title: Crystal structure of zwitterionic 4-(ammonio-methyl)-benzoate: a simple mol-ecule giving rise to a complex supra-molecular structure.
abstract: The asymmetric unit of the title compound, C8H9NO2·H2O consists of an isolated 4-(ammonio-meth-yl)benzoate zwitterion derived from 4-amino-methyl-benzoic acid through the migration of the acidic proton, together with a water molecule of crystallization that is disordered over three sites with occupancy ratios (0.50:0.35:0.15). In the crystal structure, N-H⋯O hydrogen bonds together with π-π stacking of the benzene rings [centroid-centroid distance = 3.8602 (18) Å] result in a strongly linked, compact three-dimensional structure.
authors.affiliation: Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Casilla 233, Santiago, Chile.
authors.forename: Ana María
authors.initials: AM
authors.lastname: Atria
authors.affiliation: Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago de Chile, Chile.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Garland
authors.affiliation: Departamento de Física, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, Buenos Aires, Argentina.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Baggio
keywords: 4-(ammonio­meth­yl)benzoate; N—H⋯O hydrogen bonds; crystal packing; crystal structure; zwitterion; π–π stacking