WO2005090362A1

WO2005090362A1 - High-performance optical storage media

Info

Publication number: WO2005090362A1
Application number: PCT/EP2005/051038
Authority: WO
Inventors: Leonhard Feiler; Thomas Ruch
Original assignee: Ciba Specialty Chemicals Holding Inc.
Priority date: 2004-03-18
Filing date: 2005-03-09
Publication date: 2005-09-29
Also published as: TW200540860A

Abstract

The invention relates to an optical recording medium comprising a substrate, a reflecting layer and a recording layer, wherein the recording layer comprises a compound of formula (I), or a mesomeric or tautomeric form thereof, wherein Zn+ is a proton or an n-valent ammonium, phosphonium, metal complex or alkali metal cation and n is a number (1), (2) or (3); it being possible, where appropriate, for Zn+ to be linked to R1, R2, R3 or R4 by a direct bond or by way of an O, S or NR8 bridge. R1, to R7 are hydrogen or hydrocarbon radicals defined in the description and claims; R2 and R6 can additionally be halogen or nitro. Novel compounds of formula (I) are also claimed, these being compounds in which Zn+ is a phosphonium, metal complex or alkali metal cation or which are asymmetrical.

Description

High-performance optical storage media

The field of the invention is the optical storage of information on write-once storage media, the information pits being differentiated by the different optical properties of a colorant at written and unwritten sites. This technology is usually termed "WORM" (for example, "CD-R", "DVD-R" or "DVD+R"); those terms have been retained herein.

The use of compact, high-power diode lasers which emit in the range from 630 to 690 nm makes it possible to achieve, in principle, a 4- to 5-fold improvement in data packing density and a 6- to 8-fold increase in storage capacity compared to media having blue or green layers by means of the fact that the track spacing (distance between 2 turns of the information track) and the size of the pits can be reduced to about half compared to conventional CDs.

However, this makes extraordinarily high demands of the recording layer to be used, such as a high refractive index, uniformity of script width at different pulse durations and also high light stability in daylight and, at the same time, high sensitivity to high-energy laser radiation. The known recording layers possess those properties only to an unsatisfactory degree.

FR 2019482, BE 768214 and DD 286241 A5 disclose cyanine dyes having one or two boron-containing terminal groups (so-called "dioxaborins", also referred to, depending on the author, as boranyloxy..., dionatobora... or dionatoborates), which can be used as sensitisers in photographic materials.

DE 101 52938 C1 discloses the use, in electronic semiconductor components, of symmetrical bis-dioxaborin compounds having an unsaturated linking member containing an even or odd number of carbon atoms.

Further symmetrical and asymmetrical dioxaborin complexes are disclosed, without mention of their intended application, in Dyes and Pigments 58, 41-46 (2003), including the compounds of formulae

JP-A Sho 60-71 294 discloses writable optical information media which can be written at 632 nm and which comprise neutral cyanine dyes having one dioxaborin terminal group and one N-heterocyclic terminal group, as well as quenchers, for example the mixture having the following structure:

However, that system is not compatible with today's standards (such as DVD-R or DVD+R) because at most one partly reflecting layer is advantageous and preferably no reflector layer at all is used. In addition it has been found that the quality, especially of recordings made using a laser of a wavelength about 658 ±5 nm, still leaves something to be desired.

The aim of the present invention was consequently to provide an optical recording medium wherein the recording layer has a high storage capacity along with excellent other properties. It should also be possible for that recording medium to be both written and read at the same wavelength in the range from 630 to 690 nm (preferably from 640 to 680 nm). The main features of the recording layer according to the invention are the very high initial reflectivity in the said wavelength range of the laser diodes, which reflectivity can be modified with high sensitivity; the high refractive index; the steep edge, on the bathochromic side, of the absorption band in the solid state; the good uniformity of the script width at different pulse durations; the good light-stability; the good solubility in polar solvents; and excellent compatibility with laser sources of different wavelengths both for recording and for playback.

Very surprisingly, outstanding results are obtained by using specific ionic compounds wherein the anion contains boron and the cation contains a proton, ammonium, phosphonium, metal complex or alkali metal ion. It is entirely unexpected that, in the solid layer, the refractive index is astonishingly higher than in comparable previous systems. The compounds wherein the cation is a colorant cation are especially interesting.

The invention accordingly relates to an optical recording medium comprising a substrate, a reflecting layer and a recording layer, wherein the recording layer comprises a compound of formula

or a mesomeric or tautomeric form thereof, wherein

Z is a proton or an n-valent ammonium, phosphonium, metal complex or alkali metal cation and n is a number 1 , 2 or 3; it being possible, where appropriate, for Zⁿ⁺ to be linked to Ri, R₂, R₃ or R4 by a direct bond or by way of an O, S or NR₈ bridge;

Ri and R₇ are, each independently of the other, CN; CONR₈Rg; or CrC₆alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, C₃-Cecycloalkyl, C₃-C₆cycloalkenyl or C₃-C₆hetero- cycloalkyl each unsubstituted or substituted one or more times by halogen, OR1₀, SR₁₀, NR₈R₉, OSiRnRι₂Rι₃, CORn, CRnOR₁₂ORι₃, N0₂, CN, CONR₈R₉, COOR13, SO2R13, S0₂NR₈R9, SO3R13 or by PO(OR₁₂)(ORι₃); or phenyl, benzyl, phenethyl, styryl or CrCsheteroaryl each unsubstituted or substituted one or more times by R13, halogen, ORιo, SR10, NR₈R_g, OSiRnRι₂Rι₃, CORn, CRnORι₂OR₁₃, N0₂, CN, CONR₈Rg, COORi3, S0₂Rι₃, S0₂NR₈R₉, SO3R13, PO(ORι₂)(OR₁₃), NR₈S0₂R₁₃, SiRnRi₂Ri3 or by SiORnORι₂ORι₃;

R₂ and R₆ are, each independently of the other, hydrogen, halogen, N0₂, CN, CONR₈R₉; or C C₆alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, C₃-C₆cycloalkyl, C₃-C₆cycloalkenyl or C₃-C₆heterocycloalkyl each unsubstituted or substituted one or more times by halogen, OR10, SR-io, NR₈R₉, OSiRnRι₂Ri3. CORn, CRiiOR₁₂ORi₃, N0₂, CN, CONR₈R₉, COOR13, SO2R13, S0₂NR₈R₉, SO3R13 or by PO(ORι₂)(ORι₃); or phenyl, benzyl, phenethyl, styryl, Cι-C₅heteroaryl, phenyl-N=N- or C2-C₅heteroaryl-N=N- each unsubstituted or substituted one or more times by R13, halogen, OR10, SR10, NR₈R₉, OSiRnRι₂Ri3, CORn, CR11OR12OR13, N0₂₎ CN, CONR₈Rg, COORis, S0₂Rι₃₎ S0 NR₈R₉, SO3R.3, PO(ORι₂)(ORi3), NR₈S0₂Rι₃, SiRιιRι₂Rιs or by SiORnORι₂ORι₃;

it being possible, in addition, for Ri and R₂ and/or, independently thereof, Re and R₇ to be so linked together by a linking member selected from the group consisting of single and double direct bonds and O, S and NR₈ bridges that a 5- or 6-membered ring is formed;

R₃, R-4 and R₅ are, each independently of the others, hydrogen; or d-Cβalkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, C₃-C₆cycloalkyl, C₃-C₆cycloalkenyl or C₃-C₆hetero- cycloalkyl each unsubstituted or substituted one or more times by halogen, OR1₀, SR10, NR₈Rg, OSiRnRι₂Ri3, CORn, CR11OR12OR13, N0₂, CN, CONR₈R₉, COOR13, S0₂R₁₃₎ S0₂NR₈R₉, SO₃R13 or by PO(OR₁₂)(ORι₃); or phenyl, benzyl, phenethyl, styryl or CrC₅heteroaryl each unsubstituted or substituted one or more times by R₁₃, halogen, OR10, SR10, NR₈R₉, OSiRnR₁₂Ri3, CORn, CRιιOR₁₂ORι₃₎ N0₂, CN, CONR₈Rg, COOR13, S0₂Ri3, S0₂NR₈R₉, SO3R13, PO(ORι₂)(ORι₃), NR₈S0₂Rι₃, SiRιιRι₂Rιs or by SiORnORι₂ORι₃;

