Compound, light-absorbing material, nonlinear light-absorbing material, recording medium, information recording method, and information reading method

Abstract

A compound according to one embodiment of the present disclosure is represented by formula (1).　In formula (1), R1 to R22 each independently include at least one atomic element selected from the group consisting of H, B, C, N, O, F, Si, P, S, Cl, I, and Br; and L1 and L2 each independently represent a single bond or -C≡C-.

Description

[Technical Field]

[0001] The present disclosure relates to compounds, light-absorbing materials, nonlinear light-absorbing materials, recording media, methods for recording information, and methods for reading information. [Background technology]

[0002] Among optical materials, such as light-absorbing materials, materials that exhibit nonlinear optical effects are called nonlinear optical materials. Nonlinear optical effects refer to the occurrence of optical phenomena in a material when irradiated with intense light, such as laser light, that are proportional to the square or higher-order of the electric field of the irradiated light. Examples of optical phenomena include absorption, reflection, scattering, and light emission. Second-order nonlinear optical effects, which are proportional to the square of the electric field of the irradiated light, include second-harmonic generation (SHG), the Pockels effect, and the parametric effect. Third-order nonlinear optical effects, which are proportional to the cube of the electric field of the irradiated light, include two-photon absorption, multi-photon absorption, third-harmonic generation (THG), and the Kerr effect. In this specification, multi-photon absorption, such as two-photon absorption, is sometimes referred to as nonlinear optical absorption. Materials capable of nonlinear optical absorption are sometimes referred to as nonlinear optical absorption materials. In particular, materials capable of two-photon absorption are sometimes referred to as two-photon absorption materials. Note that nonlinear optical absorption is also sometimes referred to as nonlinear absorption.

[0003] Much research has been conducted on nonlinear optical materials. In particular, inorganic materials that can be easily prepared as single crystals have been developed as nonlinear optical materials. In recent years, the development of nonlinear optical materials made from organic materials has been anticipated. Compared to inorganic materials, organic materials not only have a high degree of design freedom but also have large nonlinear optical constants. Furthermore, organic materials exhibit high-speed nonlinear response. In this specification, nonlinear optical materials containing organic materials may be referred to as organic nonlinear optical materials. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5769151 [Patent Document 2] Patent No. 5659189 [Patent Document 3] Patent No. 5821661 [Non-patent literature]

[0005] [Non-Patent Document 1] Harry L. Anderson et al, "Two-Photon Absorption and the Design of Two-Photon Dyes", Angew. Chem. Int. Ed. 2009, Vol. 48, p. 3244-3266. Summary of the Invention [Problem to be solved by the invention]

[0006] There is a need for new compounds that have nonlinear optical absorption properties for light having wavelengths in the short wavelength region. [Means for solving the problem]

[0007] The compound according to one embodiment of the present disclosure is represented by the following formula (1): [ka] In the formula (1), R 1 From R 22 each independently contains at least one atom selected from the group consisting of H, B, C, N, O, F, Si, P, S, Cl, I and Br, and L 1 and L 2 are each independently a single bond or -C≡C-.

[0008] However, the compound satisfies the following requirements (a) and (b). (a) The above R 1 , the R 2 , the R 6 , the R 7, the R 12 , the R 17 , and the R 22 is a substituent other than a substituent containing an aromatic ring. (b) The above R 1 From the R 22 are each independently a hydrogen atom or a Hammett substituent constant σ p is a substituent in which the value is in the range of -0.2 or more and 0.2 or less. [Effects of the Invention]

[0009] The present disclosure provides a new compound that has nonlinear optical absorption properties for light having wavelengths in the short wavelength region. [Brief explanation of the drawings]

[0010] [Figure 1A] FIG. 1A is a flowchart showing a method for recording information using a recording medium containing a compound according to one embodiment of the present disclosure. [Figure 1B] FIG. 1B is a flowchart illustrating a method for reading information using a recording medium including a compound according to one embodiment of the present disclosure. [Figure 2] FIG. 2 is a graph showing the 1H-NMR spectrum of compound (2)-1. [Figure 3] FIG. 3 is a graph showing the 1H-NMR spectrum of compound (3)-1. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Findings that formed the basis of this disclosure) Among organic nonlinear optical materials, two-photon absorption materials have attracted particular attention. Two-photon absorption refers to the phenomenon in which a compound absorbs two photons almost simultaneously and transitions to an excited state. Known two-photon absorption types include simultaneous two-photon absorption and stepwise two-photon absorption. Simultaneous two-photon absorption is sometimes called non-resonant two-photon absorption. Simultaneous two-photon absorption refers to two-photon absorption in a wavelength range where no single-photon absorption band exists. Stepwise two-photon absorption is sometimes called resonant two-photon absorption. In stepwise two-photon absorption, a compound absorbs the first photon and then absorbs the second photon, transitioning to a higher excited state. In stepwise two-photon absorption, a compound absorbs two photons sequentially.

[0012] In simultaneous two-photon absorption, the amount of light absorbed by a compound is typically proportional to the square of the irradiated light intensity and exhibits nonlinearity. The amount of light absorbed by a compound can be used as an indicator of the efficiency of two-photon absorption. When the amount of light absorbed by a compound exhibits nonlinearity, for example, light absorption by the compound can occur only near the focus of a laser beam with a high electric field strength. In other words, in a sample containing a two-photon absorbing material, the compound can be excited only at the desired position. Compounds that exhibit simultaneous two-photon absorption thus provide extremely high spatial resolution and are therefore being considered for use in applications such as recording layers for three-dimensional optical memories and photocurable resin compositions for stereolithography. If the two-photon absorbing material also possesses fluorescent properties, it can also be used as a fluorescent dye material for two-photon fluorescence microscopes. Using this two-photon absorbing material in three-dimensional optical memories may enable the adoption of a method for reading the ON / OFF state of the recording layer based on changes in fluorescence from the two-photon absorbing material. Current optical memories use a method to read the ON / OFF state of a recording layer based on changes in the light reflectance and light absorption rate of a two-photon absorbing material. However, when this method is applied to a three-dimensional optical memory, crosstalk can occur due to the fact that the two-photon absorption efficiency of conventional two-photon absorbing materials is lower than the one-photon absorption efficiency, which means that the ON / OFF state of other recording layers may be read.

[0013] In two-photon absorption materials, the two-photon absorption cross section (GM value) is used as an index of two-photon absorption efficiency. The unit of the two-photon absorption cross section is GM (10 -50 cm 4 ·s·molecule -1 photon -1 ) Up to now, many organic two-photon absorption materials with large two-photon absorption cross sections have been proposed. For example, many compounds with large two-photon absorption cross sections exceeding 500 GM have been reported (e.g., Non-Patent Document 1). However, in most reports, the two-photon absorption cross section was measured using laser light with a wavelength longer than 600 nm. In particular, near-infrared light with a wavelength longer than 750 nm is sometimes used as the laser light.

[0014] However, in order to apply two-photon absorption materials to industrial applications, materials that exhibit two-photon absorption properties when irradiated with laser light having a shorter wavelength are required. For example, in the field of three-dimensional optical memory, laser light having a shorter wavelength can realize a finer focused spot, thereby improving the recording density of three-dimensional optical memory. In the field of stereolithography, laser light having a shorter wavelength can realize modeling with higher resolution. Furthermore, the Blu-ray (registered trademark) disc standard uses laser light with a central wavelength of 405 nm. Thus, the development of compounds that exhibit excellent two-photon absorption properties for light in the same wavelength range as short-wavelength laser light would greatly contribute to industrial development.

[0015] Furthermore, light-emitting devices that emit high-intensity ultrashort pulse lasers tend to be large and unstable in operation. Therefore, such light-emitting devices are difficult to adopt for industrial applications from the viewpoints of versatility and reliability. In consideration of this, in order to apply two-photon absorption materials to industrial applications, materials that exhibit two-photon absorption properties even when irradiated with low-intensity laser light are required.

