WO2007093506A2 - O,p-dialkoxy-phenyl-azometal complex dyes and their use in optical layers for optical data recording - Google Patents

Abstract

The present invention relates to o,p-dialkoxy-phenyl-azometal complex dyes and their use in optical layers for optical data recording, preferably for optical data recording using a laser with a wavelength up to 450 nm. The invention further relates to a write once read many (WORM) type optical data recording medium capable of recording and reproducing information with radiation of blue laser, which employs an o,p-dialkoxy-phenyl-azometal complex dye in the optical layer.

Description

O,P-DIALKOXY-PHENYL-AZOMETAL COMPLEX DYES AND THEIR USE IN OPTICAL LAYERS FOR OPTICAL DATA RECORDING

The present invention relates to o,p-dialkoxy-phenyl-azometal complex dyes and their use in optical layers for optical data recording, preferably for optical data recording using a laser with a wavelength up to 450 nm.

The invention further relates to a write once read many (WORM) type optical data recording medium capable of recording and reproducing information with radiation of blue laser, which employs an o,p-dialkoxy-phenyl-azometal complex dye in the optical layer.

Recently, organic dyes have attracted considerable attentions in the field of diode-laser optical data storage. WORM type optical data recording media like commercial recordable compact discs (CD-R) and recordable digital versatile discs (DVD-R) can contain in the recording layer dyes based on phthalocyanine, hemicyanine, cyanine and metallized azo structures. These dyes are suitable in their respective fields with the laser wavelength criteria. Other general requirements for dye media are strong absorption, high reflectance, high recording sensitivity, enhancement of photosensitivity, low thermal conductivity as well as light and thermal stabilities, durability for storage or non-toxicity. Important criteria are also good read-out stability, which means high number of cycles at a given intensity of laser- light, and sufficient solubilities of the dyes in the organic solvents generally applied in the spin coating process.

At the recorded region of such an organic dye type optical data recording medium, the optical properties have been changed not only by a change in the optical characteristics and a decrease in the layer thickness resulting from the thermal decomposition of the dye, but also by a deformation of the substrate.

This recording principle is the same for CD-R and DVD-R, the difference remaining the spot size and the wavelength of the laser light used. CD-R are writable at a wavelength of from 770 to 830 nm and DVD-R, by using more recent compact high-performance red diode lasers, at a wavelength from 600 to 700 nm achieving then a 6- to 8 fold improvement in data packing density in comparison with conventional CDs.

However, considering factors such as the recent spread of electronic networks (e.g. Internet) and the emergence of high definition television (HDTV) broadcasting, inexpensive and convenient recording media, capable of recording image information at even larger capacity, are required. While DVD-R' s sufficiently serve as high-capacity recording media at present, demand for larger capacity and higher density has increased.

Blu-ray^® discs (Blu-ray^® disc is a standard developed by Hitachi Ltd., LG Electronics Inc., Matsushita Electric Industrial Co. Ltd., Pioneer Corporation, Royal Philips Electronics, Samsung Electronics Co. Ltd., Sharp Corporation, Sony Corporation, Thomson Multimedia) or HD-DVD discs (a standard developed by Toshiba and NEC) are going to be the next milestone in optical data recording technology. By these new specifications the data storage may be increased up to 27 Gigabytes per recording layer for a 12 cm diameter disc. By adopting a blue diode laser with a wavelength of 405 nm (GaN or SHG laser diodes), the pit size and track interval can be further reduced, again increasing the storage capacity by an order of magnitude.

The construction of such optical data recording media is known in the art. The optical recording medium comprises preferably a substrate with a guide groove for laser beam tracking, a recording layer, also called optical layer, containing an organic dye as the main component, a reflective layer and a protective layer. When recording/readout is carried out through the substrate, a transparent substrate is employed. As such a transparent substrate, one made of a resin such as polycarbonate, polymethacrylate or amorphous polyolefin, one made of glass or one having a resin layer made of radiation curable resin, i.e. photopolymerizable resin, formed on glass, may, for example, be employed. Advanced optical data recording media may comprise further layers, such as protective layers, adhesive layers or even additional optical recording layers.

For blue diode-laser optical data storage a variety of dye compounds has been proposed in the literature. JP 03132669 A discloses dyes based on anionic cobalt complexes and their use in electrophotography and optical layers.

WO 2004088649 A discloses dyes based on anionic cobalt complexes including cationic counter parts and their use in optical layers.

EP 1 621 584 A discloses neutral amino antipyrine based azo ligands, their metal complexes and their use in optical recording media.

WO 03/098617 A discloses ionic complex dyes with specific cations and their use in optical storage media.

WO 2004/072185 A discloses ionic azo metal complex dyes with heterocyclic ligands and their use in optical storage media.

Unfortunately the dye compounds described so far still show disadvantages which impede their satisfactory use as dyes for optical data storage.

There is a still a need for an optical data recording medium that is capable of recording data at high density with improved recording characteristics and with improved read-out stabilities.

Surprisingly the object was achieved by using o,p-dialkoxy-phenyl-azometal complex dyes as described below.

In the following text "halogen" represents F, Cl, Br or I, preferably F, Cl or Br, more preferably F or Cl, even more preferably Cl, if not otherwise stated; "alkyl" represents linear and branched alkyl; and "alkoxy" represents linear and branched alkoxy; any alkyl and cycloalkyl groups being unsubstituted or substituted by halogen; if not otherwise stated.

Subject of the invention is a compound of formula (I),

wherein

M represents a divalent metal atom, preferably selected from main groups 1 to 5 or from transition groups 1 or 2 or 4 to 8 of the Periodic Table of the Chemical Elements;

A represents a five or six membered unsaturated or aromatic, preferably aromatic, cycle or heterocycle, the heterocycle having 1, 2, 3 or 4, preferably 1, 2 or 3, more preferably 1 or 2 endocyclic heteroatoms independently from each other selected from the group consisting of N, O and S; the cycle or heterocycle may have 1, 2 or 3, preferably 1 or 2 endocyclic groups selected from the group consisting of the formulae (a), (b) and (c), preferably (a) and (c), the (*) denoting the endocyclic bonds,

O O O .0

(*) (*) (*) (*) (*) (*) the cycle or heterocycle being unsubstituted or substituted by as many substituents as possible substitution positions are available, preferably by 1 to

4 substituents, the substituents being independently from each other selected from the group consisting of OH, halogen, CN, CF₃, NO₂, C_1-10 alkoxy,

