Light-absorbing material, recording medium, information recording method, and information readout method

Abstract

The light-absorbing material in one aspect of the present disclosure contains a compound represented by the following formula (1) as a main component. In formula (1), R 1 ~R 14 contains at least one atom selected from the group consisting of H, C, N, O, F, P, S, Cl, I, and Br, and n is an integer of 2 or more.

Description

Technical Field

[0001] This disclosure relates to light-absorbing materials, recording media, methods for recording information, and methods for reading information. Background Technology

[0002] Materials exhibiting nonlinear optical effects, such as light-absorbing materials, are called nonlinear optical materials. Nonlinear optical effects refer to optical phenomena that occur in a material when it is irradiated with strong light, such as laser light, in a quantity proportional to the square or higher of the electric field of the irradiating light. Examples of such optical phenomena include absorption, reflection, scattering, and luminescence. Examples of second-order nonlinear optical effects proportional to the square of the electric field of the irradiating light include second harmonic generation (SHG), the Pockels effect, and parameterization effects. Examples of third-order nonlinear optical effects proportional to the cube of the electric field of the irradiating light include two-photon absorption, multiphoton absorption, third harmonic generation (THG), and the Kerr effect. In this specification, two-photon absorption and other multiphoton absorption are sometimes referred to as nonlinear optical absorption. Materials capable of nonlinear optical absorption are sometimes called nonlinear optical absorbing materials. In particular, materials capable of two-photon absorption are sometimes called two-photon absorbing materials.

[0003] Numerous studies have been actively conducted on nonlinear optical materials to date. In particular, inorganic materials that can be easily fabricated into single crystals have been developed as nonlinear optical materials. In recent years, the development of nonlinear optical materials incorporating organic materials has been anticipated. Examples of nonlinear optical materials incorporating organic materials include organic pigments. Compared to inorganic materials, organic materials not only possess higher design freedom but also larger nonlinear optical constants. Furthermore, organic materials exhibit high-speed nonlinear responses. In this specification, nonlinear optical materials incorporating organic materials are sometimes referred to as organic nonlinear optical materials.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 5769151

[0007] Patent Document 2: Japanese Patent No. 5821661

[0008] Patent Document 3: Japanese Patent No. 5659189

[0009] Non-patent literature

[0010] Non-patent literature 1: Harry L. Anderson et al, “Two-Photon Absorption and the Design of Two-Photon Dyes”, Angew. Chem. Int. Ed. 2009, Vol. 48, pp. 3244-3266. Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] There is room for improvement in the nonlinear light absorption characteristics of conventional light-absorbing materials relative to wavelengths with short wavelength regions.

[0013] Methods for solving problems

[0014] One embodiment of the light-absorbing material disclosed herein comprises

[0015] The compound represented by the following formula (1) is the main component.

[0016] [Chemical Formula 1]

[0017]

[0018] In equation (1) above, R 1 ~R 14 Each atom independently contains at least one atom selected from the group consisting of H, C, N, O, F, P, S, Cl, I, and Br, where n is an integer greater than or equal to 2.

[0019] Invention Effects

[0020] This disclosure provides light-absorbing materials with improved nonlinear light absorption characteristics relative to light wavelengths having a short wavelength region. Attached Figure Description

[0021] Figure 1A This is a flowchart of a method for recording information using a recording medium containing a light-absorbing material according to an embodiment of the present disclosure.

[0022] Figure 1B This is a flowchart of a method for reading out information using a recording medium that incorporates a light-absorbing material according to an embodiment of this disclosure.

[0023] Figure 2A This refers to the compound of Example 1. 1 Chart of H-NMR spectra.

[0024] Figure 2B yes Figure 2A A magnified view of the chart.

[0025] Figure 3A This refers to the compound of Example 2. 1 Chart of H-NMR spectra.

[0026] Figure 3B yes Figure 3A A magnified view of the chart.

[0027] Figure 4A This refers to the compound of Example 3. 1 Chart of H-NMR spectra.

[0028] Figure 4B yes Figure 4A A magnified view of the chart.

[0029] Figure 5A This refers to the compound of Example 4. 1 Chart of H-NMR spectra.

[0030] Figure 5B yes Figure 5A A magnified view of the chart.

[0031] Figure 6A This refers to the compound of Example 5. 1 Chart of H-NMR spectra.

[0032] Figure 6B yes Figure 6A A magnified view of the chart. Detailed Implementation

[0033] (The insights that form the basis of this disclosure)

[0034] In organic nonlinear optical materials, two-photon absorption materials have attracted particular attention. Two-photon absorption refers to the phenomenon where a compound absorbs two photons almost simultaneously, transitioning to an excited state. Two-photon absorption is known to include non-resonant and resonant two-photon absorption. Non-resonant two-photon absorption refers to two-photon absorption in wavelength regions where there is no single-photon absorption band. In non-resonant two-photon absorption, the compound absorbs two photons almost simultaneously, transitioning to a higher-order excited state. In resonant two-photon absorption, the compound absorbs the first photon and then further absorbs the second photon, transitioning to an even higher-order excited state. In resonant two-photon absorption, the compound absorbs the two photons sequentially.

[0035] If two-photon absorption materials further possess fluorescence properties, they can also be applied to fluorescent dye materials used in two-photon fluorescence microscopy and other applications. If this two-photon absorption material is used in a three-dimensional optical memory, it may be possible to read the ON / OFF state of the recording layer based on changes in fluorescence from the two-photon absorption material. Current optical memories use changes in the reflectivity and absorptivity of light in the two-photon absorption material to read the ON / OFF state of the recording layer. However, when applying this method to a three-dimensional optical memory, interference sometimes occurs due to other recording layers that are different from the recording layer whose ON / OFF state should be read.

[0036] For two-photon absorbing materials, the two-photon absorption cross-sectional area (GM value) is used as an indicator of two-photon absorption efficiency. The unit of two-photon absorption cross-sectional area is GM(10⁻¹⁰). -50 cm 4 ·s·molecule -1 ·photon -1 To date, many organic two-photon absorbing materials with large two-photon absorption cross-sections have been proposed. For example, many compounds with two-photon absorption cross-sections exceeding 500 GM have been reported (e.g., Non-Patent Literature 1). However, in most reports, the two-photon absorption cross-section has been measured using lasers with wavelengths longer than 600 nm. In particular, near-infrared light with wavelengths longer than 750 nm is sometimes used as the laser.

[0037] However, for the application of two-photon absorption materials in industrial applications, materials exhibiting two-photon absorption properties when irradiated with lasers of shorter wavelengths are desirable. For example, in the field of three-dimensional optical storage, short-wavelength lasers can achieve finer focusing points, thus increasing the recording density of the three-dimensional optical storage. In the field of optical modeling, short-wavelength lasers can also achieve higher resolution models. Furthermore, the Blu-ray (registered trademark) optical disc standard uses a laser with a center wavelength of 405 nm. Therefore, developing compounds that exhibit excellent two-photon absorption properties relative to light in the same wavelength range as short-wavelength lasers could significantly contribute to industrial development.