[0016] In a compound having two-photon absorption properties, the relationship between light intensity and two-photon absorption properties is expressed by the following formula (i). In this specification, a compound having two-photon absorption properties may be referred to as a two-photon absorption compound. Formula (i) is a calculation formula for calculating the decrease in light intensity -dI when a sample containing a two-photon absorption compound and having a minute thickness dz is irradiated with light of intensity I. As can be seen from formula (i), the decrease in light intensity -dI is expressed as the sum of a term proportional to the first power of the intensity I of the light incident on the sample and a term proportional to the square of the intensity I.

number

[0017] In formula (i), α is the one-photon absorption coefficient (cm -1 ) α (2) is the two-photon absorption coefficient (cm / W). From equation (i), it is clear that the intensity I of the incident light when the one-photon absorption amount and the two-photon absorption amount are equal in the sample is α / α (2) In other words, the intensity of the incident light I is expressed as α / α (2) When the incident light intensity I is smaller than α / α, one-photon absorption occurs predominantly in the sample. (2) When the α / α ratio in the sample is larger than α, two-photon absorption occurs preferentially. (2) The smaller the value of , the more likely it is that two-photon absorption can be preferentially exhibited by laser light with a lower light intensity.

[0018] Furthermore, α and α (2) can be expressed by the following formulas (ii) and (iii), respectively. In formulas (ii) and (iii), ε is the molar absorption coefficient (mol -1 L cm -1 ) where N is the number of molecules of the compound per unit volume of the sample (mol cm -3 ) N A is the Avogadro constant. σ is the two-photon absorption cross section (GM). h-(Hbar) is the Dirac constant (J·s). ω is the angular frequency of the incident light (rad / s).

number

[0019] From equations (ii) and (iii), α / α (2) is determined by ε / σ. In other words, in order to preferentially induce two-photon absorption using low-intensity laser light, it is desirable that the ratio σ / ε of the two-photon absorption cross section σ to the molar extinction coefficient ε be large for the wavelength of the irradiated laser light. When the ratio σ / ε is large at a specific wavelength for a compound, it can be said that the nonlinearity of light absorption at that wavelength is high.

[0020] Patent Documents 1 and 2 disclose compounds having a large two-photon absorption cross section for light having a wavelength around 405 nm. Patent Document 3 discloses an optical information recording medium that can shorten the writing time when using laser light having a wavelength around 405 nm, and a compound contained in the optical information recording medium.

[0021] Patent Documents 1 and 3 describe compounds with large π-electron conjugated systems. Furthermore, Patent Document 2 describes benzophenone derivatives with large π-electron conjugated systems. However, when the π-electron conjugated system of a compound is enlarged, the two-photon absorption cross section increases, while the peak resulting from one-photon absorption tends to shift to a longer wavelength region. In this specification, the shift of the peak resulting from one-photon absorption to a longer wavelength region is sometimes referred to as a long-wavelength shift or red shift. As a result of the long-wavelength shift of the peak resulting from one-photon absorption, part of the wavelength region where one-photon absorption occurs may overlap with the wavelength of the excitation light. An example of the wavelength of the excitation light is 405 nm, as specified by the Blu-ray (registered trademark) standard. In a compound, when the one-photon absorption due to the excitation light is large, the nonlinearity of the optical absorption tends to decrease. Compounds with low nonlinearity of optical absorption are not suitable for the recording layer of a multilayered three-dimensional optical memory.

[0022] Furthermore, the quantum yield of intersystem crossing is almost 100% in the benzophenone derivative disclosed in Patent Document 2. This benzophenone derivative undergoes a rapid transition from the singlet excited state to the triplet excited state, and therefore emits almost no fluorescence.

[0023] As a result of extensive investigations, the present inventors have newly discovered that a compound represented by the formula (1) described below has high nonlinear optical absorption properties for light having a wavelength in the short wavelength range. Specifically, the present inventors have discovered that the compound represented by the formula (1) has a large value of σ / ε, the ratio of the two-photon absorption cross section σ to the molar extinction coefficient ε, for light having a wavelength in the short wavelength range, and tends to have high nonlinear optical absorption. Furthermore, this compound also tends to have fluorescent properties. In this specification, the short wavelength range refers to a wavelength range including 405 nm, for example, a wavelength range of 390 nm to 420 nm.

[0024] (Summary of one aspect of the present disclosure) The compound according to the first aspect of the present disclosure is represented by the following formula (1): [ka] In the formula (1), R 1 From R 22 each independently contains at least one atom selected from the group consisting of H, B, C, N, O, F, Si, P, S, Cl, I and Br, and L 1 and L 2 are each independently a single bond or -C≡C-.

[0025] However, the compound satisfies the following requirements (a) and (b). (a) The above R 1 , the R 2 , the R 6 , the R 7 , the R 12 , the R 17 , and the R 22 is a substituent other than a substituent containing an aromatic ring. (b) The above R 1 From the R 22are each independently a hydrogen atom or a Hammett substituent constant σ p is a substituent in which the value is in the range of -0.2 or more and 0.2 or less.

[0026] The compound according to the first aspect tends to have a large ratio σ / ε of the two-photon absorption cross section σ to the molar extinction coefficient ε for light having a wavelength in the short wavelength range, and thus has a high degree of nonlinearity in optical absorption. Thus, the compound has improved nonlinear optical absorption properties for light having a wavelength in the short wavelength range. The compound according to the first aspect also tends to have fluorescent properties.

[0027] According to requirement (b), R 1 From R 22 Even if the group has a substituent, the substituent constant σ p is close to 0, and the electron-withdrawing and electron-donating properties of the substituent are small. Therefore, it is possible to prevent the energy of the highest occupied molecular orbital (HOMO: Highest Occupied Molecular Orbital) of the compound from increasing and the energy of the lowest unoccupied molecular orbital (LUMO: Lowest Unoccupied Molecular Orbital) from decreasing, which are caused by the electron-withdrawing or electron-donating properties of the substituent. In other words, it is possible to prevent the energy gap between the HOMO and the LUMO from decreasing. This prevents the peak resulting from one-photon absorption from shifting to longer wavelengths, and prevents a decrease in the ratio σ / ε for light having a wavelength in the short wavelength range. Compounds that satisfy requirement (b) tend to have higher nonlinearity in optical absorption for light having a wavelength in the short wavelength range.

[0028] In the second aspect of the present disclosure, for example, the compound according to the first aspect may be represented by the following formula (2): [ka]

[0029] In the third aspect of the present disclosure, for example, the compound according to the first aspect may be represented by the following formula (3): [ka]

[0030] In a fourth aspect of the present disclosure, for example, in a compound according to any one of the first to third aspects, R 1 From the R 22 may be, independently of one another, a hydrogen atom, a halogen atom, a hydrocarbon group, a halogenated hydrocarbon group, a substituent containing an oxygen atom, a substituent containing a nitrogen atom, a substituent containing a sulfur atom, a substituent containing a silicon atom, a substituent containing a phosphorus atom, or a substituent containing a boron atom.

[0031] According to the second to fourth aspects, the compound has improved nonlinear optical absorption properties for light having a wavelength in the short wavelength region. The compounds according to the second to fourth aspects also tend to have fluorescent properties. The compounds are suitable for use in devices that utilize light having a wavelength of 390 nm or more and 420 nm or less.

[0032] In a fifth aspect of the present disclosure, for example, in a compound according to any one of the first to fourth aspects, the R 1 From the R 22 may each be a hydrogen atom.

[0033] The compound according to the fifth embodiment tends to have higher nonlinearity in light absorption for light having a wavelength in the short wavelength region.

[0034] In the sixth aspect of the present disclosure, for example, the compound according to any one of the first to fifth aspects may be used in a device that utilizes light having a wavelength of 390 nm or more and 420 nm or less.

[0035] According to the sixth aspect, the compound is suitable for use in a device that utilizes light having a wavelength of 390 nm or more and 420 nm or less.

[0036] A light-absorbing material according to a seventh aspect of the present disclosure includes a compound according to any one of the first to sixth aspects.

[0037] According to the seventh aspect, the light-absorbing material has improved nonlinear light absorption characteristics for light having a wavelength in the short wavelength range.

[0038] A nonlinear optically absorbing material according to an eighth aspect of the present disclosure includes a compound according to any one of the first to sixth aspects.

