenol resins; amino resins, such as melamine resins, urea resins, and guanamine resins; furan resins; thermosetting polyimide resins, such as bismaleimide resins and bismaleimide triazine resins; and silicon resins, such as polysilsesquioxane.

These binder components may be used alone or in combination of two or more. Among these binder components, (meth)acrylic resins, styrene resins, polycarbonate resins, and silicon resins are preferred from the viewpoints that they are less likely to absorb the ultraviolet light emitted by the fluorene compound represented by formula (1) and that they are easier to disperse the fluorene compound uniformly.

Examples of the (meth)acrylic resin include homopolymers or copolymers of (meth)acrylic monomers such as (meth)acrylic acid, C _1-18 alkyl (meth)acrylate, C _2-18 alkyl (meth)acrylate, glycidyl (meth)acrylate, and (meth)acrylonitrile; and copolymers of the above-mentioned (meth)acrylic monomers with other copolymerizable monomers.

Examples of homopolymers or copolymers of (meth)acrylic monomers include poly(meth)acrylic acid esters such as polymethyl(meth)acrylate, methyl methacrylate-(meth)acrylic acid copolymers, methyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymers, and methyl methacrylate-(meth)acrylic acid ester copolymers.

In the copolymer of a (meth)acrylic monomer and another copolymerizable monomer, the copolymerizable monomer may be, for example, a styrene monomer such as styrene or α-methylstyrene, or maleic anhydride.

Of these (meth)acrylic resins, poly(meth)acrylic acid C _1-8 alkyl esters such as polymethyl methacrylate are preferred.

Examples of styrene-based resins include homopolymers or copolymers of styrene-based monomers such as styrene, α-methylstyrene, and vinyltoluene; copolymers of the above-mentioned styrene-based monomers and copolymerizable monomers; and impact-resistant styrene-based resins [i.e., graft copolymers and/or blends (mixtures) with rubber components].

Examples of homopolymers or copolymers of styrene-based monomers include polystyrenes such as atactic polystyrene, isotactic polystyrene (IPS), syndiotactic polystyrene (SPS), styrene-vinyltoluene copolymers, and styrene-α-methylstyrene copolymers.

Examples of copolymers of styrene-based monomers and copolymerizable monomers include styrene-acrylonitrile copolymers (AS resins), styrene-(meth)acrylic acid copolymers, styrene-(meth)acrylic acid ester copolymers (such as MS resins), styrene-maleic anhydride copolymers, styrene-phenylmaleimide copolymers, styrene-butadiene block copolymers, and styrene-butadiene-styrene block copolymers.

Examples of impact-resistant styrene resins include high impact polystyrene (HIPS); acrylonitrile-butadiene-styrene copolymer (ABS resin); AXS resins using rubber components such as acrylic rubber A, chlorinated polyethylene C, and ethylene propylene rubber (or ethylene propylene diene rubber) E instead of the butadiene rubber B of the ABS resin, specifically AAS resin, ACS resin, AES resin, etc.; (meth)acrylic acid ester-butadiene-styrene copolymers, such as methyl methacrylate-butadiene-styrene copolymer (MBS resin), etc.

Among these styrene-based resins, homopolymers or copolymers of styrene-based monomers, especially homopolymers, are preferred.

Examples of polycarbonate resins include aromatic polycarbonate resins, specifically bisphenol-type polycarbonate resins that contain bisphenols as polymerization components, such as bisphenol A polycarbonate resin and bisphenol F polycarbonate resin.

Examples of the biphenols include bisphenols such as bis(hydroxyaryl)alkanes, bis(hydroxyaryl)-arylalkanes, bis(hydroxyaryl)cycloalkanes, bis(hydroxyaryl)ethers, bis(hydroxyaryl)ketones, bis(hydroxyaryl)sulfides, bis(hydroxyaryl)sulfoxides, and bis(hydroxyaryl)sulfones; biphenols, etc.

Examples of bis(hydroxyaryl)alkanes include bis(4-hydroxyphenyl)methane (bisphenol F), 1,1-bis(4-hydroxyphenyl)ethane (bisphenol AD), 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 1,1-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)butane (bisphenol B), 2,2-bis(4-hydroxyphenyl)-3-methylbutane, 2,2-bis(4-hydroxy-3-phenylphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane (bisphenol C), and 2,2-bis(4-hydroxy-3-isopropylphenyl)propane (bisphenol G).

Examples of bis(hydroxyaryl)-arylalkanes include 1,1-bis(4-hydroxyphenyl)-1-phenylethane (bisphenol AP) and bis(4-hydroxyphenyl)-diphenylmethane (bisphenol BP).

Examples of bis(hydroxyaryl)cycloalkanes include 1,1-bis(4-hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z), and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (bisphenol TMC).

Examples of bis(hydroxyaryl) ethers include bis(4-hydroxyphenyl) ether.

Examples of bis(hydroxyaryl)ketones include bis(4-hydroxyphenyl)ketone.

Examples of bis(hydroxyaryl)sulfides include bis(4-hydroxyphenyl)sulfide.

Examples of bis(hydroxyaryl)sulfoxides include bis(4-hydroxyphenyl)sulfoxide.

Examples of bis(hydroxyaryl)sulfones include bis(4-hydroxyphenyl)sulfone (bisphenol S).

Examples of biphenols include o,o'-biphenol, m,m'-biphenol, and p,p'-biphenol.

These biphenols or bisphenols can be used alone or in combination.

Among these polycarbonate resins, bisphenol-type polycarbonate resins that contain bis(hydroxyaryl)alkanes such as bisphenol A as polymerization components are preferred.

In the silicon-based resin, the polyorganosiloxane (silicone) skeleton may contain at least one unit selected from the group consisting of monofunctional M units (units generally represented by R ₃ SiO _1/2 ), difunctional D units (units generally represented by R ₂ SiO _2/2 ), trifunctional T units (units generally represented by RSiO _3/2 ), and tetrafunctional Q units (units generally represented by SiO _4/2 ).

The group R in the formulas representing the M, D and T units is a substituent. Examples of the substituent include an alkyl group, an aryl group, a cycloalkyl group, and a vinyl group.

Examples of the alkyl group include C1-12 alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-hexyl group, n-octyl group, 2 _- ethylhexyl group, and n-decyl group.

Examples of the aryl group include C _6-14 aryl groups such as a phenyl group, a methylphenyl group (tolyl group), a dimethylphenyl group (xylyl group), a biphenylyl group, and a naphthyl group.

Examples of the cycloalkyl group include a C _5-10 cycloalkyl group such as a cyclopentyl group, a cyclohexyl group, and a methylcyclohexyl group.

These substituents can be used alone or in combination of two or more. Among these substituents, _C1-4 alkyl groups such as methyl groups and _C6-12 aryl groups such as phenyl groups are preferred, and _C6-10 aryl groups such as phenyl groups are particularly preferred because they are less likely to absorb ultraviolet light and make it easier to uniformly disperse the fluorene compound.

Furthermore, examples of the terminal group (a group bonded to a terminal silicon (Si) atom) include a hydroxyl group, an alkoxy group, a halogen atom such as a chlorine atom, etc. Examples of the alkoxy group include a _C1-4 alkoxy group such as a methoxy group, an ethoxy group, etc., and a _C1-2 alkoxy group is preferred.

