JP2007021890A - Optical recording medium, coloring matter for forming its recording layer and recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thiol type metal-complex compound type coloring matter for forming a recording layer which is excellent in solubility to solvents, and has a high recording sensitivity, for which a metal-containing compound derivative can be relatively easily synthesized, and which can correspond to optical recording with a blue color laser light when it is used for forming a recording layer of an optical recording medium, and exhibits high light resistance, heat resistance and moist heat resistance. <P>SOLUTION: The coloring matter for forming the recording layer of the optical recording medium comprises a compound expressed by general formula (1), wherein A and D are each independently a hydrocarbon group which may have a substituent, a heterocyclic group which may have a substituent, a hydrocarbon thio group which may have a substituent, or a heterocyclic thio group which may have a substituent; B and C are each independently an arbitrary mono-valent substituent or a hydrogen atom; however, A and B, and C and D may bond with each other through a connecting group or without the connecting group to form a ring except an aromatic hydrocarbon ring. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a dithiol metal complex compound dye used for forming a recording layer of an optical recording medium. In particular, the present invention relates to a dye used for an optical recording medium compatible with blue laser light. The present invention also relates to an optical recording medium having a recording layer using such a dye and a recording method thereof.

  In recent years, since it is possible to record / store / reproduce information at a high density, development of an optical recording medium using a laser beam, particularly an optical disk, has been underway. Among the optical disks, a writable compact disk (CD-R) is recently attracting attention. The CD-R usually has a structure in which a recording layer mainly composed of a dye, a metal reflective film, and a protective film are sequentially laminated on a circular plastic substrate having guide grooves. Information is recorded on the CD-R by irradiating a laser beam and absorbing the irradiation energy in the recording layer, so that heat such as decomposition, evaporation, dissolution, etc. is generated in the recording layer, reflecting layer or substrate of the laser beam irradiation portion. This is performed by a method of generating a general deformation (heat mode), a method of reversibly changing the structure of the dye contained in the recording layer of the laser light irradiated portion (photon mode), or the like. The recorded information is reproduced by reading the difference in reflectance with respect to the laser beam between the portion where thermal deformation or dye structure change due to laser light irradiation occurs and the portion where it does not occur. Therefore, it is necessary for the recording layer of the optical recording medium to efficiently absorb the energy of the laser beam, and a laser beam absorbing dye is generally used for the recording layer.

  An optical recording medium using an organic dye as a laser light absorbing dye can form a recording layer by a simple method of applying an organic dye solution, and is expected to become increasingly popular as an inexpensive optical recording medium in the future. .

  Also, in recent years, in order to increase the recording density, the wavelength of laser light used for recording has been shortened from a wavelength centered on the conventional semiconductor laser emission wavelength of 780 nm to a blue light region of about 405 nm or less. Is being considered.

  As compounds that have been attracting attention as dyes for optical recording media using lasers in the blue light region, porphyrin compounds (Patent Documents 1 and 2, etc.), cyanine compounds (Patent Documents 3, 4 etc.), polyenes Compounds (Patent Documents 5 and 6 etc.), azo compounds (Patent Documents 7 and 8 etc.), coumarin compounds (Patent Documents 9 and 10 etc.), naphthalocyanine compounds (Patent Document 11 etc.), styryl compounds (Patents) Documents 12, 13, etc.) and quinone compounds (Patent Document 14, etc.).

  However, porphyrin compounds have a highly symmetric structure and have a hard skeleton, and therefore generally have high crystallinity and low solubility in solvents. Further, agglomeration (precipitation) may occur after a solution dissolved in a solvent is applied to the substrate to form a recording layer. Cyanine compounds, polyene compounds, coumarin compounds, styryl compounds, quinone compounds, and the like are relatively weak in light resistance, and an additive such as a quencher may be required for practical use. An azo compound has a limit in adjusting the absorption maximum in the wavelength region of the blue laser. In addition, naphthalocyanine compounds have low solubility, and there is a limit to wavelength adjustment for absorption maximum.

  Patent Document 15 proposes a benzenedithiol complex-based compound typified by the following compound as a compound that has good solubility in a solvent, is stable in solution, and does not easily precipitate in a coating film of the solution.

This compound has good solubility in a solvent, is stable in solution, hardly precipitates in a coating film of the solution, and exhibits high light resistance when used as a recording layer of an optical recording medium. . However, in terms of recording sensitivity, the level is still not sufficient, and the substituted dithiolbenzene, which is a ligand moiety, is also easily oxidized, so there are restrictions on the synthesis, and the synthesis of a group of compounds with further increased recording sensitivity The current situation is difficult.
JP 2001-80217 A JP 2001-143317 A JP-A-6-40161 JP 2001-260536 A JP-A-4-78576 JP 11-334205 A JP-A-11-334204 JP 2001-271001 A JP 2000-43423 A JP 2001-96918 A JP 2000-228028 A JP 2001-71639 A JP 2002-2110 A JP 2001-234154 A JP 2003-320754 A

  The present invention has been made in view of the above circumstances, and its purpose is excellent in solubility in a solvent, high recording sensitivity, and relatively easy synthesis of a metal-containing compound derivative, and an optical recording medium. Provided is a dithiol-based metal complex compound-based recording layer forming dye that is compatible with optical recording with a blue laser beam when used for forming a recording layer, and exhibits high light resistance, high heat resistance, and high moist heat resistance. It is in.

  Another object of the present invention is to provide an optical recording medium having a recording layer using the recording layer forming dye and a recording method thereof.

As a result of intensive studies to solve the above problems, the inventors of the present invention have a specific structure as the heteroatom-containing ligand of the metal complex compound, which has excellent solubility in solvents and high recording sensitivity, In addition, the synthesis of the metal-containing compound derivative is relatively easy, and an optical recording medium using this in the recording layer can be recorded well with blue laser light, and at the same time has high light resistance, high heat resistance and high heat and humidity resistance. As a result, the present invention has been completed.
That is, the gist of the present invention is as follows.

（一般式（１）中、ＡとＤは、それぞれ独立して、置換基を有していても良い炭化水素基、置換基を有していても良い複素環基、置換基を有していても良い炭化水素チオ基、又は、置換基を有していても良い複素環チオ基を示し、ＢとＣは、それぞれ独立して、任意の１価の置換基、又は水素原子を示す。ただし、ＡとＢ、ＣとＤは、互いに、連結基を介してあるいは介さずに、結合して芳香族炭化水素環以外の環を形成しても良い。
Ｅはカウンターイオンであり、ｎは０〜２の整数を示す。即ち、一般式（１）で表される化合物は、必要に応じてｎ個のカウンターイオンＥを有することにより、中性（カチオンの価数とアニオンの価数との合計が０となる）とされている。
Ｍ^１は任意の金属原子を示す。） [1] A dye for forming a recording layer of an optical recording medium, comprising a compound represented by the following general formula (1).