R₈ and R₉ are, each independently of the other, R₁₀, [C2-C₃alkylene-0-] -Ri4 or [C₂-C₃alkylene-NRιo-]k-Ri4, k being an integer from 1 to 3; or NR₈R₉ is a five- or six- membered heterocycle optionally containing a further nitrogen or oxygen atom, which heterocycle may be substituted one or more times by Cι-C₆alkyl; each R₁₀, independently of any other Rio, is Rn, CORn, COOR1₃, CONRnRι₂₎ CN or S0₂Rι₃;

R11 and R12 are, each independently of the other, hydrogen or R₁₃; or NRnRι₂ is a five- or six-membered heterocycle optionally containing a further nitrogen or oxygen atom, which heterocycle may be substituted one or more times by Cι-C₆alkyl;

each R₁₃, independently of any other R1₃, is CrC₆alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, C3-C₆cycloalkyl, C₃-C₆cycloalkenyl or C₃-C₆heterocycloalkyl each unsubstituted or substituted one or more times by halogen, OR14, SR₁₄, NR14R15, NR14COR15, NR₁₄COORi6, NHCONR14R15. NR₁₆CONRι₄Ri5, OSiRι₄Rι₆Ri7, COR14, CR₁₄ORι₆ORi7, N0₂, CN, COORι₆, CONR14R15, S0₂NR₁₄Rι₅, S0₂Rι₆ or by S0₃Rι₆; or benzyl, phenyl or C₂-C₅heteroaryl each unsubstituted or substituted one or more times by halogen, R₁₆, OR14, SR14, NR₁₄Rι₅, NRι₄C0Rι₅, NR COORie, NHCONR14R15, NRi₆CONR₁₄Ri₅, OSiRwRieRir, COR14, CR14OR16OR-.7. N0₂, CN, COOR₁₆, CONRι₄Ri5, SO2NR14R15, S0₂Rι₆, SO3R16, PO(OR₁₆)(ORι₇), SiRι₄Rι₆Rι₇ or by SiORi4θRιβORι₇; it being possible, in addition, for R12 and R13 to be so linked together by a linking member selected from the group consisting of single and double direct bonds and O, S and NR bridges that a 5-, 6-, 7- or 8-membered ring is formed;

R14 and R15 are, each independently of the other, hydrogen, Rιβ or R17; or NR14R15 is a five- or six-membered heterocycle optionally containing a further nitrogen or oxygen atom, which heterocycle may be substituted one or more times by CrC₄alkyl;

R₁₆ and R₁₇ are, each independently of the other, Cι-C₆alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, C₃-C₆cycloalkyl, C₃-C₆cycloalkenyl, C₃-C₆heterocycloalkyl, benzyl, phenyl or C₂-C₅heteroaryl, preferably methyl, ethyl, vinyl or ethynyl, each substituted one or more times by halogen, ORι₈, SRι₈, NRι₈Rιg, CORι₈, N0₂, CN or by COORι₈; it being possible, in addition, for Rι₆ and R17 to be so linked together by a linking member selected from the group consisting of single and double direct bonds and O, S, NH and N(CrC alkyl) bridges that a 5-, 6-, 7- or 8-membered ring is formed; and

Rιs and R19 are, each independently of the other, hydrogen, methyl or ethyl.

In the case of multiple substitution it will be self-evident that the substituents, for example 1 , 2, 3, 4 or 5 substituents, may be either identical or different in some or all cases, as in, for example, trifluoromethyl, 3-bromo-4,4-dimethoxy-2-cyclo- hexenyl or 2-nitro-4-chloro-6-methyl-phenyl.

When Zⁿ⁺ is an n-valent ammonium, phosphonium or metal complex cation, it is preferably of formula N⁺R₈R₉Rι₁Ri2_I P⁺R₈R₉RιιRi2,

,N-R,ι , Rg or [L₁-M-L₂]ⁿ⁺, or a dimer of two identical or different radicals thereof,

wherein

M is a metal and Li and L₂ are, each independently of the other, ligands; Qi is O, S, NR10 or Q₄=Q_7> Q₂ is CR₂₅ or N, Q₃ is O, S, NRn or Q₂=Q₇, Q.4 is CR₂4 or N, Q₅ is CR₂₃ or N, Q₆ is O, S, NRn or Q₅=Q₇, and Q₇ is CR₂₆ or N; Q₇ in Q₄=Q7_. Qδ=Q₇ or Q₂=Q₇ preferably being in the β-position relative to N of ;

R₂o and R21 are, each independently of the other, R10, OR13 or NRnR₁₂;

R₂₃, R₂₄, R₂₅ and R₂₆ are, each independently of the others, H, halogen, OR10, SR10, NR₈Rg, 0SiRiiRi₂Ri₃, CORn, CRnORι₂ORι₃, N0₂, CN, C0NR₈R₉, COOR13, S0₂R₁₃, S0₂NR₈R₉, SO₃R₁₃; or Cι-C₆alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, C₃-C₆cycloalkyl or C₃-C₆cycloalkenyl each unsubstituted or substituted one or more times by halogen, OR or by CN; and

R₂₇ is phenyl, benzyl, phenethyl, styryl or Cι-C₅heteroaryl each unsubstituted or substituted one or more times by R13, halogen, OR10, SR10, NR₈Rg, 0SiRnRι₂Rι₃, CORn, CRnOR₁₂ORi3, N0₂, CN, C0NR₈R₉, COOR13, S0₂Rι₃, S0₂NR₈R₉, SO3R13, PO(ORι₂)(ORι₃), NR₈S0₂Ri3, SiRnRι₂Rι₃ or by SiORιιORι₂ORι₃.

Q2=Q₇, Q =Q₇ and Q₅=Q₇ are in each case 2 atoms or groups according to the definitions of Q2, Q₄, Q₅ and Q joined by a double bond.

When Zⁿ⁺ is an n-valent metal complex cation, special preference is given to its being of formula [LrM-L₂]ⁿ⁺ (π), wherein L_ι and L₂ are each independently of the

other a ligand of formula _> wherein

Qi to Q₆ and R2₃ to R₂s being as defined hereinbefore;

G₂ is OCO, OSO2, ^"N(Rιo) or, especially, ^"O or~N(S0₂Ri3);

M is a transition metal or group 13 metal cation having n+2 positive charges;

Q₈ is CR30 or N, Q₉ is CR31 or N; preferably, either Q₈ is CR30 and Q_g is CR₃ι or Q₈ and Q₉ are both N;

R₂₈ is H, halogen, OR₁₀, SR10, NR₈R₉, OSiRnR₁₂Ri3, CORn, CRnORι₂ORι₃, N0₂, CN, CONR₈Rg, COOR₁₃, S0₂Ri₃, S0₂NR₈R₉, SO₃R₁₃; or Cι-C₆alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, C₃-C₆cycloalkyl or C3-C₆cycloalkenyl each unsubstituted or substituted one or more times by halogen, ORι or by CN; and R2₉, R₃₀ and R₃1 are, each independently of the others, H, halogen, OR1₀, SR1₀, NR₈R₉, OSiRnRi₂Ri3, CORn, CRnORι₂ORι₃, N0₂, CN, CONR₈R₉, COOR₁₃₎ SO2R13, S0₂NR₈R₉ or S0₃Rι₃.

Transition metal or group 13 metal cations are, for example, Co²⁺, Co³⁺, Cu⁺, Cu²⁺, Zn²⁺, Cr°⁺, Ni²⁺, Fe²⁺, Fe³⁺, Al³⁺, Ce²⁺, Ce³*, Mn²⁺, Mn³⁺ or V³⁺, preferably Co³⁺, Cr³⁺, Fe³⁺ Ce³⁺ or Mn³⁺.

Ammonium or phosphonium cations are, for example, methylammonium, ethyl- ammonium, pentadecylammonium, isopropylammonium, dicyclohexylammonium, tetramethylammonium, tetraethylammonium, tetrabutylammonium, benzyltrimethyl- ammonium, benzyltriethylammonium, methyltrioctylammonium, tridodecy I methyl- ammonium, tetrabutylphosphonium, tetraphenylphosphonium, butyltriphenyl- phosphonium or ethyltriphenylphosphonium, and also protonated Primene 81 R™ or Rosin Amine D™. However, cationic chromophores are preferred.

