A compound of the general formula (1) ** Formula ** where Y1, Y1 ', Y2, Y2', Y3, Y3 ', Y4 and Y4' in each case are independently selected from each other from the group consisting of - H, -F, -Cl, -Br, -I, -CN, -NO2, -CHO, -R0, -C (>； = O) R0, -C (>； = O) H, -C (>； = O ) -OH, -C (>； = O) OR0, -C (>； = O) NH2, -C (>； = O) NHR0, - C (>； = O) N (R0) 2, -OH, -OR0, -OC (>； = O) H, -OC (>； = O) R0, -OC (>； = O) OR0, -OC (>； = O) NHR0, -OC (>； = O) N (R0) 2, - SH, -SR0, -SO3H, - S (>； = O) 1-2-R0, -S (>； = O) 1-2NH2, -NH2, -NHR0, -N (R0) 2, -N + (R0) 3, -N + (R0) 2O-, -NHC (>； = O) R0, -NHC (>； = O) OR0, -NHC (>； = O) NH2, - NHC (>； = O) NHR0 and -NHC (>； = O) N (R0) 2； or Y1 and Y1 ', or Y2 and Y2', or Y3 and Y3 ', or Y4 and Y4' together represent>； = O； X1, X1 ', X2, X2', X3 and X3 'in each case independently represent each other -H, -F, -Cl, -Br, -I, -NO2, -CF3, -OR5, - SR5, -SO2R5 , -S (>； = O) 2OR5, -CN, -COOR5, -CONR5, -NR6R7, or -R0； or X1 and X1 ', or X2 and X2', or X3 and X3 'together represent>； = O； or X1 and X2, or X2 and X3 together represent - (CH2) 2-6-, where the individual hydrogen atoms can also be substituted by -F, -Cl, -Br, -I, -NO2, -CF3, - OR5, -CN or -C1-6-aliphatic； or X1 and X1 ', or X2 and X2' or X3 and X3 'together represent a C3-6-cycloaliphatic, where individual hydrogen atoms can also be substituted by -F, -Cl, -Br, -I, -NO2 , -CF3, -OR5, -CN or -C1-6-aliphatic； R0 in each case independently represents -C1-8-aliphatic, -C3-12-cycloaliphatic, -aryl, -heteroaryl, -C1-8-aliphatic-C3-12-cycloaliphatic, -C1-8-aliphatic-aryl, -C1 -8-aliphatic-heteroaryl, -C3-8-cycloaliphatic-C1-8-aliphatic, -C3-8-cycloaliphaticaryl or -C3-8-cycloaliphatic-heteroaryl； R1 and R2 independently represent each other -H or -R0； or R1 and R2 together represent -CH2CH2OCH2CH2-, -CH2CH2NR8CH2CH2- or - (CH2) 3-6-； R3 represents -R0； R4 represents H or -Z-R11, where Z may be absent or -C (>； = O) -, -S (>； = O) - or -S (>； = O