(In General Formula (1), A and D each independently have a hydrocarbon group which may have a substituent, a heterocyclic group which may have a substituent, or a substituent. An optionally substituted hydrocarbon thio group or an optionally substituted heterocyclic thio group, and B and C each independently represent an arbitrary monovalent substituent or a hydrogen atom. However, A and B and C and D may be bonded to each other through a linking group or not to form a ring other than the aromatic hydrocarbon ring.
E is a counter ion, and n represents an integer of 0 to 2. That is, the compound represented by the general formula (1) has n counter ions E as necessary, so that it is neutral (the sum of the cation valence and the anion valence becomes 0). Has been.
M ¹ represents an arbitrary metal atom. )

[2] A dye for forming a recording layer of an optical recording medium, wherein A to E, n and M in the general formula (1) in [1] are as follows.
A and D each independently represent a hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent, and B and C each independently , A hydrocarbon group which may have a substituent, a heterocyclic group which may have a substituent, or a hydrogen atom; However, A and B, and C and D may be bonded to each other through a linking group or not to form a ring.
E is represented by XR ¹ R ² R ³ R ⁴ , X represents a nitrogen atom or a phosphorus atom, and R ^{1 to} R ⁴ are each independently a carbon atom that may have a substituent. A hydrogen group or a heterocyclic group which may have a substituent is shown.
* N shows the integer of 0-2.
* M represents a metal atom in Groups 4 to 11 of the periodic table.

[3] A dye for forming a recording layer of an optical recording medium, wherein A to E, n and M in the general formula (1) in [1] are as follows.
A to D each independently represent a hydrocarbon thio group that may have a substituent or a heterocyclic thio group that may have a substituent. However, A and B, and C and D may be bonded to each other through a linking group or not to form a ring.
E is represented by XR ¹ R ² R ³ R ⁴ , X represents a nitrogen atom or a phosphorus atom, and R ^{1 to} R ⁴ are each independently a carbon atom that may have a substituent. A hydrogen group or a heterocyclic group which may have a substituent is shown.
* N shows the integer of 0-2.
* M represents a metal atom in Groups 4 to 11 of the periodic table.

[4] A dye for forming a recording layer of an optical recording medium, wherein, in [1], A to E, n and M in the general formula (1) are as follows.
A and D each independently represent a hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent, and B and C each independently Represents a hydrocarbon thio group which may have a substituent or a heterocyclic thio group which may have a substituent. However, A and B, and C and D may be bonded to each other through a linking group or not to form a ring.
E is represented by XR ¹ R ² R ³ R ⁴ , X represents a nitrogen atom or a phosphorus atom, and R ^{1 to} R ⁴ are each independently a carbon atom that may have a substituent. A hydrogen group or a heterocyclic group which may have a substituent is shown.
* N shows the integer of 0-2.
* M represents a metal atom in Groups 4 to 11 of the periodic table.

[5] In the optical recording medium according to [1] to [4], M in the general formula (1) represents Ni, Pd, Pt, Cu, Co, Fe, Au, Cr, or Mn. A recording layer forming dye.

[6] In [1] to [5], the recording layer containing the recording layer forming dye is irradiated with light having an irradiance of 0.55 W / m ² at a temperature of 58 ° C. and a humidity of 50% for 40 hours. When the light resistance test is performed, the recording layer after the light resistance test has an absorption intensity at a wavelength of 350 nm of 80% or more with respect to the absorption intensity before the test. Layer forming dye.

[7] An optical recording medium comprising a recording layer containing the recording layer forming dye described in [1] to [6].

[8] The recording method for an optical recording medium according to [7], wherein recording is performed with a laser beam having a wavelength of 350 to 530 nm.

  The dye for forming a recording layer of the optical recording medium of the present invention has excellent solubility in a solvent, high recording sensitivity, and relatively easy synthesis of a metal-containing compound derivative. Moreover, it is excellent in light resistance, heat resistance, and wet heat resistance. By using this recording layer forming dye in the recording layer, it is possible to provide an inexpensive and high density optical recording medium excellent in film properties that can be recorded favorably with blue laser light.

  Embodiments of the present invention will be specifically described below, but the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.

（一般式（１）中、ＡとＤは、それぞれ独立して、置換基を有していても良い炭化水素基、置換基を有していても良い複素環基、置換基を有していても良い炭化水素チオ基、又は、置換基を有していても良い複素環チオ基を示し、ＢとＣは、それぞれ独立して、任意の１価の置換基、又は水素原子を示す。ただし、ＡとＢ、ＣとＤは、互いに、連結基を介してあるいは介さずに、結合して芳香族炭化水素環以外の環を形成しても良い。
Ｅはカウンターイオンであり、ｎは０〜２の整数を示す。即ち、一般式（１）で表される化合物は、必要に応じてｎ個のカウンターイオンＥを有することにより、中性（カチオンの価数とアニオンの価数との合計が０となる）とされている。
Ｍ^１は任意の金属原子を示す。） [Dye for recording layer formation]
The recording layer forming dye of the optical recording medium according to the present invention contains a compound represented by the following general formula (1).

(In General Formula (1), A and D each independently have a hydrocarbon group which may have a substituent, a heterocyclic group which may have a substituent, or a substituent. An optionally substituted hydrocarbon thio group or an optionally substituted heterocyclic thio group, and B and C each independently represent an arbitrary monovalent substituent or a hydrogen atom. However, A and B and C and D may be bonded to each other through a linking group or not to form a ring other than the aromatic hydrocarbon ring.
E is a counter ion, and n represents an integer of 0 to 2. That is, the compound represented by the general formula (1) has n counter ions E as necessary, so that it is neutral (the sum of the cation valence and the anion valence becomes 0). Has been.
M ¹ represents an arbitrary metal atom. )

{Explanation of words}
In the present invention, the “aromatic ring” means a ring having aromaticity, that is, a ring having a (4p + 2) π electron system (p is a natural number), and therefore, “aromatic hydrocarbon ring” and “aromatic heterocycle”. "Hydrocarbon ring group" means both "aromatic hydrocarbon ring group (aryl group)" and "non-aromatic hydrocarbon ring group", and "heterocyclic group" It means both “aromatic heterocyclic group (heteroaryl group)” and “non-aromatic heterocyclic group”.
In the present invention, “may have a substituent” means that it may have one or more substituents.

{Explanation on Substituents A and D}
In the general formula (1), each of the substituents A and D independently has a hydrocarbon group which may have a substituent, a heterocyclic group which may have a substituent, or a substituent. And a hydrocarbon thio group which may have a substituent or a heterocyclic thio group which may have a substituent.
In the general formula (1), the substituent A and the substituent D may be the same or different from each other, but are preferably the same from the viewpoint of ease of synthesis.

Specific examples of the substituents A and D include the following groups.
(A) Hydrocarbon group i) Non-aromatic hydrocarbon group Methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, 2-methylbutyl group, 3-methylbutyl group, cyclohexylmethyl group, neopentyl Group, 2-ethylbutyl group, 2-butyl group, cyclohexyl group, 3-pentyl group and the like linear, branched or cyclic alkyl group; 2-propenyl group, ethynyl group, 2-butenyl group, 3 An alkenyl group such as a butenyl group or a 2,4-pentadienyl group; an alkynyl group such as a 2-hexynyl group; Among these, an aliphatic hydrocarbon group having about 1 to 12 carbon atoms is preferable, and a branched chain aliphatic hydrocarbon group having about 3 to 12 carbon atoms is particularly preferable.
ii) aryl group (aromatic hydrocarbon ring group);
Examples thereof include a phenyl group, a naphthyl group, an anthranyl group, a fluorenyl group, a phenanthryl group, an azulenyl group, and a metallocene ring group. Among these, a monocyclic or condensed 2-membered aryl group having about 6 to 12 carbon atoms is preferable, and a monocyclic aryl group is particularly preferable.

