Crown ether-containing Schiff base as a highly efficient turn-on fluorescent sensor for determination and separation of Zn2+ in water

A highly efficient Zn2+ turn-on fluorescent sensor, [4'-benzo-15-crown-5]N-CH-(2-OH-C6H4) (HL), has been synthesized. In the presence of Zn(NO3)(2), HL displays high selectivity and sensitive enhancement of fluorescence intensity in water with the formation of [ZnL2]. Addition of an equimolar amount of KNO3 to [ZnL2] leads to the formation of {[KZnL2]NO3}(n).