TECHNICAL FIELD 0001 The present invention relates to squarylium compounds which can be used in the optical recording field, and to optical recording media using the same.

BACKGROUND ART 0002 In recent years, development of a digital versatile disc-recordable (DVD-R) as a recordable optical recording medium having a higher recording density than that of a compact disc-recordable (CD-R) has been under going. Both of CD-R and DVD-R are similar to each other in that an organic dye is utilized therein as a recording material and are also similar to each other in a principle of recording and reproducing of a signal (information). Therefore, the organic dyes developed for CD-R can basically comply with the various requirements (light resistance, solubility, and thermal decomposition properties) for the recording material of DVD-R other than spectroscopic properties. However, an oscillation wavelength of a semiconductor laser, which is used for recording the signal to DVD-R or for reproducing the signal from DVD-R, is in the range of 600-700 nm, which is shorter than that of the semiconductor laser which is used for CD-R. Accordingly, the recording material utilized for DVD-R should have an absorbance end of a longer wavelength side shorter than that of CD-R when it exists in the form of a membrane. Therefore, the dyes developed for CD-R such as cyanine dyes, azaannulene dyes and indoaniline-metal chelate dyes (Electronics Related Dyes, CMC, 1998) can not be used as the recording material for DVD-R. 0003 The present inventors have developed squarylium compounds having two different kinds of aromatic substituents in a molecule. Such squarylium compounds have a squaric acid skeleton at a center of the molecule and substituents comprising an aromatic compound on carbon atoms at two catercornered positions of the skeleton. Squarylium compounds having two same aromatic substituents are conveniently referred to as symmetric squarylium compounds (or symmetric squarylium dyes), whereas those having two different kinds of substituents are referred to as asymmetric squarylium compounds (or asymmetric squarylium dyes). 0004 A squarylium compound known in the art wherein a metal atom is coordinated thereby forming a chelate structure is a symmetric squarylium compound having an aniline derivative represented by the formula (A) as an aromatic substituent (Chem. Ber. vol. 103, 3553-3562, 1970). 2

0005 However, this compound does not have a structure in which a plurality of squarylium compounds coordinate to one metal atom, and nitrogen atoms between the aromatic ring and the squaric acid skeleton are involved in coordination. 0006 In addition, a known compound in which a plurality of squarylium analogues coordinate to one metal atom to form a chelate structure is a compound represented by the formula (B) (OXOCARBONS, ACADEMIC PRESS 1980, p. 210, edited by Robert West). 0007 However, in this compound, the substituents on the squaric acid skeleton are changed from an oxygen atom to an sulfur atom, and nitrogen atoms between the aromatic ring and the squaric acid skeleton are involved in coordination. 3

0008 Further, a complex of a compound represented by the formula (C) and a metal is known as an example which has an atom involved in coordination as a substituent on the aromatic ring, and in which a plurality of squarylium compounds and one metal atom form a complex. This complex may be used, for example, for a near infrared-ray absorbing agent, a filter for a plasma display, and the like (JP-A 2000-159776). 4

0009 (wherein X and X represent a group having active hydrogen, Y1 and Y2 represent an hydrogen atom, an alkylamino group, or the like, and k and k represent an integer of 1 to 4). 0010 However, the above reference discloses specifically only a compound represented by the formula (D) as a squarylium compound corresponding to the formula (C). Further, no specific structure for the complex is shown therein. 5

0011 (wherein Z1-Z6 represent a hydrogen atom, an alkyl group, or the like). 0012 Squarylium compounds having a structure in which a plurality of squarylium compounds coordinate to one metal atom, and in which atoms involved in coordination are an oxygen atom being a substituent on the squaric acid skeleton and an atom in a substituent on an aromatic ring, have not been known yet. 0013 In view of an oscillation wavelength of the semiconductor laser used for DVD-R, for spectroscopic properties of the recording material, which have the close relation with recording and reproducing sensitivities of the signal, it is desirable that the maximum absorption wavelength (max) of the recording material measured in a solution state is within the range of 550-600 nm and log ( is a molar extinction coefficient) at the maximum absorption wavelength is 5 or larger. 0014 In addition, for thermal decomposition properties of the recording material, which have the close relation with the recording sensitivity, it is desirable that the recording material decomposes within the temperature range of 250-350 C. 0015 Furthermore, although light resistance and solubility in a solvent which is necessary for membrane formation are also required as the property of the recording material, when the known squarylium compounds are used in a recording material for DVD-R, the obtained recording material for DVD-R is not sufficient for practical use in view of spectroscopic properties, light resistance, solubility and thermal decomposition properties. The above-mentioned compound A has a melting point of 350 C. or higher, and the compound C has a maximum absorption wavelength of 830 nm or longer. There are no property data for the compound B.

DISCLOSURE OF THE INVENTION 0016 An object of the present invention is to provide squarylium compounds having spectroscopic properties, light resistance, solubility and thermal decomposition properties suitable for a recording material for DVD-R, and optical recording media using the same. 0017 In view of the above situation, the present inventors intensively investigated and, as the result, we have found that a suqarylium compound having hydroxypyrazole as an aromatic substituent and a metal atom with a coordination ability form a chelate complex, and obtained a finding that compounds obtained by forming such a chelate complex have properties suitable for a recording material for DVD-R. 0018 The present invention was done based on such a finding, and provides squarylium compounds represented by the formula (I): 6

0019 wherein, R1 and R2 are the same or different, and represent an alkyl group optionally having a substituent, an aralkyl group optionally having a substituent, an aryl group optionally having a substituent, or a heterocyclic group optionally having a substituent; Q represents a metal atom with a coordination ability; q represents 2 or 3; and A represents an aryl group optionally having a substituent, a heterocyclic group optionally having a substituent, or YCH wherein Y represents an aryl group optionally having a substituent or a heterocyclic group optionally having a substituent, and optical recording media which has a recording layer comprising said squarylium compound. 0020 The present invention will be illustrated below, and herein the compound represented by the formula (I) is referred to as a compound (I). This is also applicable to compounds with other formula numbers added. 0021 First, in the definitions of the respective groups in the above formula (I) or the formula (II) described below, an alkyl part of the alkyl and alkoxy groups includes straight or branched alkyl groups having from 1 to 6 carbon atoms and cyclic alkyl groups having from 3 to 8 carbon atoms, such as methyl, ethyl, propyl, iso-propyl, butyl, iso-butyl, sec-butyl, tert-butyl, pentyl, iso-pentyl, 1-methylbutyl, 2-methylbutyl, tert-pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl groups, and the like. 0022 Examples of the aralkyl group include aralkyl groups having from 7 to 15 carbon atoms, such as benzyl, phenethyl, phenylpropyl and naphthylmethyl groups, and the like. 0023 Examples of the aryl group include phenyl, naphthyl, anthryl and azulenyl groups, and the like. 0024 The halogen atom includes chlorine, bromine, fluorine and iodine atoms. 0025 The substituents for the aralkyl group, the aryl group, the alkoxy group, the aromatic ring, the heterocyclic ring or the heterocyclic group are the same or different 1 to 5 subtutituents, and include a hydroxyl group, a carboxyl group, a halogen atom, an alkyl group optionally having a substituent, an alkoxy group, a nitro group, an amino group optionally having a substituent, and the like, wherein the halogen atom, the alkyl group and the alkoxy group include those as described above. 0026 The substituents for the alkyl group are the same or different 1 to 3 substituents, and include a hydroxyl group, a carboxyl group, a halogen atom, an alkoxy group, and the like, wherein the halogen atom and the alkoxy group include those as described above. Further, the substituents for the alkyl group include substituents for the alkyl group as described below. 0027 The substituents for the amino group are the same or different 1 or 2 alkyl groups, wherein the alkyl group includes those as described above. 0028 Examples of the metal atom with a coordination ability include aluminium, zinc, copper, iron, nickel, chromium, cobalt, manganese, iridium, vanadium, titanium, and the like. Among them, preferred are trivalent metals (e.g., aluminium, iron (III), chromium (III), cobalt (III), manganese (III), iridium (III), vanadium (III), and the like). Aluminium is more preferable. 0029 The aromatic ring which is formed by two adjacent R6s being taken together with two adjacent carbon atoms includes a benzene ring, a naphthalene ring, an anthracene ring, and the like. 0030 The heterocycle in the heterocyclic group or the heterocycle which is formed by R3 and R4 being taken together with an adjacent carbon atom includes 5- or 6-membered monocyclic aromatic or aliphatic heterocycles containing at least one atom selected from nitrogen, oxygen and sulfur atoms, fused di- or tri-cyclic aromatic heterocycles, which are formed by fusing 3- to 8-membered rings and which contain at least one atom selected from nitrogen, oxygen and sulfur atoms, and the like, and, more particularly, includes pyridine, pyrazine, pyrimidine, pyridazine, quinoline, isoquinoline, phthalazine, quinazoline, quinoxaline, naphthyridine, cinnoline, pyrrole, pyrazole, imidazole, triazole, tetrazole, thiophene, furan, thiazole, oxazole, indole, isoindole, indazole, benzimidazole, benzotriazole, benzothiazole, benzoxazole, purine, carbazole, pyrrolidine, piperidine, piperazine, morpholine, thiomorpholine, homopiperidine, homopiperazine, tetrahydropyridine, tetrahydroquinoline, tetrahydroisoquinoline, tetrahydrofuran, tetrahydropyran, dihydrobenzofuran, tetrahydrocarbazole, indoline rings, and the like. 0031 Examples of the alicyclic hydrocarbon ring which is formed by R3 and R4 being taken together with an adjacent carbon atom include saturated or unsaturated alicyclic hydrocarbon rings having from 3 to 8 carbon atoms, such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclopentene, 1,3-cyclopentadiene, cyclohexene and cyclohexadiene rings, and the like. 0032 In the compound (I), a compound wherein Y is an indoline ring optionally having a substituent is preferred, and, among them, more preferred is a compound wherein YCH is represented by the general formula (II): 7