[0038] Furthermore, light-emitting devices that emit extremely short pulses of laser light with high intensity are large and tend to be unstable. Therefore, from the perspective of versatility and reliability, such light-emitting devices are difficult to use in industrial applications. Considering this, in order to apply two-photon absorption materials to industrial applications, it is desirable to have materials that exhibit two-photon absorption characteristics even when irradiated with laser light of low intensity.

[0039] In compounds exhibiting two-photon absorption properties, the relationship between light intensity and two-photon absorption properties is expressed by the following equation (i). In this specification, compounds exhibiting two-photon absorption properties are sometimes referred to as two-photon absorbing compounds. Equation (i) is a formula for calculating the reduction in light intensity -dI when a sample containing a two-photon absorbing compound and having a small thickness dz is irradiated with light of intensity I. As can be seen from equation (i), the reduction in light intensity -dI is expressed as the sum of terms proportional to the first power of the intensity I of the incident light relative to the sample and terms proportional to the square of the intensity I.

[0040] [Mathematical Expression 1]

[0041]

[0042] In equation (i), α is the single-photon absorption coefficient (cm²). -1 ). α (2) Let be the two-photon absorption coefficient (cm / W). From equation (i), we know that in the sample, the intensity I of the incident light when the single-photon absorption is equal to the two-photon absorption is expressed as α / α. (2) This means that when the intensity I of the incident light is less than α / α... (2) In this case, single-photon absorption preferentially occurs in the sample. This occurs when the intensity I of the incident light is greater than α / α. (2) At this time, two-photon absorption preferentially occurs in the sample. Therefore, α / α in the sample (2) The smaller the value, the more likely the laser with lower light intensity will preferentially exhibit two-photon absorption.

[0043] Furthermore, α and α (2) It can be expressed by equations (ii) and (iii) below, respectively. In equations (ii) and (iii), ε is the molar absorptivity (mol). -1 ·L·cm -1 N is the number of compound molecules per unit volume of the sample (mol·cm⁻¹). -3 N A σ is Avogadro's constant. σ is the two-photon absorption cross-section (GM). h⁻¹(h₀) is Dirac's constant (J·s). ω is the angular frequency of the incident light (rad / s).

[0044] [Mathematical Expression 2]

[0045]

[0046]

[0047] From equations (ii) and (iii), we know that α / α (2)This is defined by ε / σ. That is, in order to preferentially exhibit two-photon absorption by lasing with low intensity, the ratio of the two-photon absorption cross-section σ to the molar absorptivity ε, relative to the wavelength of the irradiated laser, is preferably large. For compounds, it can be said that a large value of σ / ε at a specific wavelength indicates a high degree of nonlinearity in light absorption at that wavelength.

[0048] Previously, in order to achieve a high two-photon absorption cross-section, attempts were made to further extend the conjugation system of compounds with bond-type π-conjugation systems. These compounds are those whose conjugation system is extended through covalent bonds. In these compounds, multiple π-electron clouds interact through covalent bonds. However, if the conjugation system of these compounds is extended, there is a tendency for the absorption wavelength originating from single-photon absorption to shift towards longer wavelengths. In this specification, this shift of the absorption wavelength originating from single-photon absorption towards longer wavelengths is sometimes referred to as a long-wavelength shift or redshift. As a result of this long-wavelength shift, sometimes a portion of the wavelength region producing single-photon absorption overlaps with the wavelength of the excitation light. It should be noted that, as a specific example of the excitation light wavelength, 405 nm as specified in the Blu-ray (registered trademark) standard can be cited. In compounds where single-photon absorption is generated by excitation light, there is a tendency for a significant decrease in σ / ε and a significant decrease in nonlinear optical absorption characteristics.

[0049] The inventors conducted in-depth research and made a new discovery: the compound represented by formula (1) described below exhibits excellent nonlinear light absorption characteristics relative to light with wavelengths in the short wavelength region. In this specification, the short wavelength region refers to the wavelength region including 405 nm, for example, the wavelength region of 390 nm or more and 420 nm or less. In particular, the compound represented by formula (1) exhibits excellent nonlinear light absorption characteristics relative to light with wavelengths around 405 nm. Furthermore, for this compound, the longer the chain length, the greater the tendency for the nonlinear light absorption characteristics to be improved.

[0050] (A summary of one embodiment of this disclosure)

[0051] The light-absorbing material of the first aspect of this disclosure comprises

[0052] The compound represented by the following formula (1) is the main component.

[0053] [Chemical Formula 2]

[0054]

[0055] In equation (1) above, R 1 ~R 14Each atom independently contains at least one atom selected from the group consisting of H, C, N, O, F, P, S, Cl, I, and Br, where n is an integer greater than or equal to 2.

[0056] The light-absorbing material of the first scheme has a larger two-photon absorption cross-section σ / ε ratio to the molar absorptivity ε relative to light with a short wavelength region, and tends to exhibit excellent nonlinear light absorption characteristics. Thus, the nonlinear light absorption characteristics of the light-absorbing material relative to light with a short wavelength region are improved. When n in formula (1) is 2 or more, a π-stacking structure is formed in the above-mentioned compound, for example. A π-stacking structure refers to a structure in which multiple π electron clouds interact through space. Compounds that form a π-stacking structure within the molecule are sometimes called compounds via a spatial π-conjugation system. For compounds of formula (1), the longer the chain length, the more likely the nonlinear light absorption characteristics are to be improved. Compounds of formula (1) also tend to have high solubility relative to organic solvents.

[0057] In the second aspect of this disclosure, for example, the light-absorbing material according to the first aspect, the aforementioned R 1 ~R above 14 They can also be hydrogen atoms, halogen atoms, saturated hydrocarbon groups, haloalkyl groups, unsaturated hydrocarbon groups, hydroxyl groups, carboxyl groups, alkoxycarbonyl groups, aldehyde groups, acyl groups, amide groups, nitrile groups, alkoxy groups, acyloxy groups, thiols, alkylthiols, sulfonic acid groups, acylthiols, alkylsulfonyl groups, sulfonamide groups, primary amino groups, secondary amino groups, tertiary amino groups, or nitro groups, independently of each other.

[0058] In the third aspect of this disclosure, for example, the light-absorbing material according to the first or second aspect is selected from the aforementioned R. 2 The above R 3 The above R 7 The above R 8 The above R 12 and the above R 13 At least one of the constituent groups can also be an electron-donating group.

[0059] In the fourth aspect of this disclosure, for example, the light-absorbing material according to the third aspect, the electron-donating group can also be an alkoxy group.

[0060] In the fifth aspect of this disclosure, for example, in the light-absorbing material according to the third or fourth aspect, the electron-donating group can also be -OCH3.

[0061] In the sixth aspect of this disclosure, for example, the light-absorbing material according to any one of aspects 1 to 5 is selected from the above-mentioned R. 5 and the above R 10 At least one of the constituent groups can also be an electron-withdrawing group.