As positively charged organic chromophores there can be used any cations that absorb in the range from 300 to 1500 nm, especially in the range from 300 to 800 nm. Preferably, the person skilled in the art will especially select chromophore cations that have previously been proposed for use in optical information media, for example cyanine, xanthene, dipyrromethene, styryl, triphenylmethane, azo metal complex, quinonediimmonium, bipyridinium and other cations. Preference is given to cyanine, xanthene, dipyrromethene, azo metal complex and styryl cations. Such chromophores and further chromophores suitable for use in cationic form are disclosed, for example, in Dyes and Pigments 59, 63-69 (2003), EP 1 125987, EP 1 130063, EP 1 152038, EP 1 156084, EP 1 170339, EP 1 174472, JP-A-11/28865, JP-A-11/170695, JP-A-2003/119404, WO 2002/34841 , WO 2002/50210 or WO 01/75873, although those examples should on no account be regarded as a limiting selection. Mention should be made especially of the following chromophore cations:

and also paraquat and diquat types, such as alkyl and benzyl viologen or

quinone-diimmonium cations or radical cations, such as Kayasorb^® IRG™ 022, Kayasorb^® IRG™ 040,

Alkyl, alkenyl or alkynyl can be straight-chained or branched. Alkenyl is alkyl which is mono- or poly-unsaturated, it being possible for two or more double bonds to be isolated or conjugated, as appropriate. Alkynyl is alkyl or alkenyl which has one or more doubly unsaturated bonds, it being possible for the triple bonds to be isolated or conjugated with (an)other such bond(s) or conjugated with (a) double bond(s), as appropriate. Cycloalkyl and cycloalkenyl are monocyclic or polycyclic alkyl and alkenyl, respectively.

d-CeAlkyl can accordingly be, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-methyl-butyl, n-pentyl, 2-pentyl, 3-pentyl, 2,2-dimethylpropyl, 3,3-dimethylpropyl or n-hexyl. C₃-Cι₂Cycloalkyl is, for example, cyclopropyl, cyclopropylmethyl, cyclobutyl, cyclopentyl or cyclohexyl.

C₂-C₆Alkenyl is, for example, vinyl, allyl, 2-propen-2-yl, 2-buten-1-yl, 3-buten-1-yl, 1,3-butadien-2-yl, 2-penten-1-yl, 3-penten-2-yl, 2-methyl-1-buten-3-yl, 2-methyl- 3-buten-2-yl, 3-methyl-2-buten-1 -yl, 1 ,4-pentadien-3-yl or any isomer of hexenyl. C₃-C₆Cycloalkenyl is, for example, 2-cyclobuten-l-yl, 2-cyclopenten-1-yl, 2-cyclohexen-1-yl, 3-cyclohexen-1-yl or2,4-cyclohexadien-1-yl.

C₂-C₆Alkynyl is, for example, 1-propyn-3-yl, 1-butyn-4-yl, 1-pentyn-5-yl, 2-methyl-3- butyn-2-yl, 1 ,4-pentadiyn-3-yl, 1,3-pentadiyn-5-yl, 1-hexyn-6-yl, cis-3-methyl-2~ penten-4-yn-1 -yl, trans-3-methyl-2-penten-4-yn-1 -yl or 1 ,3-hexadiyn-5-yl. Halogen is chlorine, bromine, fluorine or iodine, preferably fluorine on alkyl, cycloalkyl, alkylene or cycloalkylene and chlorine or bromine on aryl, heteroaryl and aralkyl.

Cι-C₅Heteroaryl is an unsaturated or aromatic radical having 4n+2 conjugated π-electrons, for example tetrazolyl, thiadiazolyl, thiaimidazolyl, 2-thienyl, 2-furyl, 1 -pyrazolyl, 2-pyridyl, 2-thiazolyl, 2-oxazolyl, 2-imidazolyl, isothiazolyl or triazolyl.

Furthermore, aryl and aralkyl can also be aromatic groups linked to a metal, for example in the form of transition metal metallocenes known perse, more especially

wherein R₃₂ is CH₂OH, CH₂ORι₆ or COORι₆.

C₃-C₆Heterocycloalkyl is an unsaturated or partially unsaturated ring system radical, for example an epoxide, oxetane, aziridine, pyrrolidyl, piperidyl, piperazinyl, imidazolinyl, pyrazolidinyl, pyrazolinyl, morpholinyl or another Cι-C₅heteroaryl hydrogenated one or more times.

5- to 8-membered rings are, for example, cyclopentyl, cyclohexyl, cycloheptyl or cyclooctyl, preferably cyclopentyl and especially cyclohexyl.

Special mention may be made of the following substituents as R23 to R₂6 and /or R₂₈: -CH₂-CH₂-OH, -CH2-O-CH3, -CH₂-0-(CH₂)7-CH3, -CH₂-CH₂-0-CH₂-CH₃, -CH₂-CH(OCH₃)₂, -CH₂-CH₂-CH(OCH₃)_2> -CH₂-C(OCH₃)₂-CH₃, -CH₂-CH₂-0-CH₂-CH₂-0-CH₃, -(CH₂)₃-OH, -(CH₂)₆-OH, -(CH₂)₇-OH, -(CH₂)₈-OH, -(CH₂)₉-OH, -(CH₂)ιo-OH, -(CH₂)n-OH, -(CH₂)₁₂-OH, -CH₂-Si(CH₃)3, -CH2-CH2-0-Si(CH₃)2-C(CH₃)3₎ -(CH2)3-0-Si(CH₃)2-C(CH₃)3_> -(CH₂)₄-0-Si(C₆H₅)₂-C(CH₃)₃, -CH₂-CH₂-CH(CH₃)-CH₂-CH₂-CH(OH)-C(CH₃)₂-OH, -(CH₂)₅-0-Si(CH(CH₃)₂)₃, -CH₂-CH(CH₃)-CH₂-OH, -CH₂-C(CH₃)2-CH₂-OH, -CH₂-C(CH₂-OH)₃, -CH₂-CH(OH)-CH_3j -CH₂-CH(OH)-CH₂-OH, -CH₂CH₂0^} , -⁽CH₂ ⁾ ₃0-T) , -CH₂CH₂- , __CH2c³H o CH₃ - ~^^ • ^~<»U* ■

and -(CH₂)₂CH=N-R₃₃ , wherein R₃₃ is Cι-C₆alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, C₃-C₆cycloalkyl, C₅-C₆cycloalkenyl, benzyl, phenyl, Ci-Csheteroaryl or C₂-C₅hetero- cycloalkyl, each unsubstituted or substituted by one or more identical or different radicals according to the definitions given hereinbefore, or a metal complex. When R33 is Ci-Cβalkyl, it may be uninterrupted or interrupted by 1 or 2 oxygen and/or silicon atom(s). Unsubstituted alkyl or alkyl substituted by one or two hydroxy radical(s) or by one metallocenyl or azo metal complex radical is especially advantageous, especially methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-butyl, isobutyl, tert-butyl, 3-pentyl, n-amyl, tert-amyl, neopentyl, 2,2-dimethyl-but-4-yl, 2,2,4-trimethyl-pent-5-yl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclo- propylmethyl, cyclobutylmethyl or cyclopentylmethyl.

R₂₈ is preferably NR₈Rg, OR™ or SR10.

Preference is given to compounds of formula (I) wherein R₃, R4 and/or R₅ are hydrogen and/or Zⁿ⁺ is K⁺ or especially a metal complex cation.

When R_Ϊ and R₂ and/or R₆ and R7 are, as appropriate, connected to one another by a direct bond or an -0-, -S- or -NR₈- bridge, they are preferably so connected to one another that a six-membered ring is formed.

Special preference is given to compounds of formula (I) wherein R₄ is hydrogen.

Preferred ammonium and phosphonium cations are tertiary or quaternary, with special preference being given to tertiary and quaternary ammonium cations having a double bond to the N⁺ atom (for example, pyridinium or N-alkylated pyridinium). For example, compounds of formula (I) can contain, as cations, xanthene substructures which are claimed or disclosed in US-5,851,621. Special preference is given to all xanthene cations which are claimed or disclosed in WO 03/098617 and WO 03/098618, to the teaching of which reference is expressly made here.