0033 wherein R3 and R4 are the same or different, and represent an alkyl group optionally having a substituent, or R3 and R4 may be taken together with an adjacent carbon atom to form an alicyclic hydrocarbon ring or a heterocycle optionally having a substituent; R5 represents a hydrogen atom, an alkyl group optionally having a substituent, an aralkyl group optionally having a substituent or an aryl group optionally having a substituent; R6 represents a halogen atom, an alkyl group optionally having a substituent, an aralkyl group optionally having a substituent, an aryl group optionally having a substituent, a nitro group, a cyano group or an alkoxy group optionally having a substituent; and n represents an integer of 0-4, and when n is 2-4, then R6s are the same or different, or two adjacent R6s may be taken together with two adjacent carbon atoms to form an aromatic ring optionally having a substituent. 0034 A general method for preparing the compound (I) is explained below. 8

9

10

11

0035 (wherein R1, R2, A, Q and q are the same as defined above, and Y represents a hydrogen atom, potassium, sodium, or the like). 0036 Scheme (1-a) 0037 The compound (V) is prepared by reacting the compound (III) with 0.7- to 1.5-fold moles of the compound (IV) at 0-80 C. for 5 minutes to 15 hours in a solvent, if needed, in the presence of a base. 0038 Examples of the base to be used include inorganic bases such as potassium carbonate, sodium carbonate, potassium hydroxide and the like, and organic bases such as triethylamine, sodium methoxide, and the like, and so on. A preferred amount of the base to be used is 0.7- to 1.5-fold moles relative to the compound (III). 0039 Examples of the solvent to be used include methanol, ethanol, dimethylformamide, and the like. 0040 Scheme (1-b) 0041 The compound (VI) is prepared by treating the compound (V) at 0-80 C. for 30 minutes to 15 hours in an alkaline solvent or in an acidic solvent. 0042 Examples of the alkaline solvent to be used include an aqueous potassium carbonate solution, an aqueous sodium carbonate solution, an aqueous potassium hydroxide solution, and the like. 0043 Examples of the acidic solvent to be used include a 50 volume/volume % solution of hydrochloric acid in aqueous dimethyl sulfoxide, a 50 volume/volume % solution of hydrochloric acid in aqueous dimethylformamide, and the like. 0044 Scheme (1-c) 0045 The compound (VII) is prepared by reacting the compound (VI) with 0.5- to 2-fold moles of A-H at 50-120 C. for 5 minutes to 15 hours in a solvent, if needed, in the presence of 0.5- to 2-fold moles of a base. 0046 Examples of the solvent to be used include alcoholic solvents alone having from 2 to 8 carbon atoms such as ethanol, propanol, iso-propyl alcohol, butanol, octanol, and the like, and a mixture of the alcoholic solvent with benzene, toluene or xylene (50 volume/volume % or more of the alcoholic solvent is preferable). 0047 Examples of the base to be used include organic bases such as quinoline, triethylamine, pyridine, and the like, and inorganic bases such as potassium carbonate, potassium hydrogen carbonate, sodium hydrogen carbonate, and the like, and so on. 0048 Scheme (1-d) 0049 The compound (I) is prepared by reacting the compound (VII) with a material providing Qq at room temperature to 120 C. for 5 minutes to 15 hours in a solvent, if needed, in the presence of 0.5- to 2-fold moles of acetic acid. It is preferred that the material providing Qq is used so that the ratio of the mole number of the compound (VII):(the mole number of the material providing Qq)q is 1:0.5-2. 0050 Examples of the material providing Qq to be used include aluminium tris(acetylacetonate), aluminum tris(ethylacetoacetate), aluminum isopropoxide, aluminium sec-butoxide, aluminium ethoxide, aluminium chloride, copper chloride, copper acetate, nickel acetate, and the like. 0051 Examples of the solvent to be used include halogen solvents such as chloroform, dichloromethane, and the like; aromatic solvents such as toluene, xylene, and the like; ethers such as tetrahydrofuran, methyl tert-butyl ether and the like; esters such as ethyl acetate, and the like, and so on. 0052 Embodiments of the compound (I) are shown in Table 1. Additionally, the compound numbers in the table correspond to the Example numbers described below. Further, in the table, Ph represents a phenyl group, Me represents a methyl group, Pr represents a propyl group, and iPr represents an isopropyl group. 1TABLE 1Embodiments of the compoundsEx-am-pleNo.R1R2AQq1PhPr