[0062] In the seventh aspect of this disclosure, for example, the light-absorbing material according to the sixth aspect, the electron-withdrawing group can also be a halogen group.

[0063] In the eighth aspect of this disclosure, for example, according to the light-absorbing material of any one of the first to seventh aspects, the above-mentioned compound may also have a helical structure.

[0064] In the ninth aspect of this disclosure, for example, according to the light-absorbing material of any one of the first to eighth aspects, the above-mentioned compound may also have the property of absorbing specific light.

[0065] In the 10th aspect of this disclosure, for example, the light-absorbing material of any one of the 1st to 9th aspects can also be used in devices that utilize light with wavelengths of 390 nm or more and 420 nm or less.

[0066] According to schemes 2 to 10, the nonlinear light absorption characteristics of the light-absorbing material relative to light with wavelengths having a short wavelength region are improved. The light-absorbing materials of schemes 2 to 10 are suitable for use in devices utilizing light with wavelengths of 390 nm or higher and 420 nm or lower.

[0067] The recording medium of the 11th aspect of this disclosure has a recording layer comprising a light-absorbing material comprising any one of the 1st to 10th aspects.

[0068] According to the 11th embodiment, the nonlinear light absorption characteristics relative to light with wavelengths in the short-wavelength region are improved in the light-absorbing material. A recording medium having a recording layer comprising such a light-absorbing material can record information at a high recording density.

[0069] The method for recording information in the 12th embodiment of this disclosure includes:

[0070] A light source prepared to emit light with wavelengths above 390nm and below 420nm; and

[0071] The light from the aforementioned light source is focused and used to irradiate the recording layer in the recording medium of the 11th embodiment.

[0072] According to the 12th embodiment, the nonlinear light absorption characteristics relative to light with wavelengths in the short-wavelength region are improved in the light-absorbing material. If a recording method is used that employs a recording medium having a recording layer containing such a light-absorbing material, information can be recorded at a high recording density.

[0073] The information reading method of the 13th embodiment of this disclosure is, for example, a method for reading information recorded by the recording method of the 12th embodiment.

[0074] The above readout methods include:

[0075] The optical properties of the recording layer were measured by irradiating the recording layer with light; and

[0076] The above information is read from the above record layer.

[0077] In the 14th embodiment of this disclosure, for example, according to the information readout method of the 13th embodiment, the aforementioned optical characteristic may also be the intensity of light reflected in the aforementioned recording layer.

[0078] The information can be easily read according to scheme 13 or 14.

[0079] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. The present disclosure is not limited to these embodiments.

[0080] (Implementation Method)

[0081] The light-absorbing material of this embodiment includes compound A represented by the following formula (1).

[0082] [Chemical Formula 3]

[0083]

[0084] In equation (1), R 1 ~R 14 Each contains at least one atom independently selected from the group consisting of H, C, N, O, F, P, S, Cl, I, and Br. 1 ~R 14 They can also be hydrogen atoms, halogen atoms, saturated hydrocarbon groups, haloalkyl groups, unsaturated hydrocarbon groups, hydroxyl groups, carboxyl groups, alkoxycarbonyl groups, aldehyde groups, acyl groups, amide groups, nitrile groups, alkoxy groups, acyloxy groups, thiols, alkylthiols, sulfonic acid groups, acylthiols, alkylsulfonyl groups, sulfonamide groups, primary amino groups, secondary amino groups, tertiary amino groups, or nitro groups, independently of each other.

[0085] Examples of halogen atoms include F, Cl, Br, and I. In this specification, halogen atoms are sometimes referred to as halogen groups.

[0086] Saturated hydrocarbon groups are, for example, aliphatic saturated hydrocarbon groups. Specific examples of aliphatic saturated hydrocarbon groups are alkyl groups. The number of carbon atoms in the alkyl group is not particularly limited, but may be, for example, 1 or more and 20 or less. From the viewpoint of readily synthesizing compound A, the number of carbon atoms in the alkyl group may also be 1 or more and 10 or less, or 1 or more and 5 or less. By adjusting the number of carbon atoms in the alkyl group, the solubility of compound A relative to a solvent or resin composition can be adjusted. The alkyl group may be linear, branched, or cyclic. At least one hydrogen atom in the alkyl group may also be substituted by a group containing at least one atom selected from the group consisting of N, O, P, and S. Examples of alkyl groups include methyl, ethyl, propyl, butyl, 2-methylbutyl, pentyl, hexyl, 2,3-dimethylhexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecanyl, octadecyl, nonadecanyl, eicosyl, 2-methoxybutyl, 6-methoxyhexyl, etc.

[0087] A haloalkyl group is a group obtained by replacing at least one hydrogen atom in an alkyl group with a halogen atom. A haloalkyl group can also be a group obtained by replacing all hydrogen atoms in an alkyl group with a halogen atom. Examples of alkyl groups include those mentioned above. A specific example of a haloalkyl group is -CF3.

[0088] Unsaturated hydrocarbon groups contain unsaturated bonds such as carbon-carbon double bonds and carbon-carbon triple bonds. The number of unsaturated bonds in an unsaturated hydrocarbon group is, for example, 1 or more and 5 or less. The number of carbon atoms in an unsaturated hydrocarbon group is not particularly limited; it can be 2 or more and 20 or less, 2 or more and 10 or less, or 2 or more and 5 or less. Unsaturated hydrocarbon groups can be linear, branched, or cyclic. At least one hydrogen atom in an unsaturated hydrocarbon group can be replaced by a group containing at least one atom selected from the group consisting of N, O, P, and S. Examples of unsaturated hydrocarbon groups include vinyl and ethynyl groups.

[0089] Hydroxyl groups are represented by -OH. Carboxyl groups are represented by -COOH. Alkoxy carbonyl groups are represented by -COOR. a The aldehyde group is represented by -COH. The acyl group is represented by -COR. b Indicated by amide group -CONR. c R d Indicated by . Nitrile group is represented by -CN. Alkoxy group is represented by -OR. e Indicated by acyloxy group with -OCOR f The thiol group is represented by -SH. The alkylthio group is represented by -SR. g The sulfonic acid group is represented by -SO3H. The acyl thio group is represented by -SCOR. h Indicated by alkyl sulfonyl group with -SO2R i Indicated. The sulfonamide group is represented by -SO2NR.j R k Primary amines are represented by -NH2. Secondary amines are represented by -NHR. l Indicated. Tertiary amines are represented by -NR m R n Indicated. The nitro group is represented by -NO2. R a ~R n Each is an alkyl group independently of the others. Examples of alkyl groups include those described above. Wherein, the R of the amide group... c and R d and R of sulfonamide group j and R k They can also be hydrogen atoms independently of each other.

