A compound characterized by a general formula (A), wherein - R 1 is selected from, -OH, -SH and -NH 2 ; - R 2 is selected from -NO 2 , -SO 3 H, -SO 2 -OR 11 , -SO 2 -NH 2 , -SO 2 -NHR 11 , -SO 2 -NR 11 2 , -PO 3 H, -PO 2 -OR 11 , -CN, -COR 11 , -CO 2 R 11 , -CONHR 11 , -CONR 11 2 , -CF 3 , and halogen; - R 3 is selected from H, -NO 2 , -SO 3 H, -SO 2 -OR 11 , -SO 2 -NH 2 , -SO 2 -NHR 11 , -SO 2 -NR 11 2 ; -PO 3 H, -PO 2 -OR 11 , -CN, -COR 11 , -CO 2 R 11 , -CONHR 11 , -CONR 11 2 , -CF 3 , and halogen; - R 4 and R 5 are independently selected from -H, substituted C 1 -C 6 alkyl, unsubstituted C 1 -C 6 alkyl, substituted or unsubstituted C 2 -C 6 alkenyl, substituted or unsubstituted C 3 -C 6 cycloalkyl, halogen, -CN and -NO 2 ; - one of R 6 and R 7 is selected from, -CONR 9 2 and -CONR 11 R 9 and the other one of R 6 and R 7 is H, wherein - R 9 is R 10 -(Y-R 10 ) n - Y is selected from -CONR 11 -, -CO-, -COO-, -SO 3 -, -SO 2 NH-, -NR 11 -, -O-, -NR 11 CO-, -OCO-, -NR 11 COO-, -NR 11 CONR 11 -, -OCONR 11 - and -OCOO- - n is an integer selected from 0, 1, 2, 3 and 4, - each R 10 independently of any other R 10 is selected from a substituted or unsubstituted C 1 -C 8 alkyl, substituted or unsubstituted a C 2 -C 8 alkenyl, a substituted or unsubstituted C 2 -C 8 alkynyl, substituted or unsubstituted a C 3 -C 10 cycloalkyl and a substituted or unsubstituted 5- to 10- membered aryl or heteroaryl; and - each R 11 independently of any other R 11 is H or an unsubstituted C 1 -C 6 alkyl. - R 1 is selected from, -OH, -SH and -NH 2 ; - R 2 is selected from -NO 2 , -SO 3 H, -SO 2 -OR 11 , -SO 2 -NH 2 , -SO 2 -NHR 11 , -SO 2 -NR 11 2 , -PO 3 H, -PO 2 -OR 11 , -CN, -COR 11 , -CO 2 R 11 , -CONHR 11 , -CONR 11 2 , -CF 3 , and halogen; - R 3 is selected from H, -NO 2 , -SO 3 H, -SO 2 -OR 11 , -SO 2 -NH 2 , -SO 2 -NHR 11 , -SO 2 -NR 11 2 ; -PO 3 H, -PO 2 -OR 11 , -CN, -COR 11 , -CO 2 R 11 , -CONHR 11 , -CONR 11 2 , -CF 3 , and halogen; - R 4 and R 5 are independently selected from -H, substituted C 1 -C 6 alkyl, unsubstituted C 1 -C 6 alkyl, substituted or unsubstituted C 2 -C 6 alkenyl, substituted or unsubstituted C 3 -C 6 cycloalkyl, halogen, -CN and -NO 2 ; - one of R 6 and R 7 is selected from, -CONR 9 2 and -CONR 11 R 9 and the other one of R 6 and R 7 is H, wherein - R 9 is R 10 -(Y-R 10 ) n - Y is selected from -CONR 11 -, -CO-, -COO-, -SO 3 -, -SO 2 NH-, -NR 11 -, -O-, -NR 11 CO-, -OCO-, -NR 11 COO-, -NR 11 CONR 11 -, -OCONR 11 - and -OCOO- - n is an integer selected from 0, 1, 2, 3 and 4, - each R 10 independently of any other R 10 is selected from a substituted or unsubstituted C 1 -C 8 alkyl, substituted or unsubstituted a C 2 -C 8 alkenyl, a substituted or unsubstituted C 2 -C 8 alkynyl, substituted or unsubstituted a C 3 -C 10 cycloalkyl and a substituted or unsubstituted 5- to 10- membered aryl or heteroaryl; and - each R 11 independently of any other R 11 is H or an unsubstituted C 1 -C 6 alkyl. - R 9 is R 10 -(Y-R 10 ) n - Y is selected from -CONR 11 -, -CO-, -COO-, -SO 3 -, -SO 2 NH-, -NR 11 -, -O-, -NR 11 CO-, -OCO-, -NR 11 COO-, -NR 11 CONR 11 -, -OCONR 11 - and -OCOO- - n is an integer selected from 0, 1, 2, 3 and 4, - each R 10 independently of any other R 10 is selected from a substituted or unsubstituted C 1 -C 8 alkyl, substituted or unsubstituted a C 2 -C 8 alkenyl, a substituted or unsubstituted C 2 -C 8 alkynyl, substituted or unsubstituted a C 3 -C 10 cycloalkyl and a substituted or unsubstituted 5- to 10- membered aryl or heteroaryl; and - each R 11 independently of any other R 11 is H or an unsubstituted C 1 -C 6 alkyl. <EOS>