Crystal structure of zwitterionic 4-(ammoniomethyl)benzoate: a simple molecule giving rise to a complex supramolecular structure

Abstract

The asymmetric unit of the title compound, C8H9NO2·H2O consists of an isolated 4-(ammoniomethyl)benzoate zwitterion derived from 4-aminomethylbenzoic 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.