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Updated: Jan 30, 2026

Spatial Separation of Molecular Conformers and Clusters
Published on: January 9, 2014
The complete conformational panorama of formanilide-water complexes: the role of water as a conformational switch
Pablo Pinacho1, Susana Blanco, Juan Carlos López
1Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, E-47011 Valladolid, Spain. pablo.pinacho@uva.es sblanco@qf.uva.es jclopez@qf.uva.es.
Abstract:
The microsolvated complexes of formanilide, generated in a supersonic expansion, have been observed by Fourier transform microwave spectroscopy. Three 1 : 1 and one 1 : 2 formanilide-water adducts have been observed and their structures characterized by the measurement of isotopologue rotational spectra. In one of the monohydrated complexes and in the dihydrated complex, formanilide adopts a cis-configuration. In these species water closes sequential cycles with the cis amino and carbonyl groups through a network of N-HO and O-HO hydrogen bonds. Furthermore, in these complexes cis-formanilide has almost the same non planar configuration observed in the monomer. In the two monohydrated complexes detected with trans-formanilide, a planar skeleton is detected with water interacting solely with either the amino (N-H··O bond) or the carbonyl group (O-HO[double bond, length as m-dash]C bond). The observed tunnelling splittings show a rich intermolecular dynamics in those complexes. The results seem to indicate that complexation with water switches the configuration of formanilide from trans, which is more stable for the bare monomer, to cis, which is more stable for the hydrated complexes.
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