12

Al3 2PhiPr

13

Al3 3MePr

14

Al3 4PhMe

15

Al3 5PhMe

16

Al3 6MeiPr

17

Al3 7PhPr

18

Al3 83-MeC6H4Me

19

Al3 94-MeC6H4Me

20

Al3 103-MeC6H4Pr

21

Al3 113-MeC6H4Pr

22

Al3 124-MeC6H4Pr

23

Al3 13PhPr

24

Al3 144-BrC6H4Pr

25

Al3 154-BrC6H4Pr

26

Al3 164-ClC6H4Pr

27

Al3 17PhPh

28

Al3 184- MeOC6H4Ph

29

Al3 194-ClC6H4Pr

30

Al3 203-ClC6H4Pr

31

Al3 21PhCF3

32

Al3 223-ClC6H4Pr

33

Al3 234-FC6H4Pr

34

Al3 244-FC6H4Pr

35

Al3 254- CF3C6H4Pr

36

Al3 264-ClC6H4Me

37

Al3 274-FC6H4Pr

38

Al3 284- CF3C6H4Pr

39

Al3 29PhPr

40

Al3 30PhCF3

41

Al3 31MeMe

42

Al3 32PhPr

43

Al3 33PhCF3

44

Al3 34PhCF3

45

Al3 35PhCF3

46

Al3 36PhPr

47

Al3

0053 Next, the constitution of a recording medium utilizing the squarylium compound of the present invention (hereinafter, it may be referred to as a compound of the present invention) will be illustrated. 0054 The physical properties required for a material for a recording layer include optical and thermal properties, as well as light resistance. 0055 The optical properties are preferably such that there is a large absorption band at a shorter wavelength side than 600-700 nm, preferably 630-690 nm, which is a recording or reproducing wavelength of DVD-R or the like, and, further a recording or reproducing wavelength is in the vicinity of a longer wavelength end of the above-mentioned absorption band. This means that the above-mentioned material for the recording layer has a larger refractive index and extinction coefficient within 600-700 nm, which is a recording or reproducing wavelength. 0056 More specifically, the refractive index n of a single layer of the recording layer is preferably 1.5-3.0, and the extinction coefficient k of a single layer of the recording layer is preferably within the range of 0.02-0.3, for the light of the wavelength range of the recording or reproducing wavelength 5 nm in the vicinity of the longer wavelength end of the above-mentioned absorption band. When n is 1.5 or larger, a reflectance and a modulation percentage of recording become higher, and when n is 3.0 or smaller, an error does not occur with the light in the recording or reproducing wavelength range. In addition, when k is 0.02 or larger, the recording sensitivity is improved, and when k is 0.3 or smaller, the reflectance of 50% or larger can be easily obtained. 0057 In addition, the maximum absorption wavelength (max) of the material for the recording layer which is measured in a chloroform solution is preferably within the range of 550-600 nm, and since a larger extinction coefficient allows for the larger refractive index n, log ( is a molar extinction coefficient) at the maximum absorption wavelength is preferably 5 or larger. 0058 Further, for the thermal properties, it is preferred that the decomposition temperature is within the particular temperature range. More specifically, the decomposition temperature is preferably 350 C. or lower, and more preferably within the range of 250-350 C. When the decomposition temperature is 350 C. or lower, it is not necessary to raise the power of the recording laser beam, and when it is 250 C. or higher, it is preferable in a recording stability sense. 0059 Still further, for the light resistance, it is preferred that the material has a reproducing property constant for over 1,000,000 repeats and a fastness property in which no color fading occurs when the material is left in a room. 0060 The preferable substrate shape is under the condition that a track pitch is within the range of 0.7-0.8 m and a groove width at the half band width is within the range of 0.18-0.40 m. 0061 It is preferred that the substrate has a guiding groove having a depth of 1,000-2,500 . It is preferred that the track pitch is 0.7-1.0 m, and more preferably 0.7-0.8 m for the high recording density application. The groove width is preferably 0.18-0.40 m as the half band width. When the groove width is 0.18 m or wider, the adequate strength of a tracking error signal can be easily detected, whereas when it is 0.40 m or narrower, the recording portion is hardly widened in a traverse direction upon recording, being preferable. 0062 1. The Structure of an Optical Recording Medium 0063 The optical recording medium of the present invention may be formed into an air-sandwich structure or into a closely adhered structure which is applied to general recordable discs, or may be formed into a structure of a recordable optical recording medium such as DVD-R, or the like. 0064 2. The Required Properties and Embodiments of Constituent Materials for Each Layer 0065 The optical recording medium of the present invention has a basic structure in which a first substrate and a second substrate are adhered via a recording layer with an adhesive. The recording layer may be a single layer of an organic dye layer comprising the compound of the present invention, or may be a laminated layer of the organic dye layer and a metal reflective layer for enhancing the reflectance. Between the recording layer and the substrate, an undercoat layer or a protective layer may be built-up, or they may be laminated for improving the function. Preferred structures include the first substrate/the organic dye layer/the metal reflective layer/the protective layer/the adhesive layer/the second substrate and the like. 0066 a. Substrate 0067 The substrate to be used should be transmittable to the wavelength of the laser beam to be used when recording or reproducing is conducted from a substrate side, but it is not necessary for the substrate to be transmittable to the wavelength when recording or reproducing is conducted from a recording layer side. As the material for the substrate, for example, plastics such as polyester, acrylic resin, polyamide, polycarbonate resin, polyolefin resin, phenolic resin, epoxy resin, polyimide, or the like, glasses, ceramics, metals or the like may be used. Additionally, a guiding groove or a guiding pit for tracking, a preformat such as an addressing signal, or the like may be formed on a surface of the substrate. 0068 b. Recording Layer 0069 The recording layer is a layer in which some optical change is caused by irradiation with a laser beam and, thereby, an information is recorded, and should contain the compound of the present invention. The compounds of the present invention may be used alone or in combination of two or more for forming the recording layer. 0070 In addition, the compound of the present invention may be used by mixing it or laminating it with other organic dyes, metals or metal compounds for the purpose of enhancement of the optical properties, the recording sensitivity, the signal properties, or the like. Examples of the organic dye include a polymethine dye, naphthalocyanine, phthalocyanine, squarylium, croconium, pyrylium, naphthoquinone, anthraquinone (indanthrene), xanthene, triphenylmethane, azulene, tetrahydrocholine, phenanthrene and triphenothiazine dyes, metal complex compounds, and the like. Examples of the metal and metal compound include In, Te, Bi, Se, Sb, Ge, Sn, Al, Be, TeO2, SnO, As, Cd, and the like, each of which may be used in the form of dispersion mixture or lamination. 0071 In addition, it is possible to enhance the light resistance significantly by mixing a light stabilizer into the compound of the present invention. As the light stabilizer, metal complexes and aromatic amines are preferable. Embodiments of the light stabilizer will be listed below (see Tables 2 and 3). 0072 The mixing ratio of the light stabilizer relative to the compound of the present invention is preferably 5-40% by weight. When the ratio is 5% by weight or larger, the effect on light stabilization is high, and it is preferred that the ratio is 40% by weight or smaller in view of the recording or reproducing properties. 0073 In addition, macromolecular materials, for example, various materials such as ionomer resin, polyamide resin, vinyl resin, natural polymer, silicone or liquid rubber, or silane coupling agents may be dispersed and mixed into the compound of the present invention, and additives such as stabilizers (for example, transition metal complex), dispersing agents, flame retardants, lubricants, antistatic agents, surfactants or plasticizers may be used together for the purpose of modifying the properties. 0074 The recording layer may be formed using conventional methods such as a deposition, a sputtering, a chemical vapor deposition or a solvent coating. In the case where the coating method is used, the dye comprising the compound of the present invention with the aforementioned additives added optionally is dissolved in an organic solvent, and the solution is coated by the conventional coating method such as a spraying, a roller coating, a dipping or a spin coating. 0075 Examples of the organic solvent to be used generally include alcohols such as methanol, ethanol and iso-propanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, amides such as N,N-dimethylformamide and N,N-dimethylacetoamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, diethyl ether and ethyleneglycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethane, carbon tetrachloride and trichloroethane, aromatic compounds such as benzene, xylene, monochlorobenzene and dichlorobenzene, cellosolves such as methoxyethanol and ethoxyethanol, and hydrocarbons such as hexane, pentane, cyclohexane and methylcyclohexane. 0076 The membrane thickness of the recording layer is preferably 100 -10 m, more preferably 200-2,000 . 0077 Embodiments of the light stabilizer to be used in combination with the compound of the present invention are listed below. 0078 (1) Metal Complex-Light Stabilizers (see Table 2) 48

0079 wherein Ra and Rb are the same or different, and represent a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group, wherein said alkyl group, said aryl group or said heterocyclic group may have a substituent. 49

0080 wherein Ra, Rb, Rc and Rd are the same or different, and represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a cyclic alkyl group or a heterocyclic group, wherein said alkyl group, said aryl group, said cyclic alkyl group or said heterocyclic group is bound directly or indirectly via a divalent linking group. 50

0081 wherein X represents O, S or CRaRb, wherein Ra and Rb are the same or different, and represent CN, CORc, COORd, CONReRf, SO2Rg, or a group of atoms necessary for forming a 5- or 6-membered ring, and wherein RcRg are the same or different, and represent an alkyl group or an aryl group, wherein said alkyl group or said aryl group may have a substituent. 51

0082 wherein Ra, Rb, Rc and Rd are the same or different, and represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a cyclic alkyl group or a heterocyclic group, wherein said alkyl group, said aryl group, said cyclic alkyl group or said heterocyclic group is bound directly or indirectly via a divalent linking group, and Re represents a hydrogen atom, an alkyl group, an aryl group, an acyl group, a carboxyl group, an alkoxycarbonylalkyl group or a sulfo group. 52

0083 wherein Ra, Rb, Rc and Rd are the same or different, and represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a cyclic alkyl group or a heterocyclic group, wherein said alkyl group, said aryl group, said cyclic alkyl group or said heterocyclic group is bound directly or indirectly via a divalent linking group, and Re and Rf are the same or different, and represent a hydrogen atom, an alkyl group, an aryl group, an acyl group, a carboxyl group or a sulfo group. 53

0084 wherein X represents O or S, Ra, Rb and Rc are the same or different, and represent an alkyl group, an aryl group or a cyclic alkyl group, wherein said alkyl group, said aryl group or said cyclic alkyl group may have a substituent which is bound directly or via an oxy group, a thio group or an amino group, and the symbol: 0085 CCC 0086 represents CCC or CCC. 54

0087 wherein X represents O or S, Ra, Rb and Rc are the same or different, and represent an alkyl group an aryl group or a cyclic alkyl group, wherein said alkyl group, said aryl group or said cyclic alkyl group may have a substituent which is bound directly or via an oxy group, a thio group or an amino group, Rd represents an alkyl group or an aryl group, and the symbol: 0088 CCC 0089 represents CCC or CCC. 55

0090 wherein Ra and Rb are the same or different, and represent a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group, wherein said alkyl group, said aryl group or said heterocyclic group may have a substituent. 56

0091 wherein Ra, Rb, Rc and Rd are the same or different, and represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a cyclic alkyl group or a heterocyclic group, wherein said alkyl group, said aryl group, said cyclic alkyl group or said heterocyclic group is bound directly or indirectly via a divalent linking group. 57

