| Abstract: | Cocrystallization of melamine (1,3,5‐triazine‐2,4,6‐triamine, ma) with (2‐carboxyethyl)(phenyl)phosphinic acid (H2L) from water affords the title compound, C3H7N6+·C9H10O4P−·H2O or (maH)(HL)·H2O, (I). The phosphinic acid H atom of each H2L molecule is transferred to a melamine molecule. Structural analysis reveals that there are two types of secondary building units in the crystal structure, namely cationic (maH+)2]∞ ribbons and anionic {(HL)2(H2O)2]2−}∞ layers, the combination of which through hydrogen‐bond and electrostatic interactions, generates a large‐scale two‐dimensional layered structure. The thick layer is sandwich‐like, with the central (maH+)2]∞ ribbons being further stabilized by π–π stacking interactions. It is also worthy of note that two conformational isomeric R65(24) hydrogen‐bond ring motifs can be identified in the {(HL)2(H2O)2]2−}∞ layer. |