Ci-io alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃,

NO₂, Ci-io-alkyl, Cs-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-

>21_π22 21_π22

10 ,-aryl, S-C_6-io-aryl, SO₂-NR²¹R , CO-R , SO₂R , CO-NR²¹R , NH-CO-

R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²²; and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, C_1-10 alkyl, Cs-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-io-aryl, S-C_6-I₀- aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and

NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²²; and/ or this cycle or heterocycle being annealed to 1 or 2, preferably 1, five or six membered saturated, unsaturated or aromatic, preferably unsaturated, more preferably aromatic, cycle or heterocycle with 1, 2 or 3 heteroatoms independently selected from the group consisting of N, O and S, the annealed cycle or heterocycle being unsubstituted or substituted by as many substituents as possible substitution positions are available, preferably by 1 to 4 substituents, the substituents being independently from each other selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkoxy,

Ci-io alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, C_5-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, 0-C_{6- l}o-aryl, S-C_6-i₀-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-

R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, Cs-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, O-C_6-i₀-aryl, S-C_6-I0- aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and

NR²¹R²², S-Ci-I₀ alkyl, O-C_6-i₀-aryl, S-C₆-io-aiyl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²²; R⁴ and R⁵ are independently from each other selected from the group consisting of Ci_-I0 alkyl, C_5-Io cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, C_LIO alkyl, Cs-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, O-Ce-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO- NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci-I₀ alkyl, C_5-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO- NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²²; wherein R²¹, R²² and R²³ have the same definition as above; R² and R³ are independently from each other selected from the group consisting of H, halogen, CN, CF₃, NO₂, Ci_-I0 alkoxy, Ci_-I0 alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, C_5-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO- NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, Cs-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_{6- l}o-aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH- SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and

NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²²; R²¹ and R²² are independently from each other selected from the group consisting of H, Ci-io alkyl and C_6-Io aryl; and

R²³ is OH or Ci-io alkoxy;

preferably

A is selected from the group of formulae consisting of formulae (d), (e), (f), (g), (h), (i), (j), (k) and (1), more preferably of formulae (e), (g), (i), (j) and (k);

with the (**) denoting the bond to the azo group in formula (I) and with the (***) denoting the bond to the metal atom in formula (I), and with

R¹ and R⁶ having independently from R⁴ and R⁵ and from each other the same definition as R⁴ and R⁵; R⁷ having independently from R² and R³ the same definition as R² and R³.

A preferred aspect of the invention are compounds of formula (II) or (III),

wherein represents a five or six membered unsaturated or aromatic, preferably aromatic, heterocycle, the heterocycle having further 1, 2 or 3, preferably 1 or 2, more preferably 1 endocyclic heteroatoms independently from each other selected from the group consisting of N, O and S; the heterocycle may have 1 or 2, preferably 1 endocyclic groups selected from the group consisting of the formulae (a), (b) and (c), preferably (a) and (c), the (*) denoting the endocyclic bonds,

(*) (*) (*) (*) (*) (*) the heterocycle being unsubstituted or substituted by as many substituents as possible substitution positions are available, preferably by 1 to 3, more preferably 1 or 2 substituents, the substituents being independently from each other selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci-io-alkoxy, C_1-10 alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃,

NO₂, Ci-I₀ alkyl, C_5-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6- lo-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO- R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci-I₀ alkyl,

Cs-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-io-aryl, S-C_6-I₀- aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and

NR²¹R²², S-Ci-io alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²²; and/ or this N-heteroaromatic cycle being annealed to 1 or 2, preferably 1 five or six membered saturated, unsaturated or aromatic, preferably unsaturated, more preferably aromatic, cycle or heterocycle with 1 , 2 or 3 heteroatoms independently selected from the group consisting of N, O and S, the annealed cycle or heterocycle being unsubstituted or substituted by as many substituents as possible substitution positions are available, preferably by 1 to 4 substituents, the substituents being independently from each other selected from the group consisting of OH, halogen, CN, CF₃, NO₂, C_1-10 alkoxy, Ci-io alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃,

NO₂, Ci-I₀ alkyl, C_5-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6- lo-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO- R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci-I₀ alkyl,

Cs-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-io-aryl, S-C_6-I₀- aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and

NR²¹R²², S-Ci-io alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²²; represents a five or six membered unsaturated or aromatic, preferably aromatic, cycle or heterocycle, the heterocycle having further 1, 2 or 3, preferably 1 or 2, more preferably 1 endocyclic heteroatoms independently from each other selected from the group consisting of N, O and S; the cycle or heterocycle may have 1 or 2, preferably 1 endocyclic groups selected from the group consisting of the formulae (a), (b) and (c), preferably (a) and (c), the (*) denoting the endocyclic bonds,

I l (a) N (b) \\ // (C)

/-^C\ /^b\ /^\

(*) (*) (*) (*) (*) (*) the cycle or heterocycle being unsubstituted or substituted by as many substituents as possible substitution positions are available, preferably by 1 to

3, more preferably 1 or 2 substituents, the substituents being independently from each other selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci-io alkoxy, C_1-10 alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃,

NO₂, C_LIO alkyl, C_5-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_{6- l}o-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO- R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci_io alkyl, Cs-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_6-I0- aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and

NR²¹R²², S-Ci-io alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²²; and/ or this cycle or heteroaromatic cycle being annealed to 1 or 2, preferably

1 five or six membered saturated, unsaturated or aromatic, preferably unsaturated, more preferably aromatic, cycle or heterocycle with 1 , 2 or 3 heteroatoms independently selected from the group consisting of N, O and S, the annealed cycle or heterocycle being unsubstituted or substituted by as many substituents as possible substitution positions are available, preferably by 1 to 4 substituents, the substituents being independently from each other selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkoxy, Ci_-I0 alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃,

NO₂, Ci_-I0 alkyl, C_5-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, 0-C_{6- l}o-aryl, S-C_6-i₀-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO- R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl,

Cs-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, O-C_6-i₀-aryl, S-C_6-I0- aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and NR²¹R²², S-Ci_-I0 alkyl, O-C_6-i₀-aryl, S-C₆-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²²;

R¹, R⁴ and R⁵ are independently from each other selected from the group consisting of Ci_-I0 alkyl, C_5-Io cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci-I₀ alkyl, Cs-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, O-Ce-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO- NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci-I₀ alkyl, C_5-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO- NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²²; wherein R²¹, R²² and R²³ have the same definition as above;

R² and R³ are independently from each other selected from the group consisting of H, halogen, CN, CF₃, NO₂, Ci_-I0 alkoxy, Ci_-I0 alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN,

CF₃, NO₂, C_LIO alkyl, C_5-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO- NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl,

Cs-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_{6- l}o-aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH- SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and

Ci-I₀ alkyl-NR²¹R²²;

X represents C, S or S=O, preferably C or S=O;

R²¹ and R²² are independently from each other selected from the group consisting of H, Ci-io alkyl and C_6-Io aryl; and R²³ is OH or C_LIO alkoxy.