0092 wherein Ra, Rb, Rc and Rd are the same or different, and represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a cyclic alkyl group or a heterocyclic group, wherein said alkyl group, said aryl group or said cyclic alkyl group is bound directly or indirectly via a divalent linking group, Re represents a hydrogen atom, an alkyl group, an aryl group, an acyl group, a carboxyl group or a sulfo group. 0093 In the formulae (A)-(J), M represents a transition metal such as Ni, Pd, Pt, Cu, Co, or the like, and may have a charge to form a salt with a cation, and in addition, other ligands may be bonded above or below M. Such salts may be used also as a light stabilizer. The alkyl, cyclic alkyl, aryl and heterocyclic groups and substituents therefor include those described above. 0094 More preferable embodiments are shown in Table 2. 2TABLE 2Embodiments of metal complex-light stabilizersMetalCorres-ComplexpondingCounterNos.StructureRaRbRcRdReRfXMCation1(A)PhPhCuNBu42(A)C4H9C4H9Ni3(B)ClHClClNiNBu44(B)HOCH3HHCu5(C)OCoNBu46(C)SNiCN7(D)HOCH3HHCH2COOEtPdNBu48(D)HHHHCH3NiPBu49(D)HCH3HHCH3PtNPe410(E)HHHHCH3CH3NiNBu411(E)HOCH3HHC2H5C2H5PtNEt412(F)HHHOCuNBu413(F)HHHONiPBu414(F)HPhHSNiNOc415(G)HHHHONiNBu416(G)HHHHSNiPEt417(H)PhPhPdNBu418(I)HHHHNiNBu419(I)HOCH3HHNiPEt420(J)HHHHCH3NiNBu421(J)HHHHC4H9NiPBu422(J)HCH3HHC4H9CuNOc4Et: ethyl group, Bu: butyl group; Pe: pentyl group, Oc: octyl group, and Ph: phenyl group

0095 2) Aromatic Amine-Light Stabilizers (see Table 3) 0096 Following compounds may be used. 58

0097 wherein Rg, Rh, Ri and Rj are the same or different, and each represents a hydrogen atom, or an alkyl group optionally having a substituent, X represents an acid anion, and G is, when m is 1 or 2, 59

0098 wherein p is 1 or 2, and is, when m is 2, 60

0099 wherein all of existing aromatic rings may be substituted with an alkyl group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, a halogen atom or a hydroxyl group. 0100 More preferred embodiments are shown in Table 3. 3TABLE 3Embodiments of aminium, imonium and diimonium compoundsCompoundNos.RgRhRiRjGXm101C2H5C2H5C2H5C2H5Z1, p 2ClO41102C2H5C2H5C2H5C2H5Z1, p 1SbF61103C3H7C3H7C3H7C3H7Z1, p 1Br1104C3H7C3H7C3H7C3H7Z1, p 2PF61105C4H9C4H9C4H9C4H9Z1, p 1ClO41106C3H7HC3H7HZ1, p 1ClO41107C2H5C2H5C2H5C2H5Z1, p 1Cl1108C6H13HC6H13HZ1, p 1SbF61109C6H13HC6H13HZ1, p 1ClO41110C2H5C2H5C2H5C2H5Z1, p 1SbF61111C3H7C3H1C3H7C3H7Z1, p 2ClO41112C2H5C2H5C2H5C2H5Z2PF62113C2H5C2H5C2H5C2H5Z2ClO42114C3H7C3H7C3H7C3H7Z2SbF62115C3H7HC3H7HZ2AsF62116C4H9C4H9C4H9C4H9Z2I2117C6H13HC6H13HZ2ClO42

61

0101 c. Undercoat Layer 0102 The undercoat layer is used for the purpose of (1) an improvement in adherability, (2) a barrier against water, gases, or the like, (3) an improvement in the storage stability of the recording layer, (4) an enhancement of the reflectance, (5) a protection of the substrate from a solvent, (6) a formation of a guiding groove, guiding pit or preformat, or the like. With regard to the purpose of (1), macromolecular materials, for example, various polymers such as ionomer resin, polyamide resin, vinyl resin, natural resin, natural polymer, silicone, liquid rubber, or the like, silane coupling agents, or the like may be used. With regard to the purposes of (2) and (3), in addition to the aforementioned macromolecular materials, inorganic compounds such as SiO, MgF, SiO2, TiO, ZnO, TiN, SiN, or the like, and further metals or semimetals such as Zn, Cu, Ni, Cr, Ge, Se, Au, Ag, Al, or the like may be used. In addition, with regard to the purpose of (4), metals such as Al, Au, Ag, or the like, or organic films having metallic luster such as a methine dye, a xanthene dye, or the like may be used. With regard to the purposes of (5) and (6), a ultraviolet-curing resin, a thermosetting resin, a thermoplastic resin, or the like may be used. 0103 The membrane thickness of the undercoat layer is preferably 0.01-30 m, more preferably 0.05-10 m. 0104 d. Metal Reflective Layer 0105 Examples of the material for the metal reflective layer include poorly erodable metals, semimetals, and the like exhibiting a high reflectance themselves. Embodiments of the material for the metal reflective layer include Au, Ag, Cr, Ni, Al, Fe, Sn, and the like, but Au, Ag and Al are most preferred from a viewpoint of the reflectance and productivity. These metals or semimetals may be used alone or as an alloy of two of them. 0106 The method for forming a membrane includes a vapor deposition, a sputtering, and the like. The membrane thickness of the metal reflective layer is preferably 50-5,000 , more preferably 100-3,000 . 0107 e. Protective Layer, Substrate Surface-Hard Coating Layer 0108 A protective layer and a substrate surface-hard coating layer are used for the purpose of (1) a protection of the recording layer (reflection absorbing layer) from flaw, dust, dirt or the like, (2) an improvement in the storage stability of the recording layer (reflection absorbing layer), (3) an improvement in the reflectance, or the like. With regard to such purposes, the materials described for the undercoat layer may be used. In addition, SiO, SiO2 or the like may be used as an inorganic material, and thermo-softening resins such as polymethyl acrylate, polycarbonate, polystyrene, polyester, vinyl resin, cellulose, aliphatic hydrocarbons, natural rubber, styrene-butadiene, chloroprene rubber, wax, alkyd, drying oil, or rosin, thermosetting resins such as epoxy resin, phenol resin, polyurethane resin, melamine resin, or urea resin, ultraviolet-curing resins such as polyester acrylate, epoxy acrylate, urethane acrylate, or silicone acrylate, or the like may be used as an organic material, but among them, the ultraviolet-curing resins may be preferably used in that they have the excellent productivity. 0109 The membrane thickness of the protective layer or the substrate surface-hard coating layer is preferably 0.01-30 m, more preferably 0.05-10 m. In the present invention, stabilizers, dispersing agents, flame retardants, lubricants, antistatic agents, surfactants, plasticizers or the like may be incorporated into the above undercoat layer, protective layer and substrate surface-hard coating layer as described for the recording layer. 0110 f. Protective Substrate 0111 A protective substrate should be transmittable to the wavelength of the laser beam to be used when the laser beam is irradiated from this protective substrate side, whereas it may be transmittable or not to the wavelength when it is used as a mere protective plate. The materials which may be used for the protective substrate are the same as those for the substrate, and plastics such as polyester, acrylic resin, polyamide, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, or polyimide, or the like, glasses, ceramics, metals, or the like may be used. 0112 g. Adhesive, Adhesive Layer 0113 As the adhesive, any material which can adhere two recording media may be used, but from a viewpoint of the productivity, ultraviolet-curing or hot melt adhesives are preferred.

BEST MODE FOR CARRYING OUT THE INVENTION 0114 The following Examples further illustrate the present invention, but are not to be construed to limit the scope of the present invention. 0115 A. Synthesis of Squarylium Compounds

EXAMPLE 1 0116 8.95 g of 3,4-dimethoxy-3-cyclobutene-1,2-dione and 12.74 g of 1-phenyl-3-propylpyrazolin-5-one were dissolved in 150 ml of methanol. To this solution, 8.71 g of potassium carbonate was added, and then the mixture was stirred at 25 C. for 1 hour. After the reaction, the precipitate was collected by filtration. The obtained solid was added to a mixture of 3 g of potassium carbonate and 130 ml of water, followed by reacting at 50 C. for 5 hours. After the reaction was completed, 100 ml of 1 mol/l aqueous hydrochloric acid was added to the mixture, and then the insoluble material was collected by filtration. To the obtained solid were added 90 ml of n-butanol, 45 ml of toluene and 9.30 g of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, and the mixture was treated at 110 C. for 5 hours. Then, 100 ml of methanol was added thereto, and followed by reacting at 80 C. for 1 hour. The precipitate was then collected by filtration. To the obtained solid were added 175 ml of ethyl acetate, 17.5 ml of acetic acid and 4.97 g of aluminium tris(ethylacetoacetate), followed by reacting at 50 C. for 2 hours. The insoluble material was collected by filtration to give 13.75 g of the compound 1. 0117 Elemental analysis (C8 4H7 5AlCl3N9O9): Calcd. (%): C, 67.81; H, 5.08; N, 8.47. Found (%): C, 67.71; H, 4.89; N, 8.46. 1H-NMR (CDCl3) ppm: 0.96 (3H, t, J7.3 Hz), 1.02 (3H, t, J7.4 Hz), 1.04 (3H, t, J7.3 Hz), 1.26-1.81 (24H, m), 2.81-3.12 (6H, m), 3.40 (3H, s), 3.44 (6H, m), 5.63 (2H, m), 5.70 (1H, s), 6.86-6.88 (3H, m), 7.02-7.26 (15H, m), 7.83-7.97 (6H, m); IR (KBr) cm1: 2958, 1753, 1633, 1081, 794.