Special preference is given especially to cyanine cations and also cations according to formulae (I) to (IN) of WO 02/082438 (in each case without the

counter-ion X^"), cations of the basic structure according to

the left-hand portion of formula (I) of WO 03/007296, and cations according to formula (π) of WO 04/088649 (p = q = 0), wherein M^r is a transition metal of oxidation state HI (for example, Co³⁺).

Especially interesting metal complex cations have the formulae

as well as those according to WO 04/088649 of formulae

Preference is also given to metal complex cations of formula (π) wherein two ligands L| and/or L2 are bridged, for example by direct bonds or -0-, -S- or -N Re- bridges between any substituents. In that case, the bridged ligands Li and L₂ can be complexed either with the same metal cation or, where appropriate, with different metal cations, with oligomers being formed in the latter case. Bridges by way of N atoms of and/or L₂, either in the chromophore or on substituents, are especially advantageous. This oligomer formation is illustrated by the following example, without in any way being limited thereto, wherein X may be, purely by way of example, -CH₂-, -CH2-CH2-_. -CH₂-0-CH₂- or-CH₂-NH-CH₂- :

The preparation of such oligomers and similar oligomers is commonplace perse.

These preferences apply to each of the sub-structures contained in formula (I), in each case irrespective of the other sub-structures that may be present. These preferences may, of course, advantageously be combined.

Interesting compounds of formula (I) are especially those which are given in the examples hereinbelow.

Some of the compounds of formula (I) are known compounds. Those which are novel can be prepared analogously to the known compounds by methods known perse. Of special interest are the asymmetrical compounds of formula (I) and also tautomeric and mesomeric forms thereof, that is to say those wherein Ri is different to R7, R2 is different to R₆ and/or R₃ is different to R₅. Also of special interest are those compounds which, when obtained by concentrating solutions by evaporation, are not crystalline but amorphous.

The substrate, which functions as a support for the layers applied thereto, is advantageously semi-transparent (T> 10%) or, preferably, transparent (T> 90%). The support can have a thickness of from 0.01 to 10 mm, preferably from 0.1 to 5 mm.

The recording layer is applied preferably between the transparent substrate and the reflecting layer. The thickness of the recording layer is from 10 to 1000 nm, preferably from 30 to 300 nm, especially about 80 nm, for example from 60 to 120 nm. The absorption of the recording layer is typically from 0.1 to 1.0 at the absorption maximum. The layer thickness is very especially so selected in known manner in dependence upon the respective refractive indices in the non-written state and in the written state at the reading wavelength that, in the non-written state, constructive interference is obtained but, in the written state, destructive interference is obtained, or vice versa. The reflecting layer, the thickness of which can be from 10 to 150 nm, preferably has high reflectivity (R>45 %, especially R>60 %), coupled with low transparency (T< 10 %). In further embodiments, for example in media having a plurality of recording layers, the reflector layer may likewise be semi-transparent, that is to say may have comparatively high transparency (for example T> 50 %) and low reflectivity (for example R<30 %).

The uppermost layer, for example the reflective layer or the recording layer, depending upon the layer structure, is advantageously additionally provided with a protective layer, which can have a thickness of from 0.1 to 1000 μm, preferably from 0.1 to 50 μm and especially from 0.5 to 15 μm. Such a protective layer can, if desired, serve also as adhesion promoter for a second substrate layer applied thereto, which is preferably from 0.1 to 5 mm thick and consists of the same material as the support substrate.

The reflectivity of the entire recording medium is preferably at least 15 %, especially at least 40 %.

The main features of the recording layer according to the invention are the very high initial reflectivity in the said wavelength range of the laser diodes, which reflectivity can be modified with high sensitivity; the high refractive index; the very especially steep edge, on the bathochromic side, of the absorption band in the solid state (even in the case of mixtures of a plurality of compounds according to the invention); the good uniformity of the script width at different pulse durations; the good light-stability; and the good solubility in polar solvents.

The recording medium according to the invention can neither be written nor be read using the infrared laser diodes of conventional CD apparatus in accordance with the requirements of the Orange Book Standard. As a result, the risk of damage in the event of a mistaken attempt at writing in an apparatus not capable of high resolution is, advantageously, to a large extent eliminated. The use of dyes of formula (I) results in advantageously homogeneous, amorphous and low-scatter recording layers having a high refractive index, and the absorption edge is surprisingly especially steep even in the solid phase. Further advantages are high light-stability in daylight and under laser radiation of low power density with, at the same time, high sensitivity under laser radiation of high power density, uniform script width, high contrast, and also good thermal stability and storage stability.

At a relatively high recording speed, the results obtained are surprisingly better than with previously known recording media. The marks are more precisely defined relative to the surrounding medium and thermally induced deformations do not occur. The error rate (BLER) and the statistical variations in mark length (jitter) are also low both at normal and at relatively high recording speed, so that error-free recording and playback can be achieved over a large speed range. Even at a high recording speed there are scarcely any rejects, and written media are not slowed down by error correction during reading. The advantages are obtained in the entire range from 630 to 690 nm (preferably from 650 to 680 nm), but are especially pronounced at from 650 to 670 nm, more especially at 658± 5 nm.

Suitable substrates are, for example, glass, minerals, ceramics and thermosetting or thermoplastic plastics. Preferred supports are glass and homo- or co-polymeric plastics. Suitable plastics are, for example, thermoplastic polycarbonates, polyamides, polyesters, polyacrylates and polymethacrylates, polyurethanes, polyolefins, polyvinyl chloride, polyvinylidene fluoride, polyimides, thermosetting polyesters and epoxy resins. The substrate can be in pure form or may also comprise customary additives, for example UV absorbers or dyes, as proposed, for example, in JP-A-04/167 239 as light-stabilisers for the recording layer. In the latter case it may be advantageous for the dye added to the support substrate to have an absorption maximum hypsochromically shifted relative to the dye of the recording layer by at least 10 nm, preferably by at least 20 nm.

The substrate is advantageously transparent over at least a portion of the range from 630 to 690 nm (preferably as indicated above) so that it is permeable to at least 90 % of the incident light of the writing or readout wavelength. The substrate has preferably on the coating side a spiral guide groove having a groove depth of from 50 to 500 nm, a groove width of from 0.2 to 0.8 μm and a track spacing between 2 turns of from 0.4 to 1.6 μm, especially having a groove depth of from 100 to 200 nm, a groove width of 0.3 μm and a spacing between 2 turns of from 0.6 to 0.8 μm. The recording layer is advantageously of different thickness inside and outside the groove, depending on the depth of the groove; usually the thickness of the recording layer inside the groove is about from 2 to 20 times greater than outside, typically 5 to 10 times greater inside the groove than outside. The recording layer can also be present solely in the groove.

The storage media according to the invention are therefore especially advantageous for the optical recording of DVD-R or DVD + R media having the currently customary smallest pit length of 0.4 μm and track spacing of 0.74 μm. The higher recording speed compared to known media allows synchronous or even, for special effects, accelerated recording of video sequences with excellent image quality.

The recording layer may also comprise, instead of a single compound of formula (I), a mixture of such compounds with, for example, 2, 3, 4, 5, 6, 7 or 8 dioxaborins according to the invention. The use of mixtures, for example mixtures of isomers or homologues but also mixtures of differing structures, can often result in an increase in solubility and/or an improvement in amorphousness. If desired, mixtures of ion-pair compounds may have different anions, different cations, or both different anions and different cations.

For a further increase in stability it is also possible, if desired, to add known stabilisers in customary amounts, such as, for example, a nickel dithiolate described in JP-A-04/025493 as light-stabiliser.

The recording layer comprises a compound of formula (I) or a mixture of such compounds advantageously in an amount sufficient to have a substantial influence on the refractive index, for example in an amount of at least 10 % by weight, preferably from at least 30 to 70 % by weight, especially from at least 40 to 60 % by weight. The recording layer may especially advantageously comprise a compound of formula (I) or a mixture of a plurality of such compounds as the main constituent or consist exclusively or substantially of one or more compounds of formula (I). Further customary constituents are possible, for example other chromophores (for example those having an absorption maximum at from 300 to 1000 nm), UV absorbers and/or other stabilisers, ¹0₂-, triplet- or luminescence-quenchers, melting-point reducers, decomposition accelerators or any other additives that have already been described in optical recording media, for example film-formers.