These terminal groups may be used alone or in combination of two or more. Among these terminal groups, hydroxyl groups, _C1-2 alkoxy groups, etc. are usually used in many cases.

From the viewpoint of ease of forming a coating film, the silicon-based resin preferably contains at least one unit selected from the T unit and the Q unit, and more preferably contains the T unit. The proportion of T units in the entire silicon-based resin is, for example, 50 mol% or more, and the preferred ranges are 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, and more preferably 95 mol% or more, and in particular, silsesquioxane (or polysilsesquioxane) that is substantially 100 mol%. The proportion of T units in the entire silicon-based resin can be selected from the range of, for example, about 60 to 100 mol%, and is preferably 80 to 99.9 mol%.

Silsesquioxanes (or polysilsesquioxanes) may be ladder-shaped or cage-shaped, but are preferably in the form of a three-dimensional mesh (network or random structure) from the viewpoint of ease of forming a coating film. Examples of such silsesquioxanes include polyalkylsilsesquioxanes formed with T units (alkylsilsesquioxane units) in which the substituent R is an alkyl group, such as polyC _1-4 alkylsilsesquioxanes such as polymethylsilsesquioxane; polyarylsilsesquioxanes formed with T units (arylsilsesquioxane units) in which R is an aryl group, such as polyC _6-12 arylsilsesquioxanes such as polyphenylsilsesquioxane; and polysilsesquioxanes formed with T units in which R is an alkyl group and T units in which R is an aryl group.

These silsesquioxanes can be used alone or in combination of two or more. Among these silsesquioxanes, polyarylsilsesquioxanes formed from T units in which R is an aryl group are preferred, and polyC _6-10 arylsilsesquioxanes such as polyphenylsilsesquioxane are particularly preferred.

Among these binder components, when the rings Z ^1a and Z ^1b are benzene rings, it seems that the luminescence quantum efficiency is relatively easy to improve when they contain a styrene-based resin, a (meth)acrylic resin, a silicon-based resin, and especially a silicon-based resin such as silsesquioxane. In addition, when the rings Z ^1a and Z ^1b are condensed polycyclic arene rings such as naphthalene rings, it seems that the luminescence quantum efficiency is easy to improve when they contain a styrene-based resin, a (meth)acrylic resin, and especially a (meth)acrylic resin; when the rings Z ^1a and Z ^1b are ring-assembled arene rings such as biphenyl rings, it seems that the luminescence quantum efficiency is easy to improve whether it is a (meth)acrylic resin, a styrene-based resin, a polycarbonate-based resin, or a silicon-based resin, and it seems that it can be particularly greatly improved when it contains a polycarbonate-based resin. In addition, silicon-based resins such as silsesquioxane are also preferred in that they are less likely to deteriorate (or decompose) even when exposed to ultraviolet light due to excitation light or emission, and have excellent thermal stability and heat exhaust properties.

The ratio of the binder component to the total solid content may be, for example, about 1 to 99.99% by mass, and can usually be selected from a range of about 10 to 99.9% by mass, with preferred ranges being 20 to 90% by mass, 30 to 70% by mass, 35 to 65% by mass, 40 to 60% by mass, and 45 to 55% by mass in the following stepwise manner. The ratio of the fluorene compound represented by the formula (1) to the binder component can be selected from a range of, for example, the former/latter (mass ratio)=about 1/0.5 to 1/1000, with preferred ranges being 1/0.7 to 1/200, 1/0.8 to 1/100 in the following stepwise manner, and more preferred ranges being 1/1 to 1/50, 1/1 to 1/40, 1/2 to 1/30, 1/4 to 1/20, and 1/6 to 1/15 in the following stepwise manner, from the viewpoint of effectively suppressing the decrease in luminescence quantum efficiency. If the ratio of the binder component is too low, the luminescence quantum efficiency may decrease due to concentration quenching, and if the ratio of the binder component is too high, the luminescence may not occur. When the rings Z ^1a and Z ^1b are benzene rings, if the binder component contains a (meth)acrylic resin or a silicon-based resin, it seems to be easily affected by concentration quenching, and the luminescence quantum efficiency can be effectively improved by setting the ratio of the binder component to the above range. On the other hand, when the rings Z ^1a and Z ^1b are benzene rings, if the binder component contains a styrene-based resin, it seems to be less affected by concentration quenching, and the ratio of the fluorene compound represented by the formula (1) to the binder component can be, for example, the former/latter (mass ratio) = 1/0.1 to 1/3, and as a preferred range, it can also exhibit high luminescence quantum efficiency in the following stepwise ranges of 1/0.5 to 1/2, 1/0.7 to 1/1.5, and 1/0.8 to 1/1.2. That is, since the proportion of the fluorene compound can be increased without significantly reducing the high luminescence quantum efficiency, the excitation light can be efficiently absorbed and the luminescence intensity can be further improved.

The luminescent composition (or coating agent) may further contain a solvent to adjust the viscosity and improve the applicability (or handling), and may be dried and removed from the coating film after application. Examples of the solvent include hydrocarbons, halogenated hydrocarbons, alcohols, glycols, ethers, glycol ethers, glycol ether acetates, ketones, carboxylic acids, esters, carbonates, nitriles, amides, sulfoxides, water, and mixed solvents thereof.

Examples of hydrocarbons include aliphatic hydrocarbons such as hexane, alicyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as toluene and xylene.

Examples of halogenated hydrocarbons include dichloromethane, chloroform, 1,2-dichloroethane, and chlorobenzene.

Examples of the alcohols include C _1-6 alkanols such as methanol, ethanol, 1-propanol, 2-propanol, n-butanol, isobutanol, s-butanol, and t-butanol.

Examples of glycols include (poly)C _2-4 alkylene glycols such as ethylene glycol, propylene glycol, and diethylene glycol.

Examples of ethers include chain ethers such as diethyl ether, and cyclic ethers such as tetrahydrofuran and 1,4-dioxane.

Examples of glycol ethers include cellosolves, carbitols, (poly) _C2-4 alkylene glycol mono _C1-4 alkyl ethers such as triethylene glycol monomethyl ether, propylene glycol monomethyl ether, and dipropylene glycol monomethyl ether; and (poly) _C2-4 alkylene glycol di _C1-4 alkyl ethers such as ethylene glycol dimethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, and dipropylene glycol dimethyl ether.

Examples of the cellosolves include _C1-4 alkyl cellosolves such as methyl cellosolve and ethyl cellosolve, etc. Examples of the carbitols include _C1-4 alkyl carbitols such as methyl carbitol and ethyl carbitol, etc.

Examples of glycol ether acetates include cellosolve acetates, carbitol acetates, (poly)C _2-4 alkylene glycol mono C _1-4 alkyl ether acetates such as propylene glycol monomethyl ether acetate and dipropylene glycol monobutyl ether acetate.

Examples of the cellosolve acetates include C _1-4 alkyl cellosolve acetates such as methyl cellosolve acetate, etc. Examples of the carbitol acetates include C _1-4 alkyl carbitol acetates such as methyl carbitol acetate, etc.

