wherein

X independently of Y represents a nitrogen atom or a C-R² group and

Y independently of X represents a nitrogen atom or a C-R⁹ group,

R¹ for each of the two R¹ groups independently of the other represents a radical selected from the group consisting of

a C₁-C_24-alkyl radical,

a C₃-C₂₀-cycloalkyl radical,

which comprises monocyclic, bicyclic, and tricyclic cycloalkyl radicals,

a C₅-C₁₄-aryl radical,

which comprises a phenyl radical, a naplithyl radical, and a fluorenyl radical, with the proviso that if one R¹ is a non-substituted phenyl, the second R¹ cannot be a non-substituted phenyl,

and a C₂-C₁₃-heteroaryl radical,

wherein the heteroatoms comprise nitrogen, oxygen, sulfur, or a combination thereof and wherein the number of heteroatoms is from 1 to 2,

wherein the two radicals R¹ may be linked to one another,

wherein the above-mentioned radicals R¹ may each be mono- or poly-substituted independently of one another by substituents selected from the group consisting of hydrogen, a C₁-C₂₀-alkyl radical, a C₂-C₂₀-alkenyl radical, a C₃-C₈-cycloalkyl radical, a C₂-C₉-hetero-alkyl radical, a C₅-C₁₀-aryl radical, a C₂-C₉-heteroaryl radical,

wherein the heteroatoms comprise nitrogen, oxygen, sulfur, or a combination thereof

and wherein the number of hetero atoms is from 1 to 4,

a C₁-C₂₀-alkoxy radical, a C₁-C₁₀-haloalkyl radical, a hydroxyl radical, a NH—(C₁-C₂₀-alkyl) radical, a NH—(C₅-C₁₀-aryl) radical, a N (C₁-C₂₀-alkyl)₂ radical, a N (C₁-C₂₀-alkyl) (C₅-C₁₀-aryl) radical, a N(C₅-C₁₀-aryl)₂ radical, a N(C₁-C₂₀-alkyl/C₅-C₁₀-aryl₃)₃⁺ radical, a NH—CO—C₁-C₂₀-alkyl radical, a NH—CO—C₅-C₁₀-aryl radical, a COOH radical, a COOQ′ radical, a C₁-C₆-acyloxy radical, a sulfinato radical, a —SO₃H radical, a SO₃Q″ radical and a tri-C₁-C₆-alkylsilyl radical,

wherein Q′ represents either a monovalent cation or a C₁-C₈-alkyl radical and Q″ represents either a monovalent cation, a C₁-C₂₀-alkyl radical, or a C₅-C₁₀-aryl radical,

wherein two of the mentioned substituents may be bridged with one another,

R₂-R₉ independently represent hydrogen, an alkyl radical, an alkenyl radical, a cycloalkyl radical, an aromatic or heteroaromatic aryl radical, an O-alkyl radical, an NH-alkyl radical, an N-(alkyl)₂ radical, an O-(aryl) radical, an NH-(aryl) radical, an N-(alkyl)(aryl) radical, an O—CO-alkyl radical, a O—CO-aryl radical, a F, a Si(alkyl)₃ radical, a CF₃ radical, a CN radical, a CO₂H radical, a COH radical, an SO₃H radical, a CONH₂ radical, an CONH(alkyl) radical, a CON(alkyl)₂ radical, an SO₂(alkyl) radical, a SO(alkyl) radical, a SO(aryl) radical, a SO₂(aryl) radical, a SO₃(alkyl) radical, a SO₃(aryl) radical, an S-alkyl radical, an S-aryl radical, a NH—CO(alkyl) radical, a C₂(alkyl) radical, a CONH₂ radical, a CO(alkyl) radical, a NHCOH radical, a NHCO₂(alkyl) radical, a CO(aryl) radical, or a C₂(aryl) radical,

wherein two or more adjacent radicals, each independently of the other(s), may also be linked to one another so that a condensed ring system is present and

wherein in R² to R⁹

an alkyl radical comprises a hydrocarbon radical comprising from 1 to 20 carbon atoms which may be linear or branched, an alkenyl radical represents a mono- or poly-unsaturated hydrocarbon radical comprising from 2 to 20 carbon atoms which may in be linear or branched, a cycloalkyl radical comprises a hydrocarbon comprising from 3 to 20 carbon atoms, an aryl radical comprises a 5- to 14-membered aromatic radical, wherein from one to four carbon atoms in the aryl radical may be replaced by hetero atoms wherein the heteroatoms are nitrogen, sulfur, and oxygen so that a 5- to 14-membered heteroaromatic radical is present, wherein the radicals R² to R⁹ may also carry further substituents as defined for R¹.