A minimal core based fluorophore for selective detection of Zn(II) ions in aqueous solution and living cells

A minimal core based fluorophore was introduced as a selectively fluorescent “turn on” sensor for Zn2+ ions in aqueous solution. Addition of Zn2+ ions to the fluorophore generates a significant emission through a 1:1 ligand-to-metal complex. The fluorescence titration experiment of the minimal core based fluorophore with various metal ions shows that the pyromellitic diimide derivative also has the advantage of a high selectivity to Zn2+ ions over other metals such as Ni2+, or Co2+, Cu2+, Fe3+, Fe2+. More than 8 fold increase in the intensity of fluorescence was observed for the Zn2+-bound fluorophore compared to Zn-free fluorophore. Due to its small molecular size, the fluorophore was cell-permeable and successfully applied to the detection of Zn2+ in living cells. With its relatively high sensitivity to Zn2+ in living cells, the synthesized new fluorophore will be very useful in the studies on various biological functions of Zn2+.