(B) Heterocyclic group Examples include thienyl group, furyl group, pyrrolyl group, pyridyl group, imidazolyl group, pyrazolyl group, indolyl group, quinoxalinyl group, acridinyl group, thiazolyl group, and pyrazinyl group. Of these, a monocyclic 5- or 6-membered ring or a bicyclic 5-membered heterocyclic group having about 3 to 12 carbon atoms is preferable, and a monocyclic 6-membered group having about 3 to 12 carbon atoms is particularly preferable. A ring heterocyclic group.

(C) Hydrocarbon thio group (-SR)
Examples of R include the same hydrocarbon groups as those listed above.

(D) Heterocyclic thio group (-SR)
Examples of R include the same heterocyclic groups as mentioned above.

From the viewpoint of increasing absorption in the blue light region, A and D need to be efficiently conjugated with the metal complex surface. In this respect, A and D are aromatic groups, that is, aryl groups, aromatic heterocyclic rings. It is preferably a group, an arylthio group, or an aromatic heterocyclic thio group.
Substituents that the groups (a) to (d) may further have will be described later.

{Explanation on Substituents B and C}
In the general formula (1), each of the substituents B and C independently represents an arbitrary monovalent substituent or a hydrogen atom. Specific examples of the monovalent substituent include a substituent. Examples of the substituents of A and D include the substituents of (a) to (d) described above or those having a structure represented by the following general formula (2).
a-G (= Q) -R ^a (2)
(In the general formula (2), G is the valence represents 4 or more atoms, Q represents a periodic table Group 16 atom, R ^a is an alkyl group which may have a substituent, a substituent An aryl group which may have, a heterocyclic group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, and a substituent; Heteroaryloxy group which may have, alkylthio group which may have substituent, arylthio group which may have substituent, heteroarylthio group which may have substituent, substituted Represents an amino group, a hydroxyl group, or a hydrogen atom which may have a group, and when G is a pentavalent or higher atom, it may further have an optional substituent other than ^Ra , and G is In the case of an atom of 6 or more, it may have two = Q, in which case the two May be the same, it may be different. In addition, a is shows the point of attachment to the carbon thiol ring.)

In the general formula (2), examples of G include C, S, P and the like, and C and S are particularly preferable.
Specific examples of ^Ra include those described later as specific examples of the substituent introduced into the substituents A to D.

If G is a valence number of 5 or more atoms, G is even further which may have substituent R ^b in addition R ^a, which may have a substituent alkyl group, optionally substituted A good aryl group, a heterocyclic group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, and a substituent A heteroaryloxy group that may have a substituent, an alkylthio group that may have a substituent, an arylthio group that may have a substituent, a heteroarylthio group that may have a substituent, and a substituent An amino group, a hydroxyl group and the like which may be included are mentioned, and specific examples of each substituent include those described later as specific examples of the substituent introduced into the substituents A to D.
Q represents a group 16 atom of the periodic table, and is preferably O or S.

Specific examples of the substituent represented by the general formula (2) include the following. These structures are each bonded to carbon of the thiol ring at the site a.

  In the general formula (1), the substituent B and the substituent C may be the same or different from each other, but are preferably the same from the viewpoint of ease of synthesis. .

{Description of the ring formed by combining substituents A and B and substituents C and D}
The substituents A and B and the substituents C and D may form a ring other than the aromatic hydrocarbon ring through or without the substituent. For _{example, - (CH 2) 3 -} , - (CH 2) 4 - alkylene group having 2 to 6 carbon atoms such as; _{or, -OCH 2 O -, - O} (CH 2) carbon number of 2 O- etc. A condensed ring that is condensed with the thiol ring in the general formula (1) may be formed by forming about 1 to 4 alkylenedioxy groups or the like. Further, such a condensed ring may be formed by linking with a linking group having one carbon such as a carbonyl group or a thiocarbonyl group. Further, the substituents A and B and the substituents C and D may be connected to form a heterocyclic ring such as a thiophene ring or a pyridine ring that is condensed with the thiol ring in the general formula (1).

{Description of Substituents that Substituents A to D may Have}
When the substituents A to D further have a substituent, the type of the substituent is not particularly limited as long as it does not affect the stability and performance of the dye. For example, a halogen atom, a hydroxyl group, a nitro group, Cyano group, alkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group, alkoxy group, aryloxy group, heteroaryloxy group, alkylthio group, arylthio group, heteroarylthio group, amino group, acyl group, aminoacyl group Ureido group, sulfonamido group, carbamoyl group, sulfamoyl group, sulfamoylamino group, alkoxycarbonyl group, aryloxycarbonyl group, heteroaryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group, heteroarylsulfonyl group, imide group And silyl group They include those selected from the group. These substituents may be further substituted with an arbitrary substituent. Specific examples of the substituent in this case include the specific examples of the optional substituents listed above.

More specific examples of the substituent include the following.
An alkyl group having about 1 to 6 carbon atoms such as a methyl group, an ethyl group, an isopropyl group, an n-butyl group, a t-butyl group, a 2-pentyl group, and an n-hexyl group;
An alkenyl group having about 2 to 6 carbon atoms such as an ethynyl group and a propynyl group,
An alkynyl group having about 2 to 6 carbon atoms, such as an acetylenyl group,
An aryl group having about 6 to 20 carbon atoms such as a phenyl group, a naphthyl group, an anthranyl group, a phenanthryl group, a ferrocene ring group,
A heteroaryl group having about 3 to 20 carbon atoms, such as thienyl group, furyl group, pyridyl group, imidazolyl group, pyrazolyl group,
An alkoxy group having about 1 to 6 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, a t-butoxy group, and an n-butoxy group;
Aryloxy groups having about 6 to 20 carbon atoms such as phenoxy group and naphthoxy group,
A heteroaryloxy group having about 3 to 20 carbon atoms such as a thienyloxy group and a pyridyloxy group;
An alkylthio group having about 1 to 6 carbon atoms such as methylthio group, ethylthio group, isopropylthio group, n-butylthio group, sec-butylthio group, and 3-pentylthio group;
An arylthio group having about 6 to 20 carbon atoms such as a phenylthio group and a naphthylthio group;
A heteroarylthio group having about 3 to 20 carbon atoms, such as thienylthio group, pyridylthio group, imidazolylthio group, pyrazolylthio group,
An amino group optionally having a substituent having about 1 to 20 carbon atoms such as a dimethylamino group, a diethylamino group, and a diphenylamino group;
An acyl group having about 2 to 20 carbon atoms such as an acetyl group and a pivaloyl group;
An acylamino group having about 2 to 20 carbon atoms such as an acetylamino group and a propionylamino group;
A ureido group having about 2 to 20 carbon atoms, such as a 3-methylureido group,
A sulfonamide group having about 1 to 20 carbon atoms such as a methanesulfonamide group and a benzenesulfonamide group;
A carbamoyl group having about 1 to 20 carbon atoms such as a dimethylcarbamoyl group and an ethylcarbamoyl group;
A sulfamoyl group having about 1 to 20 carbon atoms, such as an ethylsulfamoyl group,
A sulfamoylamide group having about 1 to 20 carbon atoms such as a dimethylsulfamoylamide group,
An alkoxycarbonyl group having about 2 to 6 carbon atoms such as a methoxycarbonyl group and an ethoxycarbonyl group;
An aryloxycarbonyl group having about 7 to 20 carbon atoms such as a phenoxycarbonyl group and a naphthoxycarbonyl group;
A heteroaryloxycarbonyl group having about 5 to 20 carbon atoms, such as a pyridylcarbonyl group,
An alkylsulfonyl group having about 1 to 6 carbon atoms such as a methanesulfonyl group, an ethanesulfonyl group, and a trifluoromethanesulfonyl group;
An arylsulfonyl group having about 6 to 20 carbon atoms such as a benzenesulfonyl group and a monofluorobenzenesulfonyl group;
A heteroarylsulfonyl group having about 3 to 20 carbon atoms, such as a thienylsulfonyl group,
An imide group having about 4 to 20 carbon atoms, such as a phthalimide group,
Silyl group trisubstituted with a substituent selected from alkyl and aryl groups