When the recording layer comprises further chromophores, such chromophores may in principle be any dyes that can be decomposed or modified by the laser radiation during the recording, or they may be inert towards the laser radiation. When the further chromophores are decomposed or modified by the laser radiation, this can take place directly by absorption of the laser radiation or can be induced indirectly by the decomposition of the compounds of formula (I) according to the invention, for example thermally.

By their nature, colorant cations, further chromophores or coloured stabilisers can influence the optical properties of the recording layer. Preference is therefore given to the use of colorant cations, further chromophores or coloured stabilisers whose optical properties conform as far as possible or are as different as possible to those of the compounds of formula (I) or else the amount of further chromophores is kept small. If the amount of further colorant cation is to be kept small, this is preferably achieved by replacing a portion of the colorant cation by an equimolar amount of a phosphonium or, especially, ammonium cation having no appreciable absorption at from 630 to 690 nm.

When further chromophores having optical properties that conform as far as possible to those of the compounds of formula (I) are used, this should preferably be the case in the range of the longest-wavelength absorption flank. Preferably the wavelengths of the inversion points of the further chromophores and of the compounds of formula (I) are a maximum of 40 nm, especially a maximum of 20 nm, more especially a maximum of 10 nm, apart. In that case the further chromophores and the compounds of formula (I) should exhibit similar behaviour in respect of the laser radiation so that it is possible to use as further chromophores known recording agents the action of which is synergistically increased or enhanced by the compounds of formula (I).

When further chromophores or coloured stabilisers having optical properties that are as different as possible from those of compounds of formula (I) are used, they advantageously have an absorption maximum that is hypsochromically or bathochromically shifted relative to the dye of formula (I). In that case the absorption maxima are preferably at least 50 nm, especially at least 100 nm, apart. Examples thereof are UV absorbers that are hypsochromic to the dye of formula (I), or coloured stabilisers that are bathochromic to the dye of formula (I) and have absorption maxima lying, for example, in the NIR or IR range. Other dyes can also be added for the purpose of colour-coded identification, colour-masking ("diamond dyes") or enhancing the aesthetic appearance of the recording layer. In all those cases, the further chromophores or coloured stabilisers should exhibit behaviour that is preferably as inert as possible in respect of light and laser radiation.

When another dye is added in order to modify the optical properties of the compounds of formula (I), the amount of that other dye depends on the optical properties to be achieved. The person skilled in the art will have no difficulty in varying the ratio of additional dye to the compound of formula (I) until he obtains the result he desires.

When chromophores or coloured stabilisers are used for other purposes, the amount thereof should preferably be so low that their contribution to the total absorption of the recording layer in the range from 640 to 680 nm is at most 20 %, preferably at most 10 % at 658± 5 nm. In such a case, the amount of additional dye or stabiliser is advantageously at most 50 % by weight, preferably at most 10 % by weight, based on the recording layer. Further chromophores that can be used in the recording layer in addition to the compounds of formula (I) are, for example, cyanines and cyanine metal complexes (US-A-5,958,650), styryl compounds (US-A-6, 103,331), oxonol dyes (EP 833 314), azo dyes and azo metal complexes (JP-A-11/028 865), phthalocyanines (EP 232427, EP 337209, EP 373643, EP 463550, EP 492508, EP 509423, EP 511 590, EP 513370, EP 514799, EP 518213, EP 519419, EP 519423, EP 575816, EP 600427, EP 676751, EP 712904, WO 98/14520, WO 00/09522, WO 02/083796), porphyrins and azaporphyrins (EP 822546, US 5,998,093), dipyrromethene dyes and metal chelate compounds thereof (EP 822544, EP 903733), xanthene dyes and metal complex salts thereof (US 5,851 ,621) or quadratic acid compounds (EP 568877), also oxazines, dioxazines, diazastyryls, formazans, anthraquinones or phenothiazines; this list is on no account exhaustive and the person skilled in the art will interpret the list as including further known dyes.

Especially preferred additional chromophores are, especially, cyanines, xanthenes and pyrromethenes and also squarylium salts and neutral metal azo complexes. Preference is given among the cyanines to benzoindocarbocyanines, among the xanthenes to, especially, rhodamines, among the neutral metal azo complexes to, especially, those that are heterocyclic, in particular those corresponding to formula (π) wherein m = 0. Additional chromophores, which may or may not be charged, are then used especially in the form of salts with metal complex counter- ions.

However, it is very especially preferable not to add any additional chromophore, unless it is a coloured stabiliser.

Stabilisers or fluorescence-quenchers are, for example, metal complexes of N- or S-containing enolates, phenolates, bisphenolates, thiolates or bisthiolates or of azo, azomethine or formazan dyes, such as ^®lrgalan Bordeaux EL (Ciba Spezialitatenchemie AG), ^®Cibafast N3 (Ciba Spezialitatenchemie AG) or similar compounds, hindered phenols and derivatives thereof (optionally also as anions X^"), such as ^®Cibafast AO (Ciba Spezialitatenchemie AG), 7,7',8,8^,-tetracyano- quinodimethane (TCNQ) and compounds thereof (optionally as an anion of the charge transfer complex), hydroxyphenyl-triazoles or-triazines or other UV absorbers, such as ^®Cibafast W or ^®Cibafast P (Ciba Spezialitatenchemie AG) or hindered amines (TEMPO or HALS, also as nitroxides or NOR-HALS, optionally also as anions X^").

Many such structures are known, some of them also in connection with optical recording media, for example from US-5,219,707, JP-A-06/199045, JP-A-07/76169 or JP-A-07/262604. They may be, for example, salts of the metal complex anions disclosed above with any desired cations, for example the cations disclosed above.

In addition, there come into consideration neutral metal complexes, for example those metal complexes which are disclosed in EP 0 822 544, EP 0 844 243, EP 0 903 733, EP 0 996 123, EP 1 056 078, EP 1 130 584 or US 6,162,520, such as, for example,

or other known metal complexes illustrated, for example, by the compounds of formulae

The person skilled in the art will know from other optical information media, or will easily identify, which additives in which concentration are particularly well suited to which purpose. Suitable concentrations of additives are, for example, from 0.001 to 1000 % by weight, preferably from 1 to 50 % by weight, based on the recording medium of formula (I).

The recording medium according to the invention, in addition to comprising the compounds of formula (I), may additionally comprise salts, for example ammonium chloride, pentadecylammonium chloride, cobalt(π) chloride, sodium chloride, sodium sulfate, sodium methyl sulfonate or sodium methyl sulfate, the ions of which may originate, for example, from the components used. The additional salts, if present, are present preferably in amounts of up to 20 % by weight, based on the total weight of the recording layer.

Reflecting materials suitable for the reflective layer include especially metals, which provide good reflection of the laser radiation used for recording and playback, for example the metals of Main Groups III, IV and V and of the Sub-Groups of the Periodic Table of the Elements. Al, In, Sn, Pb, Sb, Bi, Cu, Ag, Au, Zn, Cd, Hg, Sc, Y, La, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and alloys thereof are especially suitable. Special preference is given to a reflective layer of aluminium, silver, copper, gold or an alloy thereof, on account of their high reflectivity and ease of production.

Materials suitable for the protective layer include chiefly plastics, which are applied in a thin layer to the support or to the uppermost layer either directly or with the aid of adhesive layers. It is advantageous to select mechanically and thermally stable plastics having good surface properties, which may be modified further, for example written on. The plastics may be thermosetting plastics or thermoplastic plastics. Preference is given to radiation-curable (for example by means of UV radiation) protective layers, which are particularly simple and economical to produce. A wide variety of radiation-curable materials are known. Examples of radiation-curable monomers and oligomers are acrylates and methacrylates of diols, triols and tetrols, polyimides of aromatic tetracarboxylic acids and aromatic diamines having Cι-C₄alkyl groups in at least two positions ortho to the amino groups, and oligomers with dialkylmaleimidyl groups, e.g. dimethylmaleimidyl groups.

The recording media according to the invention may also have additional layers, for example interference layers. It is also possible to construct recording media having a plurality of (for example, two, three, four or five) recording layers. The structure and use of such materials are known to the person skilled in the art. Where present, interference layers are preferably arranged between the recording layer and the reflecting layer and/or between the recording layer and the substrate and consist of a dielectric material, for example, as described in EP 353 393, of Ti0₂, Si₃N , ZnS or silicone resins.