Examples of ketones include chain ketones such as acetone and methyl ethyl ketone, and cyclic ketones such as cyclohexanone.

Examples of carboxylic acids include acetic acid and propionic acid.

Examples of esters include acetate esters such as methyl acetate, ethyl acetate, and butyl acetate, and lactate esters such as methyl lactate.

Examples of carbonates include chain carbonates such as dimethyl carbonate, and cyclic carbonates such as propylene carbonate.

Examples of nitriles include acetonitrile, propionitrile, and benzonitrile.

Examples of amides include N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone.

Examples of sulfoxides include dimethyl sulfoxide.

These solvents can be used alone or in combination. Among these solvents, halogenated hydrocarbons such as dichloromethane and chloroform are often used.

The proportion of the solvent can be appropriately selected depending on the viscosity of the luminescent composition, and is not particularly limited. The solids concentration of the luminescent composition is, for example, 0.01 to 50% by mass, preferably 0.1 to 10% by mass, more preferably 1 to 10% by mass, and particularly preferably 3 to 7% by mass. It may also be 0.5 to 2% by mass.

The luminescent composition may contain conventional additives. Examples of conventional additives include dyes, pigments, pigment dispersants, wetting agents, thickeners, coupling agents, defoamers, anti-settling agents, anti-skinning agents, polymerization inhibitors, polymerization initiators, hardeners, leveling agents, thixotropic agents, color separation inhibitors, matting agents, flame retardants, stabilizers, plasticizers, softeners, lubricants, release agents, and antistatic agents. Examples of the stabilizers include antioxidants, ultraviolet absorbers, light stabilizers, and ozone degradation inhibitors.

The coating agent may not substantially contain additives because the additives may absorb the excitation light for exciting the ultraviolet light emitting material or the light emitted by the excited ultraviolet light emitting material. Therefore, the luminescent composition preferably contains at least the fluorene compound represented by formula (1) and, if necessary, only a binder component and/or a solvent, i.e., does not substantially contain additives.

The luminescent properties of a luminescent composition containing a binder component or a coating film (or a coating film) containing a binder component formed using this composition may be appropriately adjusted depending on the type and concentration of the fluorene compound, the binder component, etc. The luminescent composition (or coating film) may contain at least one emission peak having a maximum wavelength λ _em,max in the range of, for example, about 350 to 420 nm in its emission (fluorescence or phosphorescence) spectrum at room temperature, for example, 25°C, and preferably contains at least one emission peak having a maximum wavelength λ _em,max in the following stepwise ranges: 355 to 395 nm, 360 to 390 nm, and 360 to 385 nm, and more preferably contains at least two emission peaks having a maximum wavelength λ _em,max in the above ranges. When rings Z ^1a and Z ^1b are polycyclic arene rings, they have, for example, at least one emission peak (or absorption band) having a maximum wavelength λ _em,max in the range of 370 to 425 nm, preferably 380 to 390 nm, and more preferably at least two emission peaks having maximum wavelengths λ _em,max in the above range.

In the emission spectrum of the luminescent composition (or coating film) containing a binder component, the half-value width of the emission peak (or absorption band) having the maximum wavelength λ _em,max can be selected, for example, from the range of 60 nm or less, or about 10 to 55 nm, and preferred ranges are 30 to 50 nm, 32 to 48 nm, and 35 to 45 nm, in the following stepwise order.

Furthermore, the luminescent composition (coating film) containing a binder component may contain at least one emission or absorption peak having a maximum wavelength λ _ex,max , for example, in the range of about 280 to 360 nm in its excitation spectrum (or absorption spectrum) at room temperature, for example, at 25°C, and preferably contains at least one emission or absorption peak having a maximum wavelength λ _ex,max , in the range of 290 to 350 nm, in the following stepwise order:

The luminescence quantum efficiency of the luminescent composition (coating film) containing the binder component can be selected from a range of, for example, about 30% or more, specifically about 40 to 100%, at room temperature, e.g., 25°C, with the preferred ranges being 50 to 95%, 60 to 90%, 65 to 85%, 70 to 85%, 75 to 85%, and 80 to 83%, in the following stepwise order.

Such luminescent compositions or coating agents can be effectively used, for example, as invisible inks such as security inks (or security markers) for the purposes of identifying counterfeit goods and preventing the counterfeiting of documents such as banknotes, coupons, and warranty cards.

In more detail, when the fluorene compound represented by the formula (1) is used as a light-emitting material, the fluorene compound is often not excited by ultraviolet light with a wavelength of about 365 nm emitted by commercially available black lights, and does not emit light. Even if it can emit light, the emitted light is often not visible light and cannot be visually recognized. Therefore, it becomes difficult for a third party to determine whether or not invisible ink has been applied, and security (or confidentiality) can be effectively improved.

Therefore, the present invention also includes a method of irradiating the luminescent composition (or a coating film formed by applying the luminescent composition and removing the solvent as necessary) with light and detecting the light emitted by the coating film (or the luminescent material in the coating film) with a detection device equipped with a spectrometer and a detector.

The coating film may be formed by applying a light-emitting composition (or coating agent) and may be formed using a conventional application method such as spin coating, gravure printing, screen printing, or inkjet printing.

The light source used for detection is a light source capable of emitting ultraviolet light with a shorter wavelength than the ultraviolet light emitted by commercially available black lights, for example, ultraviolet light with a wavelength of about 10 nm or more shorter than the detection wavelength, specifically, ultraviolet light of about 250 to 350 nm. Representative examples of such light sources include xenon lamps, deuterium lamps, ultraviolet fluorescent lamps (UV fluorescent lamps), and ultraviolet light emitting diodes (UVLEDs).

The detection device is required to have at least a specific detector, and preferably has at least the detector and a specific spectrometer, and may also have the light source. Examples of the spectrometer include spectrometers that can separate the light from the light source and the light emitted by the coating agent or coating film, such as diffraction gratings, prisms, and optical cut filters. Examples of the detector include detectors that can detect the light emitted by the luminescent composition or coating film, such as photomultiplier tubes, photodiodes, and CCD (Charge Coupled Device) sensors. Examples of such detection devices include commercially available spectrofluorometers.

The invisible ink may be printed or applied to the printed matter in various forms, such as letters (or text) or figures (or patterns), or may be applied in the form of a code, such as a barcode or a QR (Quick Response) code (registered trademark), to provide a large amount of information. In addition, by combining multiple luminescent materials, a large amount of information may be provided.

(Light-emitting element or photoelectric conversion element)
The light-emitting element (or photoelectric conversion element) of the present invention contains at least the fluorene compound represented by the formula (1) as a light-emitting material and/or a sensitizer. When the fluorene compound represented by the formula (1) is contained as a sensitizer, it usually contains other light-emitting materials.

Representative examples of light-emitting elements include current-injection type light-emitting elements such as inorganic light-emitting diodes (LEDs) and organic EL elements (or organic light-emitting diodes (OLEDs)), and organic EL elements are usually used. Current-injection type light-emitting elements such as organic EL elements are formed of an anode (transparent electrode) and a cathode (metal electrode) and an organic layer (organic thin film) or an organic-inorganic hybrid layer interposed between the electrodes. A typical configuration is often formed with the layers in the order of transparent substrate/anode/hole (positive hole) transport layer/light-emitting layer/electron transport layer/cathode. Note that if the light-emitting layer functions as a hole transport layer or electron transport layer, the hole transport layer or electron transport layer is not necessarily required.

