Thiosemicabazone based fluorescent chemosensor for transition metal ions in aqueous medium

Three highly sensitive aromatic thiosemicarbazones act as a fluorescent chemosensor for cations. Detection of transition metal ions was performed via UV-vis and fluorescence spectroscopic methods. This represents the first report on thiosemicarbazone based sensor capable of detecting transition metal ions in aqueous medium. The binding constant, stoichiometry of the complex was confirmed by using B-H plot and Job's plot method. The fluorescence enhancement of thiosemicarbazones on binding with Hg2+ , Zn2+, Co2+, Ni2+ and Sn2+ ions is due to the inhibition of photoinduced electron transfer whereas, in the case of Cu2+ and Mn2+ ions quenching of fluorescence occurring is attributed to the photoinduced electron transfer mechanism.154