Patent ID: 8821762

Claim:
A compound of formula I wherein R 1 and R 2 are independently of each other halogen, —CN, —NC, —NCO, —NCS, —OCN, —SCN, —C(═O)NR 0 R 00 , —C(═O)X 0 , —C(═O)R 0 , —NH 2 , —NR 0 R 00 , —SH, —SR 0 , —SO 3 H, —SO 2 R 0 , —OH, —NO 2 , —CF 3 , —SF 5 , an optionally substituted silyl or germanyl group, or an optionally substituted carbyl or hydrocarbyl group that optionally comprises one or more hetero atoms, R 3-6 are independently of each other H, halogen, —CN, —NC, —NCO, —NCS, —OCN, —SCN, —C(═O)NR 0 R 00 , —C(═O)X 0 , —C(═O)R 0 , —NH 2 , —NR 0 R 00 , —SH, —SR 0 , —SO 3 H, —SO 2 R 0 , —OH, —NO 2 , —CF 3 , —SF 5 , an optionally substituted silyl group, or an optionally substituted carbyl or hydrocarbyl group that optionally comprise one or more hetero atoms, wherein a pair of groups R 3 and R 4 or R 5 and R 6 optionally form a ring system with each other or with the benzene ring to which they are attached, X 0 is halogen, R 0 and R 00 are independently of each other H or an optionally substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 C atoms, and wherein the benzene rings are optionally substituted by one or more additional groups R 6 .