These substituents may be further substituted with the substituents mentioned here.
Moreover, when there are two or more substituents that the substituents A to D have, or when these substituents further have two or more substituents, they may be the same or different, and if possible, these The substituents may be bonded to form a ring.

In particular, when the substituents A to D are a suitable combination of the following 1) to 3), preferred substituents further included in the substituents A to D include an alkyl group that may have a substituent, A substituent selected from the group consisting of an alkoxy group which may have a group, an alkylthio group which may have a substituent, or a Hammett's substituent constant σm of 0.00 <σm <0 .90, more preferably an electron withdrawing group such that 0.30 <σm <0.90 and a large polarizability. More specifically, a cyano group, fluorine atom, aminocarbonyl group, nitro group, haloalkyl group, haloalkoxy group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, haloalkylsulfonyl group, acyloxy group (—OC (O)) R ¹¹ ), a sulfonyl group (—SO ₂ R ¹¹ ), a sulfamoyl group (—SO ₂ NR ¹² R ¹³ ) (where R ¹¹ is an optionally substituted hydrocarbon group, R ¹² and R ¹³ are And a hydrocarbon group or a hydrogen atom which may have a substituent.) (Hereinafter, these may be referred to as “preferable substituents”).

  There are no particular restrictions on the substitution positions of these substituents, but the position of the substituent bonded to the aromatic ring, particularly the phenyl group, reduces the symmetry of the compound represented by the general formula (1). From the viewpoint of increasing the solubility in the solvent, it is preferable that one or more substituents are bonded to the meta position, and from the viewpoint of increasing the solubility by avoiding aggregation between molecules due to steric hindrance of the molecule, It is preferred that one or more substituents are bonded to the ortho position.

{Explanation on metal atom M}
M is not particularly limited as long as it is a metal atom that can take the form of tetradentate or hexadentate, but is preferably a metal atom belonging to groups 4 to 11 of the periodic rule, more preferably Ni, Pd, Pt or the like Group 10 metal atom; Co, Fe, Cu, Au, Cr, Mn may be mentioned, and Ni, Pd, and Cu are particularly preferable from the absorption spectrum shape.

{Explanation about Counterion E}
In the general formula (1X), when the structural portion represented by the following formula (hereinafter sometimes referred to as “main structure (X)”) is not a neutral molecule, it is represented by the general formula (1). The compound may be neutral, that is, the counter ion E may be within a range of n = 2 or less so that the sum of the valence of the cation and the valence of the anion becomes zero.

The counter ion E is not particularly limited as long as it forms a salt with the main structure (X) and can be neutral. Specifically, examples of the anion include alcohol, phenol, carboxylic acid, Phosphonic acid, halogen, perchloric acid, periodic acid, cyanic acid, isocyanic acid, isothiocyanic acid, azide, nitric acid, carbonic acid, hydrogen carbonate, substituted or unsubstituted sulfuric acid, methanesulfonic acid, trifluoromethanesulfonic acid, tosylic acid Anionization of substituted or unsubstituted phosphoric acid, hexafluorophosphoric acid, hexafluoroantimonic acid, substituted or unsubstituted phosphinic acid, substituted or unsubstituted boronic acid, benzenesulfonic acid, acetic acid, trifluoroacetic acid, etc. Examples of the cation include a hydrogen cation, an alkali metal cation, an alkaline earth metal cation, an ammonium cation, Suho cation, N- substituted pyridinium cation, and the like.
Of these, those having a molecular weight of 200 or less are preferable from the viewpoint of preventing a decrease in recording sensitivity due to a decrease in absorbance.

Furthermore, the counter ion E is particularly preferably an ammonium ion or a phosphonium ion having a structure represented by the following general formula (3) due to the effect of increasing the solubility in a solvent and the reason for stable salt formation.
XR ¹ R ² R ³ R ⁴ (3)
(In General Formula (3), X represents a nitrogen atom or a phosphorus atom, and R ^{1 to} R ⁴ each independently have a hydrocarbon group that may have a substituent or a substituent. A heterocyclic group that may be present.)

Examples of the hydrocarbon groups and heterocyclic groups of the substituents R ^{1 to} R ⁴ of the ammonium ion and phosphonium ion include more specifically those exemplified as the hydrocarbon groups and heterocyclic groups of the substituents A and D. Applicable. These hydrocarbon groups and heterocyclic groups may further have a substituent. The substituents that may be present are arbitrary, and specifically, those exemplified as the substituents that the hydrocarbon groups and heterocyclic groups of the substituents A and D may have correspond.

{Explanation regarding preferred combinations of substituents A to D}
In the compound represented by the general formula (1), those in which the substituents A to D are the following 1) to 3) are particularly preferable in terms of light resistance.
1) A and D are each independently a hydrocarbon group that may have a substituent or a heterocyclic group that may have a substituent, and B and C are each independently And a hydrocarbon group which may have a substituent, a heterocyclic group which may have a substituent, or a hydrogen atom. However, A and B, and C and D may be bonded to each other through a linking group or not to form a ring.
2) A to D are each independently a hydrocarbon thio group which may have a substituent or a heterocyclic thio group which may have a substituent. However, A and B, and C and D may be bonded to each other through a linking group or not to form a ring.
3) A and D are each independently a hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent, and B and C are each independently And a hydrocarbon thio group which may have a substituent or a heterocyclic thio group which may have a substituent. However, A and B, and C and D may be bonded to each other through a linking group or not to form a ring.

（一般式（１ａ）中、Ａ〜Ｄは上記１）の通りであり、Ｘ，Ｒ^１〜Ｒ^４，ｎについても前述の通りである。また、Ｍは好ましくは周期律表第４〜１１族金属原子である。） Hereinafter, 1) to 3) will be described individually.
Among 1), the compound represented by the following general formula (1a) is preferable in terms of excellent light resistance and recording sensitivity.