Examples of transparent substrates include substrates made of inorganic materials such as glass; and substrates made of organic materials such as (meth)acrylic resins, styrene resins, polycarbonate resins, and polyester resins. Examples of polyester resins include polyalkylene arylate resins such as polyethylene terephthalate.

The substrate may be in the form of a plate, sheet, or film.

A transparent electrode is usually used as the anode, and is often made of conductive metal oxides such as ITO (indium tin oxide), FTO (fluorine-doped tin oxide), and ZnO (zinc oxide). In this specification and claims, the term "transparent electrode" refers to an electrode that can transmit at least a portion of the ultraviolet light emitted by the light-emitting material. Such an anode may be made thin or by making slits, for example.

Examples of hole transport materials that form the hole transport layer include aromatic amines such as 4,4'-bis(tolylphenylamino)biphenyl (TPD), 4,4'-bis(α-naphthyl-phenylamino)biphenyl (α-NPD), 1,1-bis[4-(tolylphenylamino)phenyl]cyclohexane (TAPC), tris[4-(tolylphenylamino)phenyl]amine (m-TDATA), and tris[4-(9-carbazolyl)phenyl]amine (TCTA); phthalocyanines such as copper phthalocyanine; conductive polymers, for example, polythiophenes such as poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid composite (PEDOT:PSS); and the like. These hole transport materials can be used alone or in combination of two or more kinds. Of these, conductive polymers such as PEDOT:PSS are often used.

The light-emitting layer may contain the fluorene compound represented by formula (1) as the light-emitting material, or may contain other conventional light-emitting materials. These light-emitting materials may be used alone or in combination of two or more. The light-emitting layer may be composed of only the light-emitting material, or may further contain a host material with the light-emitting material as a guest material (or dopant). Examples of the host material include biphenyls such as 4,4'-bis(2,2-diphenylvinyl)biphenyl (DPvBi) and 4,4'-bis(9-carbazolyl)biphenyl (CBP); (meth)acrylic resins, polycarbonate resins, silicon resins, and other binder components exemplified in the section on light-emitting compositions.

Examples of electron transport materials that form the electron transport layer include light metal organic complexes such as aluminum complexes and beryllium complexes, bisstyrylarene derivatives, oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, and silole derivatives.

Examples of aluminum complexes include tris(8-quinolinolato)aluminum(III) ( _Alq3 ), bis(2-methyl-8-quinolinolato)(p-phenylphenolato)aluminum(III) ( _BAlq2 ), tris(4-methyl-8-quinolinolato)aluminum(III) ( _Almq3 ), and tris(5-hydroxy-benzo[f]quinolinato)aluminum(III) ( _Alph3 ).

An example of a beryllium complex is bis[10-hydroxy-benzo[h]quinolinato]beryllium(II) (Bebq ₂ ).

Examples of bisstyryl arene derivatives include 4,4'-bis(2,2-di-p-tolyl-vinyl)biphenyl (DTVBi), 9,10-bis[4-(diphenylamino)styryl]anthracene (BSA-2), 4,4'-bis[2-(9-ethyl-3-carbazolyl)vinyl]biphenyl (BCzVBi), and 1,4-bis[4-(di-p-tolylamino)styryl]benzene.

Examples of oxadiazole derivatives include 2-(4-t-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (t-Bu-PBD) and 1,3-bis[5-(4-t-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (OXD-7).

Examples of triazole derivatives include 3-(biphenyl-4-yl)-5-(4-t-butylphenyl)-4-phenyl-4H-1,2,4-triazole (TAZ).

Examples of phenanthroline derivatives include 4,7-diphenyl-1,10-phenanthroline (BPhen) and 4,7-diphenyl-2,9-dimethyl-1,10-phenanthroline (BCP).

Examples of silole derivatives include 1,1-dimethyl-3,4-diphenyl-2.5-di(2,2'-bipyridyl-3-yl)silole.

These electron transport materials can be used alone or in combination of two or more.

The cathode (metal electrode) is often made of a single metal such as aluminum (Al), magnesium (Mg), or silver (Ag) or an alloy of these metals.

Between the anode and the hole transport layer, an anode buffer layer (hole injection layer), such as a copper phthalocyanine thin film, may be formed. Between the cathode and the electron transport layer, a cathode buffer layer (electron injection layer), such as an inorganic thin film, such as a lithium fluoride (LiF) thin film or a lithium oxide (Li ₂ O) thin film, or an organic thin film doped with a metal, such as lithium (Li), may be formed.

The thickness of each layer (organic phase) interposed between the anode and cathode is, for example, 0.1 to 500 nm, preferably 1 to 200 nm, and the thickness of the entire organic phase may be about 1 μm or less.

Such organic EL elements may be used as ultraviolet light sources (UV lamps) for a variety of purposes, such as sterilization, analysis, and as light sources for high color rendering white LEDs.

The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. The evaluation methods are also shown below.

[Evaluation method]
(NMR)
Measurement was carried out using BRUKER's "ULTRASHIELD 300".

(Single crystal X-ray structure analysis)
The measurement was carried out using "RAXIS-rapid II" manufactured by Rigaku Corporation.

(HPLC)
The measurement was carried out using "LC-20A" manufactured by Shimadzu Corporation.

(Light Emitting Characteristics)
The excitation spectrum and emission (fluorescence or phosphorescence) spectrum of the sample were measured at room temperature (25° C.) using a spectrofluorometer (Hitachi High-Technologies Corporation, "F-4500", light source: xenon lamp, detector: photomultiplier tube, spectroscope: diffraction grating), and the maximum wavelength λ _ex,max of the excitation spectrum, the maximum wavelength λ _em,max of the emission spectrum, and the half-width of the peak (or absorption band) containing λ _em,max were determined.

(Quantum Efficiency)
A fluorescence spectrophotometer (JASCO Corporation "FP-6500", light source: xenon lamp, detector: photomultiplier tube, spectroscope: diffraction grating) equipped with a fluorescence integrating sphere unit (JASCO Corporation "ILF-533", diameter 100 mmφ) was subjected to spectrum correction using an instrument function obtained using an attached standard light source for calibration, and the spectral area and the number of photons were made proportional to each other, and then the luminescence quantum efficiency was calculated by the absolute method. The excitation light was measured without a sample being placed to determine the spectral area of the irradiated excitation light, and then the excitation light was measured with a sample placed to determine the spectral area of the irradiated excitation light that was not absorbed by the sample, and the number of photons absorbed by the sample was calculated by calculating the difference between these values. At the same time, the emission spectrum of the sample was also observed, and the number of emitted photons was calculated from the spectral area. Finally, the luminescence quantum efficiency was calculated from the number of emitted photons relative to the number of absorbed photons.

