Crystal structure and Hirshfeld surface analysis of 1-carb­oxy-2-(34-di­hydroxy­phen­yl)ethan-1-aminium bromide 2-ammonio-3-(34-di­hydroxy­phen­yl)propano­ate

摘要

In the title mol­ecular salt, C9H12NO4 ⁺·Br⁻·C9H11NO4, one of the dopa mol­ecules is in the cationic form in which the α-amino group is protonated and the α-carb­oxy­lic acid group is uncharged, while the second dopa mol­ecule is in the zwitterion form. The Br⁻ anion occupies a special position and is located on a twofold rotation axis. The two dopa mol­ecules are inter­connected by short O—H⋯O hydrogen bonds. In the crystal, the various units are linked by O—H⋯O, N—H⋯Br and N—H⋯O hydrogen bonds, forming a three-dimensional framework. The title compound was refined as an inversion twin with an absolute structure parameter of 0.023 (8).