Synthesis and Photophysical Properties of Naphthalimide Schiff Bases

Abstract

A designed novel napthalimide based derivatives (abbreviated as probe 1 and probe 2) were synthesized and used as chromo-fluorescent sensor potentially. Probe 1 showed absorption peak at 420 nm and emission peak at 500 nm. Upon addition of CN⁻ ions, probe 1 displayed instant colour change from yellow to brown with a red shift of 40 nm. However, in case of emission spectra, formation of two emission bands was observed at 500 nm and 560 nm. The binding constant for probe 1.CN⁻ was determined to be 2.9108 M-1 and limit of detection was found to be 7.510-7 M. Probe 1 also showed its high selectivity towards Cr3+ ions through “turn-on” emission response at 500 nm. The determined binding constant for probe 1.Cr3+ was determined to be 6.0104 M-1, while limit of detection was calculated to be 7.610-9 M. On the other hand, probe 2 showed absorption peak at 430 nm and emission peak at 500 nm. In the presence of CN⁻ anion, red shift of 72 nm and formation of new band at 502 nm has been observed whereas no such change was detected in fluorescence spectra. Binding constant and limit of detection for CN⁻, was found to be 6.5105 M-1 and 6.010⁻⁸ M respectively.