In a more preferred aspect of the invention

M is selected from the group consisting of Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mn²⁺, Cu²⁺, N ;i2+ , Co .2+ , Zn 2+ , Fe ,2+.

B is selected from the group of formulae consisting of formulae (d), (e), (f), (g), (h) and (i), preferably of formulae (e), (g) and (i), more preferably of formulae (e) and (i);

with the (**) denoting the bond to the azo group and with the (***) denoting the bond to the metal atom in formula (II);

C is from the group of formulae consisting of formulae (j), (k) and (1), preferably of formulae (j) and (k);

with the (**) denoting the bond to the azo group and with the (***) denoting the bond to the metal atom in formula (III); wherein

R¹, R⁴, R⁵ and R⁶ are independently from each other selected from the group consisting of Ci-io alkyl and C_5-10 cycloalkyl; R², R³ and R⁷ are independently from each other selected from the group consisting of H, halogen, CN, CF₃, NO₂, C_1-10 alkoxy, C_1-10 alkyl and Cs-io-cycloalkyl; X represents C or S=O.

In an even more preferred aspect of the invention

M is selected from the group consisting of Cu , Ni , Co , Zn , preferably Cu²⁺ and Ni²⁺.

In an even more preferred aspect of the invention A and B are independently from each other selected from the group of formulae consisting of formulae (e), (g) and (i), preferably (e) and (i),

with the (**) denoting the bond to the azo group and with the (***) denoting the bond to the metal atom in formulae (I) or (II); in another even more preferred aspect of the invention

A and C are independently from each other selected from the group of formulae consisting of formulae (j) and (k),

with the (**) denoting the bond to the azo group and with the (***) denoting the bond to the metal atom in formulae (I) or (III); wherein

R¹, R⁴, R⁵ and R⁶ are independently from each other selected from the group consisting of Ci-io alkyl and C_5-10 cycloalkyl; R², R³ and R⁷ are independently from each other selected from the group consisting of H, halogen, CN, CF₃, NO₂, C_1-10 alkoxy, C_1-10 alkyl and Cs-io-cycloalkyl; X represents C or S=O.

In another even more preferred aspect of the invention

R⁴ and R⁵ are independently from each other selected from the group consisting of methyl, ethyl, propyl, isopropyl, n-butyl, sec. -butyl, tert.-butyl, cyclohexyl and CF₃, preferably methyl, ethyl, propyl and isopropyl.

In an even more preferred aspect of the invention

R¹ and R⁶ are independently from each other selected from the group consisting of methyl, ethyl, propyl, isopropyl, n-butyl, sec. -butyl, tert.-butyl and cyclohexyl, preferably methyl and ethyl.

In an even more preferred aspect of the invention

R², R³ and R⁷ are independently from each other selected from the group consisting of H, F, Cl, CN, CF₃, NO₂, methoxy, ethoxy, methyl, ethyl, propyl, isopropyl, n-butyl, sec. -butyl, tert.-butyl and cyclohexyl, preferably H, Cl, methoxy and methyl.

In an even more preferred aspect of the invention X represents C or S=O.

A further subject of the invention is a compound of formula (7), (8), (9), (10), (11), (12), (13), (14), (15), (16), (17) or (18);

and the use of these compounds in optical layers, preferably as a dye.

Preparation of the inventive compounds of formula (I)

The compounds of formula (I) are prepared by complexing reaction of two equivalents of a compound of the formula (IV) and one equivalent of a divalent metal salt;

wherein M represents a divalent metal atom, preferably selected from main groups 1 to 5 or from transition groups 1 or 2 or 4 to 8 of the Periodic Table of the Chemical

Elements;

A represents a five or six membered unsaturated or aromatic, preferably aromatic, cycle or heterocycle, the heterocycle having 1, 2, 3 or 4, preferably 1, 2 or 3, more preferably 1 or 2 endocyclic heteroatoms independently from each other selected from the group consisting of N, O and S; the cycle or heterocycle may have 1, 2 or 3, preferably 1 or 2 endocyclic groups selected from the group consisting of the formulae (a), (b) and (c), preferably (a) and (c), the (*) denoting the endocyclic bonds,

(*) (*) (*) (*) (*) (*) the cycle or heterocycle being unsubstituted or substituted by as many substituents as possible substitution positions are available, preferably by 1 to 4 substituents, the substituents being independently from each other selected from the group consisting of OH, halogen, CN, CF₃, NO₂, C_1-10 alkoxy, Ci-io alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci-io-alkyl, C_5-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6- lo-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO- R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²²; and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, C_1-10 alkyl, Cs-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-io-aryl, S-C_6-I₀- aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and

NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²²; and/ or this cycle or heterocycle being annealed to 1 or 2, preferably 1, five or six membered saturated, unsaturated or aromatic, preferably unsaturated, more preferably aromatic, cycle or heterocycle with 1, 2 or 3 heteroatoms independently selected from the group consisting of N, O and S, the annealed cycle or heterocycle being unsubstituted or substituted by as many substituents as possible substitution positions are available, preferably by 1 to 4 substituents, the substituents being independently from each other selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci-I₀ alkoxy,

Ci-io alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci-I₀ alkyl, C_5-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6- lo-aryl, S-C_6-i₀-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-

R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, Cs-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, O-C_6-i₀-aryl, S-C_6-I₀- aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and

NR²¹R²², S-Ci-I₀ alkyl, O-C_6-i₀-aryl, S-C₆-io-aiyl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²²; wherein R²¹ and R²² are independently from each other selected from the group consisting of H, Ci-I₀ alkyl and C_6-I₀ aryl; and R²³ is OH or Ci-I₀ alkoxy; R⁴ and R⁵ are independently from each other selected from the group consisting of Ci-io alkyl, C_5-10 cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci-I₀ alkyl, Cs-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO- NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, C_5-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, O-Ce-io-aryl, S-C_6-i₀-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO- NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²²; wherein R²¹, R²² and R²³ have the same definition as above; R² and R³ are independently from each other selected from the group consisting of H, halogen, CN, CF₃, NO₂, Ci_-I0 alkoxy, Ci_-I0 alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, C_5-i₀-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, O-Ce-io-aryl, S-C_6-i₀-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO- NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, C_5-I o-cyclo alkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, O-C_6-i₀-aryl, S-C_{6- l}o-aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH- SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and

NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²²; wherein R²¹, R²² and R²³ have the same definition as above.

