Compound having one of the two general structures I and II: where R 1, R 2, R 3, R 4, R 5, R 6, R 7, R 8 are selected from: -H, -(C 1 -C 12)-alkyl, -O-(C 1 -C 12)-alkyl, -O-(C 6 -C 20)-aryl, - (C 6 -C 20)-aryl, -S-alkyl, -S-aryl, halogen, COO-(C 1 -C 12)-alkyl, CONH-(C 1 -C 12)-alkyl, -CO-(C 1 -C 12)-alkyl, -CO-(C 6 -C 20)-aryl, -COOH, -OH, -SO 3 H, -CN, -NH 2, -N[(C 1 -C 12)-alkyl] 2; R 1 ', R 2 ', R 3 ', R 4 ', R 5 ', R 6 ', R 7 ', R 8 ', R 1 ", R 2 ", R 3 ", R 4 ", R 5 ", R 6 ", R 7 ", R 8 " are selected from: -H, -(C 1 -C 12)-alkyl, -O-(C 1 -C 12)-alkyl, -O-(C 6 -C 20)-aryl, -(C 6 -C 20)-aryl, -S-alkyl, -S-aryl, halogen, COO-(C 1 -C 12)-alkyl, CONH-(C 1 -C 12)-alkyl, -CO-(C 1 -C 12)-alkyl, -CO-(C 6 -C 20)-aryl, -COOH, -OH, -SO 3 H, -NH 2, -N[(C 1 -C 12)-alkyl] 2; R 9 ', R 10 ', R 11 ', R 12 ', R 9 ", R 10 ", R 11 ", R 12 " are selected from: -H, -(C 6 -C 20)-aryl; where the alkyl and aryl groups mentioned may be substituted as follows: (C1-C12)-alkyl and O-(C1-C12)-alkyl may each be unsubstituted or substituted by one or more identical or different radicals selected from (C3-C12)-cycloalkyl, (C3-C12)-heterocycloalkyl, (C6-C20)-aryl, fluorine, chlorine, cyano, formyl, acyl and alkoxycarbonyl; substituted -(C6-C20)-aryl groups and -(C6-C20)-aryl-(C6-C20)-aryl groups may have one or more substituents, depending on the ring size; these substituents are each independently selected from -H, -(C1-C12)-alkyl, -O-(C1-C12)-alkyl, -O-(C6-C20)-aryl, -(C6-C20)-aryl, halogen, -COO-(C1-C12)-alkyl, -CONH-(C1-C12)-alkyl, - (C6-C20)-aryl-CON[(C1-C12)-alkyl]2, -CO-(C1-C12)-alkyl, -CO-(C6-C20)-aryl, -COOH, -OH, -SO 3 H, -SO3Na, NO2, - CN, -NH2, -N[(C1-C12)-alkyl]2. R 1, R 2, R 3, R 4, R 5, R 6, R 7, R 8 are selected from: -H, -(C 1 -C 12)-alkyl, -O-(C 1 -C 12)-alkyl, -O-(C 6 -C 20)-aryl, - (C 6 -C 20)-aryl, -S-alkyl, -S-aryl, halogen, COO-(C 1 -C 12)-alkyl, CONH-(C 1 -C 12)-alkyl, -CO-(C 1 -C 12)-alkyl, -CO-(C 6 -C 20)-aryl, -COOH, -OH, -SO 3 H, -CN, -NH 2, -N[(C 1 -C 12)-alkyl] 2; R 1 ', R 2 ', R 3 ', R 4 ', R 5 ', R 6 ', R 7 ', R 8 ', R 1 ", R 2 ", R 3 ", R 4 ", R 5 ", R 6 ", R 7 ", R 8 " are selected from: -H, -(C 1 -C 12)-alkyl, -O-(C 1 -C 12)-alkyl, -O-(C 6 -C 20)-aryl, -(C 6 -C 20)-aryl, -S-alkyl, -S-aryl, halogen, COO-(C 1 -C 12)-alkyl, CONH-(C 1 -C 12)-alkyl, -CO-(C 1 -C 12)-alkyl, -CO-(C 6 -C 20)-aryl, -COOH, -OH, -SO 3 H, -NH 2, -N[(C 1 -C 12)-alkyl] 2; R 9 ', R 10 ', R 11 ', R 12 ', R 9 ", R 10 ", R 11 ", R 12 " are selected from: -H, -(C 6 -C 20)-aryl; (C1-C12)-alkyl and O-(C1-C12)-alkyl may each be unsubstituted or substituted by one or more identical or different radicals selected from (C3-C12)-cycloalkyl, (C3-C12)-heterocycloalkyl, (C6-C20)-aryl, fluorine, chlorine, cyano, formyl, acyl and alkoxycarbonyl; substituted -(C6-C20)-aryl groups and -(C6-C20)-aryl-(C6-C20)-aryl groups may have one or more substituents, depending on the ring size; these substituents are each independently selected from -H, -(C1-C12)-alkyl, -O-(C1-C12)-alkyl, -O-(C6-C20)-aryl, -(C6-C20)-aryl, halogen, -COO-(C1-C12)-alkyl, -CONH-(C1-C12)-alkyl, - (C6-C20)-aryl-CON[(C1-C12)-alkyl]2, -CO-(C1-C12)-alkyl, -CO-(C6-C20)-aryl, -COOH, -OH, -SO 3 H, -SO3Na, NO2, - CN, -NH2, -N[(C1-C12)-alkyl]2.