EXAMPLE 2 0118 In a manner similar to that in Example 1 except that 1-phenyl-3-isopropylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 9.84 g of the compound 2 was obtained. 0119 Elemental analysis (C8 4H7 5AlCl3N9O9): Calcd. (%): C, 67.81; H, 5.08; N, 8.47. Found (%): C, 67.60; H, 4.97; N, 8.38. 1H-NMR (CDCl3) ppm: 1.22-1.35 (18H, m), 1.37-1.62 (18H, m), 3.38 (3H, m), 3.66-3.89 (3H, m), 5.61 (2H, m), 5.68 (1H, s), 6.85-6.87 (3H, m), 7.00-7.52 (15H, m), 7.86-7.98 (6H, m); IR (KBr) cm1: 2966, 1764, 1570, 1085, 793.

EXAMPLE 3 0120 In a manner similar to that in Example 1 except that 1-methyl-3-propylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 3.44 g of the compound 3 was obtained. 0121 Elemental analysis (C6 9H6 9AlCl3N9O9): Calcd. (%): C, 63.67; H, 5.34; N, 9.68. Found (%): C, 63.81; H, 5.57; N, 9.46. IR (KBr) cm1: 2960, 1763, 1587, 1099, 798.

EXAMPLE 4 0122 In a manner similar to that in Example 1 except that 1-phenyl-3-methylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, and 1,3,3-trimethyl-2-methyleneindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 0.68 g of the compound 4 was obtained. 0123 Elemental analysis (C7 8H6 6AlN9O9): Calcd. (%): C, 72.04; H, 5.12; N, 9.69. Found (%): C, 71.95; H, 5.11; N, 9.42. 1H-NMR (CDCl3) ppm: 1.60 (18H, m), 2.42 (3H, s), 2.52 (3H, s), 2.64 (3H, s), 3.48 (6H, m), 3.58 (3H, m), 5.65 (2H, m), 5.74 (1H, s), 6.97-7.30 (21H, m), 7.82-8.01 (6H, m); IR (KBr) cm1: 2964, 1763, 1601, 1095, 798.

EXAMPLE 5 0124 In a manner similar to that in Example 1 except that 3-methyl-1-phenyl pyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 0.99 g of the compound 5 was obtained. 0125 Elemental analysis (C7 8H6 3AlCl3N9O9): Calcd. (%): C, 66.74; H, 4.52; N, 9.98. Found (%): C, 65.61; H, 4.59; N, 9.74. 1H-NMR (CDCl3) ppm: 1.64 (18H, m), 2.44 (3H, s), 2.54 (3H, s), 2.62 (3H, s), 3.42 (6H, m), 3.46 (3H, m), 5.60 (2H, m), 5.69 (1H, s), 6.87-6.89 (3H, m), 7.00-7.34 (15H, m), 7.80-7.97 (6H, m); IR (KBr) cm1: 2966, 1763, 1600, 1091, 793.

EXAMPLE 6 0126 In a manner similar to that in Example 1 except that 1-metyl-3-isopropylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 0.70 g of the compound 6 was obtained. 0127 Elemental analysis (C6 9H6 9AlCl3N9O9): Calcd. (%): C, 63.67; H, 5.34; N, 9.56. Found (%): C, 63.67; H, 5.55; N, 9.68. 1H-NMR (CDCl3) ppm: 1.24-1.31 (18H, m), 1.57-1.88 (18H, m), 3.13 (9H, m), 3.45 (3H, m), 3.74-3.81 (3H, m), 5.71 (2H, m), 6.85-6.87 (3H, m), 7.17-7.27 (6H, m); IR (KBr) cm1: 2966, 1763, 1610, 1166, 798.

EXAMPLE 7 0128 In a manner similar to that in Example 1 except that 2.65 g of 5-bromo-1,3,3-trimethyl-2-methyleneindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 4.23 g of the compound 7 was obtained. 0129 Elemental analysis (C84H75AlBr3N9O9): Calcd. (%): C, 62.23; H, 4.66; N, 7.78. Found (%): C, 62.34; H, 4.65; N, 7.80. 1H-NMR (CDCl3) ppm: 0.94-1.07 (9H, m), 1.56-1.81 (24H, m), 2.81-3.12 (6H, m), 3.39-3.43 (9H, m), 5.63-5.70 (3H, m), 6.81-6.83 (3H, m), 7.01-7.24 (12H, m), 7.38-7.41 (3H, m), 7.82-7.96 (6H, m); IR (KBr) cm1: 2960, 1765, 1603, 1074, 1012.

EXAMPLE 8 0130 In a manner similar to that in Example 1 except that 3.76 g of 3-methyl-1-(3-methylphenyl)pyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 5.60 g of the compound 8 was obtained. 0131 Elemental analysis (C81H69AlCl3N9O9): Calcd. (%): C, 65.69; H, 4.81; N, 8.62. Found (%): C, 65.97; H, 4.71; N, 8.35. IR (KBr) cm1: 2927, 1763, 1635, 1082, 1009.

EXAMPLE 9 0132 In a manner similar to that in Example 1 except that 3.76 g of 3-methyl-1-(4-methylphenyl)pyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 5.97 g of the compound 9 was obtained. 0133 Elemental analysis (C81H69AlCl3N9O9): Calcd. (%): C, 67.56; H, 4.81; N, 8.72. Found (%): C, 67.29; H, 4.71; N, 8.50. IR (KBr) cm1: 2926, 1763, 1635, 1084, 939.

EXAMPLE 10 0134 In a manner similar to that in Example 1 except that 5.41 g of 1-(3-methylphenyl)-3-propylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, and 3.59 g of 1,3,3-trimethyl-2-methyleneindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 5.09 g of the compound 10 was obtained. 0135 Elemental analysis (C87H84AlN9O9): Calcd. (%): C, 73.24; H, 5.93; N, 8.84. Found (%): C, 73.18; H, 5.78; N, 8.78. 1H-NMR (CDCl3) ppm: 0.94-1.04 (9H, m), 1.53-1.78 (24H, m), 2.12-2.24 (9H, m), 2.75-3.11 (6H, m), 3.46 (9H, m), 5.65-5.75 (3H, m), 6.84-6.86 (3H, m), 6.93-7.05 (9H, m), 7.11-7.15 (3H, m), 7.25-7.31 (3H, m), 7.60-7.85 (6H, m); IR (KBr) cm1: 2960, 1763, 1635, 1072, 939.

EXAMPLE 11 0136 In a manner similar to that in Example 1 except that 1.94 g of 1-(3-methylphenyl)-3-propylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 2.89 g of the compound 11 was obtained. 0137 Elemental analysis (C87H81AlCl3N9O9): Calcd. (%): C, 68.30; H, 5.93; N, 8.24. Found (%): C, 68.24; H, 5.63; N, 8.44. 1H-NMR (CDCl3) ppm: 0.94-1.07 (9H, m), 1.39-1.81 (24H, m), 2.14-2.25 (9H, m), 2.77-3.11 (6H, m), 3.42-3.45 (9H, m), 5.60-5.70 (3H, m), 6.84-6.88 (6H, m), 6.99-7.07 (6H, m), 7.23-7.27 (3H, m), 7.59-7.81 (6H, m); IR (KBr) cm1: 2960, 1763, 1637, 1072, 941.

EXAMPLE 12 0138 In a manner similar to that in Example 1 except that 5.41 g of 1-(4-methylphenyl)-3-propylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 4.75 g of the compound 12 was obtained. 0139 Elemental analysis (C87H81AlCl3N9O9): Calcd. (%): C, 68.30; H, 5.34; N, 8.24. Found (%): C, 68.50; H, 5.50; N, 8.44. 1H-NMR (CDCl3) ppm: 0.94-1.06 (9H, m), 1.42-1.78 (24H, m), 2.21 (9H, s), 2.81-3.11 (6H, m), 3.38-3.44 (9H, m), 5.62-5.69 (3H, m), 6.85-7.02 (12H, m), 7.23-7.26 (3H, m), 7.66-7.81 (6H, m); IR (KBr) cm1: 2960, 1763, 1635, 1074, 937.

