Abstract: The invention provides a fluorescent whitening agent or optical brightener of formula (I) or (II) having the structure: (I) (II), wherein Y is Z or X?L; wherein: A is CR1R2(CH2)n wherein R1 is H, CH2OH or COZ, R2 is H or CH2OH and wherein n is 1 or 2, or wherein A is an optionally substituted aromatic or heteroaromatic ring fused with N and X wherein N and X are respectively bound to adjacent carbon atoms on the ring; X is O, S or N—H; Y is Z or X?L; the or each Z is independently OH, OM, OR3, O(CH2)qSO3M, NH2, NHOH, NHR4 or NR42, wherein M is selected from an alkali metal or an alkaline earth metal; R3 represents a linear or branched alkyl, an aryl, an alkaryl, an aralkyl, a linear or branched alkyl alcohol, a linear or branched alkyl alcohol polyol, a hydroxyalkylamine, a polyhydric alcohol, a sugar, a linear or branched alkyl ether, a polyester having from 2 to 1000 repeat units, or a polyoxyalkylene chain having from 2 to 1000 repeating units; q is 1 to 5; R4 is independently selected from methyl, ethyl,