(In the general formula (1a), A to D are as described in the above 1), and X, R ^{1 to} R ⁴ and n are also as described above. M is preferably a group 4-11 metal atom in the periodic table. )

  In order to have high recording sensitivity and high light resistance, particularly preferably, A and D are each independently a phenyl group which may have a substituent, or a pyridyl group which may have a substituent. And B and C are each independently a phenyl group, pyridyl group, or hydrogen atom which may have a substituent. Examples of the substituent that may be further included herein include the above-mentioned preferred substituents, and specific substituents are the same as those described above.

Further, in this case, the portion of the main structure X is neutral and there is no counter ion XR ¹ R ² R ³ R ⁴ when n = 0, or XR ¹ R ² as a counter ion when n = 1. Those having an ammonium ion which may have a substituent of R ³ R ⁴ or a phosphonium ion which may have a substituent are preferable. As a substituent of the ammonium ion and phosphonium ion, an alkyl group which may have a substituent is preferable.

（一般式（１ｂ）中、Ａ〜Ｄは上記２）の通りであり、Ｘ，Ｒ^１〜Ｒ^４，ｎについても前述の通りである。また、Ｍは好ましくは周期律表第４〜１１族金属原子である。） Among 2), the compound represented by the following general formula (1b) is preferable in terms of excellent recording sensitivity and absorption wavelength region.

(In the general formula (1b), A to D are as described above 2), and X, R ^{1 to} R ⁴ and n are also as described above. M is preferably a group 4-11 metal atom in the periodic table. )

  Particularly preferably, A to D are each independently an aliphatic hydrocarbon thio group which may have a substituent in order to have a preferable region in terms of high recording sensitivity and absorption wavelength region. Examples of the substituent that may be further included herein include the above-mentioned preferred substituents, and specific substituents are the same as those described above.

Further, in this case, the portion of the main structure X is neutral and there is no counter ion XR ¹ R ² R ³ R ⁴ when n = 0, or XR ¹ R ² as a counter ion when n = 1. Those having an ammonium ion which may have a substituent of R ³ R ⁴ or a phosphonium ion which may have a substituent are preferable. As a substituent of the ammonium ion and phosphonium ion, an alkyl group which may have a substituent is preferable.

（一般式（１ｃ）中、Ａ〜Ｄは上記３）の通りであり、Ｘ，Ｒ^１〜Ｒ^４，ｎについても前述の通りである。また、Ｍは好ましくは周期律表第４〜１１族金属原子である。） Among 1), the compound represented by the following general formula (1c) is preferable in terms of excellent recording sensitivity and absorption wavelength region.

(In the general formula (1c), A to D are as described in the above 3), and X, R ^{1 to} R ⁴ and n are also as described above. M is preferably a group 4-11 metal atom in the periodic table. )

  In order to have high recording sensitivity and high light resistance, particularly preferably, A and D are each independently a phenyl group which may have a substituent, and B and C are each independently, It is a phenylthio group having a substituent at least in the ortho position and / or the meta position. Examples of the substituent that may be further included include the above-described preferred substituents.

Further, in this case, the portion of the main structure X is neutral and there is no counter ion XR ¹ R ² R ³ R ⁴ when n = 0, or XR ¹ R ² as a counter ion when n = 1. Those having an ammonium ion which may have a substituent of R ³ R ⁴ or a phosphonium ion which may have a substituent are preferable. As a substituent of the ammonium ion and phosphonium ion, an alkyl group which may have a substituent is preferable.

{Molecular weight of the compound represented by the general formula (1)}
The compound represented by the general formula (1) usually has a molecular weight of 2000 or less, particularly 1500 or less, particularly preferably 1000 or less, from the viewpoint of preventing sensitivity from being reduced due to a decrease in absorbance.
Moreover, it is preferable that the compound represented by the general formula (1) is usually insoluble in water.

{Specific examples of the compound represented by the general formula (1)}
Preferable specific examples of the compound represented by the general formula (1) include, for example, those exemplified below. However, it is not limited to the following compounds.

  In the following exemplary compounds, Ni is shown as the central metal, but these may be replaced with any of Pd, Pt, Cu, Co, Fe, Au, Cr, Mn, and others. In the following, Me: methyl group, Et: ethyl group, Bu: butyl group, Ac: acetyl group.

{Synthesis Method of Compound Represented by General Formula (1)}
Of the compounds represented by the general formula (1), the compounds represented by the general formula (1a) are known compounds described in, for example, Mol. Crsyt. Liq. Cryst. (Lett), 56, 249 (1980). It can be synthesized according to the method. The compound represented by the general formula (1b) can be synthesized according to a known method described in, for example, J. Mat. Chem., 1861 (1994).

  The compound represented by the general formula (1c) is, for example, [1,3] -dithiol- according to a known method described in Mol. Cryst. Liq. Crst. (Lett), 56, 249 (1980). After obtaining a 2-one derivative, after reacting with a low nucleophilic base; for example, lithium hexamethyldisilazide or lithium diisopropylamide, the desired precursor is obtained by reaction with various electrophilic reagents. For example, J. et al. Mat. Chem. , 1861 (1994) and the like, and can be obtained as a target metal complex by metallization.

Specific examples of producing the compound represented by the general formula (1) include, for example, a method according to the following procedure.
[1] [1,3] -Dithiol-2-one derivative and a compound represented by the following formulas (a) to (e) in an amount of 1.5 to 2 equivalents to this R ^A S-SR ^B ·· Formula (a)
ClC (O) OR ^A ... Formula (b)
ClC (O) NR ^A R ^B Formula (c)
ClS (O) ₂ NR ^A R ^B Formula (d)
ClP (O) R ^A (OR ^B ) Formula (e)
(In formulas (a) to (e), R ^A and R ^B each independently represents a hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent. Preferred specific examples are the same as those exemplified as specific examples of the substituents A to D in the general formula (1).
The anhydrous THF (tetrahydrofuran) solution mixed with is cooled to -78 ° C.
Here, the amount of anhydrous THF solution as a solvent is preferably about 1 to 10 ml with respect to 1 mmol of the [1,3] -dithiol-2-one derivative.

  [2] To this reaction solution, 1.05 to 1.2 times equivalent of 1M lithium hexamethyldisilazide hexane solution or 2M lithium diisopropylamide with respect to [1,3] -dithiol-2-one derivative A heptane / THF solution is added dropwise in about 5 to 10 minutes.

[3] The mixed solution is gradually warmed to 0 ° C. over 2 hours, poured into an ice-saturated aqueous ammonium chloride solution, and an ester solvent such as ethyl acetate (or a halogen solvent such as chloroform or diethyl ether). And the like, and then the solvent is removed under reduced pressure to obtain the target intermediate.
Usually, since this reaction does not produce a by-product, the subsequent nickel metallization can be carried out as it is, but it may be purified by silica gel column chromatography if necessary.

{Solubility of the compound represented by the general formula (1)}
The compound represented by the general formula (1) is excellent in solubility in a solvent for preparing a coating solution for forming a recording layer, which will be described later, has good recording sensitivity, and is easy to synthesize. It should be noted that the solubility in this case means that the solubility in a coating solvent evaluated at room temperature (usually 15 to 30 ° C.) (a state where there is no visual precipitation) is 1.5% by weight or more, and more preferably 2 0.0% by weight or more, particularly preferably 3.0% by weight or more. In the application of the present invention, the upper limit of the solubility is not particularly limited, but is usually 20% by weight or less, particularly about 10% by weight or less.

