A reversible fluorescent-colorimetric imino-pyridyl bis-Schiff base sensor for expeditious detection of Al3+ and HSO3- in aqueous media

摘要

A reversible fluorescent-colorimetric imino-pyridyl bis-Schiff base receptor L ((NE)-E-1, (NE)-E-4)-N-1,N-4-bis(pyridine-4-ylmethylene)benzene-1,4-diamine for the detection of both Al3+ and HSO3- in aqueous medium has been developed. Receptor L exhibits an excellent selective fluorescent-colorimetric response toward Al3+. The sensitivity of the fluorescent based assay (0.903 mu M) for Al3+ is far below the limit recommended in the World Health Organization (WHO) guidelines for drinking water (7.41 mu M). From H-1 NMR data, the Job plot and the ESI-MS spectrum, 1 : 2 stoichiometric complexation between L and Al3+ has been established. Receptor L shows remarkable detection ability in a wide pH range of 4-11 and was successfully utilised in the determination of Al3+ in aqueous solution of bovine serum albumin protein, and of HSO3 in real food samples. Moreover, L shows a highly selective colorimetric response to HSO3- by changing its colour from yellow to colorless immediately without any interference from other anions.