The compounds of formula (IV) are called azo ligands.

The divalent metal salt is derived from a metal preferably selected from the group consisting of Cu, Ni, Co, Zn, Fe. Salts of the divalent metal are preferably sulfates, halides (preferably fluoride, chloride, bromide, iodide, more preferably chloride and bromide, especially chlorides) and acetates and their respective hydrates.

More preferred metal salts are derived from Co, Ni and Cu; even more preferably cobalt-, nickel- or copper-sulfate; cobalt-, nickel- or copper- halide, preferably - chloride; cobalt-, nickel- or copper-acetate, and their respective hydrates, especially the metal salt is selected from the group consisting of CU(SCM)₂, CU(SO₄)₂*5 H₂O, CuCl₂, Ni(OAc)₂, Ni(OAc)₂*4 H₂O, MC1₂*6 H₂O, Co(SO₄)₂ and CoSO₄*7H₂O; preferably from the group consisting OfNi(OAc)₂, Cu(SO₄)₂*5 H₂O, CuCl₂, Co(SO₄)₂ and CoSO₄*7H₂O, more preferably from Ni(OAc)₂, CuCl₂ and Cu(SO₄)₂*5 H₂O.

Preparation of the compound of formula (IV)

The compounds of formula (IV) are prepared by azo coupling reaction of the respective diazo component and the respective coupling agent. The diazo component is prepared by diazotization reaction of the respective amine compound. These amine compounds and the coupling agents are known substances.

It is possible to use more than one amine component and/or more than one coupling agent resulting in the respective mixture of compounds of formula (IV).

The azo coupling reaction may be carried out in water, non-aqueous solvents and in mixtures thereof. Non-aqueous solvents are alcohols such as methanol, ethanol, propanol, butanol, pentanol, etc., dipolar aprotic solvents such as DMF, DMSO, NMP and water-immiscible solvents such as toluene or chlorobenzene. Preferably the azo coupling reaction is carried out in water.

The azo coupling reaction is preferably carried out in a stoichiometric ratio of coupling component and diazo component. The azo coupling reaction is generally done at temperatures between -30⁰C to 10O⁰C, preference being given to temperatures of -10⁰C to 30⁰C, and particular preference to temperatures of -5°C to 20⁰C. The azo coupling reaction may be carried out in an acidic as well as an alkaline medium. Preference is given to pH <10, particular preference to pH between 3 to 9.

Preferably the compound of formula (IV) is isolated following standard methods, in case of a precipitate preferably by filtration, and preferably dried.

Preparation of the compounds of formula (I) by complexing reaction

Preferably, the compounds of formula (I) are prepared by complexing reaction of a solution of one equivalent of a divalent metal salt with a boiling solution of two equivalents of the compound of formula (IV). It is possible to use more than one compound of formula (IV), preferably a mixture of 2 or 3 compounds of formula (IV). Preferably in this case the combined amounts of the compounds of formula (IV) should be equal to two equivalents of the metal salt. It is also possible to use more than one metal salt, preferably a mixture of 2 or 3 metal salts, preferably in the required stoichiometric amounts with regard to the compound of formula (IV); and a combination of these measures is also possible.

The compounds of formula (IV) can be added to the metal salt or vice versa.

The complexing reaction can be carried out in suspension or in solution, preferably in suspension.

The complexing reaction usually results in a precipitate, the precipitate is isolated following standard methods, preferably by filtration.

The solvents that can be used in the complexing reaction are water, solvents and mixtures thereof. The solvents are preferably selected from the group consisting of

C_1-8 alcohols, nitriles, preferably acetonitrile, acetone, aromatic solvents such as toluene or chlorobenzene, DMF, DMSO, NMP.

More preferred solvents are C_1-8 alcohols, especially ethanol, and acetonitrile. It is also possible to add the metal salt already at an earlier stage of the synthesis of the compounds of formula (I) or their precursors, preferably before, during or after the azo coupling reaction, more preferably after the azo coupling reaction to the resulting suspension or solution of the compounds of formula (IV).

Even more preferably the compounds of formula (IV) are isolated and dried after synthesis, and the complexing reaction is carried out in a separate step.

Preferably the compounds of formula (IV) are present as a suspension in the complexing reaction.

The complexing reaction is generally done at temperatures between 20⁰C to 200⁰C, preferably at temperatures between 50⁰C to 170⁰C, particularly preferably at temperatures between 80⁰C to 150⁰C, further particularly preferably the complexing reaction is carried out at reflux temperature and at atmospheric pressure.

Preferably the compounds of formula (I) are isolated following standard methods, usually they form a precipitate which is isolated preferably by filtration and dried.

A further subject of the invention is therefore a process for the preparation of the compounds of formula (I), as well as of the compounds of formula (I) in all the preferred aspects of the formula (I) as described above, by a complexing reaction of the compounds of the formula (IV) with divalent metal salts; with the azo ligands preferably prepared by a azo coupling reaction of the respective diazo components and the respective coupling agents.

The compounds of formulae (7), (8), (9), (10), (11), (12), (13), (14), (15), (16), (17) and (18) are prepared accordingly using the respective azo ligands of formulae (1), (2), (3), (4), (5) or (6)

and the respective metal salts derived from copper and nickel in the complexing reaction.

Therefore a further subject of the invention is a process for the preparation of the compounds of formulae (7), (8), (9), (10), (11), (12), (13), (14), (15), (16), (17) and (18) by a complexing reaction of the respective compounds of the formulae (1), (2), (3), (4), (5) and (6) (the azo ligands) with the respective divalent metal salts; with the azo ligands preferably prepared by a azo coupling reaction of the respective diazo components and the respective coupling agents. The subject of the invention is further the use of the compounds of formula (I) as defined above and the use of the compounds of formula (I) in all the preferred aspects of the formula (I) as described above, in an optical layer for optical data recording.

The subject of the invention is further the use of the compounds of formula (I) as defined above and the use of the compounds of formula (I) in all the preferred aspects of the formula (I) as described above, as a dye in an optical layer for optical data recording.

A further subject of the present invention is an optical layer comprising at least one compound of formula (I) and the use of said optical layer for optical data recording media. An optical layer according to the invention may also comprise a mixture of two or more, preferably of two or three, more preferably of two compounds of formula (I). A further subject of the invention therefore is an optical data recording medium comprising an optical layer comprising at least one compound of formula (I).

