Structure and stability of glycine-(H2O)3 cluster and anion:: Zwitterion vs. canonical glycine

Calculations are presented for the glycine-(H2O)(3)(-) cluster anion, with glycine in canonical or zwitterionic form. The zwitterionic anions are predicted to be considerably lower in energy than the canonical anions,, and the latter forms are found to be prone to isomerization to the zwitterionic anions. Therefore, we predict that the zwitterionic anions would be observed predominantly in the gas phase at low temperature. In contrast, calculated stability of neutral glycine-(H2O)(3) clusters indicates that only the canonical forms of the anions would be observed in photoelectron experiments, if anions are produced from preformed neutrals. (C) 2006 Wiley Periodicals, Inc.