A highly selective and sensitive fluorescent chemosensor for Zn2+

A new selective Zn2+ fluorescent chemosensor, o-vanillin-4-ethoxybenzoylhydrazone (1), was designed and prepared. Free 1 mainly displayed very weak fluorescence at 480 nm upon excitation at 403 nm. It displayed high selectivity for Zn2+ and had a 518-fold fluorescent enhancement upon binding of Zn2+, while the other cation ions had only little influence on the fluorescence of 1. Mechanism of enhancement of 1's fluorescence by Zn2+ was briefly discussed.