[Recording layer]
When forming a recording layer using the recording layer forming dye of the optical recording medium of the present invention, one type of the compound represented by the general formula (1) may be used alone, or two or more types may be mixed. May be used.

  In order to form a recording layer of an optical recording medium using the recording layer forming dye of the present invention, a vacuum deposition method, a sputtering method, a doctor blade method, a cast method, a spin coating method, an immersion method, etc. are generally performed. A thin film forming method can be used. Of these, spin coating is preferred from the standpoints of mass productivity and cost. When the recording layer is formed by spin coating, the rotational speed is preferably 500 to 5000 rpm, and after spin coating, treatment such as heating or exposure to solvent vapor may be performed as necessary. The film thickness of the recording layer is not particularly limited, but is usually 10 nm to 5 μm, preferably 20 nm to 2 μm.

  The recording layer may contain a binder in order to improve the film properties. As the binder, one kind of known materials such as polyvinyl alcohol, polyvinyl pyrrolidone, ketone resin, nitrocellulose, cellulose acetate, polyvinyl butyral, and polycarbonate can be used alone or in admixture of two or more. When the ratio of the binder occupying the recording layer is too high, the recording sensitivity is remarkably lowered. Therefore, when the binder and further various additives described below are used, the ratio of the recording layer forming dye of the present invention to the formed recording layer is The amount is usually 10% by weight or more, preferably 50% by weight or more, particularly preferably 90% by weight or more.

  Further, the recording layer may contain a singlet oxygen quencher for improving stability and light resistance, a recording sensitivity improving agent, and the like.

  Examples of the singlet oxygen quencher include chelates of acetylacetonate, bisphenyldithiol, salicylaldehyde oxime, bisdithio-α-diketone, and the like, and transition metals, and these may be used alone. Two or more kinds may be used in combination.

  Examples of the recording sensitivity improver include metal compounds in which a metal such as a transition metal is contained in the form of atoms, ions, clusters, etc., for example, ethylenediamine complex, azomethine complex, phenylhydroxyamine complex, phenanthroline. And organometallic compounds such as complex, dihydroxyazobenzene complex, dioxime complex, nitrosoaminophenol complex, pyridyltriazine complex, acetylacetonate complex, metallocene complex, and so on. You may use, and may use 2 or more types together. The type of metal atom is not particularly limited, but a transition metal is preferable.

  In the recording layer, dyes of other systems can be used in combination as required. Other types of dyes that can be used in combination have absorption in the laser light wavelength range for recording, absorb the energy of the irradiated laser light, and decompose and evaporate into the recording layer, reflective layer or substrate of the irradiated part. It is preferable to form pits accompanied by thermal deformation such as melting. In addition, a dye suitable for recording with a near-infrared laser beam having a wavelength selected from the range of 770 to 830 nm for CD-R and a red laser beam selected from the range of 620 to 690 nm for DVD-R is used in combination. Thus, an optical recording material corresponding to recording with laser beams in a plurality of wavelength regions can be used. Specific examples of other dyes include metal-containing azo dyes, phthalocyanine dyes, naphthalocyanine dyes, cyanine dyes, azo dyes, squarylium dyes, metal-containing indoaniline dyes, and triarylmethane dyes. Examples include dyes, merocyanine dyes, azurenium dyes, naphthoquinone dyes, anthraquinone dyes, indophenol dyes, xanthene dyes, oxazine dyes, and pyrylium dyes, and these may be used alone. Two or more kinds may be used in combination.

  When the recording layer is formed by a doctor blade method, a cast method, a spin coating method, a dipping method, etc., first, the recording layer forming dye, binder, singlet oxygen quencher, recording sensitivity improver and other agents of the present invention are used. A pigment is dissolved in a solvent to prepare a coating solution. The solvent is not particularly limited as long as it does not attack the substrate, and ketone alcohol solvents such as diacetone alcohol and 3-hydroxy-3-methyl-2-butanone, cellosolv solvents such as methyl cellosolve and ethyl cellosolve Chain hydrocarbon solvents such as n-hexane and n-octane, alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, n-butylcyclohexane, t-butylcyclohexane and cyclooctane, Ether solvents such as diisopropyl ether and dibutyl ether, perfluoroalkyl alcohol solvents such as tetrafluoropropanol (TFP), octafluoropentanol and hexafluorobutanol, and solvents such as methyl lactate, ethyl lactate and methyl isobutyrate. Roxyester solvents and the like can be mentioned, but perfluoroalkyl alcohol solvents such as TFP, octafluoropentanol, hexafluorobutanol and the like are more preferable from the industrial aspect, and are generally used industrially at present. It is particularly preferable to use TFP. In addition, these solvents may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  The concentration of the recording layer forming dye of the present invention in the coating solution is appropriately determined according to the solvent solubility, but is usually 0.7% by weight or more, preferably 1.0% by weight or more, and usually 10% by weight. % Or less, preferably 3.0% by weight or less. If the dye concentration in the coating solution is excessively low, the formation efficiency of the recording layer is deteriorated. If the dye concentration in the coating solution is excessively high, problems such as dye crystallization occur in the film forming process.

  In addition, in order to efficiently recover the excess dye after spin coating, the dye compound can be dissolved in the coating solvent even when the concentration is usually 1.5 times or more, preferably 2 times or more the concentration of the coating solution. It is preferable that

  The singlet oxygen quencher is usually used in an amount of about 5 to 30% by weight with respect to the dye, and the recording sensitivity improver is usually used in an amount of about 10 to 30% by weight with respect to the dye.

[Optical recording medium]
The optical recording medium of the present invention has a recording layer formed as described above using the recording layer forming dye of the present invention.

  As the substrate of the optical recording medium on which the recording layer is formed, a substrate transparent to the laser beam to be used, such as glass and various plastics, is preferably used. Examples of plastics include acrylic resin, methacrylic resin, polycarbonate resin, vinyl chloride resin, vinyl acetate resin, nitrocellulose, polyester resin, polyethylene resin, polypropylene resin, polyimide resin, polystyrene resin, epoxy resin, etc., In view of cost, moisture absorption resistance and the like, polycarbonate resin injection molded is preferable.

  Usually, a layer other than the recording layer such as a reflective layer, a protective layer, and an undercoat layer is further provided on the substrate as necessary, and used as an optical recording medium.

  Examples of the reflective layer include those made of a metal such as gold, silver, aluminum, or an alloy thereof, but silver is preferable to gold or aluminum because of the reflectance with respect to laser light having a wavelength of 550 nm or less. The metal reflective layer is formed on the recording layer by vapor deposition, sputtering, ion plating, or the like. Here, an intermediate layer may be provided between the metal reflective layer and the recording layer in order to improve the adhesion between the layers, or to increase the reflectance.

  Examples of the material for the protective layer formed on the reflective layer include an ultraviolet curable resin composition.

  Furthermore, two optical recording media having the above-described configuration may be bonded via an adhesive layer to form a double-sided recording type optical recording medium, or the recording layer may be provided on both sides of the substrate or on one side.