[Preparation of fluorene compounds]
(Synthesis Example 1) Preparation of BEPF-Br

2,7-dibromofluorene (14.9 g, 46 mmol), potassium t-butoxide (t-BuOK, 12.39 g, 110.4 mmol, 2.4 eq.), and dimethyl sulfoxide (DMSO, 300 mL) were placed in a 500 mL four-necked eggplant flask, and after heating to 50°C to dissolve, (2-bromoethyl)benzene (25.54 g, 138 mmol, 3 eq.) was added dropwise. After completion of the dropwise addition, the mixture was heated and stirred at 60°C for 5 hours. After returning to room temperature, toluene (490 mL) and distilled water (580 mL) were added to extract the reaction product into the organic layer. The organic layer was further washed with distilled water (580 mL x 3 times), and the solvent of the organic layer was removed to obtain a pale yellow solid. Reprecipitation with toluene (25 mL)/methanol (240 mL) at about 70° C. was repeated three times, and the obtained solid was dried to obtain 9,9-bis(2-phenylethyl)-2,7-dibromofluorene (BEPF-Br) as a white solid (3.4 g, 14% yield). The structure was confirmed by ¹ H NMR. The purity was 99% by HPLC.

^1H NMR (300MHz, _CDCl3 ): δ (ppm) 1.86-1.94 (m, 4H), 2.28-2.33 (m, 4H), 6.93 (q, 4H), 7 .08-7.20 (m, 6H), 7.50-7.61 (m, 6H).

(Example 1) Preparation of BEPF-Ph

BEPF-Br (2.01 g, 3.77 mmol), phenylboronic acid (1.38 g, 11.3 mmol), 2M potassium carbonate aqueous solution (25 mL), tetrabutylammonium bromide (TBAB, 2 drops) and toluene (51 mL) were placed in a 200 mL three-necked eggplant flask, and Pd(PPh ₃ ) ₄ (0.13 g, 0.11 mmol) was added under a nitrogen atmosphere, followed by heating and stirring at 120° C. for 5 hours. After returning to room temperature, dichloromethane (30 mL) and distilled water (50 mL) were added for extraction. The organic layer was further washed with distilled water (50 mL x 2 times), and the organic layer was dehydrated with magnesium sulfate, and the solvent was removed to obtain a yellow oily substance. The crystals were purified by silica gel chromatography (mobile phase or solvent: hexane/dichloromethane (volume ratio) = 10/1) to obtain 9,9-bis(2-phenylethyl)-2,7-diphenylfluorene (BEPF-Ph) as white crystals (1.38 g, yield 69%). The structure was confirmed by ¹ H NMR and single crystal X-ray structure analysis. The measurement results are shown below and in FIG. 43. The purity was 99% by HPLC.

¹ H NMR (300 MHz, CDCl ₃ ): δ (ppm) 1.95-2.10 (m, 4H), 2.33-2.55 (m, 4H), 6.88-6.98 (m, 4H), 7.00-7.21 (m, 6H), 7.32-7.43 (m, 2H), 7.45-7.55 (m, 4H), 7.60-7.75 ( m, 8H), 7.82-7.90 (m, 2H).

Crystal system: orthorhombic, space group: Pca2 ₁ (29), a (Å) = 11.1097, b (Å) = 11.7420, c (Å) = 23.9349, V (Å ³ ) = 3122.31 , Z=4, R1=9.23%

(Synthesis Example 2) Preparation of BMPF-Br

2,7-dibromofluorene (9.66 g, 30.0 mmol), potassium t-butoxide (t-BuOK, 8.08 g, 72 mmol, 2.4 eq.) and dimethyl sulfoxide (DMSO, 210 mL) were placed in a 500 mL four-necked eggplant flask, and after heating to 50° C. and dissolving, benzyl bromide (15.39 g, 90 mmol, 3 eq.) was added dropwise. After completion of the dropwise addition, the mixture was heated and stirred at 60° C. for 3.5 hours. After returning to room temperature, the precipitated white solid was filtered, washed with distilled water, and dried to obtain 9,9-bis(benzyl)-2,7-dibromofluorene (BMPF-Br) as a white solid (10.3 g, yield 68%). The structure was confirmed by ¹ H NMR. The purity was 99% by HPLC.

^1H NMR (300MHz, _CDCl3 ): δ (ppm) 3.32 (s, 4H), 6.65 (d, 4H), 6.93-7.01 (m, 6H), 7.19-7 .51 (m, 6H).

(Example 2) Preparation of BMPF-Ph

In a 200 mL three-necked eggplant flask, BMPF-Br (1.90 g, 3.77 mmol), phenylboronic acid (1.38 g, 11.3 mmol), 2 M potassium carbonate aqueous solution (25 mL), tetrabutylammonium bromide (TBAB, 2 drops) and toluene (51 mL) were placed, and Pd(PPh ₃ ) ₄ (0.13 g, 0.11 mmol) was added under a nitrogen atmosphere, and the mixture was heated and stirred at 120° C. for 5 hours. After returning to room temperature, dichloromethane (50 mL) and distilled water (50 mL) were added for extraction. The organic layer was further washed with distilled water (50 mL x 2 times), and the organic layer was dehydrated with magnesium sulfate, and the solvent was removed to obtain a yellow oily substance. The crystals were purified by silica gel chromatography (solvent: hexane/dichloromethane (volume ratio) = 4/1) to give 9,9-bis(phenylmethyl)-2,7-diphenylfluorene (BMPF-Ph) as white crystals (1.03 g, yield 55%). The structure was confirmed by ¹ H NMR. The purity was 99% by HPLC.

^1H NMR (300MHz, _CDCl3 ): δ (ppm) 3.44 (s, 4H), 6.72-6.80 (m, 4H), 6.90-7.05 (m, 6H), 7 .34-7.43 (m, 2H), 7.44-7.55 (m, 8H), 7.58 (t, 2H), 7.62-7.77 (m, 4H).

(Example 3) Preparation of BEPF-Np

BEPF-Br (0.0532 g, 0.10 mmol), 2-naphthaleneboronic acid (0.0378 g, 0.22 mmol), 2M potassium carbonate aqueous solution (4 mL), and toluene (8 mL) were placed in a 100 mL three-necked eggplant flask. Pd(PPh ₃ ) ₄ (0.0023 g, 0.0020 mmol) was added under a nitrogen atmosphere and the mixture was heated and stirred at 120° C. for 12 hours. After returning the temperature to room temperature, dichloromethane (10 mL) and distilled water (20 mL) were added for extraction. The organic layer was further washed with distilled water (20 mL x 2), dehydrated with magnesium sulfate, and the solvent was removed to obtain a yellow oil. After purification by silica gel chromatography (solvent; hexane/dichloromethane (volume ratio) = 10/1), recrystallization (solvent; hexane/dichloromethane (volume ratio) = 10/1) was performed to obtain 9,9-bis(2-phenylethyl)-2,7-(2-naphthyl)fluorene (BEPF-Np) as white crystals (0.0165 g, yield 26%). The structure was confirmed by ¹ H NMR and single crystal X-ray structure analysis. The measurement results are shown below and in FIG. 44.

¹ H NMR (300 MHz, CDCl ₃ ): δ (ppm) 2.08-2.14 (m, 4H), 2.48-2.54 (m, 4H), 6.95-6.98 (m, 4H), 7.06-7.18 (m, 6H), 7.50-7.55 (m, 4H), 7.79-8.11 (m, 16H).

