Experimental and theoretical studies of the conformational structures of the mixed clusters of 1-cyanonaphthalene with water.

A concerted experimental (mass-selective, double-resonance laser spectroscopic technique) and theoretical (correlated quantum chemistry calculation) study of hydrogen-bonded clusters of 1-cyanonaphthalene (CNN) with water has been carried out to probe geometrical structures of the conformational isomers. The structures of the two low-energy conformers of CNN-H2O and CNN-(H2O)2, calculated at the MP2/cc-pVDZ level of theory, are consistent with the mass-selective infrared-ultraviolet double-resonance spectra and the partially resolved rotational band contours of the S1 <-- S0 origin bands. The facile loss of a neutral water molecule from the cluster ion of CNN-(H2O)2, relative to that of CNN-H2O, is in accord with the proposed structures of the clusters.