EXAMPLE 13 0140 In a manner similar to that in Example 1 except that 1.40 g of 1,3,3-trimethyl-2-methylene-4,5-benzindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 2.61 g of the compound 13 was obtained. 0141 Elemental analysis (C96H84AlN9O9): Calcd. (%): C, 75.13; H, 5.52; N, 8.21. Found (%): C, 75.37; H, 5.43; N, 7.98. 1H-NMR (CDCl3) ppm: 0.92-1.04 (9H, m), 1.53-1.95 (24H, m), 2.80-3.30 (6H, m), 3.59-3.66 (9H, m), 5.78-5.92 (3H, m), 6.96-7.29 (12H, m), 7.37-8.24 (21H, m); IR (KBr) cm1: 2960, 1763, 1632, 1074.

EXAMPLE 14 0142 In a manner similar to that in Example 1 except that 5.84 g of 1-(4-bromophenyl)-3-propylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 7.33 g of the compound 14 was obtained. 0143 Elemental analysis (C84H72AlBr3Cl3N9O9): Calcd. (%): C, 58.50; H, 4.21; N, 7.31. Found (%): C, 58.37; H, 4.30; N, 7.07. 1H-NMR (CDCl3) ppm: 0.98-1.03 (9H, m), 1.60-1.77 (24H, m), 2.83-3.09 (6H, m), 3.47 (9H, br s), 5.66-5.71 (3H, m), 6.88-6.93 (3H, m), 7.14-7.20 (3H, m), 7.27-7.29 (9H, m), 7.78-7.83 (6H, m); IR (KBr) cm1: 2929, 1765, 1070.

EXAMPLE 15 0144 In a manner similar to that in Example 1 except that 5.84 g of 1-(4-bromophenyl)-3-propylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, and 4.18 g of 1,3,3-trimethyl-2-methylene-4,5-bonzindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 5.48 g of the compound 15 was obtained. 0145 Elemental analysis (C96H81AlBr3N9O9): Calcd. (%): C, 65.09; H, 4.61; N, 7.12. Found (%): C, 64.95; H, 4.68; N, 6.89. 1H-NMR (CDCl3) ppm: 0.96-1.07 (9H, m), 1.48-1.93 (24H, m), 2.87-3.03 (6H, m), 3.61-3.72 (9H, m), 5.90-5.97 (3H, m), 7.15-7.29 (9H, m), 7.31-7.47 (6H, m), 7.58-7.68 (3H, m), 7.81-8.05 (12H, m); IR (KBr) cm1: 2929, 1763.

EXAMPLE 16 0146 In a manner similar to that in Example 1 except that 9.47 g of 1-(4-chlorophenyl)-3-methlpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, and 4.60 g of 1,3,3-trimethyl-2-methylene-4,5-benzindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 8.14 g of the compound 16 was obtained. 0147 Elemental analysis (C96H81AlCl3N9O9): Calcd. (%): C, 70.39; H, 4.98; N, 7.70. Found (%): C, 69.99; H, 5.04; N, 7.48. 1H-NMR (CDCl3) ppm: 0.96-1.07 (9H, m), 1.51-1.94 (24H, m), 2.86-3.23 (6H, m), 3.61-3.71 (9H, m), 5.88-5.97 (3H, m), 7.00-7.14 (6H, m), 7.20-7.33 (3H, m), 7.40-8.12 (21H, m); IR (KBr) cm1: 2931, 1763, 947.

EXAMPLE 17 0148 In a manner similar to that in Example 1 except that 15.36 g of 1,3-diphenylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 14.22 g of the compound 17 was obtained. 0149 1H-NMR (CDCl3) ppm: 1.57 (18H, br s), 3.40 (9H, br s), 5.70 (3H, m), 6.80-6.87 (3H, m), 7.00-7.52 (27H, m), 7.65-7.80 (3H, m), 7.99-8.10 (6H, m).

EXAMPLE 18 0150 In a manner similar to that in Example 1 except that 13.31 g of 3-(4-methoxyphenyl)-3-phenylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 7.30 g of the compound 18 was obtained. 0151 1H-NMR (CDCl3) ppm: 1.58 (18H, br s), 3.39-3.68 (18H, m), 5.68 (3H, m), 6.57-6.86 (9H, m), 7.14-7.27 (9H, m), 7.34-7.45 (6H, m), 7.52-7.70 (6H, m), 7.87-7.90 (6H, m).

EXAMPLE 19 0152 In a manner similar to that in Example 1 except that 9.47 g of 1-(4-chlorophenyl)-3-propylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 7.72 g of the compound 19 was obtained. 0153 Elemental analysis (C84H72AlCl6N9O9): Calcd. (%): C, 63.40; H, 4.56; N, 7.92. Found (%): C, 63.73; H, 4.77; N, 7.77. 1H-NMR (CDCl3) ppm: 0.96-1.06 (9H, m), 1.60-1.78 (24H, m), 2.81-3.10 (6H, m), 3.47 (9H, br s), 5.65-5.72 (3H, m), 6.88-6.92 (3H, m), 7.04-7.06 (3H, m), 7.12-7.17 (6H, m), 7.26-7.29 (3H, m), 7.82-7.90 (6H, m); IR (KBr) cm1: 2962, 1763, 1570, 1074.

EXAMPLE 20 0154 In a manner similar to that in Example 1 except that 9.47 g of 1-(3-chlorophenyl)-3-propylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 7.72 g of the compound 20 was obtained. 0155 Elemental analysis (C84H72AlCl6N9O9): Calcd. (%): C, 63.40; H, 4.56; N, 7.92. Found (%): C, 63.73; H, 4.62; N, 7.82. 1H-NMR (CDCl3) ppm: 0.95-1.05 (9H, m), 1.55-1.78 (24H, m), 2.73-3.07 (6H, m), 3.48-3.62 (9H, m), 5.64-5.73 (3H, m), 6.89-6.91 (3H, m), 7.00-7.19 (9H, m), 7.26-7.28 (3H, m), 7.76-8.10 (6H, m); IR (KBr) cm1: 2962, 1763, 1599, 1074.

EXAMPLE 21 0156 In a manner similar to that in Example 1 except that 9.12 g of 1-phenyl-3-trifluoromethylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, and 2.01 g of 1,3,3-trimethyl-2-methylene-4,5-benzindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 3.87 g of the compound 21 was obtained. 0157 Elemental analysis (C90H63AlF9N9O9): Calcd. (%): C, 67.04; H, 3.94; N, 7.82. Found (%): C, 67.09; H, 3.98; N, 7.79. 1H-NMR (CDCl3) ppm: 1.63-2.14 (18H, m), 3.66-3.77 (9H, m), 5.56-6.15 (3H, m), 6.93-7.31 (12H, m), 7.36-7.73 (9H, m), 7.80-8.39 (12H, m); IR (KBr) cm1: 2936, 1772, 991.

EXAMPLE 22 0158 In a manner similar to that in Example 1 except that 5.29 g of 1-(3-chlorophenyl)-3-propylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, and 4.02 g of 1,3,3-trimethyl-2-methylene-4,5-benzindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 7.56 g of the compound 22 was obtained. 0159 Elemental analysis (C96H81AlCl3N9O9): Calcd. (%): C, 70.39; H, 4.98; N, 7.70. Found (%): C, 70.11; H, 5.03; N, 7.55. 1H-NMR (CDCl3) ppm: 0.94-1.05 (9H, m), 1.47-2.00 (24H, m), 2.78-3.36 (6H, m), 3.60-3.66 (9H, m), 5.82-5.94 (3H, m), 6.96-7.12 (6H, m), 7.18-7.31 (3H, m), 7.39-7.67 (6H, m), 7.79-8.40 (15H, m); IR (KBr) cm1: 2929, 1763, 945.

EXAMPLE 23 0160 In a manner similar to that in Example 1 except that 5.28 g of 1-(3-fluorophenyl)-3-propylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, and 4.62 g of 1,3,3-trimethyl-2-methylene-4,5-benzindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 8.94 g of the compound 23 was obtained. 0161 Elemental analysis (C96H81AlF3N9O9): Calcd. (%): C, 72.58; H, 5.14; N, 7.93. Found (%): C, 72.30; H, 5.32; N, 7.65. 1H-NMR (CDCl3) ppm: 0.94-1.06 (9H, m), 1.56-1.92 (24H, m), 2.86-3.26 (6H, m), 3.60-3.69 (9H, m), 5.84-5.95 (3H, m), 6.72-6.89 (6H, m), 7.20-7.33 (3H, m), 7.42-7.71 (9H, m), 7.79-8.13 (12H, m); IR (KBr) cm1: 2931, 1734, 949.