The recording media according to the invention can be produced by processes known per se, it being possible for various methods of coating to be employed depending upon the materials used and their mode of operation.

Suitable coating methods are, for example, immersion, pouring, brush-coating, blade-application and spin-coating, as well as vapour-deposition methods carried out under a high vacuum. When, for example, pouring methods are used, solutions or suspensions in organic solvents are generally employed. When solvents are employed, care should be taken that the supports used are insensitive to those solvents. Suitable coating methods and solvents are described, for example, in EP 401 791.

The recording layer is applied preferably by the application of a dye solution or suspension by spin-coating, solvents that have proved satisfactory being especially alcohols, e.g. 2-methoxyethanol, n-propanol, isopropanol, isobutanol, n-butanol, 1- methoxy-2-propanol, amyl alcohol or 3-methyl-1-butanol, or preferably fluorinated alcohols, for example 2,2,2-trifluoroethanol or 2,2,3,3-tetrafluoro-1-propanol, and mixtures thereof. Of course it is also possible to use other solvents or solvent mixtures, for example those solvent mixtures described in EP 511 598 and

EP 833316. Ethers (dibutyl ether), ketones (2,6-dimethyl-4-heptanone, 5-methyl-2- hexanone), esters (for example, the lactic acid esters known from WO 03/098617) or saturated or unsaturated hydrocarbons (toluene, xylene or, as disclosed in WO 03/034146, tert-butyl-benzene and similar compounds) can also be used, where appropriate also in the form of mixtures (e.g. dibutyl ether/2,6-dimethyl-4- heptanone) or as components of mixtures.

The person skilled in the art of spin-coating will generally try out, as a matter of routine, all solvents known to him and also binary and ternary mixtures thereof in order to find the solvents or solvent mixtures that result in a good-quality and, at the same time, cost-effective recording layer comprising the solid components of his choice. In the course of such optimisation it is also possible to use known methods of process technology as a result of which the number of experiments to be carried out can be minimised. The invention therefore relates also to a method of producing an optical recording medium, wherein a solution of a compound of formula (I) in an organic solvent is applied to a substrate having depressions. The application is preferably carried out by spin-coating.

The application of the metallic reflective layer is preferably effected by sputtering, vapour-deposition in vacua or by chemical vapour deposition (CVD). The sputtering technique is especially preferred for the application of the metallic reflective layer on account of the high degree of adhesion to the support. Such techniques are known and are described in specialist literature (e.g. J.L. Vossen and W. Kern, "Thin Film Processes", Academic Press, 1978).

The structure of the recording medium according to the invention is governed primarily by the readout method; known function principles include the measurement of the change in transmission or, preferably, reflection, but it is also known, for example, to measure the fluorescence instead of the transmission or reflection.

When the recording material is structured for a change in reflection, the following structures, for example, may be used: transparent support / recording layer (optionally multilayered) / reflective layer and, if expedient, protective layer (not necessarily transparent); or support (not necessarily transparent) / reflective layer / recording layer and, if expedient, transparent protective layer. In the first case, the light is incident from the support side, whereas in the latter case the radiation is incident from the recording layer side or, where applicable, from the protective layer side. In both cases the light detector is located on the same side as the light source. The first-mentioned structure of the recording material to be used in accordance with the invention is generally preferred. When the recording material is structured for a change in light transmission, the following different structure, for example, comes into consideration: transparent support / recording layer (optionally multilayered) and, if expedient, transparent protective layer. The light for recording and for readout can be incident either from the support side or from the recording layer side or, where applicable, from the protective layer side, the light detector in this case always being located on the opposite side.

Suitable lasers are those having a wavelength of from 630 to 690 nm, for example commercially available lasers having a wavelength of 633, 635, 647, 650, 670 or 680 nm, especially semi-conductor lasers, such as GaAsAI, InGaAIP or GaAs laser diodes having a wavelength especially of about 635, 650 or 658 nm. The recording is generally effected, for example, point for point in a manner known per se, by modulating the laser in accordance with the mark lengths and focussing its radiation onto the recording layer. It is known from the specialist literature that other methods are currently being developed which it will also be possible to use.

The method according to the invention allows the storage of information with great reliability and stability, distinguished by very good mechanical and thermal stability and by high light-stability and by sharp boundary zones of the pits. Special advantages include the high contrast, the low jitter and the surprisingly high signal/noise ratio, so that problem-free readout is achieved. The high storage capacity is especially advantageous in the video and multimedia field.

Readout of information is carried out according to methods known per se by registering the change in absorption or in reflection using laser radiation, for example as described in "CD-Player und R-DAT Recorder" (Claus Biaesch- Wiepke, Vogel Buchverlag, Wϋrzburg 1992).

The information-containing medium according to the invention is especially an optical information material of the WORM type. It can be used, for example, as a playable DVD (digital versatile disk), as storage material for a computer or as an identification and security card or for the production of diffractive optical elements, for example holograms.

The invention accordingly relates also to a method for the optical recording, storage or playback of information, wherein a recording medium according to the invention is used. The recording and/or the playback advantageously take place in a wavelength range of from 630 to 690 nm, preferably as indicated hereinbefore.

The invention relates also to the compounds used in accordance with the invention, insofar as they are novel. The invention accordingly relates also to a compound of formula (I), or a tautomeric or mesomeric form thereof, wherein Z^π+ is phosphonium, metal complex or alkali metal cation.

The Examples that follow illustrate the invention in greater detail (unless otherwise indicated, all percentages are by weight):

Example 1 : 16.22 g of 4-hydroxycoumarin are dissolved in 00 ml of pyridine with 1 drop of piperidine as catalyst. 11.4 ml of acetyl chloride are slowly added dropwise to the yellow solution, cooling with an ice bath, the colour of the solution slowly changing to orange-red and a product precipitating out. After the addition is complete, heating is carried out to 37°C and that temperature is maintained for a further 19 hours. The suspension is then stirred into 300 g of ice, and hydrochloric acid (cone.) is added until all the product has precipitated out. The precipitate is filtered off, washed with water and dried for 18 hours at 80°C / 10⁴ Pa. 29.55 g of a light-brown powder are obtained, which is mixed with 54.6 ml of boron trifluoride etherate. After heating for 1 hour at reflux and cooling, the precipitate is filtered off under suction, washed with ether and dried for 18 hours at 80°C/10⁴ Pa. 34.3 g of a brown solid are obtained, which is stirred into a mixture of 11.6 ml of triethyl orthoformate, 19.0 ml of triethylamine and 340 ml of acetic anhydride. The reaction mixture is heated at 60°C for 30 minutes. After cooling to 23°C and after a further 90 minutes, the precipitate is filtered off under suction and washed with hexane. The solid is dried for 18 hours at 80°C/10⁴ Pa. There are obtained 10.5 g of a dark solid of formula

UV/VIS (DMF): λ_max=576 nm; ε= 207000.

Examples 2-7: The procedure is analogous to Example 1 although, instead of triethylamine, equimolar amounts of other amines are used. The corresponding ammonium salts having the following UV/VIS spectra in dimethylformamide are obtained:

Example 8: 8.11 g of benzoylacetone are mixed with 18.85 ml of boron trifluoride etherate in an ice bath and stirred for a further 40 minutes with ice cooling. The colourless precipitate is filtered off under suction, washed with diethyl ether and dried for 18 hours at 80°C/10⁴ Pa. The colourless powder is further processed in analogous manner to Example 1 , a coloured product having the following main component being obtained:

Example 9: In analogous manner to the previous Examples (but adding 120 ml of diethyl ether in the final step for better stirring), a light-yellowish product having the following main component is obtained:

Example 10: 34.2 g of dehydroacetic acid are stirred into 100 ml of acetic anhydride at 23°C. 104 ml of boron trifluoride etherate are added dropwise to the beige suspension over a period of 30 minutes. The mixture is then heated at 85°C for YA hours, a yellow suspension being produced. After cooling to 25°C, the suspension is filtered, followed by washing with 200 ml of diethyl ether and drying for 18 hours at 60°C / 10⁴ Pa. There is obtained a light-yellow product of formula:

17.0 g of this light-yellow product are stirred in 150 ml of acetic anhydride, 15.5 g of diphenylformamidine are added and the mixture is heated at 65°C for 2^ΛA hours. The yellow suspension formed is filtered, followed by washing with 100 ml of diethyl ether and drying of the filter residue for 18 hours at 60°C / 10⁴ Pa. There is obtained a yellow product of formula (cis isomerism of the enamine not confirmed):

2.55 g of this yellow product, together with 1.7 g of the intermediate product of Example 8 (benzoylacetone reacted with boron trifluoride etherate), are stirred in 20 ml of dichloromethane. 2 ml of acetic anhydride are then added and the mixture is then heated to reflux (40°C). 2.2 ml of triethylamine are then added, whereupon the mixture immediately turns red. After refluxing for 2 hours, the mixture is allowed to cool to 20°C. The precipitate that separates out is filtered off; 50 ml of ether are added to the filtrate and the newly formed precipitate is filtered off. Both residues are combined, washed with 50 ml of diethyl ether and dried for 18 hours at 60°C/10⁴ Pa. There is obtained a blue product of formula:

UVΛ/IS (DMF): λ_max = 570 nm; ε= 120500.