[0090] Specific examples of alkoxy carbonyl groups are -COOCH3, -COO(CH2)3CH3, and -COO(CH2)7CH3. Specific examples of acyl groups are -COCH3. Specific examples of amide groups are -CONH2. Specific examples of alkoxy groups are methoxy, ethoxy, 2-methoxyethoxy, butoxy, 2-methylbutoxy, 2-methoxybutoxy, 4-ethylthiobutoxy, pentoxy, hexoxy, heptoxy, octoxy, nonoxy, decoxy, undecyloxy, dodecyloxy, tridecyloxy, tetradecyloxy, pentadecyloxy, hexadecyloxy, heptadecanyloxy, octadecyloxy, nonadecanyloxy, and eicosyloxy. Specific examples of acyloxy groups are -OCOCH3. Specific examples of alkyl thio groups are -SCH3. Specific examples of acyl thio groups are -SCOCH3. Specific examples of alkyl sulfonyl groups are -SO2CH3. Specific examples of sulfonamide groups are -SO2NH2. Specific examples of tertiary amino groups are -N(CH3)2.

[0091] In equation (1), the choice is free R 2 R 3 R 7 R 8 R 12 and R 13 At least one of the constituent groups is, for example, an electron-donating group. R can also be used. 2 R 3 R 7 R 8 R 12 and R 13 Each is an electron-donating group. R 2 R 3 R 7 R 8 R 12 Or R 13 Compound A, which has an electron-donating group, can be readily synthesized. Compound A also tends to exhibit high nonlinear optical absorption properties.

[0092] The term "electron-donating group" refers to, for example, the substituent constant σ in the Hammett equation. p Substituents with negative values. Examples of electron-donating groups include alkyl, alkoxy, hydroxy, and amino groups. Electron-donating groups can also be alkoxy or -OCH3. Electron-donating groups can also be alkyl or -C(CH3)3.

[0093] In equation (1), the choice is free R 5 and R 10 At least one of the constituent groups is, for example, an electron-withdrawing group. R can also be used. 5 and R 10 Each is an electron-withdrawing group. R 5 Or R 10 Compound A, being an electron-withdrawing group, can be readily synthesized. Compound A also tends to exhibit excellent stability.

[0094] Electron-withdrawing groups, for example, refer to the aforementioned σ group. p Substituents with positive values. Examples of electron-withdrawing groups include halogen groups, carboxyl groups, nitro groups, thiols, sulfonic acid groups, acyloxy groups, alkylthiols, alkylsulfonyl groups, sulfonamide groups, acyl groups, acylthiols, alkoxycarbonyl groups, and haloalkyl groups. Electron-withdrawing groups can also be halogen groups or -Br groups.

[0095] In equation (1), R 1 ~R 14 In the middle, R 1 R 4 R 6 R 9 R 11 and R 14 Each can also have a ratio of R 1 R 4 R 6 R 9 R 11 and R 14 Other substituents have small volume. At this point, in R... 1 R 4 R 6 R 9 R 11 and R 14 In this compound, steric hindrance is less likely to occur. Therefore, compound A tends to easily form a π-stacking structure and exhibit improved nonlinear optical absorption characteristics. 1 R 4 R 6 R 9 R 11 and R 14 Each can also be a hydrogen atom.

[0096] In equation (1), n ​​is an integer greater than or equal to 2. n can also be greater than or equal to 6, 10, 12, or 14. The larger the value of n, the longer the chain length of compound A. For compound A, a longer chain length tends to result in improved nonlinear light absorption properties. That is, for compound A, unlike previous compounds via bond-type π-conjugation systems, there is a tendency to suppress the decrease in nonlinear light absorption properties even with π-conjugation system expansion. There is no specific upper limit for n; for example, 46. Specific examples of n include 2, 6, 10, 12, and 14.

[0097] Compound A, for example, has a helical structure. The helical structure can be either dextrorotatory or levorotatory. In light-absorbing materials, compounds A with a dextrorotatory helical structure can coexist with compounds A with a levorotatory helical structure. The rotation direction of the helical structure of compound A tends to reverse easily in solution.

[0098] If compound A has a helical structure, a π-stacking structure is easily formed within it. For example, in formula (1), when n is 2, compound A has a tetramer structure of anterophenylene. In the case of compound A having a helical structure, the two anterophenylene atoms at the ends of compound A can form a π-stacking structure. In formula (1), the larger the value of n, the greater the number of anterophenylene atoms that can form a π-stacking structure. It should be noted that, for the trimer structure of anterophenylene with n = 1 in formula (1), a π-stacking structure will not form. Therefore, the trimer structure of anterophenylene hardly exhibits nonlinear light absorption characteristics.

[0099] As a specific example of compound A represented by formula (1), compound B represented by formula (2) can be listed below.

[0100] [Chemical Formula 4]

[0101]

[0102] In equation (2), multiple Z values ​​are identical. In equation (1), R... 2 R 3 R 7 R 8 R 12 and R 13 Each is equivalent to one of the multiple Zs. Z is, for example, an alkoxy group such as -OCH3. In equation (2), the multiple Xs are identical to each other. R in equation (1) 5 and R 10 Each is equivalent to one of multiple X's. X can be, for example, a halogen group such as -Br.

[0103] The method of synthesizing compound B represented by formula (2) is not particularly limited. Compound B can be synthesized, for example, by using the coupling reaction described in the examples.

[0104] Compound A, represented by Equation (1), exhibits high nonlinear optical absorption characteristics due to a large ratio of its two-photon absorption cross-section σ to its molar absorptivity ε relative to light with a short wavelength region. The ratio of σ / ε for compound A relative to light with a short wavelength region tends to be larger than that of conventional two-photon absorption compounds disclosed in Patent Documents 1-3. For example, when compound A is irradiated with light having a wavelength of 405 nm, a significant tendency for nonlinear optical absorption occurs in compound A. As described above, with respect to compound A, the longer the chain length, the greater the tendency for nonlinear optical absorption characteristics. If compound A with enhanced nonlinear optical absorption characteristics is utilized, for example, the recording density of a three-dimensional optical memory can be increased.

[0105] The two-photon absorption cross-section of compound A relative to light with a wavelength of 405 nm can be greater than 1 GM, 10 GM, 30 GM, 50 GM, 70 GM, 100 GM, 200 GM, or 300 GM. There is no particular upper limit to the two-photon absorption cross-section of compound A; for example, it can be 10,000 GM. The two-photon absorption cross-section can be determined, 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 for determining nonlinear optical constants. In the Z-scan method, the sample is moved along the direction of the laser beam near the focal point. The change in the amount of light transmitted through the sample is recorded. In the Z-scan method, the power density of the incident light changes depending on the position of the sample. Therefore, when measuring nonlinear light absorption in a sample, if the sample is located near the focal point of the laser beam, the amount of transmitted light is attenuated. The two-photon absorption cross-section can be calculated by fitting the change in transmitted light intensity to a theoretical curve predicted by the intensity of the incident light, the thickness of the sample, and the concentration of compound A in the sample.