EXAMPLE 24 0162 In a manner similar to that in Example 1 except that 5.28 g of 1-(4-fluorophenyl)-3-propylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 11.35 g of the compound 24 was obtained. 0163 Elemental analysis (C84H72AlF3Cl3N9O9): Calcd. (%): C, 65.43; H, 4.71; N, 8.18. Found (%): C, 65.28; H, 4.62; N, 8.00. 1H-NMR (CDCl3) ppm: 0.96-1.06 (9H, m), 1.60-1.80 (24H, m), 2.82-3.11 (6H, m), 3.47 (9H, br s), 5.64-5.72 (3H, m), 6.75-6.92 (9H, m), 7.07-7.17 (3H, m), 7.25-7.28 (3H, m), 7.80-7.92 (6H, m); IR (KBr) cm1: 2962, 1765, 1579, 1074.

EXAMPLE 25 0164 In a manner similar to that in Example 1 except that 2.16 g of 3-propyl-1-(4-trifluoromethylphenyl)pyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 4.44 g of the compound 25 was obtained. 0165 Elemental analysis (C87H72AlCl3F9N9O9): Calcd. (%): C, 61.76; H, 4.29; N, 7.45. Found (%): C, 61.51; H, 4.42; N, 7.20. 1H-NMR (CDCl3) ppm: 0.92-1.03 (9H, m), 1.58-1.74 (24H, m), 2.87-3.08 (6H, m), 3.45-3.49 (9H, m), 5.69 (3H, m), 6.90-6.95 (3H, m), 7.20-7.47 (12H, m), 8.08 (6H, m); IR (KBr) cm1: 2962, 1765, 1551, 1065.

EXAMPLE 26 0166 In a manner similar to that in Example 1 except that 8.35 g of 1-(4-chlorophenyl)-3-methylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, and 6.64 g of 1,3,3-trimethyl-2-methylene-4,5-benzindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 9.51 g of the compound 26 was obtained. 0167 Elemental analysis (C90H69AlCl3N9O9): Calcd. (%): C, 69.56; H, 4.48; N, 8.11. Found (%): C, 69.65; H, 4.40; N, 8.27. 1H-NMR (CDCl3) ppm: 1.48-1.82 (18H, m), 2.49-2.71 (9H, m), 3.60-3.69 (9H, m), 5.62-5.91 (3H, m), 7.00-7.48 (18H, m), 7.58-8.08 (12H, m); IR (KBr) cm1: 2929, 1732, 945.

EXAMPLE 27 0168 In a manner similar to that in Example 1 except that 11.53 g of 1-(4-fluorophenyl)-3-methylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, and 7.08 g of 1,3,3-trimethyl-2-methylene-4,5-benzindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 11.00 g of the compound 27 was obtained. 0169 Elemental analysis (C90H69AlCl3F3N9O9): Calcd. (%): C, 71.85; H, 4.62; N, 8.38. Found (%): C, 71.92; H, 4.94; N, 8.10. 1H-NMR (CDCl3) ppm: 1.65-1.92 (18H, m), 2.50-2.78 (9H, m), 3.62-3.70 (9H, m), 5.84-5.94 (3H, m), 6.75-6.91 (6H, m), 7.23-7.33 (3H, m), 7.40-7.67 (6H, m), 7.82-8.10 (15H, m); IR (KBr) cm1: 2929, 1736, 945.

EXAMPLE 28 0170 In a manner similar to that in Example 1 except that 2.16 g of 3-propyl-1-(4-trifluoromethylphenyl)pyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, and 1.29 g of 1,3,3-trimethyl-2-methylene-4,5-benzindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 1.22 g of the compound 28 was obtained. 0171 Elemental analysis (C99H81AlF9N9O9): Calcd. (%): C, 68.39; H, 4.70; N, 7.25. Found (%): C, 68.68; H, 4.89; N, 7.05. 1H-NMR (CDCl3) ppm: 0.95-1.08 (9H, m), 1.44-1.93 (24H, m), 2.89-3.30 (6H, m), 3.63-3.72 (9H, m), 5.88-6.00 (3H, m), 7.20-7.52 (15H, m), 7.61-8.30 (15H, m); IR (KBr) cm1: 2931, 1765, 947.

EXAMPLE 29 0172 In a manner similar to that in Example 1 except that 1.02 g of 5-methoxy-1,3,3-trimethyl-2-methyleneindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 1.70 g of the compound 29 was obtained. 0173 Elemental analysis (C87H84AlN9O12): Calcd. (%): C, 70.86; H, 5.74; N, 8.55. Found (%): C, 70.67; H, 5.89; N, 8.54. 1H-NMR (CDCl3) ppm: 1.02 (9H, m), 1.24-1.76 (24H, m), 2.80-3.12 (6H, m), 3.44-3.48 (9H, m), 3.67 (9H, m), 5.65 (3H, m), 6.57-6.90 (9H, m), 6.98-7.01 (3H, m), 7.10-7.18 (6H, m), 7.84-8.00 (6H, m); IR (KBr) cm1: 2958, 1763, 1016.

EXAMPLE 30 0174 In a manner similar to that in Example 1 except that 18.25 g of 1-phenyl-3-trifluoromethylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, 4.04 g of the compound 30 was obtained. 0175 1H-NMR (CDCl3) ppm: 1.19-1.77 (18H, m), 3.47-3.61 (9H, m), 5.52-6.00 (3H, m), 6.84-7.43 (18H, m), 7.52-8.18 (6H, m).

EXAMPLE 31 0176 In a manner similar to that in Example 1 except that 11.80 g of 1,3-dimethylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, and 18.25 g of 1,3,3-trimethyl-2-methylene-4,5-benzindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 13.65 g of the compound 31 was obtained. 0177 1H-NMR (CDCl3) ppm: 1.78-1.98 (18H, m), 2.54-2.67 (9H, m), 3.33-3.41 (9H, m), 3.56-3.63 (9H, m), 5.80 (3H, m), 7.28 (3H, m), 7.44 (3H, m), 7.63 (3H, m), 7.84-7.96 (9H, m).

EXAMPLE 32 0178 In a manner similar to that in Example 1 except that 1.72 g of 3,3-dimethyl-2-methyleneindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 2.46 g of the compound 32 was obtained. 0179 Elemental analysis (C81H72AlN9O9): Calcd. (%): C, 72.47; H, 5.41; N, 9.39. Found (%): C, 72.77; H, 5.42; N, 9.26. 1H-NMR (CDCl3) ppm: 0.88-1.11 (9H, m), 1.24-1.55 (18H, m), 1.57-1.83 (6H, m), 2.53-3.07 (6H, m), 5.21-5.65 (3H, m), 6.78-7.37 (21H, m), 7.57-8.04 (6H, m), 11.5-12.81 (3H, m); IR (KBr) cm1: 2962, 1770, 1013.

EXAMPLE 33 0180 In a manner similar to that in Example 1 except that 18.25 g of 1-phenyl-3-trifluoromethylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, and 9.71 g of 5-methoxy-1,3,3-trimethyl-2-methyleneindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 13.19 g of the compound 33 was obtained. 0181 1H-NMR (CDCl3) ppm: 1.24-1.79 (18H, m), 3.50-3.69 (9H, m), 3.75-3.88 (9H, m), 5.48-5.98 (3H, m), 6.49-7.29 (18H, m), 7.71-8.15 (6H, m).

EXAMPLE 34 0182 In a manner similar to that in Example 1 except that 18.25 g of 1-phenyl-3-trifluoromethylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, and 9.20 g of 5-methyl-1,3,3,5-tetramethyl-2-methyleneindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 11.79 g of the compound 34 was obtained. 0183 1H-NMR (CDCl3) ppm: 1.25-1.79 (18H, m), 2.18-2.45 (9H, m), 3.50-3.64 (9H, m), 5.53-6.01 (3H, m), 6.62-7.30 (18H, m), 7.69-8.11 (6H, m).

EXAMPLE 35 0184 In a manner similar to that in Example 1 except that 18.25 g of 1-phenyl-3-trifluoromethylpyrazolin-5-one was used instead of 1-phenyl-3-propylpyrazolin-5-one, and 10.09 g of 1-methyl-2-methyleneindoline-3-spirocyclohexane was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 12.34 g of the compound 35 was obtained. 0185 Elemental analysis (C87H69AlF9N9O9): Calcd. (%): C, 66.03; H, 4.39; N, 7.97. Found (%): C, 65.81; H, 4.46; N, 7.87. 1H-NMR (CDCl3) ppm: 1.35-1.59 (6H, m), 1.68-2.17 (24H, m), 3.84 (9H, m), 5.59-5.92 (3H, m), 7.09 (9H, m), 7.26-7.46 (9H, m), 7.85-8.00 (9H, m); IR (KBr) cm1: 2936, 1771, 987.