Further, the invention relates to a method for producing optical layers on a substrate comprising the following steps (a) providing a substrate, (b) dissolving at least one compound of formula (I) in an organic solvent to form a solution,

(c) coating the solution (b) on the substrate (a),

(d) evaporating the solvent to form an optical layer (also called dye layer or recording layer).

(a) Substrate

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

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, polyolefms, polyvinyl chloride, polyvinylidene fluoride, polyimides, thermosetting polyesters and epoxy resins. The most preferred substrates are polycarbonate (PC) or polymethylmethacrylate (PMMA).

The substrate can be in pure form or may also comprise customary additives, for example UV absorbers as light-stabilizers for the optical layer.

The substrate is advantageously transparent over at least a portion of the range from 350 to 500 nm, so that it is permeable to at least 90% of the incident light of the writing or readout wavelength.

(b) Organic solvents Organic solvents are selected from Ci-S alcohol, halogen substituted Ci-S alcohols, Ci-S ketone, Ci-S ether, halogen substituted Ci_-4 alkane, nitriles, preferably acetonitrile, or amides, or mixtures thereof.

Preferred Ci-S alcohols or halogen substituted Ci-S alcohols are for example methanol, ethanol, isopropanol, diacetone alcohol (DAA), 2,2,3, 3-tetrafluoropropanol, trichloroethanol, 2-chloroethanol, octafluoropentanol or hexafluorobutanol, more preferred 2,2,3,3-tetrafiuoro-l-propanol.

Preferred Ci-S ketones are for example acetone, methylisobutylketone, methylethylketone, or 3-hydroxy-3-methyl-2-butanone.

Preferred halogen substituted Ci_-4 alkanes are for example chloroform, dichloromethane or 1-chlorobutane.

Preferred amides are for example dimethylformamide or dimethylacetamide. (c) Coating methods

Suitable coating methods are, for example, immersion, pouring, brush-coating, blade- application and spin-coating, as well as vapor-deposition methods carried out under a high vacuum. When pouring methods are used, solutions in organic solvents are generally used. When solvents are employed, care should be taken that the supports used are insensitive to those solvents. The optical layer is preferably applied by spin- coating with a dye solution.

(d) Optical layer (also called dye layer or recording layer) The optical layer is preferably arranged 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, more preferably from 70 to 250 nm, especially about 80 nm, for example from 60 to 120 nm.

The optical layer comprises a compound of formula (I) preferably in an amount sufficient to have a substantial influence on the refractive index, for example at least 30% by weight of the total weight of the optical layer, more preferably at least 60% by weight, most preferably at least 80% by weight.

Further customary components are stabilizers, for example ¹O₂-, triplet- or luminescence quenchers, melting-point reducers, decomposition accelerators or any other additives that have already been described in optical data recording media. Preferably, stabilizers or fluorescence-quenchers are added if desired.

Stabilizers, ¹O₂-, triplet- or luminescence-quenchers are, for example, metal complexes of N- or S-containing enolates, phenolates, bisphenolates, thiolates or bisthiolates, hindered phenols and derivatives thereof such as o-hydroxyphenyl-triazoles or -triazines or other UV absorbers, such as hindered amines (TEMPO or HALS, as well as nitroxides or NOR-HALS), and also as cations diimmonium, Paraquat™ or Orthoquat salts, such as ^®Kayasorb IRG 022, ^®Kayasorb IRG 040, optionally also as radical ions, such as N,N,N',N'-tetrakis(4-dibutylaminophenyl)-p-phenylene amine-ammonium hexafluorophosphate, hexafluoroantimonate or perchlorate. The latter are available from Organica (Wolfen/DE); ^®Kayasorb brands are available from Nippon Kayaku Co. Ltd. In a preferred aspect, the present invention provides for an optical layer suitable for high-density recording material, e.g. of the WORM disc format, in a laser wavelength range of from 350-450nm, preferably around 405 nm.

Preparation of the optical data recording medium

A method for producing an optical data recording medium comprising an optical layer according to the invention usually comprises the following additional steps (e) applying a metal layer (also called reflective layer) onto the optical layer, (f) applying a second polymer based layer to complete the disk (cover layer or protective layer).

(e) Reflective layer

The application of the metallic reflective layer is preferably effected by sputtering, vapor-deposition in vacuum or by chemical vapor deposition (CVD). The sputtering technique is especially preferred for the application of the metallic reflective 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 aluminum, silver, copper, gold or an alloy thereof, on account of their high reflectivity and ease of production.

(f) Cover layer (also called protective layer)

Materials suitable for the cover layer include plastics, which are applied in a thin layer to the support or the uppermost layer either directly or with the aid of adhesive layers. The material of the cover layer may for example be the same as the material of the substrate. It is advantageous to select mechanically and thermally stable plastics having good surface properties, which may be modified further. The plasties may be thermosetting plasties and thermoplastic plasties. Preference is given to radiation-cured (e.g. using 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, trio Is and tetrols, polyimides of aromatic tetracarboxylic acids and aromatic diamines having Ci-C4alkyl groups in at least two ortho-positions of the amino groups, and oligomers with dialkylmaleinimidyl groups, e.g. dimethyl maleinimidyl groups.

A high-density optical data recording medium according to the invention therefore preferably is a recordable optical disc comprising: a first substrate, which is a transparent substrate with grooves, a optical layer (recording layer), which is formed on the first substrate surface using the compounds of formula (I), a reflective layer formed on the optical layer, a second substrate, which is a transparent substrate connected to the reflective layer with an attachment layer.

The optical data recording medium according to the invention is preferably a recordable optical disc of the WORM type. It may be used, for example, as a playable HD-DVD (high density digital versatile disc) or Blu-ray^® disc, as storage medium for a computer or as an identification and security card or for the production of diffractive optical elements, for example holograms.

The optical data recording media according to the invention may also have additional layers, for example interference layers. It is also possible to construct optical data recording media having a plurality of (for example two) recording layers. The structure and the use of such materials are known to the person skilled in the art. Preferred, if present, are interference layers that are arranged between the recording layer and the reflecting layer and/or between the recording layer and the substrate and consist of a dielectric material Of TiO₂, Si₃N₄, ZnS or silicone resins.

These optical data recording media according to the invention can be produced by processes known in the art. Readout methods

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

When the optical data recording medium is structured for a change in reflection, the following structures can 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 according to the invention is generally preferred.

