Highly sensitive and selective determination of cupric ions by using N,N′-bis(salicylidene)-o-phenylenediamine as fluorescent chemosensor and related applications

A sensitive and selective copper(II) fluorescence Schiff base chemical sensor receptor 1 (short for N,N′-bis(salicylidene)-o-phenylenediamine) has been prepared. The fluorescence of receptor 1 in pH 8.2 phosphate buffer solution can be dramatically quenched by Cu2+, whereas it is nearly unaffected by other metal ions. Based on this, a sensitive and selective fluorescent quenching method for Cu2+ detection has been established. Under the optimum conditions, a good linear relation exists between the quenching efficiency (F0/F) and the concentration of Cu2+ in the range of 1.0×10−7–2.5×10−6 mol L−1. The detection limit (3σ) for Cu2+ determination is 2.0×10−8 mol L−1. The present method has been successfully used for quantification of Cu2+ in soybean milk powder. Furthermore, the fluorescence switch property of the system was explored, and the system might be applied for determination of glutathione and construction of molecular logic gate.