[0039] According to the eighth aspect, in the nonlinear optical absorption material, the nonlinear optical absorption characteristics for light having a wavelength in the short wavelength region are improved.

[0040] A recording medium according to a ninth aspect of the present disclosure comprises a recording layer containing a compound according to any one of the first to sixth aspects.

[0041] According to the ninth aspect, the compound has improved nonlinear optical absorption characteristics for light having a wavelength in the short wavelength region. The compound used in the ninth aspect also tends to have fluorescent properties. A recording medium having a recording layer containing such a compound can record information at a high recording density.

[0042] An information recording method according to a tenth aspect of the present disclosure includes: providing a light source that emits light having a wavelength of 390 nm or more and 420 nm or less; and condensing the light from the light source and irradiating the light onto the recording layer of the recording medium according to the ninth aspect.

[0043] According to the tenth aspect, the compound has improved nonlinear optical absorption characteristics for light having a wavelength in the short wavelength region. The compound used in the tenth aspect also tends to have fluorescent properties. According to a method for recording information using a recording medium containing such a compound, information can be recorded at a high recording density.

[0044] A method for reading information according to an eleventh aspect of the present disclosure is, for example, a method for reading the information recorded by the recording method according to the tenth aspect, measuring optical characteristics of the recording layer by irradiating the recording layer of the recording medium with light; and reading the information from the recording layer.

[0045] In a twelfth aspect of the present disclosure, for example, in the information reading method according to the eleventh aspect, the optical property may be the intensity of fluorescent light emitted from the recording layer.

[0046] According to the eleventh or twelfth aspect, when reading out information, it is possible to suppress the occurrence of crosstalk due to other recording layers.

[0047] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments.

[0048] (Embodiment) Compound A of this embodiment is represented by the following formula (1). [ka]

[0049] In formula (1), R 1 From R 22 R each independently contain at least one atom selected from the group consisting of H, B, C, N, O, F, Si, P, S, Cl, I and Br. 1 From R 22 may be, independently of one another, a hydrogen atom, a halogen atom, a hydrocarbon group, a halogenated hydrocarbon group, a substituent containing an oxygen atom, a substituent containing a nitrogen atom, a substituent containing a sulfur atom, a substituent containing a silicon atom, a substituent containing a phosphorus atom, or a substituent containing a boron atom.

[0050] Examples of halogen atoms include F, Cl, Br, and I. In this specification, halogen atoms may be referred to as halogen groups.

[0051] The number of carbon atoms in the hydrocarbon group is not particularly limited and may be, for example, 1 to 20, or may be 1 to 10, or may be 1 to 5. By adjusting the number of carbon atoms in the hydrocarbon group, it is possible to adjust the solubility of compound A in a solvent or resin composition. The hydrocarbon group may be linear, branched, or cyclic.

[0052] Examples of the hydrocarbon group include saturated aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, and unsaturated aliphatic hydrocarbon groups. The saturated aliphatic hydrocarbon group may be an alkyl group. Examples of the saturated aliphatic hydrocarbon group include -CH3, -CH2CH3, -CH2CH2CH3, -CH(CH3)2, -CH(CH3)CH2CH3, -C(CH3)3, -CH2CH(CH3)2, -(CH2)3CH3, -(CH2)4CH3, -C(CH2CH3)(CH3)2, -CH2C(CH3)3, -(CH2)5CH3, -(CH2)6CH3, -(CH2)7CH3, -(CH2)8CH3, -(CH2)9CH3, and -(CH2) 10 CH3, -(CH2) 11 CH3, -(CH2) 12 CH3, -(CH2) 13 CH3, -(CH2) 14 CH3, -(CH2) 15 CH3, -(CH2) 16 CH3, -(CH2) 17 CH3, -(CH2) 18 CH3, -(CH2) 19 Examples of the alicyclic hydrocarbon group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and an adamantyl group. Examples of the aliphatic unsaturated hydrocarbon group include -CH=CH2, -C≡CH, -C≡CCH3, -C(CH3)=CH2, -CH=CHCH3, and -CH2CH=CH2.

[0053] A halogenated hydrocarbon group refers to a group in which at least one hydrogen atom contained in a hydrocarbon group is substituted with a halogen atom. The halogenated hydrocarbon group may be a group in which all hydrogen atoms contained in the hydrocarbon group are substituted with halogen atoms. Examples of halogenated hydrocarbon groups include halogenated alkyl groups and halogenated alkenyl groups.

[0054] Examples of halogenated alkyl groups include -CF3, -CH2F, -CH2Br, -CH2Cl, -CH2I, -CH2CF3, etc. Examples of halogenated alkenyl groups include -CH=CHCF3, etc.

[0055] The substituent containing an oxygen atom is, for example, a substituent having at least one selected from the group consisting of a hydroxyl group, a carboxyl group, an aldehyde group, an ether group, an acyl group, and an ester group.

[0056] Examples of the substituent having a hydroxyl group include a hydroxyl group itself and a hydrocarbon group having a hydroxyl group. In this substituent, the hydroxyl group can be deprotonated to form -O - Examples of hydrocarbon groups having a hydroxyl group include -CH2OH, -CH(OH)CH3, -CH2CH(OH)CH3, and -CH2C(OH)(CH3)2.

[0057] Examples of substituents having a carboxyl group include the carboxyl group itself and hydrocarbon groups having a carboxyl group. In this substituent, the carboxyl group can be deprotonated to -CO2 - The hydrocarbon group having a carboxyl group may be in the form of -CH2CH2COOH, -C(COOH)(CH3)2, -CH2CO2 - Examples include:

[0058] Examples of the substituent having an aldehyde group include the aldehyde group itself and hydrocarbon groups having an aldehyde group, such as -CH=CHCHO.

[0059] Examples of substituents having an ether group include an alkoxy group, a halogenated alkoxy group, an alkenyloxy group, an oxiranyl group, and a hydrocarbon group having at least one of these functional groups. At least one hydrogen atom contained in the alkoxy group may be substituted with a group containing at least one atom selected from the group consisting of N, O, P, and S. Examples of the alkoxy group include a methoxy group, an ethoxy group, a 2-methoxyethoxy group, a butoxy group, a 2-methylbutoxy group, a 2-methoxybutoxy group, a 4-ethylthiobutoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, a decyloxy group, an undecyloxy group, a dodecyloxy group, a tridecyloxy group, a tetradecyloxy group, a pentadecyloxy group, a hexadecyloxy group, a heptadecyloxy group, an octadecyloxy group, a nonadecyloxy group, an eicosyloxy group, -OCHO - , -OCH2CH2O - , -O(CH2)3O - Examples of halogenated alkoxy groups include -OCHF2, -OCH2F, and -OCH2Cl. Examples of alkenyloxy groups include -OCH=CH2. Examples of hydrocarbon groups having a functional group such as an alkoxy group include -CH2OCH3, -C(OCH3)3, a 2-methoxybutyl group, and a 6-methoxyhexyl group.

[0060] Examples of substituents having an acyl group include the acyl group itself and hydrocarbon groups having an acyl group. Examples of acyl groups include -COCH3. Examples of hydrocarbon groups having an acyl group include -CH=CHCOCH3.

[0061] Examples of substituents having an ester group include an alkoxycarbonyl group, an acyloxy group, and a hydrocarbon group having at least one of these functional groups. Examples of alkoxycarbonyl groups include -COOCH3, -COO(CH2)3CH3, and -COO(CH2)7CH3. Examples of acyloxy groups include -OCOCH3. Examples of hydrocarbon groups having a functional group such as an acyloxy group include -CH2OCOCH3.

[0062] The nitrogen atom-containing substituent is, for example, a substituent having at least one selected from the group consisting of an amino group, an imino group, a cyano group, an azido group, an amide group, a carbamate group, a nitro group, a cyanamide group, an isocyanate group, and an oxime group.