  Information recording on the optical recording medium obtained as described above is usually performed by irradiating the recording layer with laser light focused to about 0.4 to 0.6 μm. When the recording layer absorbs the energy of the laser beam, thermal deformation such as decomposition, heat generation, and melting occurs in the laser beam irradiated portion. The recorded information is reproduced by reading the difference in reflectance between the portion where the thermal deformation is caused by the laser beam and the portion where the thermal deformation does not occur.

  For high-density recording, the shorter the wavelength of the laser beam used, the better, and laser light with a wavelength of 350 nm to 530 nm is particularly preferable. Typical examples of such laser light include blue laser light having center wavelengths of 405 nm and 410 nm, and blue-green high-power semiconductor laser light having a center wavelength of 515 nm. Other than these, (a) a semiconductor laser beam capable of continuous oscillation having a fundamental oscillation wavelength of 740 to 960 nm, or (b) a solid-state laser beam capable of continuous oscillation having a fundamental oscillation wavelength of 740 to 960 nm that is excited by the semiconductor laser beam. The light etc. which are obtained by wavelength-converting either by a 2nd harmonic generation element (SHG) are also mentioned.

  The SHG may be any piezo element that lacks reflection symmetry, but KDP, ADP, BNN, KN, LBO, a compound semiconductor, and the like are preferable. As a specific example of the second harmonic, in the case of a semiconductor laser having a fundamental oscillation wavelength of 860 nm, a wavelength 430 nm of its harmonic wave, and in the case of a solid-state laser excited by a semiconductor laser, a Cr-doped LiSrAlF6 crystal (basic oscillation wavelength of 860 nm ) Wavelength of 430 nm and the like.

  Of the absorption wavelength and absorbance of the optical recording medium, the preferred one depends on the type of laser light used for recording. For example, for a blue laser having a central wavelength of 405 to 410 nm, the maximum absorption wavelength (λmax) of the absorption spectrum of the optical recording medium is 300 to 400 nm, and the molar absorption coefficient at λmax is 5000 or more, more preferably The maximum absorption wavelength (λmax) of the absorption spectrum of the optical recording medium is 370 to 490 nm for a blue laser having a center wavelength of 430 nm, and is preferably 30,000 or more, more preferably 30,000 or more. The molar extinction coefficient is preferably 20000 or more.

  In particular, the dithiol-based metal complex compound represented by the general formula (1) according to the present invention is suitable for an optical recording medium using these blue laser beams. In addition, since the synthesis is relatively easy, an inexpensive optical recording medium can be provided.

In addition, since the dithiol-based metal complex compound represented by the general formula (1) according to the present invention is excellent in light resistance, the optical recording generally includes the dithiol-based metal complex compound according to the present invention in a recording layer. The medium does not easily deteriorate even if it is left under high temperature and high humidity and direct light. The dithiol-based metal complex compound generally has an absorption in the vicinity of 300 to 400 nm, and the deterioration of the absorption is required to be small. Light resistance refers to the rate of change of absorption intensity at 350 nm absorption. Specifically, among optical recording media containing the dithiol-based metal complex compound according to the present invention in the recording layer, a preferable temperature is 58 ° C. -Humidity 50%-80% or more, preferably 90% or more, more preferably 95% or more of the dithiol-based metal complex compound even when left for 40 hours under irradiation with a xenon lamp (intensity 0.55 W / m ² ). Remains without degradation. Further, among the optical recording media containing the dithiol-based metal complex compound in the recording layer, particularly preferable ones are usually left for 40 hours or longer, preferably 80 hours or longer, more preferably 120 hours or longer under the irradiation conditions. 99% or more remains without deterioration.

  In addition, the dithiol-based metal complex compound according to the present invention is excellent in recording laser sensitivity. Specifically, the optical recording medium containing the dithiol-based metal complex compound according to the present invention in the recording layer preferably has a laser intensity when irradiated with blue laser light having a center wavelength of 404 nm and NA = 0.85. Good recording pits can be formed even at 10 mW or less. It should be noted that good recording pit formation is possible here when the recording surface of an optical recording medium is irradiated with blue laser light having a specific laser intensity, and the formation of pits can be confirmed visually or using an optical microscope. Say.

  Furthermore, the dithiol-based metal complex compound according to the present invention is excellent in film properties. That is, it is industrially advantageous in that no whitening phenomenon derived from crystallization of the compound is observed on the disk surface after the recording layer is formed by spin coating.

  Embodiments of the present invention will be described below by way of examples. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded.

<Synthesis of recording layer forming dye>
Example 1

  To 1.0 g (3.75 mmol) of 4,5-bis (sec-propylthio) -1,3-dithiol-2-one obtained by a known method, 8.3 mL (2.2 mL) of a 1M sodium methoxide-methanol solution was obtained. Equivalent) and stirred at 25 ° C. for 30 minutes. To this was added 0.5 equivalent of nickel chloride hexahydrate dissolved in 1 mL of methanol, and the mixture was further stirred at 25 ° C. for 30 minutes. To this mixed solution, 50 mL of toluene and 10 g of silica gel (Wako Co., Ltd .: silica gel C300 (trade name)) were added, and the reaction was carried out by stirring for 7 hours while bubbling air. The obtained green reaction solution was filtered and the silica gel was filtered off. The filtrate was washed with water and then concentrated. Methanol (25 mL) was added thereto, and after rinsing, the solid was collected by filtration to obtain a dithiol-based nickel complex compound (I) in a yield of 78% (EI MS: 536).

Example 2

  4.7 g (11.4 mmol) of [1,3] dithiol-2-one derivative obtained by a known method is dissolved in 30 mL of THF, 1M sodium methoxide-methanol solution (23 mL) is added, and the mixture is stirred at 25 ° C. for 30 minutes. did. To this reaction solution, 0.5 equivalent of nickel chloride hexahydrate dissolved in 5 mL of methanol was added, and the mixture was further stirred at 25 ° C. for 3 hours. This reaction solution was poured into a mixed solvent of 90 mL of toluene and 12 mL of acetic acid, and stirred at 40 ° C. for 3 hours while bubbling air. The reaction solution was concentrated, and the resulting crude product was dissolved in chloroform, washed with water, and the organic layer was concentrated. 50 mL of methanol was added thereto, and after washing, the solid was collected by filtration to obtain 3.8 g (81% yield) of dithiol-based nickel complex compound (II) (EI MS: 828).

Example 3

Dissolve 2.21 g (6.57 mmol) of 4-phenyl- [1,3] dithiol-2-one derivative and 2.43 g (9.86 mmol) of substituted diphenyl disulfide in anhydrous THF (13 mL) and cool to -78 ° C. did. To this reaction solution, LIN (TMS: tetramethylsilane) ₂ hexane solution (1M, 7.4 mL) was added over 2 minutes. The reaction solution was heated to 0 ° C. over 2 hours and poured into an ice-saturated aqueous ammonium chloride solution. The mixture was extracted with ethyl acetate, and the organic layer was washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated. The resulting crude product was purified by column chromatography (developing solvent; 3% ethyl acetate / hexane) to give 4-phenyl-5-tolylthio- [1,3] dithiol-2-one derivative in 95% yield. Obtained (EI MS: 417).

