Naphthalene based colorimetric sensor for bioactive anions: experimental and DFT study.

A simple anion selective colorimetric sensor L has been designed by combining 2-hydroxy-1-naphthaldehyde with 2-aminothiophenol. Sensor L portrayed a necked-eye detectable color change from light green to red upon addition of AcO(-), F(-) and H(2)PO(4)(-) anions in CH(3)CN, where as no significant color change was observed upon addition of other anions such as Cl(-), Br(-), I(-) and HSO(4)(-). Sensor L showed selectivity towards AcO(-) under competitive environment, with a detection limit (3σ/S) down to 1.1×10(-7) M. In addition, the anion sensing ability of L was explored in mixed H(2)O/CH(3)CN (v/v) medium. Further, the nature of interactions between the sensor L and AcO(-) was investigated by (1)H NMR and the probable structure of the L-AcO(-) complex was predicted by B3LYP/6-31G(d,p) method.