title: Hydrogen-Bond Cooperativity in Formamide2 -Water: A Model for Water-Mediated Interactions.
abstract: The rotational spectrum of formamide2 -H2 O formed in a supersonic jet has been characterized by Fourier-transform microwave spectroscopy. This adduct provides a simple model of water-mediated interaction involving the amide linkages, as occur in protein folding or amide-association processes, showing the interplay between self-association and solvation. Mono-substituted (13) C, (15) N, (18) O, and (2) H isotopologues have been observed and their data used to investigate the structure. The adduct forms an almost planar three-body sequential cycle. The two formamide molecules link on one side through an N-H⋅⋅⋅O hydrogen bond and on the other side through a water-mediated interaction with the formation of C=O⋅⋅⋅H-O and O⋅⋅⋅H-N hydrogen bonds. The analysis of the quadrupole coupling effects of two (14) N-nuclei reveals the subtle inductive forces associated to cooperative hydrogen bonding. These forces are involved in the changes in the C=O and C-N bond lengths with respect to pure formamide.
authors.affiliation: Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, 47011, Valladolid, Spain.
authors.forename: Susana
authors.initials: S
authors.lastname: Blanco
authors.affiliation: Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, 47011, Valladolid, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Pinacho
authors.affiliation: Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, 47011, Valladolid, Spain. jclopez@qf.uva.es.
authors.forename: Juan Carlos
authors.identifier: 0000-0003-1028-779X
authors.initials: JC
authors.lastname: López
keywords: cooperative effects; formamide; hydrogen bonds; rotational spectroscopy; water-mediated interactions