Example 11: The dark-blue product of the following structure is obtained analogously to Example 10:

UVΛ IS (DMF): λ_max = 589 nm; ε = 206700.

Example 12: The dark-blue product of the following structure is obtained analogously to Example 11 :

UVΛ IS (DMF): λ_max=589 nm; ε = 205300.

Example 13: The dark-blue product of the following structure is obtained analogously to the previous Examples:

UVΛ IS (DMF): λ_max=587 nm; ε= 147000.

Example 14: The dark-blue product of the following structure is obtained analogously to the previous Examples:

UVΛ IS (DMF): λ_max=584 nm; ε = 166000.

Example 15: The dark-blue product of the following structure is obtained analogously to the previous Examples:

UVΛ IS (DMF): λ_max = 558 nm; ε = 197600.

Example 16: The dark-blue product of the following structure is obtained analogously to the previous Examples:

UVΛ IS (DMF): λ_max = 574 nm; ε= 167600. Example 17: The dark-blue product of the following structure is obtained analogously to the previous Examples:

UVΛ IS (DMF): λ_max=557 nm; ε= 161 300.

Example 18: The dark-blue product of the following structure is obtained analogously to the previous Examples:

UVΛ IS (DMF): λ_max=554 nm; ε = 179500.

Example 19: The dark-blue product of the following structure is obtained analogously to the previous Examples:

UVΛ IS (DMF): λ_max=573 nm; ε= 194700.

Example 20: 1.0 % by weight of the compound according to Example 1 is dissolved in 2-butanone and applied to a planar glass substrate by spin-coating.

Example 21: 1.0 % by weight of very finely ground compound according to

Example 7 is suspended in 2,2,3,3-tetrafluoro-1-propanol and applied to a planar glass substrate by spin-coating. Examples 22-23: The optical parameters of the solid layers according to Examples 20 and 21 are determined by means of an ETA spectral reflectance and transmittance tester (Steag ETA-Optik GmbH) at 658 nm:

Examples 24-38: The solids according to Examples 2 to 6 and 10 to 19 are coated onto glass analogously to Examples 20 and 21 , and their optical parameters are measured in accordance with Examples 22 and 23.

Example 39: A solution of 1 g of the compound of formula

in 90 g of 1-methoxy-2-propanol and 3 g of 2-butanone is filtered through a Teflon filter having a pore size of 0.2 μm and applied to the surface of a 0.6 mm thick, grooved polycarbonate disc (groove depth: 170 nm, groove width 330 nm, track pitch 0.74 μm) having a diameter of 120 mm by the spin-coating method at 1800 rev/min. The excess solution is spun off by increasing the speed of rotation. When the solvent has evaporated, the dye remains behind in the form of a uniform amorphous solid layer. Drying is carried out in a circulating air oven at 70°C (20 minutes). The optical values are good (n₆₅₈=2.4 / k₆₅₈ = 0.05). In a vacuum- coating apparatus (Twister, Balzers Unaxis), a 120 nm thick silver layer is then applied to the recording layer by atomisation. A protective layer of a UV-curable photopolymer (™650-020, DSM) is then applied by spin-coating. The recording support has, at 658 nm, a reflectivity within the specifications of DVD-R and DVD+R. On a commercial testing device (DDU-1000, Pulstec Japan), marks are written into the active layer at a speed of 3.5 m/s and a power of 7.5 mW using a laser diode of wavelength 658 nm. Then, on a commercial testing device (DVD Pro, Audio Dev), the dynamic parameters are established. The medium is distinguished especially by high sensitivity.

Example 40: The procedure is analogous to Example 39 but there is used the compound of formula

Examples 41-57: Analogously to Examples 39 and 40, optical recording media are produced using the solids according to Examples 1 to 7 and 10 to 19, onto which marks are written using a laser diode of wavelength 658 nm.

Examples 58-94: Analogously to Examples 1 to 57, the compounds of the following formulae are prepared and used in recording materials:

Ex. Structure A.IT13X [nm]

(solid 58 590 layer)

(solid 59 586 layer)

The compound of Example 66, in the form of a solid layer, has the following optical values: n=2.11; k=0.02. The compound of Example 69, in the form of a solid layer, has the following optical values: n = 1.82; k = 0.01. The compound of Example 74, in the form of a solid layer, has the following optical values: n=2.37; k=0.02. The compound of Example 85, in the form of a solid layer, has the following optical values: n = 1.84; k=0.03.

Claims

What is claimed is:

1. An optical recording medium comprising a substrate, a reflecting layer and a recording layer, wherein the recording layer comprises a compound of formula

or a mesomeric or tautomeric form thereof, wherein

Zⁿ⁺ is a proton or an n-valent ammonium, phosphonium, metal complex or alkali metal cation and n is a number 1 , 2 or 3; it being possible, where appropriate, for Zⁿ⁺ to be linked to Ri, R₂, R3 or R4 by a direct bond or by way of an O, S or NR₈ bridge;

Ri and R₇ are, each independently of the other, CN; CONR₈Rg; or Cι-C₆alkyl, C2-C6alkenyl, C₂-C6alkynyl, C₃-C₆cycloalkyl, C₃-C₆cycloalkenyl or C₃-Cβhetero- cycloalkyl each unsubstituted or substituted one or more times by halogen, OR₁₀, SR10, NR₈R₉, OSiRιιRι₂Rι₃, CORn, CRιιOR₁₂ORι₃, N0₂, CN, CONR₈R₉, COORι₃, SO2R1_3. S0₂NR₈R₉, S0₃R_i3 or by PO(ORι₂)(OR₁₃); or phenyl, benzyl, phenethyl, styryl or Ci-Csheteroaryl each unsubstituted or substituted one or more times by Rιs, halogen, OR10, SR10, NR₈R₉, OSiRnRι₂Rι₃, CORn, CR11OR12OR13, N0₂, CN, CONRsRg, COOR13, S0₂Ri3, S0₂NR₈R₉, SO3R13, PO(ORι₂)(ORι₃), NR₈S0₂Rι₃, SiRiiRi₂R_i3 or by SiORnORι₂ORι₃;

R₂ and R₆ are, each independently of the other, hydrogen, halogen, N0₂, CN, CONRsRg; or C C₆alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, C₃-C₆cycloalkyl,

C₃-C6cycloalkenyl or C₃-C₆heterocycloalkyl each unsubstituted or substituted one or more times by halogen, OR10, SR10, NR₈Rg, OSiRnRι₂Ri3, CORn, CRnORi2θRι₃, N0_2l CN, CONR₈R₉, COOR₁₃, S0₂Rι₃, S0₂NR₈R₉, SO3R1₃ or by PO(ORι₂)(ORι₃); or phenyl, benzyl, phenethyl, styryl, CrC₅heteroaryl, phenyl-N=N- or C₂-C₅heteroaryl-N=N- each unsubstituted or substituted one or more times by Ri₃, halogen, OR10, SR10, NR₈R₉, OSiRnRι₂Rι₃, CORn, CRnORι₂ORι₃, N0₂, CN, CONRsRg, COORi3, SO2R1₃, S0₂NR₈R₉, S0₃Rιs, PO(ORi₂)(OR₁₃), NR₈S0₂Rι₃, SiRnR₁₂Rι₃ or by SiORnORι₂ORι₃;

