Substituent effects on the photophysical properties of fluorescent 2-benzoylmethylenequinoline difluoroboranes: A combined experimental and quantum chemical study Dedication: This publication is dedicated to the memory of Prof. Jerzy Pa̧czkowski

In this study, we demonstrate a successful synergy between theory and experiment and report on the photophysical properties of a recently synthesized series of substituted 2-benzoylmethylenequinoline difluoroboranes with a view towards the effect of substitution on their properties. In general difluoroboranes are known to have a bright fluorescence but for some analogs the properties are not fully understood. Quantum chemistry methods have been applied in order to explain a complex structure of the absorption and emission spectra and to gain an insight into the charge redistribution upon the excitation of the investigated molecules. We demonstrate that the spectra of this important class of compounds can be satisfactorily simulated using quantum chemistry methods. In particular, the absorption and emission band structure was resolved and the spectral features were assigned to C-H wagging and skeletal vibrations of the polycyclic core.