Crystal system: monoclinic, space group: P 2 ₁ /c (14), a (Å) = 11.8115 (10), b (Å) = 11.4194 (9), c (Å) = 26.925 ( 2), β (°) = 99.012 (7), V (Å ³ ) = 3586.82, Z = 4, R1 = 8.6%

(Example 4) Preparation of BEPF-BPh

BEPF-Br (0.165 g, 0.31 mmol), 4-biphenylboronic acid (0.135 g, 0.68 mmol), 2M potassium carbonate aqueous solution (10 mL), and toluene (20 mL) were placed in a 100 mL three-necked eggplant flask. Pd(PPh ₃ ) ₄ (0.0062 g, 0.0054 mmol) was added under a nitrogen atmosphere and heated and stirred at 120° C. for 12 hours. After returning to room temperature, dichloromethane (20 mL) and distilled water (40 mL) were added for extraction. The organic layer was further washed with distilled water (40 mL x 2), dehydrated with magnesium sulfate, and the solvent was removed to obtain a yellow oil. After purification by silica gel chromatography (solvent; hexane/dichloromethane (volume ratio) = 10/1), recrystallization (solvent; hexane/dichloromethane (volume ratio) = 10/1) was performed to obtain 9,9-bis(2-phenylethyl)-2,7-(4-biphenylyl)fluorene (BEPF-BPh) as white crystals (0.159 g, yield 75%). The structure was confirmed by ¹ H NMR and single crystal X-ray structure analysis. The measurement results are shown below and in FIG. 45.

¹ H NMR (600 MHz, CDCl ₃ ): δ (ppm) 2.06-2.09 (m, 4H), 2.45-2.48 (m, 4H), 6.95-6.96 (m, 4H), 7.06-7.17 (m, 6H), 7.37-7.50 (m, 6H), 7.66-7.89 (m, 18H).

Crystal system: triclinic, space group: P -1 (2), a (Å) = 5.8868 (6), b (Å) = 16.3359 (17), c (Å) = 19.803 (2) , α (°) = 91.332 (6), β (°) = 92.731 (7), γ (°) = 96.212 (7), V (Å ³ ) = 1890.27, Z = 2 , R1=9.99%

(Reference Example 1) Preparation of BEPF

9H-fluorene (1.66 g, 10.0 mmol), t-BuOK (3.36 g, 30 mmol, 3.0 eq.) and DMSO (90 mL) were placed in a 500 mL four-necked eggplant flask, and dissolved by heating to 60° C., after which (2-bromoethyl)benzene (4.44 g, 24 mmol, 2.4 eq.) was added dropwise. After the dropwise addition was completed, the mixture was heated and stirred at 60° C. for 5 hours. After returning to room temperature, distilled water (20 mL) was added to extract the reaction product. The solvent in the organic layer (or extract) was removed to obtain a pale yellow solid (3.2 g). The product was recrystallized with methanol, filtered and dried to obtain 9,9-bis(2-phenylethyl)fluorene (BEPF) as a white solid (1.2 g, 32% yield). The structure was confirmed by ¹ H NMR. The purity was 99% by HPLC.

¹ H NMR (300 MHz, CDCl ₃ ): δ (ppm) 1.86-1.94 (m, 4H), 2.31-2.36 (m, 4H), 6.94 (t, 4H), 7 .06-7.11 (d, 6H), 7.14-7.19 (m, 8H).

(Reference Example 2) Preparation of BMPF

9H-fluorene (1.66 g, 10.0 mmol), t-BuOK (3.36 g, 30 mmol, 3.0 eq.) and DMSO (90 mL) were placed in a 500 mL four-necked eggplant flask, and dissolved by heating to 60°C. Then, benzyl bromide (4.10 g, 24 mmol, 2.4 eq.) was added dropwise. After the dropwise addition, the mixture was heated and stirred at 60°C for 3.5 hours. After returning to room temperature, distilled water (20 mL) was added to extract the reaction product. The solvent in the organic layer (or extract) was removed to obtain a pale yellow solid (3.0 g). The product was recrystallized with a mixed solvent of ethyl acetate (100 mL)/hexane (100 mL), filtered, and dried to obtain 9,9-bis(benzyl)-fluorene (BMPF) as a white solid (2.4 g, 69% yield). The structure was confirmed by ¹ H NMR. HPLC showed the purity to be 99%.

^1H NMR (300MHz, _CDCl3 ): δ (ppm) 3.40 (s, 4H), 6.69 (d, 4H), 6.91-7.01 (m, 6H), 7.17-7 .44 (m, 8H).

(Reference Example 3) Preparation of BEPF-Si

BEPF-Br (2.13 g, 4 mmol) was placed in a 100 mL eggplant flask and dried under reduced pressure, and dehydrated THF (3 mL) and Me ₃ SiCl (1.3 g, 12 mmol, 3 eq.) were added and dissolved under a nitrogen atmosphere. Magnesium (0.68 g, 28 mmol, 7 eq.) was placed in another 100 mL eggplant flask and dried under reduced pressure while stirring, and then dehydrated THF (0.9 mL) was added under a nitrogen atmosphere. The solution containing BEPF-Br was added dropwise to this flask. After the dropwise addition was completed, the mixture was stirred at room temperature for 3 hours. After returning to room temperature, 10% by mass hydrochloric acid (20 mL) was added to dissolve magnesium, and THF (30 mL) was added to extract the reaction product. The solvent of the organic layer (or the extract) was removed, and an orange oily substance (about 1 g) was obtained. The oily product was purified by silica gel chromatography (silica gel: 20 g, elution solvent: hexane) to obtain 9,9-bis(2-phenylethyl)-2,7-bis(trimethylsilyl)fluorene (BEPF-Si) as white crystals (0.6 g, yield 29%). The structure was confirmed by ¹ H NMR. The purity was 99% by HPLC.

^1H NMR (300MHz, _CDCl3 ): δ (ppm) 0.34 (s, 18H), 1.92-1.97 (m, 4H), 2.32-2.37 (m, 4H), 6 .89-6.92 (m, 4H), 7.06-7.19 (m, 6H), 7.52-7.77 (m, 6H).

(Reference Example 4) Preparation of BMPF-Si

BMPF-Br (1.51 g, 3 mmol) was placed in a 100 mL eggplant flask and dried under reduced pressure, and dehydrated tetrahydrofuran (THF, 2.5 mL) and trimethylchlorosilane (Me ₃ SiCl, 0.98 g, 9 mmol, 3 eq.) were added and dissolved under a nitrogen atmosphere. Magnesium (0.51 g, 21 mmol, 7 eq.) was placed in another 100 mL eggplant flask and dried under reduced pressure while stirring, and then dehydrated THF (0.5 mL) was added under a nitrogen atmosphere. The solution containing the BMPF-Br was added dropwise to this flask. After the dropwise addition, the mixture was stirred at room temperature for 3 hours. 10% by mass hydrochloric acid (20 mL) was added to dissolve magnesium, and THF (30 mL) was added to extract the reaction product. The solvent of the organic layer (or extract) was removed to obtain a pale yellow solid (0.6 g). The obtained solid was purified by silica gel chromatography (silica gel: 15 g, elution solvent: hexane) to obtain 9,9-bis(benzyl)-2,7-bis(trimethylsilyl)fluorene (BMPF-Si) as white crystals (0.50 g, yield 34%). The structure was confirmed by ¹ H NMR. The purity was 99% by HPLC.

