Colorimetric probe and optical behaviours of new azomethine derivatives of sulfonamide

Abstract

Syntheses, colorimetric anion probe properties, density functional theory (DFT) studies, and optical properties of the Schiff bases; 4-fluoro-N-(2-hydroxy-5-methylbenzylidene) benzenesulfonamide (1), 4-fluoro-N-(2-hydroxy-5-nitrobenzylidene)benzenesulfonamide (2) and 4-fluoro-N-[(2-hydroxynaphthalen-1-yl)methylene]benzenesulfonamide (3) were reported. The structure of the compounds was elucidated using MS, FTIR, and UV-visible spectroscopic techniques. Their structures were examined by theoretical calculations using density functional theory (DFT). The colorimetric response of the Schiff base receptors in DMSO was investigated before and after the addition of an equivalent amount of each anion to evaluate the anion recognition properties. The ultrafast transient absorption spectroscopy measurements were performed to investigate the energy transfer dynamics and decay kinetics of the compounds 1-3. The fluorescence and wavelength-dependent pump-probe measurements of the compounds showed that the excited state lifetime of compound 2 is shorter than compounds 1 and 3. The fluorescence properties of compounds 1-3 were compatible with the pump-probe spectroscopy measurements. The compounds with longer ESA lifetimes showed higher fluorescence.