Novel selective "on-off" fluorescence sensor based on julolidine hydrazone-Al complex for Cu ion: DFT study.

A hydrazone (T1) was synthesized by reacting 8-hydroxyjulolidine-9-carboxaldehyde with 2-furoic hydrazide and then modified with Al ion to form a novel hydrazone Al complex (T1-Al) in an aqueous solution (8% propylene glycol in 10 mM HEPES pH 5.5). The T1-Al complex was studied as a Cu selective sensor due to its highly efficient capacibility of paramagnetic quenching. The results showed that the T1-Al complexed sensor possesses remarkable sensitivity and selectivity for Cu ion in 8% propylene glycol in 10 mM HEPES pH 5.5 as compared with other tested analytes. Notably, this sensor has a broad linear detection range of 10-110 µM for Cu ion and a detection limit level of 0.62 µM, which is lower than the Cu concentration threshold in drinking water designated by the United States Environmental Protection Agency (EPA). Additionally, it was detectable for the presence of Cu ion in mineral water and tap water samples. The selectivity of T1-Al complexed sensor with Cu ion could be explained by the basis of computation with Gaussian software complied with the basis sets of B3LYP/6-31 G(d,p)/LANL2DZ. Furthermore, only T1 exhibited anticancer efficacy against HeLa and U251 cells with MTT assay.