The electronic origin of the ground state spectral features and excited state deactivation in cycloalkanones: the role of intermolecular H-bonding in neat and binary mixtures of solvents

In this study, a D–A cycloalkanone (K1) has been investigated by steady state absorption and fluorescence in neat solvents and in three binary mixtures of nonpolar aprotic/polar protic, polar aprotic/polar protic, and polar protic/polar protic solvents. The experimental findings were complemented by density functional theory (DFT), time-dependent density functional theory (TD-DFT), and NBO quantum-mechanical calculations. Experimentally, effective changes in absorption and fluorescence were observed by solute–solvent interaction. The binary K1-solvent1-solv2 configuration, modeled at the B3LYP-DFT level, confirms involvement of inter-molecular H-bonding with the carbonyl C=O in the fluorescence deactivation process (quenching). This is supported by considerable electron delocalization from C=O to the solvent’s hydroxyl (nO → σ*H-O). This type of hyperconjugation was found to be the main driver for solute–solvent stabilization.

Other Information

Published in: Journal of Molecular Modeling
License: https://creativecommons.org/licenses/by/4.0
See article on publisher's website: http://dx.doi.org/10.1007/s00894-019-4015-6