title: Molecular modeling of dipeptide and its analogous systems with water.
abstract: Intermolecular hydrogen-bond interactions in the monohydrated complexes of formamide, N-methylacetamide and glycylglycine have been studied using ab initio and DFT methods. The geometries were optimized using second-order Møller-Plesset perturbation theory and the B3LYP DFT functional with the 6-311++G** basis set. It is observed that hydrogen-bond interactions at the carbonyl group of the peptide moiety are stronger than those at the amino group of the formamide and N-methylacetamide molecules. Because of the presence of cyclic hydrogen-bonding interactions in glycylglycine, the interaction at the amino group is higher than at the carbonyl. The 13C and 15N NMR shielding values were calculated for the non-hydrated and monohydrated complexes. Condensed Fukui functions have also been calculated for non-hydrated formamide, N-methylacetamide and glycylglycine molecules at the B3LYP/6-311++G** level of theory, and the results are discussed.
authors.affiliation: Department of Physics, Bharathiar University, 641 046, Coimbatore, India.
authors.forename: Paranthaman
authors.initials: P
authors.lastname: Selvarengan
authors.forename: Ponmalai Gounder
authors.initials: PG
authors.lastname: Kolandaivel
mesh_terms: D000081:Acetamides / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D003198:Computer Simulation; D004151:Dipeptides / Q000737:chemistry; D005998:Glycine / Q000737:chemistry*; D006033:Glycylglycine / Q000737:chemistry; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D012984:Software; D014867:Water / Q000737:chemistry*
chemical_list: D000081:Acetamides; D004151:Dipeptides; D010455:Peptides; D014867:Water; D006033:Glycylglycine; D002244:Carbon; D005998:Glycine; C018595:N-methylacetamide