Compound of formula a) which is substituted at at least one of the carbon atoms 1, 2, 3, 4, 5, 6, 7, 8 with a moiety R acryl of formula where in said formula R 1 is hydrogen or a (C 1 -C 6)-alkyl group, X is a carboxamide (-C N-) or a carboxylic ester (-C O-) or a sulphonamide (-SO 2 N-) group, Y is a saturated or unsaturated or linear or branched optionally substituted moiety having 2-10 carbon atoms or a polyether having from one up to five (-CH 2 -CH 2 -O-)- or (-C(CH 3)H-CH 2 -O-)- groups or a polyamine having from one to five nitrogen atoms, and Z is oxygen or sulphur, b) and the compound of formula is at not less than one further carbon atom, 1, 2, 3, 4, 5, 6, 7, 8 substituted with a moiety of formula where in said formula the carbon atoms of the compound of formula are each independently substituted with hydrogen, halogen, a cyano group, a nitro group or an optionally substituted alkyl, alkenyl, alkynl, aralkyl, aryl or heteroaryl group or an optionally substituted alkylthio group or any substituted carbamoyl group, which also may be linked bridgingly to a moiety of formula, or a trifluoromethyl group or a trifluoromethoxy group or a moiety R acryl ' of formula, where in said formula R 1' is hydrogen or a (C1-C6)-alkyl group, X' is a carboxamide (-C N-) or a carboxylic ester (-C O-) or a sulphonamide (-SO 2 N-) group, Y' is a saturated or unsaturated or linear or branched optionally substituted moiety having 2-10 carbon atoms or a polyether having from one to five (-CH 2 -CH 2 -O-)- or (-C(CH 3)H-CH 2 -O-)- groups or a polyamine having from one to five nitrogen atoms, and Z is oxygen or sulphur, c) the remaining carbon atoms of the compound of formula are each independently substituted with hydrogen, halogen, a cyano group, a nitro group or an optionally substituted alkyl, alkenyl, alkynyl, aralkyl, aryl or heteroaryl group or an optionally substituted alkylthio group or a trifluoromethyl group or a trifluoromethoxy group. a) which is substituted at at least one of the carbon atoms 1, 2, 3, 4, 5, 6, 7, 8 with a moiety R acryl of formula where in said formula R 1 is hydrogen or a (C 1 -C 6)-alkyl group, X is a carboxamide (-C N-) or a carboxylic ester (-C O-) or a sulphonamide (-SO 2 N-) group, Y is a saturated or unsaturated or linear or branched optionally substituted moiety having 2-10 carbon atoms or a polyether having from one up to five (-CH 2 -CH 2 -O-)- or (-C(CH 3)H-CH 2 -O-)- groups or a polyamine having from one to five nitrogen atoms, and Z is oxygen or sulphur, R 1 is hydrogen or a (C 1 -C 6)-alkyl group, X is a carboxamide (-C N-) or a carboxylic ester (-C O-) or a sulphonamide (-SO 2 N-) group, Y is a saturated or unsaturated or linear or branched optionally substituted moiety having 2-10 carbon atoms or a polyether having from one up to five (-CH 2 -CH 2 -O-)- or (-C(CH 3)H-CH 2 -O-)- groups or a polyamine having from one to five nitrogen atoms, and Z is oxygen or sulphur, b) and the compound of formula is at not less than one further carbon atom, 1, 2, 3, 4, 5, 6, 7, 8 substituted with a moiety of formula where in said formula the carbon atoms of the compound of formula are each independently substituted with hydrogen, halogen, a cyano group, a nitro group or an optionally substituted alkyl, alkenyl, alkynl, aralkyl, aryl or heteroaryl group or an optionally substituted alkylthio group or any substituted carbamoyl group, which also may be linked bridgingly to a moiety of formula, or a trifluoromethyl group or a trifluoromethoxy group or a moiety R acryl ' of formula, where in said formula R 1' is hydrogen or a (C1-C6)-alkyl group, X' is a carboxamide (-C N-) or a carboxylic ester (-C O-) or a sulphonamide (-SO 2 N-) group, Y' is a saturated or unsaturated or linear or branched optionally substituted moiety having 2-10 carbon atoms or a polyether having from one to five (-CH 2 -CH 2 -O-)- or (-C(CH 3)H-CH 2 -O-)- groups or a polyamine having from one to five nitrogen atoms, and Z is oxygen or sulphur, R 1' is hydrogen or a (C1-C6)-alkyl group, X' is a carboxamide (-C N-) or a carboxylic ester (-C O-) or a sulphonamide (-SO 2 N-) group, Y' is a saturated or unsaturated or linear or branched optionally substituted moiety having 2-10 carbon atoms or a polyether having from one to five (-CH 2 -CH 2 -O-)- or (-C(CH 3)H-CH 2 -O-)- groups or a polyamine having from one to five nitrogen atoms, and Z is oxygen or sulphur, c) the remaining carbon atoms of the compound of formula are each independently substituted with hydrogen, halogen, a cyano group, a nitro group or an optionally substituted alkyl, alkenyl, alkynyl, aralkyl, aryl or heteroaryl group or an optionally substituted alkylthio group or a trifluoromethyl group or a trifluoromethoxy group.