When the optical data recording medium is structured for a change in light transmission, the following different structure 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 350-500 nm, for example commercially available lasers having a wavelength of 405 to 414 nm, especially semi-conductor lasers. The recording is done, for example, point for point, by modulating the laser in accordance with the mark lengths and focusing its radiation onto the recording layer. It is known from the specialist literature that other methods are currently being developed which may also be suitable for use.

The process 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 excellent readout is achieved.

The readout of information is carried out according to methods known in the art by registering the change in absorption or reflection using laser radiation.

The invention accordingly relates also to a method for the optical data recording, storage and playback of information, wherein an optical data recording medium according to the invention is used. The recording and the playback advantageously take place in a wavelength range of from 350 to 500 nm.

The compounds of formula (I) provide for particularly preferable properties when used in optical layers for optical data recording media according to the invention. They possess the required optical characteristics, demonstrated when used in the form of a solid film:

• an advantageously homogeneous, amorphous and low-scattering optical layer,

• a high refractive index at the longer wavelength flank of the absorption band, which preferably achieves n values of the refractive index of from 1.0 to 3.0 in the range of from 350 to 500 nm,

• a high sensitivity under laser radiation of high power density and good playback characteristics in the desired spectral range,

• an enhanced photosensitivity and stability (in daylight and under laser radiation of low power density ) compared to dyes already known in the art, • an uniform script width and a high contrast,

• an absorption maximum λ max in the preferred range between 390 nm and 470 nm as being preferred for blue laser applications, more precisely from 400 to 460 nm,

• a decomposition point DP in the preferred temperature range between 220⁰C and 300⁰C, more precisely 230⁰C to 290⁰C

• a sufficient heat release (HR) Recording performance of a compound is related to specific parameters measured on disc like:

• a low simulated bit error rate (SbER)

• a low inner parity error rate (PI error) • a high reflectivity (R)

• a low laser recording power (Pw or OPC: optimum power control)

• good readout stability at several laser reading powers.

• an appropriate partial response signal to noise ratio (PRSNR)

The absorption edge is surprisingly steep even in the solid phase.

The compounds of formula (I) also show a narrow decomposition temperature of 250- 350⁰C, fitting with the thermal requirements. Additionally, these compounds show a high solubility in organic solvents, which is ideal for the spin-coating process to manufacture optical layers.

Examples

UV-vis

For UV-vis spectra, λ max and ε values of a compound are determined by using an UV- vis spectrophotometer, the compound was dissolved in CH₂Cl₂, DMSO or in tfp. The values are obtained by balancing the measurements performed on compound solutions at three different concentrations.

Thermal Decomposition: Decomposition point (DP) and heat release (HR) For the determination of DP and HR, the compound is incorporated into a sealed aluminum pan. Analysis conditions are as following: Temperature range from 25 to 400⁰C, heating rate 10°C/min, nitrogen flow of 50 ml/min. Values are determined by single measurement.

Partial response signal to noise ratio (PRSNR) A definition and the measuring techniques of PRSNR are described in a book available from DVD Format Logo Licensing Co., Ltd. for example, Annex H of Version 0.9, PART 1 Physical Specifications, DVD Specifications for High Density Read-Only Disk.

Simulated bit error rate (SbER)

A definition and the measuring techniques of SbER are described in a book available from DVD Format Logo Licensing Co., Ltd. for example, Annex H of Version 0.9, PART 1 Physical Specifications, DVD Specifications for High Density Read-Only Disk.

PRSNR and SbER are measured in a state in which information has been recorded in the adjacent tracks.

Reflectivity (R) A definition and the measuring techniques for the light reflectivity (R) is described in a book available from DVD Format Logo Licensing Co., Ltd. for example, Annex D of Version 0.9, PART 1 Physical Specifications, DVD Specifications for High Density Read-Only Disk. Example 1:

A mixture of 15.3 g of 2,4-dimethoxy-phenylamine, 120 ml of water and 34.3 g of concentrated hydrochloric acid (30% w/w) was gradually admixed with 24.5 ml of sodium nitrite (33% w/v) at 0⁰C. After 1 hour of reaction at 0⁰C, the dark diazotization solution was added drop wise to an alkaline solution of 22.6 g of l,3-diethyl-2- thiobarbituric acid while maintaining pH at 7.5-9 with sodium hydroxide (30% w/w). The batch was stirred 3 hours, then filtered with suction. The precipitate was washed with water and dried. 34.1 g of the compound of formula (1) was obtained.

Example 2

A mixture of 15.3 g of 2,4-dimethoxy-phenylamine, 120 ml of water and 34.3 g of concentrated hydrochloric acid (30% w/w) was gradually admixed with 24.5 ml of sodium nitrite (33% w/v) at 0⁰C. After 1 hour of reaction at 0⁰C, the dark diazotization solution was added drop wise to an alkaline solution of 15.1 g of 1,3 -dimethyl- barbituric acid while maintaining pH at 7.5-9 with sodium hydroxide (30% w/w). The batch was stirred 3 hours, then filtered with suction. The precipitate was washed with water and dried. 27.1 g of the compound of formula (2) was obtained.

Example 3

A mixture of 15.3 g of 2,4-dimethoxy-phenylamine, 120 ml of water and 34.3 g of concentrated hydrochloric acid (30% w/w) was gradually admixed with 24.5 ml of sodium nitrite (33% w/v) at 0⁰C. After 1 hour of reaction at 0⁰C, the dark diazotization solution was added drop wise to an alkaline solution of 20.6 g of l-butyl-4-methyl-2,6- dioxo-l,2,5,6-tetrahydro-pyridine-3-carbonitrile while maintaining pH at 7.5-9 with sodium hydroxide (30% w/w). The batch was stirred 3 hours, then filtered with suction. The precipitate was washed with water and dried. 31.2 g of the compound of formula (3) was obtained.

Examples 4-6

The preparation according to example 1 was done using the respective coupling agent in a stoichiometric ratio with regard to the respective amine component to yield the compounds of formula (4), (5) and (6). Example 7 - 18

7.2 g of compound of formula (1), prepared according to example 1, and 1.6 g of sodium acetate were suspended in 100 ml of ethanol. After 15 minutes stirring at reflux,

1.3 g of anhydrous copper chloride are added to the mixture. . After some minutes, a dark brown suspension of the copper complex dye results. The mixture is heated at reflux for 6 hours and then cooled down to room temperature. The resulting precipitate is filtered off and the press cake washed with deionized water and dried. 7.8 g of the compound of the formula (7) is obtained.

The complexing reaction was repeated with the respective metal salts and with the respective compounds of formula (1), (2), (3), (4), (5) or (6), prepared according to examples 1 to 6, to yield compounds of formulae (8) to (18), the combinations and the details are given in tables (Al) and (A2).