[0106] Compound A can also have a molar absorptivity of 50 mol% relative to light with a wavelength of 405 nm. -1 ·L·cm -1 The following can also be 10 mol -1 ·L·cm -1 The following can also be 5 mol -1 ·L·cm -1 The following can also be 2 mol -1 ·L·cm-1 The following can also be 1 mol -1 ·L·cm -1 The following is a lower limit for the molar absorptivity of compound A; it is not specifically limited, for example, it is 0.01 mol. -1 ·L·cm -1 The molar absorptivity can be determined, for example, according to the method specified in Japanese Industrial Standard (JIS) K0115:2004. In the determination of the molar absorptivity, a light source with a photon density that produces almost no two-photon absorption for compound A is used. Furthermore, in the determination of the molar absorptivity, the concentration of compound A is adjusted to 500 mmol / L. This concentration is very high compared to the concentration used in the experiment for determining the molar absorptivity of the absorption peak. The molar absorptivity can be used as an indicator of single-photon absorption.

[0107] For compound A, the two-photon absorption cross-section σ(GM) relative to light with wavelengths in the short wavelength region is related to the molar absorptivity ε(mol). -1 ·L·cm -1 The ratio σ / ε of compound A relative to light with a wavelength of 405 nm can be greater than 20, 30, 50, 70, 100, 150, or 200. There is no specific upper limit to the ratio σ / ε of compound A; for example, it could be 5000.

[0108] When compound A undergoes two-photon absorption, it absorbs approximately twice the energy of the light irradiating it. The wavelength of light possessing approximately twice the energy of light with a wavelength of 405 nm is, for example, 200 nm. When compound A is irradiated with light having a wavelength around 200 nm, single-photon absorption can also occur in compound A. Furthermore, in compound A, single-photon absorption can also occur for light with wavelengths near the wavelength region that produces two-photon absorption.

[0109] Compound A also exhibits a tendency for high solubility relative to organic solvents. This solubility is significantly enhanced when the rotation direction of the helical structure of compound A can be easily reversed in solution. As an example, compound A has a solubility of over 100 mg in 1 mL of chloroform at 25°C. There is no particular upper limit to this solubility, but it could be, for example, 500 mg. Compound A's high solubility relative to organic solvents makes it easy to handle and readily applicable to device applications.

[0110] The light-absorbing material of this embodiment may also contain compound A, represented by formula (1), as a main component. "Main component" refers to the component most abundant in the light-absorbing material by weight. The light-absorbing material is, for example, substantially formed from compound A. "Substantially formed from..." means excluding other components that alter the essential characteristics of the material. The light-absorbing material may contain impurities in addition to compound A. Because the light-absorbing material of this embodiment contains compound A, it tends to exhibit excellent nonlinear light absorption characteristics relative to light with wavelengths in the short wavelength region. The light-absorbing material of this embodiment containing compound A functions, for example, as a two-photon absorbing material.

[0111] The light-absorbing material of this embodiment is used, for example, in devices that utilize light with wavelengths in the short wavelength region. As an example, the light-absorbing material of this embodiment is used in devices that utilize light with wavelengths 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 storage devices. A specific example of a three-dimensional optical storage device is a three-dimensional optical disc. Examples of modeling machines include 3D printers and other light modeling machines. Examples of fluorescence microscopes include two-photon fluorescence microscopes. The light used in these devices, for example, has a high photon density near the focal point. The power density near the focal point of the light used in the device is, for example, 0.1 W / cm². 2 Above and 1.0×10 20 W / cm 2 The power density near the focal point of this light can also be 1.0 W / cm². 2 The above can also be 1.0 × 10 2 W / cm 2 The above can also be 1.0 × 10 5 W / cm 2 The above. As a light source for the device, for example, a femtosecond laser such as a Ti:sapphire laser, or a pulsed laser with a pulse amplitude of picosecond to nanosecond, such as a semiconductor laser, can be used.

[0112] The recording medium, for example, includes a thin film referred to as a recording layer. Information is recorded in the recording layer of the recording medium. As an example, the thin film serving as the recording layer contains a light-absorbing material according to this embodiment. That is, this disclosure provides a recording medium, from another aspect, which includes a light-absorbing material comprising the aforementioned compound A.

[0113] In addition to containing light-absorbing materials, the recording layer further contains a polymer compound that functions as a binder. The recording medium also includes a dielectric layer in addition to the recording layer. For example, a recording medium may have multiple recording layers and multiple dielectric layers. In a recording medium, multiple recording layers and multiple dielectric layers may also be alternately stacked.

[0114] Next, the method for recording information using the aforementioned recording medium will be explained. Figure 1A This is a flowchart of a method for recording information using the aforementioned recording medium. First, in step S11, a light source is prepared to emit light with a wavelength of 390 nm or more and 420 nm or less. For example, a femtosecond laser such as a Ti:sapphire laser, or a pulsed laser with a pulse amplitude of picoseconds to nanoseconds, such as a semiconductor laser, can be used as the light source. Next, in step S12, the light from the light source is focused using a lens or the like, and then irradiated onto the recording layer in the recording medium. Specifically, the light from the light source is focused using a lens or the like, and then irradiated onto the recording area in the recording medium. The power density near the focal point of this light is, for example, 0.1 W / cm². 2 Above and 1.0×10 20 W / cm 2 The power density near the focal point of this light can also be 1.0 W / cm². 2 The above can also be 1.0 × 10 2 W / cm 2 The above can also be 1.0 × 10 5 W / cm 2 That's all. In this specification, the term "recording area" refers to a spot existing in the recording layer that can record information when illuminated.

[0115] In the recording area after irradiation with the aforementioned light, physical or chemical changes occur. For example, compound A, which absorbs light, generates heat when returning from a transition state to a ground state. This heat causes the binder present in the recording area to deteriorate. Consequently, the optical properties of the recording area change. For example, the intensity of light reflected from the recording area, the reflectivity of light in the recording area, the absorptivity of light in the recording area, and the refractive index of light in the recording area change. In the recording area after irradiation with light, sometimes the intensity of fluorescent light emitted from the recording area or the wavelength of the fluorescent light also changes. As a result, information can be recorded in the recording layer, specifically in the recording area (step S13).

[0116] Next, the method for reading information using the aforementioned recording medium will be explained. Figure 1BThis is a flowchart of a method for reading information using the aforementioned recording medium. First, in step S21, light is irradiated onto the recording layer of the recording medium. Specifically, light is irradiated onto the recording area of ​​the recording medium. The light used in step S21 may be the same as or different from the light used to record information in the recording medium. Next, in step S22, the optical characteristics of the recording layer are measured. Specifically, the optical characteristics of the recording area are measured. In step S22, for example, as an optical characteristic of the recording area, the intensity of light reflected from the recording area is measured. In step S22, as an optical characteristic of the recording area, the reflectivity of light in the recording area, the absorptivity of light in the recording area, the refractive index of light in the recording area, the intensity of fluorescence emitted from the recording area, the wavelength of the fluorescence, etc., may also be measured. Next, in step S23, information is read from the recording layer, specifically the recording area.