R₃, R4 and R₅ are, each independently of the others, hydrogen; or CrC_Θalkyl, C2-C6alkenyl, C₂-C6alkynyl, C₃-C₆cycloalkyl, C₃-C6cycloalkenyl or CjrCβhetero- cycloalkyl each unsubstituted or substituted one or more times by halogen, OR10, SRιo, NR₈Rg, OSiRιιRι₂Rι₃, CORn, CRnORι₂ORι₃, N0₂, CN, CONR₈R₉, COOR13, S0₂Rι₃, S0₂NR₈R₉, SO3R13 or by PO(ORι₂)(ORι₃); or phenyl, benzyl, phenethyl, styryl or Ci-Csheteroaryl each unsubstituted or substituted one or more times by Ri₃, halogen, OR10, SRι₀, NR₈R₉, OSiRnRι₂Rι₃, CORn, CRnOR₁₂ORι₃, N0₂, CN, CONRsRg, COORis, SO2R13, S0₂NR₈R₉, SO3R13, PO(ORι₂)(ORι₃), NR₈S0₂Rι₃, SiR Ri2Ri3 or by SiORnOR₁₂ORi₃;

R₈ and Rg are, each independently of the other, R₁₀, [C2-C₃alkylene-0-]k-Rι₄ or [C₂-C₃alkylene-NRi₀-]k-Ri4, k being an integer from 1 to 3; or NR₈R₉ is a five- or six- membered heterocycle optionally containing a further nitrogen or oxygen atom, which heterocycle may be substituted one or more times by Cι-C₆alkyl;

each R10, independently of any other R1₀, is Rn, CORn, COORι₃, CONR11R12, CN or S0₂Rι₃;

R11 and R12 are, each independently of the other, hydrogen or R ₃; or NR1 R12 is a five- or six-membered heterocycle optionally containing a further nitrogen or oxygen atom, which heterocycle may be substituted one or more times by Cι-C₆alkyl;

each R₁₃, independently of any other Rι_3l is Cι-C₆alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, C₃-C₆cycloalkyl, C₃-Cecycloalkenyl or C₃-C₆heterocycloalkyl each unsubstituted or substituted one or more times by halogen, OR , SRu, NR₁₄Rι₅, NRι₄CORι_5> NRι₄COOR₁₆, NHCONR₁ R s, NR₁₆CONRι₄Ri5, OSiRι₄Rι₆Rι₇, COR , CRι₄ORι₆OR₁₇, N0_2l CN, COORι₆, CONR₁₄Rι₅, SO2NR14R15, S0₂Rι₆ or by S0₃Rι₆; or benzyl, phenyl or C₂-C₅heteroaryl each unsubstituted or substituted one or more times by halogen, Rι₆, ORι₄, SR₁ , NR14R15. NRι₄COR₁₅, NRι₄COORι₆,

NHCONRι₄Ri5, NRι₆CONRι₄Ri5,

COR14, CR₁₄OR₁₆ORi7, N0₂, CN, COOR16, CONR14R15, S0₂NR₁₄Ri₅, S0₂Ri6, S0₃Rie, PO(ORι₆)(ORι₇), SiRι₄Rι₆R .7 or by SiOR ORiβOR ?; it being possible, in addition, for R ₂ and R1₃ to be so linked together by a linking member selected from the group consisting of single and double direct bonds and O, S and NR14 bridges that a 5-, 6-, 7- or 8-membered ring is formed;

R₁₄ and R₁₅ are, each independently of the other, hydrogen, Rι₆ or R17; or NR14R15 is a five- or six-membered heterocycle optionally containing a further nitrogen or oxygen atom, which heterocycle may be substituted one or more times by Cι-C₄alkyl;

R₁₆ and R₁₇ are, each independently of the other, CrC₆alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, C₃-Cβcycloalkyl, C₃-C₆cycloalkenyl, C₃-C₆heterocycloalkyl, benzyl, phenyl or C₂-C₅heteroaryl, preferably methyl, ethyl, vinyl or ethynyl, each substituted one or more times by halogen, OR₁₈, SRι₈, NRι₈Rιg, CORι₈, N0₂, CN or by COORι₈; it being possible, in addition, for Rι₆ and R17 to be so linked together by a linking member selected from the group consisting of single and double direct bonds and O, S, NH and N(Cι-C alkyl) bridges that a 5-, 6-, 7- or 8-membered ring is formed; and

Rι₈ and Rig are, each independently of the other, hydrogen, methyl or ethyl.

2. An optical recording medium according to claim 1 , wherein R₃, R4 and/or R₅ are hydrogen and/or Zⁿ⁺ is K⁺ or a metal complex cation.

3. An optical recording medium according to either claim 1 or claim 2, wherein Zⁿ⁺ is an n-valent ammonium, phosphonium or metal complex cation of formula N⁺R₈R₉RiiRi₂, P⁺R₈R₉RnRi₂,

or a dimer of two identical or different radicals thereof, wherein

^25

M is a metal and Li and L₂ are, each independently of the other, ligands; Qi is O, S, NR₁₀ or Q₄=Q7, Q2 is CR₂₅ or N, Q₃ is O, S, NRn or Q₂=Q₇, Q₄ is CR₂₄ or N, Q₅ is CR₂₃ or N, Q₆ is O, S, NRn or Q₅=Q7, and Q₇ is CR₂₆ or N; Q₇ in Q₄=Q₇,

Q₅=Q₇ or Q₂=Q7 preferably being in the β-position relative to N of G. :| ; V-

R₂₀ and R₂ι are, each independently of the other, R1₀, OR₁₃ or NRnRι₂;

R₂₃, R₂₄, R₂₅ and R₂₆ are, each independently of the others, H, halogen, OR10, SR10, NRsRg, OSiR Rι₂Ri3, CORn, CRnORι₂ORι₃, N0₂, CN, CONR₈R₉, COOR13, S0₂Ri₃, S0₂NR₈R₉, S0₃Rι₃; or Cι-C_ealkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, C₃-C₆cycloalkyl or Cs-Cβcycloalkenyl each unsubstituted or substituted one or more times by halogen, OR14 or by CN; and R₂₇ is phenyl, benzyl, phenethyl, styryl or Ci-Csheteroaryl each unsubstituted or substituted one or more times by R13, halogen, OR10, SR10, NR₈R₉, OS1R11R12R13. CORn, CR11OR12OR13, N0₂, CN, CONR₈R₉, COORι₃, S0₂Rι₃, S0₂NR₈R₉, SO3R13, PO(ORι₂)(OR₁₃), NR₈S0₂R₁₃, SiRnRι₂Ri3 or by SiORnORι₂ORι₃.

4. An optical recording medium according to claim 1 , 2 or 3, wherein Zⁿ⁺ is Co ⁺, Co³⁺, Cu⁺, Cu²⁺, Zn ⁺, Cr Ni²⁺, Fe²⁺, Fe³⁺, Al³⁺, Ce²⁺, Ce³⁺, Mn²⁺, Mn³⁺ or V³⁺, preferably Co³⁺, Cr⁵*, Fe³⁺ Ce³⁺ or Mn³⁺.

5. An optical recording medium according to claim 4, wherein Zⁿ⁺ is an n-valent metal complex cation of formula [L M-L₂]ⁿ⁺ (π), wherein M is Co³⁺, Cr³⁺, Fe³⁺ Ce³⁺ or Mn³⁺.

6. A method of optically recording, storing or playing back information, wherein a recording medium according to claim 1, 2, 3, 3 or 5 is used.

7. A method according to claim 6, wherein the recording and/or playback are carried out in the wavelength range from 630 to 690 nm, preferably from 640 to 680 nm, especially from 650 to 670 nm, more especially at 658 ±5 nm .

8. A method of producing an optical recording medium, wherein a solution of a compound of formula (I) according to claim 1 , 2, 3, 4 or 5 in an organic solvent is applied to a substrate having depressions.

9. A compound of formula (I) according to claim 1 , 2, 3, 4 or 5 or a tautomeric or mesomeric form thereof, wherein Zⁿ⁺ is a phosphonium, metal complex or alkali metal cation.

10. A compound of formula (I) according to claim 1 , 2, 3, 4 or 5 or a tautomeric or mesomeric form thereof, wherein Ri is different to R7, R₂ is different to R₆ and/or R₃ is different to R₅.