Water complexes of styrene and 4-fluorostyrene: A combined electronic, vibrational spectroscopic and ab-initio investigation

Abstract

The binary complexes of water with styrene and fluorostyrene were investigated using LIF and FDIR spectroscopic techniques. The difference in the shifts of S-1 -> S-0 electronic transitions clearly points out the disparity in the intermolecular structures of these two binary complexes. The FDIR spectra in the O-H stretching region indicate that water is a hydrogen bond donor in both complexes. The formation of a single O-H center dot center dot center dot pi hydrogen-bonded complex with styrene and an in-plane complex with fluorostyrene was inferred based on the analysis of the FDIR spectra in combination with ab initio calculations. The in-plane complex with fluorostyrene is characterized by the presence of O-H center dot center dot center dot F and C-H center dot center dot center dot O hydrogen bonds, leading to formation of a stable six-membered ring. The synergistic effect of O-H center dot center dot center dot F and C-H center dot center dot center dot O hydrogen bonds overwhelms the O-H center dot center dot center dot pi interaction in fluorostyrene-water complexes.