[0117] In information readout methods, the recording area containing information can be located using the following method. First, light is irradiated onto a specific area of ​​the recording medium. This light can be the same as or different from the light used to record information on the recording medium. Next, the optical characteristics of the area after irradiation are measured. Examples of optical characteristics include, for instance, the intensity of light reflected from the area, the reflectivity of light in the area, the absorptivity of light in the area, the refractive index of light in the area, the intensity of fluorescence emitted from the area, and the wavelength of fluorescence emitted from the area. Based on the measured optical characteristics, it is determined whether the area after irradiation is a recording area. For example, if the intensity of light reflected from the area is below a certain value, the area is determined to be a recording area. On the other hand, if the intensity of light reflected from the area exceeds a certain value, the area is determined not to be a recording area. It should be noted that the method for determining whether an area after irradiation is a recording area is not limited to the method described above. For example, if the intensity of light reflected from the area exceeds a certain value, the area can also be determined to be a recording area. Furthermore, if the intensity of light reflected from the area is below a certain value, the area can also be determined not to be a recording area. If the area is determined not to be a recording area, the same operation is performed on other areas of the recording medium. This allows the recording area to be located.

[0118] The recording and reading methods using the aforementioned recording medium can be performed, for example, by a known recording apparatus. The recording apparatus, for example, includes a light source for illuminating a recording area in the recording medium, a measuring instrument for measuring the optical properties of the recording area, and a controller for controlling the light source and the measuring instrument.

[0119] A photoforming machine, for example, cures a photocurable resin composition by irradiating it with light. As an example, the photocurable resin composition for photoforming includes a light-absorbing material as described in this embodiment. In addition to the light-absorbing material, the photocurable resin composition may also include a polymerizable compound and a polymerization initiator. The photocurable resin composition may further include additives such as adhesive resins. The photocurable resin composition may also include epoxy resin.

[0120] If a fluorescence microscope is used, for example, light can be shone onto a biological sample containing a fluorescent dye material, and the fluorescence emitted from the dye material can be observed. As an example, the fluorescent dye material to be added to the biological sample includes the light-absorbing material of this embodiment.

[0121] Example

[0122] The present disclosure will be further described in detail below through embodiments. It should be noted that the following embodiments are examples, and the present disclosure is not limited to the following embodiments.

[0123] [Example 1]

[0124] (Synthesis of compound OP4Br)

[0125] First, a tetrahydrofuran solution containing 2,2'-dibromo-4,4',5,5'-tetramethoxybiphenyl was prepared under an argon atmosphere. Next, 28 mmol of a 1.57 mol / L n-butyllithium hexane solution was added to this solution, and the mixture was stirred at -78°C for 30 minutes. Then, copper cyanide powder (1.04 g, 12 mmol) was added to the reaction solution, and the mixture was stirred at room temperature for 2 hours. Next, durquinone powder (5.70 g, 35 mmol) was added to the reaction solution, and the mixture was stirred at room temperature for 1.5 hours. This carried out the coupling reaction of 2,2'-dibromo-4,4',5,5'-tetramethoxybiphenyl. The reaction solution was then injected into an ammonia solution, and the organic layer was extracted with ethyl acetate. The extracted organic layer was washed with a saturated ammonium chloride solution and water, and dried with magnesium sulfate. After drying, the ethyl acetate was removed by vacuum distillation. The compound OP4Br of Example 1 was synthesized by purification of the crude product by column chromatography. The compound OP4Br is represented by the following formula (3).

[0126] [Chemical Formula 5]

[0127]

[0128] Compound OP4Br via 1 Identification was performed using H-NMR and quality analysis. Figure 2AIt represents compound OP4Br from Example 1. 1 Chart of H-NMR spectra. Figure 2B yes Figure 2A A magnified view of the chart. The compound OP4Br. 1 The results of H-NMR spectroscopy and mass analysis using a high-resolution mass spectrometry (HRMS) device employing electrospray ionization-time-of-flight mass analysis are described below. It should be noted that... 1 The 1H-NMR spectrum showed a high magnetic field shift in the peak originating from hydrogen atoms bonded to the benzene ring. This result indicates that the compound OP4Br has a helical structure.

[0129] 1 HNMR (600MHz, CD3CN): δ (ppm) 7.15-6.73 (m, 6H), 6.43 (br.2H), 3.78 (s.6H), 3.74 (br.12H), 3.51 (s.6H). HRMS (ESI-TOFmass): calcd.for C 32 H 32 Br2O8[M] + : m / z=704.04; found: 704.00.

[0130] [Example 2]

[0131] (Synthesis of compound OP8Br)

[0132] First, a tetrahydrofuran solution (42 mL) containing 1.01 g, 1.4 mmol of compound OP4Br synthesized in Example 1 was prepared under an argon atmosphere. Next, 2.2 mmol of a 1.58 mol / L n-butyllithium hexane solution was added to this solution, and the mixture was stirred at -78 °C for 30 min. Then, copper cyanide powder (64.6 mg, 0.72 mmol) was added to the reaction solution, and the mixture was stirred at room temperature for 2 h. Next, durquinone powder (356 mg, 2.2 mmol) was added to the reaction solution, and the mixture was stirred at room temperature for 1.5 h. This carried out the coupling reaction of compound OP4Br. Next, the reaction solution was injected into an ammonia solution, and the organic layer was extracted with ethyl acetate. The extracted organic layer was washed with a saturated ammonium chloride solution and water, and dried with anhydrous magnesium sulfate. After drying, the ethyl acetate was removed by vacuum distillation. The crude product was purified by column chromatography to synthesize compound OP8Br of Example 2. The compound OP8Br is represented by the following formula (4).

[0133] [Chemical Formula 6]

[0134]

[0135] Compound OP8Br via 1 Identification was performed using H-NMR. Figure 3A This refers to compound OP8Br from Example 2. 1 Chart of H-NMR spectra. Figure 3B yes Figure 3A A magnified view of the chart. Compound OP8Br. 1 The H-NMR spectrum is as follows. Similar to Example 1, from... 1 The results of H-NMR spectroscopy showed that the compound OP8Br has a helical structure.

[0136] 1 HNMR (600MHz, CD3CN): δ (ppm) 6.73 (s, 2H), 6.72 (s, 2H), 6.48 (s, 2H), 5.90 (s, 2H), 5.89 (s, 2H), 5.83 (s, 2H), 5.77 (s, 2H) ), 5.34(s, 2H), 3.73(s, 6H), 3.71(s, 6H), 3.70(s, 6H), 3.55(s, 6H), 3.54(s, 6H), 3.48(s, 6H), 3.46(s, 6H), 3.09(s, 6H).

[0137] [Example 3]

[0138] (Synthesis of compound OP12Br)

[0139] First, prepare the o-phenylene 12 polymer represented by the following formula (5).

