OH stretching vibrations and hydrogen-bonded structures of 7-hydroxyquinoline-(H2O)1-3 investigated by IR-UV double-resonance spectroscopy

Hydrogen(H)-bonded structures of 7-hydroxyquinoline-(H2O)(n) clusters were investigated based on the analysis of the infrared spectra of the OH stretching vibrations in combination with ab initio calculations. For 7-hydroxyquinoline-(H2O)(1), two isomers due to different H-bonding sites were found to coexist: in one of them 7-hydroxyquinoline acts as a proton donor. and in the other the OH group of water is H-bonded to the nitrogen site of 7-hydroxyquinoline. For 7-hydroxyquinoline-(H2O)(2-3). the structures were determined to be bridge forms, in which a linear-form water cluster is H-bonded to the OH hydrogen and to the nitrogen of 7-hydroxyquinoline. (C) 2001 Elsevier Science B.V. All rights reserved.