Structural, Quantum Chemical and Spectroscopic Investigations on Photophysical Properties of Fluorescent Saccharide Sensor: Theoretical and Experimental Studies

Structure, Hirshfeld surface, spectra and photophysical properties of boronic acid-based carbohydrate sensor (5-fluoro-2-methoxyphenyl) boronic acid (BA8) has been reported by experimental methods (XRD/FT-IR/UV/steady state fluorescence) and theoretically by Density functional theory (DFT) model with most accurate functionals (B3LYP/CAM-B3LYP/ M06-2X). The comparison of theoretical and experimental data exhibited good agreement. Natural bond orbital (NBO) and frontier molecular orbitals (FMOs) have been analysed. The sensing ability of the compound with carbohydrates (D-glucose and D-fructose) were studied by UV/fluorescence spectra. The variation of absorbance and fluorescence on pH was rationale with the estimated acid-base dissociation constants (pKa). Quantum yield (phi) and fluorescence lifetimes (tau) for the compound and its esters with sugars were calculated. The results of absorbance, fluorescence measurements and calculated photophysical properties indicated fairly selectivity of BA8 with fructose more than the glucose, which is ascertained from both experimental and theoretical results.