[0140] [Chemical Formula 7]

[0141]

[0142] Next, a dimethylformamide solution (20 mL) containing N-bromosuccinimide (18.5 g, 1.1 mmol) and the above-mentioned o-phenylene 12 polymer (0.90 g, 0.5 mmol) was prepared and stirred at 0 °C for 1 hour. Then, the solution was heated to room temperature and stirred for 4 hours. This was used to carry out the bromination reaction of the o-phenylene 12 polymer. The reaction solution was then injected into water and extracted with chloroform. The extract was washed with saturated brine and dried with magnesium sulfate. After drying, the chloroform was removed by vacuum distillation. The obtained crude product was purified by column chromatography to synthesize the compound OP12Br of Example 3. The compound OP12Br is represented by the following formula (6).

[0143] [Chemical Formula 8]

[0144]

[0145] Compound OP12Br via 1 Identification was performed using H-NMR. Figure 4A This refers to compound OP12Br from Example 3. 1 Chart of H-NMR spectra. Figure 4B yes Figure 4A A magnified view of the chart. Compound OP12Br. 1 The H-NMR spectrum is as follows. Similar to Example 1, from... 1 The results of H-NMR spectroscopy showed that the compound OP12Br has a helical structure.

[0146] 1 HNMR (600MHz, CD3CN): δ (ppm) 6.64 (s, 2H), 6.64 (s, 2H), 6.37 (s, 2H), 5.83 (s, 2H), 5.76(s, 2H), 5.74(s, 2H), 5.55(s, 2H), 5.53(s, 2H), 5.51(s, 2H), 5.50(s, 2H), 5.40 (s, 2H), 5.14 (s, 2H), 3.68 (s, 6H), 3.66 (s, 6H), 3.65 (s, 6H), 3.50 (s, 6H), 3.47 (s, 6H), 3.43(s, 6H), 3.43(s, 6H), 3.42(s, 6H), 3.40(s, 6H), 3.39(s, 6H), 3.38(s, 6H).

[0147] [Example 4]

[0148] (Synthesis of compound OP14Br)

[0149] First, prepare the o-phenylene 14 polymer represented by the following formula (7).

[0150] [Chemical Formula 9]

[0151]

[0152] Next, a dimethylformamide solution (20 mL) containing N-bromosuccinimide (9.3 g, 0.53 mmol) and the above-mentioned o-phenylene 14 polymer (0.59 g, 0.25 mmol) was prepared and stirred at 0 °C for 1 hour. Then, the solution was heated to room temperature and stirred for 4 hours. This was used to carry out the bromination reaction of the o-phenylene 14 polymer. The reaction solution was then injected into water and extracted with chloroform. The extract was washed with saturated brine and dried with magnesium sulfate. After drying, the chloroform was removed by vacuum distillation. The obtained crude product was purified by column chromatography to synthesize the compound OP14Br of Example 4. The compound OP14Br is represented by the following formula (8).

[0153] [Chemical Formula 10]

[0154]

[0155] Compound OP14Br via 1 Identification was performed using H-NMR. Figure 5A This refers to compound OP14Br from Example 4. 1 Chart of H-NMR spectra. Figure 5B yes Figure 5A A magnified view of the chart. Compound OP14Br. 1 The H-NMR spectrum is as follows. Similar to Example 1, from... 1 The results of H-NMR spectroscopy showed that the compound OP14Br has a helical structure.

[0156] 1 HNMR (600MHz, CD3CN): δ (ppm) 6.63 (s, 2H), 6.62 (s, 2H), 6.36 (s, 2H), 5.85 (s, 2H), 5.74 (s, 2H) ), 5.69(s, 2H), 5.54(s, 2H), 5.50(s, 2H), 5.46(s, 2H), 5.45(s, 2H), 5.42(s, 2H), 5.37(s, 2H), 5.35(s, 2H), 5.12(s, 2H), 3.67(s, 6H), 3.65(s, 6H), 3.64(s, 6H), 3.48(s, 6H), 3.47(s, 6H), 3. 42(s, 6H), 3.41(s, 6H), 3.40(s, 6H), 3.39(s, 6H), 3.369(s, 12H), 3.365(s, 12H), 3.02(s, 6H).

[0157] [Example 5]

[0158] (Synthesis of compound OP16Br)

[0159] First, a tetrahydrofuran solution (60 mL) containing OP8Br (1.0 g, 0.80 mmol) synthesized in Example 2 was prepared under an argon atmosphere. Next, 3.2 mmol of a 1.8 mol / L tert-butyllithium hexane solution was added to this solution, and the mixture was stirred at -78 °C for 10 min. Then, the solution was stirred at -40 °C for 15 min and cooled again to -78 °C. Next, copper cyanide powder (72 mg, 0.8 mmol) was added to the resulting reaction solution, and the mixture was stirred at room temperature for 1.5 h. Next, durquinone powder (200 mg, 1.2 mmol) was added to the reaction solution, and the mixture was stirred at room temperature for 12 h. This carried out the coupling reaction of compound OP8Br. Next, the reaction solution was injected into an ammonia solution, and the organic layer was extracted with ethyl acetate. The extracted organic layer was washed with a saturated ammonium chloride solution and water, and dried with anhydrous magnesium sulfate. After drying, the ethyl acetate was removed by vacuum distillation. The compound OP16Br of Example 5 was synthesized by purifying the crude product using column chromatography. The compound OP16Br is represented by the following formula (9).

[0160] [Chemical Formula 11]

[0161]

[0162] Compound OP16Br via 1 Identification was performed using H-NMR and quality analysis. Figure 6A This refers to compound OP16Br from Example 5. 1 Chart of H-NMR spectra. Figure 6B yes Figure 6A A magnified view of the chart. Compound OP16Br. 1 The results of H-NMR spectroscopy and mass analysis using a high-resolution mass analyzer (HRMS) employing electrospray ionization-time-of-flight mass analysis are described below. Similar to Example 1, the results were obtained from... 1 The results of H-NMR spectroscopy showed that the compound OP16Br has a helical structure.

[0163] 1HNMR (600MHz, CD3CN): δ (ppm) 6.624 (s, 2H), 6.616 (s, 2H), 6.36 (s, 2H), 5.84 (s, 2H), 5.73 (s, 2H), 5.68 (s, 2H), 5.52 (s, 2H), 5.48(s, 2H), 5.45(s, 2H), 5.43(s, 2H), 5.37(s, 2H), 5.36(s, 2H), 5.33(s, 2H), 5.32(s, 2H), 5.30(s, 2H), 5.10(s, 2H ), 3.67(s, 6H), 3.64(s, 6H), 3.63(s, 6H), 3.47(s, 6H), 3.45(s, 6H), 3.401(s, 6H), 3.398(s, 6H), 3.39(s, 6H), 3.37(s, 6 H), 3.36(s, 6H), 3.354(s, 12H), 3.349(s, 6H), 3.341(s, 6H), 3.337(s, 6H), 3.02(s, 6H).HRMS(ESI-TOFmass): calcd.for C 128 H 128 Br2O 32 [M] + : m / z=2334.68; found: 2335.12.

