Hydrogen-Bonded Bridges in Complexes of o-Cyanophenol:  Laser-Induced Fluorescence and IR/UV Double-Resonance Studies

The o -cyanophenol molecule and its hydrogen-bonded complexes with one and two molecules of water and methanol have been investigated by laser-induced fluorescence excitation, dispersed emission, and IR/UV double-resonance spectroscopy combined with DFT calculations. The sole conformer observed in the jet has a cis geometry due to the stabilizing interaction between the OH and CN substituents. The shifts of the electronic transition and the modification of the OH ground-state frequencies together with the calculated geometry point to a cyclic structure of the complexes. In the 1:1 complexes, the solvent OH binds as a proton acceptor to the phenol OH and as a proton donor to the CN group. The 1:2 complexes involve in a similar way the insertion of the solvent dimer (water) 2 or (methanol) 2 between the OH and CN substituents of the molecule.