[0063] Examples of substituents having an amino group include primary amino groups, secondary amino groups, tertiary amino groups, quaternary amino groups, and hydrocarbon groups having at least one of these functional groups. In these substituents, the amino group may be protonated. Examples of tertiary amino groups include -N(CH3)2. Examples of hydrocarbon groups having a functional group such as a primary amino group include -CH2NH2, -CH2N(CH3)2, -(CH2)4N(CH3)2, and -CH2CH2NH3. + , -CH2CH2NH(CH3)2 + , -CH2CH2N(CH3)3 + Examples include:

[0064] Examples of the substituent having an imino group include the imino group itself and hydrocarbon groups having an imino group. Examples of the imino group include -N=CCl2.

[0065] Examples of substituents having a cyano group include the cyano group itself and hydrocarbon groups having a cyano group, such as -CHCN and -CH=CHCN.

[0066] Examples of the substituent having an azido group include the azido group itself and a hydrocarbon group having an azido group.

[0067] Examples of substituents having an amide group include the amide group itself and hydrocarbon groups having an amide group. Examples of amide groups include -CONH, -NHCHO, -NHCOCH, -NHCOCF, -NHCOCHCl, and -NHCOCH(CH). Examples of hydrocarbon groups having an amide group include -CHCONH and -CHNHCOCH.

[0068] Examples of substituents having a carbamate group include the carbamate group itself and hydrocarbon groups having a carbamate group, such as -NHCOOCH3, -NHCOOCH2CH3, and -NHCO2(CH2)3CH3.

[0069] Examples of substituents having a nitro group include the nitro group itself and hydrocarbon groups having a nitro group, such as —C(NO2)(CH3)2.

[0070] Examples of the substituent having a cyanamide group include the cyanamide group itself and a hydrocarbon group having a cyanamide group. The cyanamide group is represented by —NHCN.

[0071] Examples of the substituent having an isocyanate group include the isocyanate group itself and a hydrocarbon group having an isocyanate group. The isocyanate group is represented by —N═C═O.

[0072] Examples of the substituent having an oxime group include the oxime group itself and a hydrocarbon group having an oxime group. The oxime group is represented by -CH=NOH.

[0073] The substituent containing a sulfur atom is, for example, a substituent having at least one selected from the group consisting of a thiol group, a sulfide group, a sulfinyl group, a sulfonyl group, a sulfino group, a sulfonic acid group, an acylthio group, a sulfenamide group, a sulfonamide group, a thioamide group, a thiocarbamide group, and a thiocyano group.

[0074] Examples of the substituent having a thiol group include a thiol group itself and a hydrocarbon group having a thiol group. The thiol group is represented by -SH.

[0075] Examples of substituents having a sulfide group include alkylthio groups, alkyldithio groups, alkenylthio groups, alkynylthio groups, thiacyclopropyl groups, and hydrocarbon groups having at least one of these functional groups. At least one hydrogen atom contained in the alkylthio group may be substituted with a halogen group. Examples of alkylthio groups include -SCH3, -S(CH2)F, -SCH(CH3)2, and -SCH2CH3. Examples of alkyldithio groups include -SSCH3. Examples of alkenylthio groups include -SCH=CH2 and -SCH2CH=CH2. Examples of alkynylthio groups include -SC≡CH. Examples of hydrocarbon groups having a functional group such as an alkylthio group include -CH2SCF3.

[0076] Examples of the substituent having a sulfinyl group include the sulfinyl group itself and a hydrocarbon group having a sulfinyl group. Examples of the sulfinyl group include -SOCH3.

[0077] Examples of substituents having a sulfonyl group include the sulfonyl group itself and hydrocarbon groups having a sulfonyl group. Examples of sulfonyl groups include -SO2CH3. Examples of hydrocarbon groups having a sulfonyl group include -CH2SO2CH3 and -CH2SO2CH2CH3.

[0078] Examples of the substituent having a sulfino group include the sulfino group itself and a hydrocarbon group having a sulfino group. In this substituent, the sulfino group can be deprotonated to form -SO2 - It may be in the state of

[0079] Examples of the substituent having a sulfonic acid group include the sulfonic acid group itself and a hydrocarbon group having a sulfonic acid group. In this substituent, the sulfonic acid group can be deprotonated to form -SO3 - It may be in the state of

[0080] Examples of substituents having an acylthio group include the acylthio group itself and hydrocarbon groups having an acylthio group. Examples of the acylthio group include -SCOCH3.

[0081] Examples of the substituent having a sulfenamide group include the sulfenamide group itself and a hydrocarbon group having a sulfenamide group. Examples of the sulfenamide group include -SN(CH3)2.

[0082] Examples of the substituent having a sulfonamide group include the sulfonamide group itself and hydrocarbon groups having a sulfonamide group. Examples of the sulfonamide group include -SO2NH2 and -NHSO2CH3.

[0083] Examples of substituents having a thioamide group include the thioamide group itself and hydrocarbon groups having a thioamide group. Examples of thioamide groups include -NHCSCH3 and the like. Examples of hydrocarbon groups having a thioamide group include -CH2SC(NH2)2 + Examples include:

[0084] Examples of substituents having a thiocarbamide group include the thiocarbamide group itself and hydrocarbon groups having a thiocarbamide group. Examples of the thiocarbamide group include -NHCSNHCH2CH3.

[0085] Examples of substituents having a thiocyano group include the thiocyano group itself and hydrocarbon groups having a thiocyano group, such as —CH2SCN.

[0086] The silicon atom-containing substituent is, for example, a substituent having at least one group selected from the group consisting of a silyl group and a siloxy group.

[0087] Substituents having a silyl group include the silyl group itself and hydrocarbon groups having a silyl group. Examples of silyl groups include -Si(CH3)3, -SiH(CH3)2, -Si(OCH3)3, -Si(OCH2CH3)3, -SiCH3(OCH3)2, -Si(CH3)2OCH3, -Si(N(CH3)2)3, -SiF(CH3)2, -Si(OSi(CH3)3)3, and -Si(CH3)2OSi(CH3)3. Examples of hydrocarbon groups having a silyl group include -(CH2)2Si(CH3)3.

[0088] Examples of the substituent having a siloxy group include the siloxy group itself and hydrocarbon groups having a siloxy group, such as -CH2OSi(CH3)3.

[0089] The substituent containing a phosphorus atom is, for example, a substituent having at least one group selected from the group consisting of a phosphino group and a phosphoryl group.

[0090] Examples of the substituent having a phosphino group include the phosphino group itself and hydrocarbon groups having a phosphino group, such as -PH2, -P(CH3)2, -P(CH2CH3)2, -P(C(CH3)3)2, and -P(CH(CH3)2)2.

[0091] Examples of substituents having a phosphoryl group include the phosphoryl group itself and hydrocarbon groups having a phosphoryl group, such as —CH2PO(OCH2CH3)2.

[0092] An example of a substituent containing a boron atom is a substituent having a boronic acid group. Examples of the substituent having a boronic acid group include the boronic acid group itself and a hydrocarbon group having a boronic acid group.

[0093] However, compound A satisfies the following requirements (a) and (b). (a)R 1 , R 2 , R 6 , R 7 , R 12 , R 17 , and R 22 is a substituent other than a substituent containing an aromatic ring. (b)R 1 From R 22 are each independently a hydrogen atom or a Hammett substituent constant σ p is a substituent in which the value is in the range of -0.2 or more and 0.2 or less.

[0094] In requirement (a), R 1 , R 2 , R 6 , R 7 , R 12 , R 17 , and R 22 does not contain an aromatic ring. Aromatic rings include not only those composed of carbon atoms but also heteroaromatic rings containing heteroatoms such as oxygen atoms, nitrogen atoms, and sulfur atoms. Examples of aromatic rings include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a furan ring, a pyrrole ring, a pyridine ring, and a thiophene ring. Specific examples of substituents containing an aromatic ring include an aryl group (-Ar) and an arylethynyl group (-C≡C-Ar). R 1 From R 22 may be a substituent other than a substituent containing an aromatic ring.

[0095] In requirement (b), Hammett's substituent constant σ p is an index of the electron-withdrawing and electron-donating properties of the substituent. The substituent constant σ p is disclosed in, for example, CORWIN HANSCH et al., "A Survey of Hammett Substituent Constants and Resonance and Field Parameters", Chem. Rev. 1991, Vol. 91, pp. 165-195. The substituent constant σ p Examples of the substituents having a value of -0.2 or more and 0.2 or less include -F, -I, hydrocarbon groups, and silyl groups. 1 From R 22 When at least two of these are substituents other than hydrogen atoms, the substituents may be, independently of one another, -F, -CH3, -CH2CH2CH3, or -Si(CH3)3.