EXAMPLE 36 0186 In a manner similar to that in Example 1 except that 0.56 g of 5,7-dichloro-1,3,3-trimethyl-2-methyleneindoline was used instead of 5-chloro-1,3,3-trimethyl-2-methyleneindoline, 0.70 g of the compound 36 was obtained. 0187 Elemental analysis (C84H72AlCl6N9O9): Calcd. (%): C, 63.40; H, 4.56; N, 7.92. Found (%): C, 63.18; H, 4.46; N, 7.82. 1H-NMR (CDCl3) ppm: 0.94-1.08 (9H, m), 1.35-1.82 (24H, m), 2.81-3.13 (6H, m), 3.80 (9H, m), 5.64-5.72 (3H, m), 6.87-7.24 (15H, m), 7.79-7.95 (6H, m); IR (KBr) cm1: 2960, 1765, 1070. 0188 B. Characterization of Squarylium Compounds

EXAMPLE 37 0189 The maximum absorption wavelengths (max) and the molar extinction coefficients at the maximum absorption wavelength for the compounds obtained in Examples 1-36 were measured in a chloroform solution. Results are listed in Table 4.

EXAMPLE 38 0190 The decomposition temperatures for the compounds obtained in Examples 1-36 were measured. Results are listed in Table 4.

COMPARATIVE EXAMPLE 1 0191 Similarly, the maximum absorption wavelengths (max), the molar extinction coefficients at the maximum absorption wavelength in a chloroform solution, and the decomposition temperature were measured for the squarylium compounds which were not treated for metal complexation in Examples 1-6 (Compounds 1b-6b) (i.e., these had not been complexed with a metal). Results are listed in Table 5. 4TABLE 4Spectroscopic Properties and Decomposition Temperatureof Squarylium CompoundsSpectroscopicProperties(in Chloroform)DecompositionExamplemaxTemperatureCompound(nm)log ( C.)1572.55.43152572.55.43303586.55.43254568.55.43275572.05.43126587.55.43347573.05.43178570.55.43169569.55.433110570.05.432811573.05.431812572.05.431513589.55.432714573.05.431315561.05.428516590.55.430017577.55.428618577.05.429219573.05.431120574.05.431021589.55.430122591.05.430223589.55.430124572.55.431125573.55.429626585.55.431927589.05.432428591.55.427729582.05.430130572.55.429031583.05.229732582.55.331533583.05.330034572.55.430435580.05.328636573.05.4310

0192

5TABLE 5Spectroscopic Properties and Decomposition Temperatureof Squarylium CompoundsSpectrolscopicPropertiesComparative(in Chloroform)DecompositionExamplemaxTemperatureCompound(nm)log ( C.)1b577.55.12802b578.55.22893b570.05.22704b571.05.22905b576.55.33006b571.05.2270

EXAMPLE 39 0193 The optical constants for thin films of the compounds obtained in Examples 1-6 were measured. Results are listed in Table 6.

COMPARATIVE EXAMPLE 2 0194 Similarly, the optical constants for thin films of the squarylium compounds which were not treated for metal complexation in Examples 1-6 (Compounds 1b-6b) were measured. Results are listed in Table 7. 6TABLE 6Optical Constants for Squarylium CompoundsExample 650 nm 660 nmCompoundnknk12.8150.0782.6070.03822.7720.0952.5750.04932.6280.0582.4800.03542.7660.0802.5910.04852.8720.1152.6620.05562.4520.0622.3420.048

0195

7TABLE 7Optical Constants for Squarylium CompoundsComparativeExample 650 nm 660 nmCompoundnknk1b2.6340.1352.4820.0862b2.5980.0792.4510.0413b2.4820.0842.3670.0594b2.5720.1002.4460.0535bimpossible to make a thin filmdue to crystal formation6b2.4500.0522.3430.037

0196 From Tables 6 and 7, it can be seen that metal complexation caused a larger refractive index and an improved solubility in an organic solvent.

EXAMPLE 40 0197 Thin films of the compounds obtained in Examples 1, 2, and 4 were irradiated with the light from a xenon lamp (50,000 luxes) to determine a photodeteriorating rate constant from the change in their optical densities in time course. Results are listed in Table 8. The photodeteriorating rate constants were calculated using the following equation:

dOD/dtkOD

0198 OD: Optical density for the thin film of the squarylium compound; 0199 k: Photodeteriorating rate constant.

COMPARATIVE EXAMPLE 3 0200 Similarly, photodeteriorating rate constants for thin films of the squarylium compounds which were not treated for metal complexation in Example 1,2 and 4 (Compounds 1b, 2b, and 4b) were determined. Results are listed in Table 8. 8TABLE 8Photodeteriorating Rate Constantsfor the Thin Film of the Squarylium CompoundsRatio of the PhotodeterioratingCompound inRate Constants: k0/kComparative Example/k0: non-metal complexCompound in Examplek: metal complex1b/17.22b/26.54b/45.8

0201 From Table 8, it can be seen that metal complexation caused improved light resistance. 0202 C. Characterization of Optical Recording Media Using a Squarylium Compound 0203 Examples relating to the optical recording media will be illustrated below.

EXAMPLE 41 0204 A solution prepared by dissolving the compound 1 in 2,2,3,3-tetrafluoro-1-propanol was spinner-coated on an injection molded-polycarbonate substrate of 0.6 mm thickness having a guiding groove of the groove depth of 1,750 , the half band width of 0.38 m, and the track pitch of 0.74 m to form an organic dye layer having the thickness of 900 . 0205 Then, a gold reflective layer having the thickness of 1,200 was provided thereon by a sputtering method, a protective layer having the thickness of 7 m was further provided thereon with an acrylic photopolymer, and then an injection molded-polycarbonate flat substrate having the thickness of 0.6 mm was adhered thereto with an acrylic photopolymer to prepare an optical recording medium. 0206 An EFM signal was recorded on the prepared optical recording medium with tracking (linear speed of 3.5 m/sec.) using the semiconductor laser beam having an oscillation wavelength of 658 nm and a beam diameter of 1.0 m, and then the recorded signal was reproduced with a continuous beam of the semiconductor laser having an oscillation wavelength of 658 nm (reproduction power of 0.7 mW). The resulting signal properties are listed in Table 9.

EXAMPLES 42-46 0207 The optical recording medium was formed according to the completely same way as that in Example 41 except that the compound 2, 4, 5 or 6 was used instead of the compound 1, and the signal properties thereof were measured. The resulting signal properties are listed in Table 9. 9TABLE 9Signal Properties of Recording MediaReflectanceModulation(%):Percentagegrooved(%):portionI14/I14HJitter (%)Example 415063.37.8Example 424963.78.0Example 434761.87.9Example 444862.98.0Example 454862.58.1Example 464963.18.3

0208 From Table 9, it can be seen that signal properties of the high reflectance, high modulation percentage and low jitter which are conformable to DVD-R standard were obtained according to the optical recording medium of the present invention.

EXAMPLE 47 0209 An optical recording medium was formed using a mixture of the compound 1 and the metal complex No. 3 (see Table 2; weight ratio of compound 1/metal complex No. 310/3) instead of the compound 1. 0210 The recording medium was irradiated with the light from a xenon lamp (50,000 luxes) for 10 hours, and a remaining ratio of an optical density was evaluated. The remaining ratio of an optical density was calculated by the following equation:

Remaining ratio of an optical densityId/Io100 (%)

0211 Id: Optical density after irradiation; 0212 I0: Optical density before irradiation. 0213 The results of the light resistance test are listed in Table 10.

EXAMPLES 48-50 0214 An optical recording medium was formed in a manner similar to that in Example 47, using the aromatic amine compound No. 104 (see Table 3) instead of the metal complex No. 3 (Example 48), and further using a mixture of the compound 2 and the metal complex No. 12 (see Table 2) (Example 49) or a mixture of the compound 2 and the aromatic amine compound No. 113 (see Table 3) (Example 50) instead of a mixture of the compound 1 and the metal complex No. 3. A light resistance test was performed on the resulting optical recording medium in a manner similar to that in Example 47. The results of the light resistance test are listed in Table 10. 10TABLE 10Results of Light Resistance Test of Optical Recording MediaCompoundLight StabilizerRemaining Ratio ofNo.No.Optical Density %Example 471382Example 48110489Example 4921285Example 50211391

0215 From Table 10, it can be seen that excellent light resistance was obtained according to the optical recording medium of the present invention.

INDUSTRIAL APPLICABILITY 0216 According to the present invention, there can be provided squarylium compounds having spectroscopic and thermal decomposition properties suitable for an oscillation wavelength of a semiconductor laser used for a digital versatile disc-recordable (DVD-R). Also, DVD-R media having the excellent light resistance as well as the high reflectance and modulation depth can be provided by using the squarylium compound of the present invention as an optical recording material.