  1M sodium methoxide-methanol solution (13 mL) was added to a solution of 2.87 g (6.25 mmol) of 4-phenyl-5-tolylthio- [1,3] dithiol-2-one derivative in 18 mL of THF, and the mixture was added at 25 ° C. Stir for 30 minutes. To this reaction solution, 0.5 equivalent of nickel chloride hexahydrate dissolved in 5 mL of methanol was added, and the mixture was further stirred at 25 ° C. for 30 minutes. This mixed solution was poured into a mixed solvent of 60 mL of toluene and 7 mL of acetic acid, and stirred for 5 hours while bubbling air. After concentrating the solvent, the resulting crude product was washed with methanol and filtered. The precipitate was washed again with ethyl acetate and filtered to obtain 2.13 g (74% yield) of dithiol-based nickel complex compound (III) (EI MS: 920).

Example 4

  Using 1.94 g (6.57 mmol) of 4-phenyl- [1,3] dithiol-2-one derivative and 2.43 g (9.86 mmol) of diphenyl disulfide, according to Example 3, 4-phenyl-5-phenylthio- The [1,3] dithiol-2-one derivative was obtained in 91% yield (EI MS: 417).

  Using 2.49 g (5.98 mmol) of the 4-phenyl-5-phenylthio- [1,3] dithiol-2-one derivative, according to Example 3, 1.92 g (77%) of the dithiol-based nickel complex compound (IV) Yield) (EI MS: 836).

Example 5

  Using 3.35 g (9.82 mmol) of the [1,3] dithiol-2-one derivative obtained by a known method, the reaction was carried out according to Example 2 to obtain 79 of dithiol-based nickel complex compound (V). % Yield (EI MS: 686).

Example 6
A dithiol-type nickel complex compound “MIR-1021” manufactured by Midori Chemical was prepared.

<Preparation of optical recording medium>
Each dithiol-based nickel complex compound produced or prepared in Examples 1 to 6 was dissolved in 1.0% by weight in methylene chloride, and after removing fine dust by filtration, the resulting solution was 120 mm in diameter and 1. mm thick. The solution was dropped on a 2 mm injection-molded polycarbonate substrate, applied by spin coating (4900 rpm), and dried at 80 ° C. for 30 minutes to obtain a transparent coating film (film thickness of about 50 nm).
No whitening phenomenon due to crystallization of the compound was observed in any of the coating films.

<Light resistance test>
The optical recording medium produced by the above method was subjected to a light resistance test under the conditions of temperature 58 ° C.−humidity 50% / xenon lamp (intensity 0.55 W / m ² ) irradiation. Table 1 shows the change rate of the absorption intensity and the absorption maximum wavelength at a wavelength of 350 nm.
From this result, it is clear that the optical recording medium using the dithiol-based nickel complex compound according to the present invention is remarkably excellent in light resistance.

<Evaluation of optical recording media>
When the optical recording medium produced by the above method was irradiated with a semiconductor laser having a central wavelength of 404 nm and NA = 0.85 at various intensity, as shown in Table 2, all the dithiols of Examples 1 to 6 were irradiated. In an optical recording medium using a nickel complex compound, good recording pit formation was confirmed with semiconductor laser light having a recording laser intensity of 5.0 mW. Further, in Examples 2, 4, 5 and 6, the recording laser intensity was Even with a 2.6 mW semiconductor laser beam, formation of good recording pits was confirmed.

Claims (8)

A dye for forming a recording layer of an optical recording medium, comprising a compound represented by the following general formula (1):

(In General Formula (1), A and D each independently have a hydrocarbon group which may have a substituent, a heterocyclic group which may have a substituent, or a substituent. An optionally substituted hydrocarbon thio group or an optionally substituted heterocyclic thio group, and B and C each independently represent an arbitrary monovalent substituent or a hydrogen atom. However, A and B and C and D may be bonded to each other through a linking group or not to form a ring other than the aromatic hydrocarbon ring.
E is a counter ion, and n represents an integer of 0 to 2. That is, the compound represented by the general formula (1) has n counter ions E as necessary, so that it is neutral (the sum of the cation valence and the anion valence becomes 0). Has been.
M ¹ represents an arbitrary metal atom. ) The dye for forming a recording layer of an optical recording medium according to claim 1, wherein A to E, n and M in the general formula (1) are as follows.
A and D each independently represent a hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent, and B and C each independently , A hydrocarbon group which may have a substituent, a heterocyclic group which may have a substituent, or a hydrogen atom; However, A and B, and C and D may be bonded to each other through a linking group or not to form a ring.
E is represented by XR ¹ R ² R ³ R ⁴ , X represents a nitrogen atom or a phosphorus atom, and R ^{1 to} R ⁴ are each independently a carbon atom that may have a substituent. A hydrogen group or a heterocyclic group which may have a substituent is shown.
* N shows the integer of 0-2.
* M represents a metal atom in Groups 4 to 11 of the periodic table. The dye for forming a recording layer of an optical recording medium according to claim 1, wherein A to E, n and M in the general formula (1) are as follows.
A to D each independently represent a hydrocarbon thio group that may have a substituent or a heterocyclic thio group that may have a substituent. However, A and B, and C and D may be bonded to each other through a linking group or not to form a ring.
E is represented by XR ¹ R ² R ³ R ⁴ , X represents a nitrogen atom or a phosphorus atom, and R ^{1 to} R ⁴ are each independently a carbon atom that may have a substituent. A hydrogen group or a heterocyclic group which may have a substituent is shown.
* N shows the integer of 0-2.
* M represents a metal atom in Groups 4 to 11 of the periodic table. The dye for forming a recording layer of an optical recording medium according to claim 1, wherein A to E, n and M in the general formula (1) are as follows.
A and D each independently represent a hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent, and B and C each independently Represents a hydrocarbon thio group which may have a substituent or a heterocyclic thio group which may have a substituent. However, A and B, and C and D may be bonded to each other through a linking group or not to form a ring.
E is represented by XR ¹ R ² R ³ R ⁴ , X represents a nitrogen atom or a phosphorus atom, and R ^{1 to} R ⁴ are each independently a carbon atom that may have a substituent. A hydrogen group or a heterocyclic group which may have a substituent is shown.
* N shows the integer of 0-2.
* M represents a metal atom in Groups 4 to 11 of the periodic table.   5. The optical recording medium according to claim 1, wherein M in the general formula (1) represents Ni, Pd, Pt, Cu, Co, Fe, Au, Cr, or Mn. A recording layer forming dye. 6. The recording layer according to claim 1, wherein the recording layer containing the recording layer forming dye is irradiated with light having an irradiance of 0.55 W / m ² at a temperature of 58 ° C. and a humidity of 50% for 40 hours. When the light resistance test is performed, the recording layer after the light resistance test has an absorption intensity at a wavelength of 350 nm of 80% or more with respect to the absorption intensity before the test. Layer forming dye.   An optical recording medium comprising a recording layer containing the recording layer forming dye according to any one of claims 1 to 6.   8. The recording method for an optical recording medium according to claim 7, wherein recording is performed with a laser beam having a wavelength of 350 to 530 nm.