Application Example 1

The optical and thermal properties of the compounds of formula (I) were studied. The compounds of formula (I) show high absorption at the desired wavelengths. In addition, the shapes of the absorption spectra, that still remain critical to the disc reflectivity and formation of clean mark edges, are composed of one major band, comprised in a range of from 350 to 500 nm.

More precisely, n values of the refractive index were evaluated between 1.0 and 2.7. Light stabilities were found comparable to commercial dyes which are already stabilized with quenchers for the use in optical data recording.

Sharp threshold of thermal decomposition within the required temperature range characterizes the compounds of formula (I) which are desirable for the application in optical layers for optical data recording.

Application Example 2 - Optical layer and optical data recording medium

1.4% by weight of the mixture according to Example 1 are dissolved in 2,2',3,3'- tetrafluoro-1-propanol and the solution is filtered through a Teflon filter of pore size 0.2 μm and applied by spin-coating at 1000 rpm to the surface of a 0.6 mm thick, grooved polycarbonate disc of 120 mm diameter. The excess solution is spun off by increasing the rotational speed. On evaporation of the solvent, the dye remains behind in the form of a uniform, amorphous solid layer, the optical layer. After drying the optical layer in a circulating-air oven at 70⁰C (10 min) in a vacuum coating apparatus, a 100 μm thick silver layer is then applied to the recording layer by atomization. Then a 6 μm thick protective layer of a UV curable photopolymer (650-020, DSM) is applied thereto by means of spincoating. Finally, a second substrate is provided to combine with the resin protection layer using an attachment layer. This completes the manufacturing of a high- density recordable optical disc, the optical data recording medium.

Evaluation tests are performed using an optical disk evaluation device available from Pulse Tech Co., Ltd.

The testing conditions are the following ones: • Numerical aperture (NA) of the optical head: 0.65

• Wavelength of a laser light for recording and reproduction: 405 nm

• Constant linear velocity (CLV): 6.61 m/sec.

• Track pitch: 400 nm

• Wobble amplitude of the groove track: 14 nm • Groove depth: 90 nm.

Results obtained are summarized in the table (B).

A test for evaluating a degree of degradation due to repetition reproduction is conducted for each of the write-once optical disks made for the described dye recording layers. Readings are carried out at a reading laser power of 0.4 mW and the degrees of degradation of PRSNR and SbER are then measured. Maximum cycle number was found within the specifications.

Claims

Claims

1. An optical layer comprising a compound of formula (I),

wherein

M represents a divalent metal atom;

A represents a five or six membered unsaturated or aromatic, cycle or heterocycle, the heterocycle having 1, 2, 3 or 4 endocyclic heteroatoms independently from each other selected from the group consisting of N, O and

S; the cycle or heterocycle may have 1 , 2 or 3 endocyclic groups selected from the group consisting of the formulae (a), (b) and (c), the (*) denoting the endocyclic bonds,

O O O .0

(*) (*) (*) (*) (*) (*) the cycle or heterocycle being unsubstituted or substituted by as many substituents as possible substitution positions are available, the substituents being independently from each other selected from the group consisting of OH, halogen, CN, CF₃, NO₂, C_1-10 alkoxy, C_1-10 alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci-io-alkyl, Cs-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-

>21_π22 21_π22

10 ,-aryl, S-C_6-io-aryl, SO₂-NR²¹R , CO-R , SO₂R , CO-NR²¹R , NH-CO-

R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²²; and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, C_1-10 alkyl, Cs-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-io-aryl, S-C_6-I₀- aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and

NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²²; and/ or this cycle or heterocycle being annealed to 1 or 2 five or six membered saturated, unsaturated or aromatic cycle or heterocycle with 1 , 2 or 3 heteroatoms independently selected from the group consisting of N, O and

S, the annealed cycle or heterocycle being unsubstituted or substituted by as many substituents as possible substitution positions are available, the substituents being independently from each other selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkoxy, Ci_-I0 alkyl, C_5-10- cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, Cs-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, 0-C_{6- l}o-aryl, S-C₆-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO- R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, Cs-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-io-aryl, S-C_6-I₀- aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and

NR²¹R²², S-Ci-I₀ alkyl, 0-C₆-io-aiyl, S-C₆-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²²; R⁴ and R⁵ are independently from each other selected from the group consisting of Ci_-I0 alkyl, C_5-Io cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, C_LIO alkyl, C_5-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, O-Ce-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO- NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci-I₀ alkyl, C_5-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO- NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²²; wherein R²¹, R²² and R²³ have the same definition as above; R² and R³ are independently from each other selected from the group consisting of H, halogen, CN, CF₃, NO₂, Ci_-I0 alkoxy, Ci_-I0 alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, C_5-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO- NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, Cs-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_{6- l}o-aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH- SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and

NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²²; R²¹ and R²² are independently from each other selected from the group consisting of H, Ci-io alkyl and C_6-Io aryl; and

R²³ is OH or Ci-io alkoxy.

2. An optical layer according to claim 1 comprising a compound of formula (II) or

(in),

represents a five or six membered unsaturated or aromatic, preferably aromatic, heterocycle, the heterocycle having further 1, 2 or 3 endocyclic heteroatoms independently from each other selected from the group consisting of N, O and

S; the heterocycle may have 1 or 2 endocyclic groups selected from the group consisting of the formulae (a), (b) and (c), preferably (a) and (c), the (*) denoting the endocyclic bonds,

O O

,c. (a) (b) ⁰V/⁰

(C)

(*) (*) (*) (*) (*) (*) the heterocycle being unsubstituted or substituted by as many substituents as possible substitution positions are available, the substituents being independently from each other selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci-io-alkoxy, Ci_io alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci-I₀ alkyl, C_5-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6- lo-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO- R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci-I₀ alkyl, Cs-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-io-aryl, S-C_6-I₀- aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and

NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²²; and/ or this N-heteroaromatic cycle being annealed to 1 or 2, five or six membered saturated, unsaturated or aromatic, cycle or heterocycle with 1 , 2 or 3 heteroatoms independently selected from the group consisting of N, O and S, the annealed cycle or heterocycle being unsubstituted or substituted by as many substituents as possible substitution positions are available, the substituents being independently from each other selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci_io alkoxy, Ci_io alkyl, Cs-I₀- cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci-I₀ alkyl, Cs-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, 0-C_6- lo-aryl, S-C_6-i₀-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO- R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, Cs-io-cycloalkyl, Ci-I₀ alkoxy, NR²¹R²², S-Ci-I₀ alkyl, O-C_6-i₀-aryl, S-C_6-I₀- aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and

