| abstract |
Compounds, most of which are novel, and which have been found to have properties very suitable for use in fluorescent inks intended for marking security documents, are of formula In wherein R¹, R², R³ and R⁴ are independently H, Z or Z-substituted phenyl; and Ar is optionally Z-substituted phenyl or heterocyclyl; in which the Z's are independently selected from C₁₋₄alkyl, OH, C₁-C₄ alkoxy, halogen, NO₂, NH₂, C₁₋₄ alkylamino, di(C₁₋₄ alkyl)amino and phenyl; provided that R¹, R², R³ and R⁴ are not all H when Ar is alkylphenyl or alkoxyphenyl. |