^1H NMR (300MHz, _CDCl3 ): δ (ppm) 0.30 (s, 18H), 3.32 (s, 4H), 6.65 (d, 4H), 6.91-7.03 (m , 6H), 7.35-7.38 (q, 6H).

(Reference Example 5) Preparation of BMPF-tBu

2,7-di(t-butyl)-9H-fluorene (8.35 g, 30 mmol), t-BuOK (12.12 g, 108 mmol, 3.6 eq.), and DMSO (200 mL) were placed in a 500 mL four-necked recovery flask and dissolved by heating to 60° C., after which benzyl bromide (18.0 g, 105 mmol, 3.5 eq.) was added dropwise. After completion of the dropwise addition, the mixture was heated and stirred at 60° C. for 5 hours. After returning to room temperature, distilled water (400 mL) was added to obtain an orange powder. This powder was purified by reprecipitation with toluene (40 mL)/methanol (300 mL) and then further purified by silica gel chromatography (silica gel: 50 g, elution solvent: hexane/dichloromethane (volume ratio) = 10/1) to obtain 9,9-bis(benzyl)-2,7-di(t-butyl)fluorene (BMPF-tBu) as white crystals (0.85 g, yield 6.2%). The structure was confirmed by ¹ H NMR. The purity was 99% by HPLC.

^1H NMR (300MHz, _CDCl3 ): δ (ppm) 1.36 (s, 18H), 3.30 (s, 4H), 6.68-6.71 (q, 4H), 6.91-7 .99 (m, 6H), 7.19-7.31 (m, 6H).

[Emission properties of fluorene compounds]
(Light Emitting Properties in the Solid State)
The solid-state excitation spectrum, emission spectrum, and luminescence quantum efficiency of the fluorene compounds prepared in the Examples and Reference Examples were measured. Table 1 shows the correspondence between the samples and the obtained spectra, and the spectrum measurement conditions, while Table 2 and Figures 1 to 7 and 15 to 16 show the measurement results. In Table 1, "emission wavelength" refers to the wavelength at which the emission intensity was monitored in the excitation spectrum, and "excitation wavelength" refers to the wavelength of the excitation light in the emission spectrum (the same applies to Table 3 below).

(Light Emission Characteristics in Solution State)
The fluorene compounds prepared in the Examples and Reference Examples were dissolved in dichloromethane at the concentrations shown in Table 3, and the excitation spectrum, emission spectrum, and emission quantum efficiency in the solution state were measured. Table 3 shows the correspondence between the samples and the obtained spectra, and the spectrum measurement conditions, and Table 4 and Figures 8 to 14 and 17 to 18 show the measurement results.

As is clear from Tables 2 and 4 and Figures 1 to 18, it was found that in the examples, light with a relatively narrow half-width can be emitted in the short wavelength region of about 350 to 400 nm. In addition, in the measurements of the dichloromethane solution, no significant effects such as concentration quenching were confirmed in any of the examples and reference examples, and the samples were sufficiently diluted to a degree that did not affect the results of the emission spectrum and luminescence quantum efficiency.

Furthermore, the luminescence quantum efficiency of the Examples was significantly higher than that of the Reference Examples. In particular, it was found that the compounds exhibited extremely high luminescence quantum efficiency even in the solid state, which is more susceptible to the effect of concentration quenching than in the solution state, and therefore can be effectively used as luminescent materials for organic electroluminescence. Among the Examples, Examples 1 and 2, in which rings Z ^1a and Z ^1b are benzene rings, exhibited particularly high luminescence quantum efficiency even in the solid state, and maintained the same level as in the solution state.

In Examples 3 and 4 in which rings Z ^1a and Z ^1b are polycyclic arene rings, λ _em,max was shifted slightly to the long wavelength side compared to Examples 1 and 2. In particular, Example 3 in which rings Z ^1a and Z ^1b are naphthalene rings had the highest luminescence quantum efficiency in a solution state. Moreover, in Example 4 in which rings Z ^1a and Z ^1b are biphenyl rings, the half width in the emission spectrum was slightly wider than that in Examples 1 to 3.

(Light Emitting Properties in Coating State)
0.01g or 0.001g of the fluorene compound prepared in Examples 1 to 4 and 0.01g of the binder component described below were mixed in chloroform so that the solid content concentration was 5% by mass to prepare a mixed liquid (coating agent). In detail, as shown in Table 5, each fluorene compound and each binder component were used alone and mixed to prepare a total of 24 types of coating agents in which the ratio of the two was fluorene compound/binder component (mass ratio) = 1/1 or 1/10.

Each of the obtained coating agents was applied onto a quartz substrate ("Labo-USQ" manufactured by Taiko Seisakusho Co., Ltd.) using a spin coater ("1H-D7" manufactured by Mikasa Co., Ltd., 1000 rpm) and dried on a hot plate at 90°C for 30 minutes to form a coating film. The excitation spectrum, emission spectrum, and emission quantum efficiency were measured using each of the formed coating films. Table 5 shows the correspondence between the samples and the obtained spectra, as well as the spectrum measurement conditions, and Table 5 and Figures 19 to 42 show the measurement results. The resins used as binder components are shown below.

PS: polystyrene, manufactured by PS Japan Co., Ltd. PC: polycarbonate, manufactured by Mitsubishi Engineering Plastics Co., Ltd. PMMA: polymethyl methacrylate, manufactured by Mitsubishi Rayon Co., Ltd. PPSQ: polyphenylsilsesquioxane, prepared by the method described below.

Preparation of PPSQ 1 mmol of trimethoxyphenylsilane, 1.5 mL of tetrahydrofuran as a solvent, 60 μL of formic acid as an acid catalyst, and 60 μL of water were mixed, and the mixture was heated and stirred at 90° C. for 3 hours to carry out hydrolysis and condensation reactions and was dried to solidify. After cooling, the remaining acid was washed away with pure water, and then 1.5 mL of tetrahydrofuran was added to make a solution again, which was heated and stirred at 110° C. for 2 hours and dried to solidify, thereby synthesizing polyphenylsilsesquioxane (PPSQ, a compound represented by the following formula).

In Table 5, for the coating film using the fluorene compound (BEPF-Ph or BMPF-Ph) in Examples 1 and 2, the excitation spectrum at an emission wavelength of 400 nm and the emission spectrum at an excitation wavelength of 320 nm were measured; for the coating film using BEPF-Np in Example 3, the excitation spectrum at an emission wavelength of 450 nm and the emission spectrum at an excitation wavelength of 330 nm were measured; for the coating film using BEPF-BPh in Example 4, the excitation spectrum at an emission wavelength of 450 nm and the emission spectrum at an excitation wavelength of 320 nm were measured.

As is clear from Table 5 and Figures 19 to 42, the fluorene compounds obtained in the examples were able to emit light with a relatively narrow half-width in the short wavelength region of about 350 to 400 nm, even in the form of a coating film, and demonstrated high luminescence quantum efficiency.