[0096] Substituent constant σ p Substituents with a value in the range of -0.2 to 0.2 tend to have low electron-withdrawing and electron-donating properties. Therefore, in compound A satisfying requirement (b), an increase in HOMO energy and a decrease in LUMO energy due to the electron-withdrawing or electron-donating properties of the substituent can be suppressed. In other words, a decrease in the energy gap between the HOMO and LUMO can be suppressed. This prevents the peak resulting from one-photon absorption from shifting to longer wavelengths, and a decrease in the ratio σ / ε for light having a wavelength in the short wavelength region can be suppressed. Compound A satisfying requirement (b) tends to have high nonlinearity in optical absorption for light having a wavelength in the short wavelength region.

[0097] In compound A, R 1 From R 22 may each be a hydrogen atom. In this case, compound A tends to exhibit higher nonlinearity in optical absorption for light having a wavelength in the short wavelength region.

[0098] In formula (1), L 1 and L 2are each independently a single bond or -C≡C-. 1 and L 2 may be the same or different. 1 and L 2 may each be represented by a single bond. Specifically, compound A may be compound B represented by the following formula (2): [ka]

[0099] R in Equation (2) 1 From R 22 is the same as that described above for equation (1). R in equation (2) 1 From R 22 Specific examples of combinations of R are shown in Tables 1 to 3 below. In Tables 1 to 3, the compound entries are 1 From R 22 The abbreviation for compound B having the formula: Me means -CH3. Pr means -CH2CH2CH3.

[0100] [Table 1]

[0101] [Table 2]

[0102] [Table 3]

[0103] In formula (1), L 1 and L 2 may each be represented by -C≡C-. Specifically, compound A may be compound C represented by the following formula (3): [ka]

[0104] R in Equation (3) 1 From R 22 is the same as that described above for equation (1). R in equation (3) 1 From R 22 Specific examples of combinations of R are shown in Tables 4 to 6 below. In Tables 4 to 6, the compound entries are 1 From R 22 The abbreviation of compound C having the formula:

[0105] [Table 4]

[0106] [Table 5]

[0107] [Table 6]

[0108] The synthesis method of compound B represented by formula (2) and compound C represented by formula (3) is not particularly limited, and for example, Sonogashira cross-coupling reaction or the like can be used. Compound B represented by formula (2) can be synthesized, for example, by the following method. First, compound D represented by formula (4) below, compound E represented by formula (5) below, and compound F represented by formula (6) below are prepared. [ka]

[0109] In equation (4), X 1 and X 2 are each independently a halogen atom or B(OH)2. 1 and X 2 Examples of the halogen atom in the formula (4) include Br and I. 1 From R 4 , R 10 From R14 , and R 20 From R 22 is the same as that described above for equation (1). R in equation (5) 5 From R 9 , and R in Eq. (6) 15 From R 19 is also the same as that described above for equation (1).

[0110] Next, a coupling reaction is carried out between Compound D, Compound E, and Compound F. This allows synthesis of Compound B. The conditions for the coupling reaction can be appropriately adjusted depending on, for example, the types of substituents contained in Compound D, Compound E, and Compound F.

[0111] Compound C represented by formula (3) can be synthesized, for example, by the following method: First, compound G represented by formula (7), compound H represented by formula (8), and compound I represented by formula (9) are prepared. [ka]

[0112] X in equation (8) 3 , and X in Eq. (9) 4 are each independently a halogen atom or B(OH)2. 3 and X 4 Examples of the halogen atom in the formula (7) include Br and I. 1 , R 2 , R 12 and R 22 is the same as that described above for equation (1). 3 From R 11 , and R in Eq. (9) 13 From R 21 is also the same as that described above for equation (1).

[0113] Next, a coupling reaction is carried out between Compound G, Compound H, and Compound I, thereby synthesizing Compound C. The conditions for the coupling reaction can be appropriately adjusted depending on, for example, the types of substituents contained in Compound G, Compound H, and Compound I.

[0114] Compound A represented by formula (1) has excellent two-photon absorption properties and tends to have small one-photon absorption with respect to light having a wavelength in the short wavelength region. For example, when compound A is irradiated with light having a wavelength of 405 nm, two-photon absorption may occur in compound A, but one-photon absorption may hardly occur.

[0115] The two-photon absorption cross section of compound A for light having a wavelength of 405 nm may be greater than 1 GM, greater than 10 GM, greater than 20 GM, greater than 100 GM, greater than 400 GM, or greater than 600 GM. The upper limit of the two-photon absorption cross section of compound A is not particularly limited, and may be, for example, 10,000 GM or 1,000 GM. The two-photon absorption cross section can be measured, for example, by the Z-scan method described in J. Opt. Soc. Am. B, 2003, Vol. 20, p. 529. The Z-scan method is widely used as a method for measuring nonlinear optical constants. In the Z-scan method, a measurement sample is moved along the direction of irradiation of a laser beam near the focal point where the beam is focused. At this time, changes in the amount of light transmitted through the measurement sample are recorded. In the Z-scan method, the power density of the incident light changes depending on the position of the measurement sample. Therefore, if the sample undergoes nonlinear optical absorption, the amount of transmitted light will be attenuated when the sample is positioned near the focus of the laser beam. The two-photon absorption cross section can be calculated by fitting the change in the amount of transmitted light to a theoretical curve predicted from the intensity of the incident light, the thickness of the sample, and the concentration of compound A in the sample.

[0116] The two-photon absorption cross section may be a calculated value obtained by computational chemistry. Several methods have been proposed for estimating the two-photon absorption cross section by computational chemistry. For example, the calculated value of the two-photon absorption cross section can be calculated based on the second-order nonlinear response theory described in J. Chem. Theory Comput. 2018, Vol. 14, p. 807.

[0117] The molar extinction coefficient of compound A for light with a wavelength of 405 nm is 100 mol -1 L cm -1 may be less than 10 mol -1 L cm -1 It may be less than 1 mol -1 L cm -1 It may be 0.1 mol or less. -1 L cm -1 The lower limit of the molar extinction coefficient of compound A is not particularly limited, and may be, for example, 0.00001 mol -1 L cm -1 The molar extinction coefficient can be measured, for example, by a method conforming to the provisions of Japanese Industrial Standards (JIS) K0115:2004. To measure the molar extinction coefficient, a light source is used that irradiates light with a photon density that causes almost no two-photon absorption by compound A. Furthermore, to measure the molar extinction coefficient, the concentration of compound A is adjusted to 500 mmol / L. This concentration is much higher than the concentration used in the measurement test of the molar extinction coefficient at the light absorption peak. The molar extinction coefficient can be used as an index of one-photon absorption.

[0118] The molar extinction coefficient may be a calculated value using a quantum chemistry calculation program, such as Gaussian 16 (manufactured by Gaussian).

[0119] Compound A has a molar absorption coefficient ε (mol -1 L cm -1The ratio σ / ε of the two-photon absorption cross section σ(GM) to the wavelength of 405 nm of compound A tends to be large. The ratio σ / ε of compound A to light having a wavelength of 405 nm may be 20 or more, 50 or more, 100 or more, 500 or more, 1000 or more, 1500 or more, or 2000 or more. The upper limit of the ratio σ / ε of compound A is not particularly limited and may be, for example, 50,000 or 20,000.

[0120] When compound A undergoes two-photon absorption, compound A absorbs approximately twice the energy of light irradiated onto compound A. The wavelength of light having approximately twice the energy of light having a wavelength of 405 nm is, for example, 200 nm. When compound A is irradiated with light having a wavelength around 200 nm, one-photon absorption may occur in compound A. Furthermore, compound A may undergo one-photon absorption with light having a wavelength close to the wavelength range in which two-photon absorption occurs.