[0164] [Compare Examples 1 and 2]

[0165] The compound of Comparative Example 1 shown in Formula (10) below, namely hexa(phenylethynyl)benzene (HPEB), was synthesized using the methods 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. Furthermore, the compound of Comparative Example 2 shown in Formula (11) below, namely compound 1f, was synthesized using the method disclosed in paragraph

[0083] of Patent Document 2.

[0166] [Chemical Formula 12]

[0167]

[0168] Determination of Two-Photon Absorption Cross-Section

[0169] For the compounds of the examples and comparative examples, the two-photon absorption cross-section (BCR) relative to light with a wavelength of 405 nm was measured. The BCR was measured using the Z-scan method described in J. Opt. Soc. Am. B, 2003, Vol. 20, p. 529. A Ti:sapphire pulsed laser was used as the light source for measuring the BCR. Specifically, the sample was irradiated with the second harmonic of the Ti:sapphire pulsed laser. The laser pulse amplitude was 80 fs. The laser repetition frequency was 1 kHz. The average power of the laser varied within a range of 0.01 mW to 0.08 mW. The light from the laser had a wavelength of 405 nm. Specifically, the light from the laser had a center wavelength of 402 nm to 404 nm. The full width at half maximum (FW) of the light from the laser was 4 nm.

[0170] <Determination of molar absorptivity>

[0171] For the compounds in the examples and comparative examples, the molar absorptivity was determined according to the method specified in JIS K0115:2004. Specifically, first, a test sample was prepared with the concentration of the compound adjusted to 500 mmol / L. For the test sample, the absorption spectrum was measured. The absorbance at a wavelength of 405 nm was read from the obtained spectrum. The molar absorptivity was calculated based on the concentration of the compound in the test sample and the optical path length of the cell used for the measurement.

[0172] The two-photon absorption cross-section σ(GM) and molar absorptivity ε(mol) obtained by the above method are used to... -1 ·L·cm -1 The values ​​and ratios σ / ε are shown in Table 1.

[0173] Table 1

[0174]

[0175] In conventional π-conjugated compounds via bond type, to improve the ratio σ / ε reflecting nonlinear light absorption characteristics, it is necessary to increase the two-photon absorption cross-section σ and decrease the molar absorptivity ε. Generally, to increase the two-photon absorption cross-section σ, the π-conjugated system of the pigment is expanded. However, as the chain length is extended, the light absorption wavelength undergoes a long-wavelength shift, and the molar absorptivity ε at the excitation wavelength (405 nm) increases. That is, there is a limit to the improvement of nonlinear light absorption characteristics using the above methods. The π-conjugated compound of this disclosure has a chemical structure corresponding to compound A represented by formula (1). Since the π-conjugated compound has a sharply twisted helical structure, even if the chain length is extended, the light absorption wavelength will not undergo a long-wavelength shift, and the increase in molar absorptivity ε can be suppressed. That is, the nonlinear light absorption characteristics of the π-conjugated compound are improved by extending the chain length of the π-conjugated compound.

[0176] As can be seen from Table 1, for the compounds of Examples 1 to 5 corresponding to compound A represented by formula (1), even with chain length elongation, the two-photon absorption cross-sectional area σ increases, but the increase in molar absorptivity ε is suppressed. As a result, it is found that compared with the compounds of the comparative examples, the nonlinear light absorption characteristic σ / ε is improved, and the two-photon absorption characteristic is improved. Therefore, the longer the chain length of the pigment using the spatial conjugated system of this disclosure, the better it is possible to balance the increase in two-photon absorption cross-sectional area and the decrease in molar absorptivity, thus further improving the nonlinear light absorption characteristics.

[0177] It should be noted that the two-photon absorption cross-section of compound OP3Br, which has a trimer structure of o-phenylene, cannot be determined by the above method. Compound OP3Br is represented by the following formula (12). From this result, it can be seen that n in formula (1) must be an integer greater than 2. That is, compound A must be a polymer of o-phenylene tetramer or higher.

[0178] [Chemical Formula 13]

[0179]

[0180] Industrial availability

[0181] The light-absorbing material disclosed herein can be used in recording layers of three-dimensional optical memories, photocurable resin compositions for photomasking, and other applications. The light-absorbing material of this disclosure exhibits high nonlinear light absorption characteristics relative to light with wavelengths having a short wavelength range. Therefore, the light-absorbing material of this disclosure can achieve extremely high spatial resolution in applications such as three-dimensional optical memories and modeling machines. Furthermore, when using the light-absorbing material of this disclosure, even under irradiation with low-intensity laser light, two-photon absorption can be preferentially induced compared to single-photon absorption, compared to conventional light-absorbing materials.

Claims

1. A light-absorbing material comprising a compound represented by formula (1) as a main component, In the above formula (1), R 1 ~R 14 comprises at least one atom independently selected from the group consisting of H, C, N, O, F, P, S, CI, I and Br, n is an integer greater than or equal to 2.

2. The light-absorbing material according to claim 1, wherein, The R 1 ~The R mentioned 14 Each group can be a hydrogen atom, halogen atom, saturated hydrocarbon group, haloalkyl group, unsaturated hydrocarbon group, hydroxyl group, carboxyl group, alkoxycarbonyl group, aldehyde group, acyl group, amide group, nitrile group, alkoxy group, acyloxy group, thiol group, alkylthio group, sulfonic acid group, acylthio group, alkylsulfonyl group, sulfonamide group, primary amino group, secondary amino group, tertiary amino group, or nitro group.

3. The light-absorbing material according to claim 1 or 2, wherein, Choose freely from the R 2 The R 3 The R 7 The R 8 The R 12 and the R 13 At least one of the groups is an electron-donating group.

4. The light-absorbing material according to claim 3, wherein, The electron-donating group is an alkoxy group.

5. The light-absorbing material according to claim 3 or 4, wherein, The electron-donating group is -OCH3.

6. The light-absorbing material according to any one of claims 1 to 5, wherein, Choose freely from the R 5 and the R 10 At least one of the constituent groups is an electron-withdrawing group.

7. The light-absorbing material according to claim 6, wherein, The electron-withdrawing group is a halogen group.

8. The light-absorbing material according to any one of claims 1 to 7, wherein, The compound has a helical structure.

9. The light-absorbing material according to any one of claims 1 to 8, wherein, The compound has the property of absorbing specific types of light.

10. The light-absorbing material according to any one of claims 1 to 9, which is used in a device that utilizes light having a wavelength of 390 nm or more and 420 nm or less.

11. A recording medium comprising a recording layer comprising the light-absorbing material according to any one of claims 1 to 10.

12. A method for recording information, comprising: A light source is prepared to emit light with wavelengths above 390nm and below 420nm; The light from the light source is focused to irradiate the recording layer in the recording medium of claim 11.

13. A method for reading information, which is a method for reading information recorded by the recording method of claim 12. The readout method includes: The optical properties of the recording layer are measured by irradiating the recording layer with light; and The information is read from the recording layer.

14. The readout method according to claim 13, wherein, The optical property is the intensity of light reflected in the recording layer.

Images