Figure 5: (a) Cambridge Crystallographic Database (CSD) search queries for six-membered hydrogen bond conjugated rings between the two oxygens of the α-carboxylate with a molecule of water in the vicinity. Hydrogen bonds and long-range dipolar interactions are defined by the geometric constraints and Å and and Å. C (gray), N (blue), any group (cyan), H (light-yellow), and O (red). (b) Plot of the number of structures versus the distances (H1⋯O1) and (H2⋯O2). (c) Plot of the number of structures versus the distances (OW⋯O1) and (OW⋯O2). (d) Distribution of the torsion angle O1–C–O2⋯OWversus the number of structures.