In the coating film of the fluorene compound of Examples 1 and 2 in which the rings Z ^1a and Z ^1b are benzene rings, when the binder component is PMMA or PPSQ, especially PPSQ, in the example in which the mass ratio of the fluorene compound to the binder component is 1/10, the luminescence quantum efficiency can be greatly improved compared to the example in which it is 1/1. The reason for this is unclear, but it is presumed that the ratio of the fluorene compound, which is the luminescent material, is reduced to reduce the effect of concentration quenching. On the other hand, when the binder component is PS, a relatively high luminescence quantum efficiency is obtained even when the mass ratio is 1/1 and the fluorene compound is contained at a high concentration, and it is presumed that the fluorene compound is easily dispersed in PS without agglomeration, and is in a state in which concentration quenching is difficult to occur. Conversely, when the binder component is PC, the luminescence quantum efficiency is lower than in PS regardless of the concentration, so it is presumed that the fluorene compound forms aggregates of a certain size and disperses in PC, and is under the influence of a certain degree of concentration quenching.

In addition, in the coating films of Examples 3 and 4 in which the rings Z ^1a and Z ^1b are polycyclic arene rings, λ _em,max shifted slightly to the long wavelength side compared to the coating films of Examples 1 and 2, showing the same tendency as in the solid and solution states. In addition, when the luminescence quantum efficiency of the coating film of Example 3, the coating film of Example 4, and the coating films of Examples 1 and 2 were compared at the same concentration, it was presumed that the binder components that gave higher luminescence quantum efficiency were different, and the type of rings Z ^1a and Z ^1b greatly influenced the compatibility with the binder component. In particular, in the coating film of Example 4 in which the rings Z ^1a and Z ^1b were biphenyl rings, a relatively high luminescence quantum efficiency was obtained regardless of the binder component. In addition, the half-width in the emission spectrum of the fluorene compound of Example 4 was slightly wider in the solid and solution states than in Examples 1 to 3, but no significant difference was observed in the coating film state.

The fluorene compound of the present invention can be effectively used as a light-emitting material and/or a sensitizer. In particular, unlike inorganic light-emitting bodies formed from inorganic materials, the fluorene compound is soluble in organic solvents and can be easily dispersed uniformly in matrix materials such as various resins, and therefore can easily and efficiently form a coating layer or coating film on substrates with complex shapes. Therefore, the fluorene compound can be effectively used as a light-emitting material and/or a sensitizer in applications such as coating agents for invisible inks, light-emitting elements (or photoelectric conversion elements), etc.

Light-emitting elements (or photoelectric conversion elements) include, for example, current-injection type light-emitting elements such as organic EL elements. Representative examples include ultraviolet light sources (UV lamps), specifically, light sources for sterilization, analysis, and high color rendering white LEDs; visible light sources, specifically, light sources for displays, lighting, and other uses.

In addition, the fluorene compounds of the present invention have excellent heat resistance, so they can be effectively used as additives such as heat resistance improvers and resin modifiers.

Claims (8)

The following formula (1)

(In the formula, Z ^1a and Z ^{1b each} represent a benzene ring ;
Z ^2a and Z ^2b each represent a benzene ring;
R ^1a , R ^1b , R ^3a and R ^3b each independently represent at least one selected from the group consisting of an alkyl group, a cycloalkyl group, a halogen atom, a hydroxyl group, a group [-OR ^A ] (wherein R ^A represents an alkyl group or a cycloalkyl group), a hydroxy(poly)alkoxy group, a thiol group, a group [-SR ^A ] (wherein R ^A represents an alkyl group or a cycloalkyl group) , a carboxyl group, an alkoxycarbonyl group, an amino group , a cyano group and a nitro group;
^R2a and ^R2b each independently represent at least one selected from the group consisting of an alkyl group, a halogen atom, and a cyano group;
A ^1a and A ^1b each independently represent a linear or branched C _1-4 alkylene group;
k1 and k2 each independently represent an integer of 0 or more;
m1 and m2 each represent 1;
n1 and n2 each independently represent an integer of 0 to 3 ;
p1 and p2 each independently represent an integer of 0 or more;
m1+n1 and m2+n2 each independently represent an integer of 1 to 4.
It is expressed as
A luminescent composition comprising a compound having an emission spectrum in a solid state that includes at least one emission peak having a maximum wavelength λ _em,max of 350 to 450 nm and a half-width of 60 nm or less, and has a luminescence quantum efficiency of 40% or more. The luminescent composition according to claim 1, wherein the compound represented by formula (1) is a luminescent material and/or a sensitizer. The luminescent composition according to claim 1 or 2, which is a coating agent. The following formula (2)

(In the formula, X ^1a and X ^1b each independently represent a halogen atom and/or a fluorinated alkanesulfonyloxy group, or a boronic acid group and/or a boronic acid ester group; Z ^2a , Z ^2b , R ^2a , R 2b , R ^3a , R ^3b , A ^1a , A ^1b , m1, m2, n1, n2, p1 and p2 are the same as in formula (1), ^and m1+n1 and m2+n2 each independently represent an integer of 1 to 4.)
and a compound represented by the following formula (3):

(In the formula, ^X2 represents a boronic acid group and/or a boronic acid ester group, or a halogen atom and/or a fluorinated alkanesulfonyloxy group, ^Z1 is the same as ^Z1a and/or ^Z1b in the formula (1), ^R1 is the same as ^R1a and/or ^R1b in the formula (1), and k is the same as k1 and/or k2 in the formula (1).
A method for producing the luminescent composition according to any one of claims 1 to 3, comprising a step of coupling reaction with a compound represented by the following formula: The following formula (4)

(In the formula, Z ^1a , Z ^1b , R ^1a , R ^1b , R ^2a , R ^2b , k1, k2, m1, m2, n1 and n2 are the same as in formula (1), and m1+n1 and m2+n2 each independently represent an integer of 1 to 4.)
and a compound represented by the following formula (5):

(wherein ^X3 represents a halogen atom, ^Z2 is the same as ^Z2a and/or ^Z2b in formula (1), ^R3 is the same as ^R3a and/or ^R3b in formula (1), ^A1 is the same as ^A1a and/or ^A1b in formula (1), and p is the same as p1 and/or p2 in formula (1).
A method for producing the luminescent composition according to any one of claims 1 to 3, comprising a step of reacting a compound represented by the following formula: A method for exciting a compound represented by formula (1) according to any one of claims 1 to 3 , which has an emission spectrum in a solid state, includes at least one emission peak having a maximum wavelength λ _em,max of 350 to 450 nm and a half-width of 60 nm or less, and has an emission quantum efficiency of 40% or more , to emit light. A method for detecting light emitted from a coating film formed from the luminescent composition according to any one of claims 1 to 3 by irradiating the coating film with light using a detection device equipped with at least a detector. A light-emitting device comprising a compound represented by formula (1) according to any one of claims 1 to 3 , which has an emission spectrum in a solid state, at least one emission peak having a maximum wavelength λ _em,max of 350 to 450 nm and a half-width of 60 nm or less, and has a luminescence quantum efficiency of 40% or more .

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