[0121] Compound A also tends to emit fluorescent light. The wavelength of the fluorescent light emitted by compound A may be 405 nm or more and 660 nm or less, and in some cases, may be 300 nm or more and 650 nm or less. The fluorescence quantum yield Φf of compound A may be 0.05 or more, 0.1 or more, or 0.5 or more. The upper limit of the fluorescence quantum yield Φf of compound A is not particularly limited, and is, for example, 0.99. In this specification, "quantum yield" specifically means internal quantum yield. The fluorescence quantum yield can be measured, for example, using a commercially available absolute PL quantum yield measurement device.

[0122] Compound A represented by formula (1) can be used, for example, as a component of a light-absorbing material. That is, in another aspect, the present disclosure provides a light-absorbing material containing compound A represented by formula (1). The light-absorbing material contains, for example, compound A as a main component. "Main component" means the component contained in the light-absorbing material in the largest amount by weight. The light-absorbing material, for example, consists essentially of compound A. "Consisting essentially of" means excluding other components that alter the essential characteristics of the referenced material. However, the light-absorbing material may contain impurities in addition to compound A.

[0123] The light-absorbing material functions as a nonlinear light-absorbing material, such as a two-photon absorbing material. In particular, a light-absorbing material containing compound A has excellent two-photon absorption properties for light having a wavelength in the short wavelength region. In another aspect, the present disclosure provides a nonlinear light-absorbing material containing compound A represented by formula (1).

[0124] Compound A is used, for example, in devices that utilize light having a wavelength in the short wavelength range. As an example, compound A is used in devices that utilize light having a wavelength of 390 nm or more and 420 nm or less. Examples of such devices include recording media, modeling machines, and fluorescence microscopes. Examples of recording media include three-dimensional optical memories. A specific example of three-dimensional optical memories is a three-dimensional optical disk. Examples of modeling machines include optical modeling machines such as 3D printers. Examples of fluorescence microscopes include two-photon fluorescence microscopes. Light used in these devices has a high photon density, for example, near its focus. The power density near the focus of light used in the device is, for example, 0.1 W / cm. 2 Over 1.0 x 10 20 W / cm 2 The power density near the focal point of this light is 1.0 W / cm 2 It may be 1.0 x 10 or more. 2 W / cm 2 It may be 1.0 x 10 or more. 5 W / cm 2As the light source of the device, for example, a femtosecond laser such as a titanium sapphire laser, or a pulsed laser having a pulse width of picoseconds to nanoseconds such as a semiconductor laser can be used.

[0125] The recording medium includes, for example, a thin film called a recording layer. In the recording medium, information is recorded in the recording layer. As an example, the thin film serving as the recording layer contains compound A. That is, from another aspect thereof, the present disclosure provides a recording medium containing the above-mentioned compound A.

[0126] The recording layer may further contain a polymer compound that functions as a binder in addition to compound A. The recording medium may have a dielectric layer in addition to the recording layer. The recording medium may have, for example, a plurality of recording layers and a plurality of dielectric layers. In the recording medium, a plurality of recording layers and a plurality of dielectric layers may be alternately laminated.

[0127] Next, a method for recording information using the above-mentioned recording medium will be described. FIG. 1A is a flowchart showing the method for recording information using the above-mentioned recording medium. First, in step S11, a light source is prepared that emits light having a wavelength of 390 nm or more and 420 nm or less. As the light source, for example, a femtosecond laser such as a titanium sapphire laser, or a pulsed laser having a pulse width of picoseconds to nanoseconds such as a semiconductor laser can be used. Next, in step S12, the light from the light source is focused with a lens or the like and irradiated onto the recording layer of the recording medium. More specifically, the light from the light source is focused with a lens or the like and irradiated onto the recording region in the recording layer of the recording medium. The power density near the focus of this light is, for example, 0.1 W / cm. 2 Over 1.0 x 10 20 W / cm 2 The power density near the focal point of this light is 1.0 W / cm 2 It may be 1.0 x 10 or more. 2 W / cm 2 It may be 1.0 x 10 or more. 5 W / cm 2In this specification, the recording area means a spot that exists in the recording layer and that can record information when irradiated with light.

[0128] In the recording area irradiated with the light, a physical or chemical change occurs, changing the optical characteristics of the recording area. For example, the intensity of the fluorescent light emitted from the recording area decreases. In the recording area irradiated with the light, the intensity of the light reflected from the recording area, the reflectance of the light in the recording area, the absorbance of the light in the recording area, the refractive index of the light in the recording area, the wavelength of the fluorescent light emitted from the recording area, etc. may also change. This allows information to be recorded in the recording layer, specifically in the recording area (step S13).

[0129] Next, a method for reading information using the above-described recording medium will be described. FIG. 1B is a flowchart illustrating a method for reading information using the above-described recording medium. First, in step S21, light is irradiated onto the recording layer of the recording medium. More specifically, light is irradiated onto a recording area in the recording layer of the recording medium. The light used in step S21 may be the same as or different from the light used to record information on the recording medium. Next, in step S22, the optical characteristics of the recording layer are measured. More specifically, the optical characteristics of the recording area are measured. In step S22, for example, the intensity of fluorescence emitted from the recording area may be measured. In step S22, the optical characteristics of the recording area may include the intensity of light reflected from the recording area, the reflectance of light in the recording area, the absorptance of light in the recording area, the refractive index of light in the recording area, and the wavelength of fluorescence emitted from the recording area. Next, in step S23, information is read from the recording layer, more specifically, the recording area.

[0130] In the information reading method, the recording area where information is recorded can be found by the following method. First, light is irradiated onto a specific area of ​​the recording medium. This light may be the same as or different from the light used to record information on the recording medium. Next, the optical characteristics of the area irradiated with light are measured. Examples of optical characteristics include the intensity of fluorescence emitted from the area, the intensity of light reflected from the area, the reflectance of light in the area, the absorbance of light in the area, the refractive index of light in the area, and the wavelength of fluorescence emitted from the area. Whether or not the area irradiated with light is a recorded area is determined based on the measured optical characteristics. For example, if the intensity of fluorescence emitted from the area is equal to or less than a specific value, the area is determined to be a recorded area. On the other hand, if the intensity of fluorescence exceeds a specific value, the area is determined to be not a recorded area. Note that the method for determining whether or not the area irradiated with light is a recorded area is not limited to the above method. For example, if the intensity of fluorescence emitted from the area exceeds a specific value, the area may be determined to be a recorded area. Alternatively, if the intensity of the fluorescence emitted from the region is equal to or less than a specific value, the region may be determined to be a non-recorded region. If the region is determined to be a non-recorded region, the same operation is performed on other regions of the recording medium. This allows the search for a recorded region.

[0131] The information recording and reading methods using the above-mentioned recording medium can be performed, for example, by a known recording device that includes, for example, a light source that irradiates a recording area of ​​the recording medium with light, a measuring device that measures the optical characteristics of the recording area, and a controller that controls the light source and the measuring device.

[0132] The modeling machine performs modeling by, for example, irradiating a photocurable resin composition with light and curing the resin composition. As an example, a photocurable resin composition for stereolithography contains compound A. The photocurable resin composition contains, for example, a polymerizable compound and a polymerization initiator in addition to compound A. The photocurable resin composition may further contain an additive such as a binder resin. The photocurable resin composition may also contain an epoxy resin.

[0133] The fluorescence microscope can be used to observe the fluorescence emitted from a biological sample containing a fluorescent dye material by irradiating the sample with light. For example, the fluorescent dye material to be added to the biological sample contains compound A. [Example]

[0134] The present disclosure will be described in more detail below with reference to examples. Note that the following examples are merely illustrative and the present disclosure is not limited to the following examples.

