title: Strong hydrogen-bonded amino acid dimers in L-alanine alaninium nitrate.
abstract: The title compound, C3H7NO2*C3H8NO2+*NO3-, contains L-alanine-alaninium dimers bonded via the carboxyl groups by a strong asymmetric hydrogen bond with an O...O distance of 2.4547 (19) A. The neutral alanine molecule exists as a zwitterion, where the carboxyl group is dissociated and the amino group is protonated. The alaninium cation has both groups in their acidic form. The alanine molecule and the alaninium cation differ only slightly in their conformation, having an N-C(alpha)-C=O torsion angle close to -25 degrees. The dimers and the nitrate anion are joined through a three-dimensional hydrogen-bond network, in which the full hydrogen-bonding capabilities of the amino groups of the two alanine moieties are realised.
authors.affiliation: CEMDRX, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, P-3004-516 Coimbra, Portugal.
authors.forename: M
authors.initials: M
authors.lastname: Ramos Silva
authors.forename: J A
authors.initials: JA
authors.lastname: Paixão
authors.forename: A
authors.initials: A
authors.lastname: Matos Beja
authors.forename: L
authors.initials: L
authors.lastname: Alte da Veiga
mesh_terms: D000409:Alanine / Q000031:analogs & derivatives / Q000737:chemistry*; D018360:Crystallography, X-Ray / Q000379:methods; D019281:Dimerization; D004151:Dipeptides / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation
chemical_list: D004151:Dipeptides; C435323:alanine alaninium nitrate; D000409:Alanine