NR²¹R²², S-Ci-I₀ alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²²; represents a five or six membered unsaturated or aromatic cycle or heterocycle, the heterocycle having further 1, 2 or 3 endocyclic heteroatoms independently from each other selected from the group consisting of N, O and S; the cycle or heterocycle may have 1 or 2 endocyclic groups selected from the group consisting of the formulae (a), (b) and (c), preferably (a) and (c), the (*) denoting the endocyclic bonds,

(*) (*) the cycle or heterocycle being unsubstituted or substituted by as many substituents as possible substitution positions are available, the substituents being independently from each other selected from the group consisting of OH, halogen, CN, CF₃, NO₂, C_1-10 alkoxy, C_1-10 alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, C_5-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, 0-C_{6- l}o-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO- R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, Cs-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_6-I0- aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and NR²¹R²², S-Ci-io alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³,

SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²²; and/ or this cycle or heteroaromatic cycle being annealed to 1 or 2, five or six membered saturated, unsaturated or aromatic cycle or heterocycle with 1 , 2 or 3 heteroatoms independently selected from the group consisting of N, O and S, the annealed cycle or heterocycle being unsubstituted or substituted by as many substituents as possible substitution positions are available, the substituents being independently from each other selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci_io alkoxy, Ci_io alkyl, Cs_-I0- cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, Cs-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, 0-C_{6- l}o-aryl, S-C_6-i₀-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO- R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, Cs-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, O-C_6-i₀-aryl, S-C_6-I0- aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²², and

NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²²; R¹, R⁴ and R⁵ are independently from each other selected from the group consisting of Ci-io alkyl, C_5-Io cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, C_LIO alkyl, Cs-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, O-C_6-i₀-aryl, S-C_6-i₀-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-

NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, Cs-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, O-C_6-i₀-aryl, S-C_6-i₀-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO-

NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²²; wherein R²¹, R²² and R²³ have the same definition as above;

R² and R³ are independently from each other selected from the group consisting of H, halogen, CN, CF₃, NO₂, Ci_-I0 alkoxy, Ci_-I0 alkyl, Cs-io-cycloalkyl, and unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents being independently selected from the group consisting of OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, C_5-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, O-C_6-i₀-aryl, S-C_6-i₀-aryl, SO₂-NR²¹R²², CO-R²³, SO₂R²³, CO- NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents being independently selected from OH, halogen, CN, CF₃, NO₂, Ci_-I0 alkyl, Cs-io-cycloalkyl, Ci_-I0 alkoxy, NR²¹R²², S-Ci_-I0 alkyl, O-C_6-i₀-aryl, S-C_{6- l}o-aryl, SO₂-NR²¹R²², CO-R²³, SO₂ R²³, CO-NR²¹R²², NH-CO-R²¹, NH- SO₂-R²¹ and Ci_-I0 alkyl-NR²¹R²², and NR²¹R²², S-Ci_-I0 alkyl, 0-C_6-io-aryl, S-C_6-io-aryl, SO₂-NR²¹R²², CO-R²³,

SO₂R²³, CO-NR²¹R²², NH-CO-R²¹, NH-SO₂-R²¹ and Ci-I₀ alkyl-NR²¹R²²;

X represents C, S or S=O; R²¹ and R²² are independently from each other selected from the group consisting of H,

Ci-io alkyl and C_6-10 aryl; and R²³ is OH or Ci-io alkoxy.

3. An optical layer according to claim 1, wherein

A is selected from the group of formulae consisting of formulae (d), (e), (f),

(g), (h), (i), G), (k) and (l);

with the (**) denoting the bond to the azo group in formula (I) and with the (***) denoting the bond to the metal atom in formula (I), and with

R¹ and R⁶ having independently from R⁴ and R⁵ and from each other the same definition as R⁴ and R⁵ as defined in claim 1 ; R⁷ having independently from R² and R³ the same definition as R² and R³ as defined in claim 1.

4. An optical layer according to one or more of claims 1 to 3, wherein

M is selected from the group consisting of Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mn²⁺, Cu²⁺,

Ni²⁺, Co²⁺, Zn²⁺, Fe²⁺;

R¹, R⁴, R⁵ and R⁶ are independently from each other selected from the group consisting of Ci-io alkyl and C_5-Io cycloalkyl;

R², R³ and R⁷ are independently from each other selected from the group consisting of H, halogen, CN, CF₃, NO₂, C_1-10 alkoxy, C_1-10 alkyl and Cs-io-cycloalkyl; X represents C or S=O.

5. An optical layer according to one or more of claims 1 to 4, wherein M is selected from the group consisting of Cu²⁺, Ni²⁺, Co²⁺, Zn²⁺;

R⁴ and R⁵ are independently from each other selected from the group consisting of methyl, ethyl, propyl, isopropyl, n-butyl, sec. -butyl, tert.-butyl, cyclohexyl and CF₃;

R¹ and R⁶ are independently from each other selected from the group consisting of methyl, ethyl, propyl, isopropyl, n-butyl, sec. -butyl, tert.-butyl and cyclohexyl;

R², R³ and R⁷ are independently from each other selected from the group consisting of H, F, Cl, CN, CF₃, NO₂, methoxy, ethoxy, methyl, ethyl, propyl, isopropyl, n-butyl, sec. -butyl, tert.-butyl and cyclohexyl; X represents C or S=O.

6. A method for producing an optical layer as defined in one or more of claims 1 to 5, comprising the following steps

(a) providing a substrate,

(b) dissolving at least one compound of formula (I), as defined in claim 1 , or of formula (II) or (III), as defined in claim 2, in an organic solvent to form a solution,

(c) coating the solution (b) on the substrate (a),

(d) evaporating the solvent to form an optical layer.

7. A method according to claim 6, wherein the substrate is polycarbonate (PC) or polymethylmethacrylate (PMMA).

8. A method according to claim 6 or 7, wherein the organic solvent is selected from C_1-8 alcohol, halogen substituted C_1-8 alcohols, C_1-8 ketone, C_1-8 ether, halogen substituted Ci_-4 alkane, or amides.

9. A method according to one or more of claims 6 to 8, wherein the optical layer obtained has a thickness from 10 to 1000 nm.

10. An optical data recording medium comprising an optical layer as defined in one or more of claims 1 to 5.

11. A compound of formula (7), (8), (9), (10), (11), (12), (13), (14), (15), (16), (17) or (18).