[0135] [Synthesis of compound (2)-1] First, 2.0 g (5.1 mmol) of 4,4′′-dibromo-1,1′:3′,1′′-terphenyl (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.03 g (0.15 mmol) of copper(I) iodide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 20 mL of tetrahydrofuran (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 10 mL of diisopropylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) were added to a 50 mL reactor. Next, the reactor was degassed and then purged with argon gas. Next, 2.1 mL (20.6 mmol) of phenylacetylene (manufactured by Tokyo Chemical Industry Co., Ltd.), 1.0 mL (0.52 mmol) of a solution containing tri-tert-butylphosphine (manufactured by Tokyo Chemical Industry Co., Ltd.) at a concentration of 0.5 mol / L, and 0.03 g (0.15 mmol) of palladium(II) acetate (manufactured by Tokyo Chemical Industry Co., Ltd.) were added to the solution in the reactor. The solution was heated and stirred in an oil bath at an internal temperature of 40°C for 3 hours. Next, the solution was allowed to cool, and 40 mL of methanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added to precipitate a solid. This solid was collected by filtration and recrystallized in toluene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to synthesize compound (2)-1 in Table 1 above. Compound (2)-1 was obtained by 1 The compound (2)-1 was identified by H-NMR. 1 1 is a graph showing the H-NMR spectrum of compound (2)-1. 1 The 1 H-NMR spectrum was as follows: 1H-NMR (600MHz, CHLOROFORM-D) δ7.83 (s, 1H), 7.67-7.52 (m, 15H), 7.40-7.35 (m, 6H).

[0136] [Synthesis of compound (3)-1] First, 4.5 g (17.4 mmol) of 1-bromo-4-phenylethynylbenzene (Tokyo Chemical Industry Co., Ltd.), 0.04 g (0.16 mmol) of copper(I) iodide (Fujifilm Wako Pure Chemical Industries, Ltd.), 10 mL of tetrahydrofuran (Fujifilm Wako Pure Chemical Industries, Ltd.), and 5.0 mL of diisopropylamine (Tokyo Chemical Industry Co., Ltd.) were added to a 30 mL reactor and degassed for 10 minutes. Next, 1.0 g (7.9 mmol) of 1,3-diethynylbenzene (Tokyo Chemical Industry Co., Ltd.), 3.0 mL (1.58 mmol) of a solution containing 0.5 mol / L of tri-tert-butylphosphine (Tokyo Chemical Industry Co., Ltd.), and 0.2 g (0.23 mmol) of bis(dibenzylideneacetone)palladium(0) (Tokyo Chemical Industry Co., Ltd.) were added to the solution in the reactor. The solution was heated and stirred in an oil bath at an internal temperature of 50°C for 12 hours. The resulting suspension was allowed to cool to room temperature, after which tap water was added and extraction was carried out using toluene. The extract was washed with saturated saline and dried using anhydrous magnesium sulfate. The extract was then concentrated to obtain a brown solid. The brown solid was washed with methanol and purified by silica gel column chromatography to synthesize compound (3)-1 in Table 4 above. Compound (3)-1 was obtained by 1 The compound (3)-1 was identified by H-NMR. 1 1 is a graph showing the H-NMR spectrum of compound (3)-1. 1 The 1 H-NMR spectrum was as follows: 1 H-NMR (600MHz, CHLOROFORM-D) δ7.72 (s, 1H), 7.55-7.49 (m, 14H), 7.39-7.34 (m, 7H).

[0137] [Compounds of Comparative Examples 1 to 8] The compounds of Comparative Examples 2 to 5 shown in Table 11 below were prepared. The compounds of Comparative Examples 1 to 8 are represented by the following formulas (10) to (17), respectively. The compound represented by formula (10) corresponds to the compound A represented by formula (1) that does not satisfy requirement (a). The compounds represented by formulas (15) to (17) correspond to the compound A represented by formula (1) that does not satisfy requirement (b). Compound D-29, the compound of Comparative Example 2 shown in formula (11) below, was synthesized according to the method described in Japanese Patent No. 5659189, paragraphs

[0222] to

[0230] . Compound 1f, the compound of Comparative Example 3 shown in formula (12) below, was synthesized according to the method described in Japanese Patent No. 5821661, paragraph

[0083] . Hexakis(phenylethynyl)benzene (HPEB), the compound of Comparative Example 4 shown in formula (13) below, was synthesized according to the method described in K. Kondo et al., J. Chem. Soc., Chem. Commun. 1995, 55-56 and W. Tao et al., J. Org. Chem. 1990, 55, 63-66. 1,3,5-tri(phenylethynyl)benzene, the compound of Comparative Example 5 shown in formula (14) below, was purchased from Sigma-Aldrich and used. [ka] [ka]

[0138] <Measurement of two-photon absorption cross section> The two-photon absorption cross sections of Compound (2)-1, Compound (3)-1, and the compounds of Comparative Examples 2 to 5 were measured for light having a wavelength of 405 nm. The two-photon absorption cross sections were measured using the Z-scan method described in J. Opt. Soc. Am. B, 2003, Vol. 20, p. 529. A titanium sapphire pulsed laser was used as the light source for measuring the two-photon absorption cross sections. Specifically, the second harmonic of the titanium sapphire pulsed laser was irradiated onto the sample. The laser pulse width was 80 fs. The laser repetition rate was 1 kHz. The average laser power was varied in the range of 0.01 mW to 0.08 mW. The light emitted from the laser had a wavelength of 405 nm. Specifically, the light emitted from the laser had a central wavelength of 403 nm to 405 nm. The full width at half maximum of the light emitted from the laser was 4 nm.

[0139] <Prediction of two-photon absorption cross section> The two-photon absorption cross sections for light having a wavelength of 405 nm were predicted for the compounds disclosed in Tables 1 to 6 above, and the compounds of Comparative Examples 1, 3, and 6 to 8. Specifically, the two-photon absorption cross sections were calculated by density functional theory (DFT) calculations based on the second-order nonlinear response theory described in J. Chem. Theory Comput. 2018, Vol. 14, p. 807. Turbomole version 7.3.1 (COSMOlogic) was used as the software for the DFT calculations. def2-TZVP was used as the basis function. B3LYP was used as the functional.

[0140] In predicting the two-photon absorption cross section, the calculated and measured two-photon absorption cross sections of known two-photon absorption compounds were identified in advance, and linear regression was performed. The regression equation obtained by this linear regression was used to calculate the calculated two-photon absorption cross section of the above-mentioned compound.

[0141] <Measurement of molar extinction coefficient> The molar absorption coefficients of Compound (2)-1, Compound (3)-1, and the compounds of Comparative Examples 2 to 5 were measured according to the method specified in JIS K0115:2004. Specifically, a solution in which the compound was dissolved in a solvent was first prepared as a measurement sample. The concentration of the compound in this solution was adjusted to 500 mmol / L. Next, the absorption spectrum of the measurement sample was measured. The absorbance at a wavelength of 405 nm was read from the obtained spectrum. The molar absorption coefficient was calculated based on the concentration of the compound in the measurement sample and the optical path length of the cell used for the measurement.

[0142] <Prediction of molar extinction coefficient> The molar absorption coefficients were predicted for the compounds disclosed in Tables 1 to 6 above, as well as for Comparative Examples 1, 3, and 6 to 8. DFT calculations were used to predict the molar absorption coefficients. Specifically, excited-state calculations were first performed for the compounds using Gaussian 16 (Gaussian), a quantum chemistry calculation program. The basis function for the excited-state calculations was 6-31++G(d,p). CAM-B3LYP was used as the functional. The excited-state calculations calculated the energy required to excite the compounds and the oscillator strength (f). The oscillator strength correlates with the molar absorption coefficient. Next, the absorption spectrum was assumed to have a Gaussian distribution, and the half-width was specified. Specifically, the half-width was specified as 0.4 eV, and the absorption spectrum was plotted based on the absorption wavelength and oscillator strength. The absorbance at a wavelength of 405 nm was read from the obtained absorption spectrum. This absorbance was considered to be the calculated molar absorption coefficient.

[0143] In predicting the molar absorption coefficient, calculated and measured molar absorption coefficients of known two-photon absorption compounds were identified in advance, and linear regression was performed. The regression equation obtained by this linear regression was used to calculate the molar absorption coefficients of the above-mentioned compounds.

[0144] <Measurement of fluorescence quantum yield> The internal quantum yield of fluorescence was measured for Compound (2)-1, Compound (3)-1, and the compounds of Comparative Examples 2 to 4. Measurement samples were prepared by dissolving the compounds in chloroform (CLF) solvent. An absolute PL quantum yield measurement device (C9920-02 manufactured by Hamamatsu Photonics KK) was used for the measurements. The excitation wavelength was set to the peak wavelength of one-photon absorption of the compounds. The measurement wavelength was appropriately adjusted within the range of 350 nm to 650 nm so as not to overlap with the absorption wavelength band of the compounds. CLF solvent was used as a reference.

[0145] The measured and calculated values ​​of the two-photon absorption cross section σ(GM) obtained by the above method, and the molar absorption coefficient ε(mol -1 L cm -1 Tables 7 to 11 show the measured and calculated values ​​of the two-photon absorption cross section, the ratio σ / ε, and the fluorescence quantum yield Φf(-). In Tables 7 to 11, the ratio σ / ε was calculated based on the measured values ​​of the two-photon absorption cross section and the measured values ​​of the molar extinction coefficient. For compounds for which the measured values ​​of the two-photon absorption cross section and the molar extinction coefficient were not obtained, the ratio σ / ε was calculated based on these calculated values. In Tables 7 to 11, "No Data" means that no data was obtained. As shown in Tables 7 to 10, the compound of Example 1 is Compound (2)-1, the compound of Example 2 is Compound (3)-1, the compounds of Examples 3 to 52 are Compounds (2)-2 to (2)-51, respectively, and the compounds of Examples 53 to 88 are Compounds (3)-2 to (3)-51, respectively.

[0146] [Table 7]

[0147] [Table 8]

[0148] [Table 9]

[0149] [Table 10]

[0150] [Table 11]

[0151] As can be seen from Tables 7 to 11, the compounds of the examples corresponding to compound A, which is represented by formula (1) and satisfies requirements (a) and (b), all had larger values ​​of the ratio σ / ε for light having a wavelength of 405 nm than the compounds of the comparative examples. These results demonstrate that compound A exhibits high nonlinearity in optical absorption for light having a wavelength in the short wavelength range, and has improved nonlinear optical absorption properties. Furthermore, the compounds of Examples 1 and 2 also possessed fluorescent properties. In contrast, the compounds of Comparative Examples 1 to 8 tended to have smaller two-photon absorption cross-sections σ or larger molar extinction coefficients ε compared to the examples. Therefore, the compounds of Comparative Examples 1 to 8 had smaller values ​​of the ratio σ / ε.

[0152] As can be seen from formula (1), compound A has a V-shaped molecular skeleton. A comparison of Example 2 and Comparative Examples 1 and 5 reveals that a V-shaped molecular skeleton is more suitable for improving the ratio σ / ε than a three-branched molecular skeleton. That is, it is presumed that the V-shaped molecular skeleton is the reason why compound A had a large ratio σ / ε for light having a wavelength of 405 nm.

[0153] Furthermore, as Reference Example 1, in formula (2), R 1 is a nitro group, and R 2 From R 22 For a compound in which R is a hydrogen atom, the two-photon absorption cross section and the molar absorption coefficient were calculated, and the value of the ratio σ / ε was calculated. The obtained value of the ratio σ / ε for Reference Example 1 was 130. 1 is a dimethylamino group, and R 2 From R 22For compounds in which R is a hydrogen atom, the two-photon absorption cross section and the molar extinction coefficient were calculated, and the value of the ratio σ / ε was calculated. The obtained value of the ratio σ / ε for Reference Example 2 was 120. As can be seen from the comparison of Examples 3, 11, 19, and 27 with Reference Examples 1 and 2, in Compound A, 1 From R 22 When at least one of the substituents is a substituent other than a hydrogen atom, the Hammett's substituent constant σ p When the substituent constant σ is in the range of -0.2 or more and 0.2 or less, the ratio σ / ε tends to be large. p In the case of a substituent having a value in the range of -0.2 to 0.2, it is presumed that this is due to its low electron-withdrawing and electron-donating properties. Specifically, when the electron-withdrawing and electron-donating properties of the substituent are low, the energy gap between the HOMO and the LUMO can be prevented from decreasing. This prevents the peak resulting from one-photon absorption from shifting to longer wavelengths, and prevents a decrease in the ratio σ / ε for light having a wavelength in the short wavelength region. In fact, in Examples 3 to 34, the molar extinction coefficient values ​​calculated by DFT calculation tended to be smaller than those in Examples 35 to 48, and were comparable to those of the unsubstituted Example 1.

[0154] In Examples 3 to 10, the substituent constant σ of the methyl group p In Examples 11 to 18, the substituent constant σ of the propyl group is p In Examples 19 to 26, the substituent constant σ of the fluoro group is p In Examples 27 to 34, the substituent constant σ of the trimethylsilyl group is p In Reference Example 1, the substituent constant σ of the nitro group is −0.07. p In Reference Example 2, the substituent constant σ of the dimethylamino group is 0.78. p is -0.83. [Industrial Applicability]

[0155] The compounds of the present disclosure can be used in applications such as recording layers for three-dimensional optical memories and photocurable resin compositions for stereolithography. The compounds of the present disclosure exhibit highly nonlinear optical absorption properties for light with wavelengths in the short wavelength range. Therefore, the compounds of the present disclosure can achieve extremely high spatial resolution in applications such as three-dimensional optical memories and modeling machines. Furthermore, the compounds of the present disclosure tend to have high fluorescence quantum yields. Therefore, when these compounds are used in the recording layers of three-dimensional optical memories, a method can be adopted in which the ON / OFF state of the recording layer is read based on changes in fluorescence from the compound. The compounds of the present disclosure can also be used as fluorescent dye materials for two-photon fluorescence microscopes and the like. Compared to conventional compounds, the compounds of the present disclosure can exhibit two-photon absorption in preference to one-photon absorption, even when irradiated with laser light of low light intensity.

Claims

1. A compound represented by the following formula (1): 【Chemical 1】 In the formula (1), R 1 From R 22 are hydrogen atoms, L 1 and L 2 are each independently a single bond or —C≡C—.

2. Represented by the following formula (2): The compound of claim 1. 【Chemistry 2】

3. Represented by the following formula (3): The compound of claim 1. 【Chemistry 3】

4. A compound represented by the following formula (1): The compound is used in a device that utilizes light having a wavelength of 390 nm or more and 420 nm or less. compound. 【Chemistry 4】 In the formula (1), R 1 From R 22 each independently contain at least one atom selected from the group consisting of H, B, C, N, O, F, Si, P, S, Cl, I and Br, L 1 and L 2 represent, independently of one another, a single bond or —C≡C—, The R 1 , the R 2 , the R 6 , the R 7 , the R 12 , the R 17 , and the R 22 is a substituent other than a substituent containing an aromatic ring, The R 1 From the above R 22 are each independently a hydrogen atom or a Hammett substituent constant σ p is a substituent in the range of -0.2 or more and 0.2 or less, The substituent having a Hammett's substituent constant σ p in the range of −0.2 to 0.2 is —F, —I, an alkyl group, or a silyl group.

5. 5. A compound according to claim 1, Light-absorbing material.

6. 5. A compound according to claim 1, Nonlinear optical absorbing materials.

7. A recording layer containing a compound represented by the following formula (1): Recording medium. 【Chemistry 5】 In the formula (1), R 1 From R 22 each independently contain at least one atom selected from the group consisting of H, B, C, N, O, F, Si, P, S, Cl, I and Br, L 1 and L 2 represent, independently of one another, a single bond or —C≡C—, The R 1 , the R 2 , the R 6 , the R 7 , the R 12 , the R 17 , and the R 22 is a substituent other than a substituent containing an aromatic ring, The R 1 From the above R 22 are each independently a hydrogen atom or a Hammett substituent constant σ p is a substituent in the range of -0.2 or more and 0.2 or less, The substituent having a Hammett's substituent constant σ p in the range of −0.2 to 0.2 is —F, —I, an alkyl group, or a silyl group.

8. providing a light source that emits light having a wavelength of 390 nm or more and 420 nm or less; and irradiating the light from the light source onto the recording layer of the recording medium according to claim 7. How information is recorded.

9. A method for reading the information recorded by the recording method according to claim 8, comprising the steps of: measuring optical characteristics of the recording layer by irradiating the recording layer of the recording medium with light; reading the information from the recording layer. How to read the information.

10. the optical property is the intensity of the fluorescent light emitted from the recording layer; The reading method according to claim 9.

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