Crystallographic and theoretical interpretation of supramolecular architecture in a new salt hydrate of DL-Tartaric acid and Dimethylamine (DLTA-DA)

Abstract

Herein, DL-tartaric acid normally used as a coformer in cocrystal engineering is exploited to create the hybrid molecule with secondary amine utilizing the supramolecular synthon approach. The crystal engineering tactics are potentially applied to a wide range of crystalline materials and the nature of the intermolecular interactions, hydrogen bonds in particular which decide the supramolecular stabilization of the solid form can be studied. The mechanochemical mixing of DL-tartaric acid and aqueous dimethylamine showed salt-pseudopolymorphism, resulted in N-methylmethanaminium-3-carboxy-2,3-dihydroxypropanoate hydrate. The interactions present between the molecules were demonstrated by simulating the FTIR spectrum which showed O − H stretching of the carboxylic group that did not match with experimental value as only one supramolecular unit was considered; whereas the experimental spectrum displayed a broad band for O − H stretch at 3200 cm−1. The salt crystallized in the monoclinic system with space group I2/a. The complementary hydrogen bond functionalities present in the molecules instilled the formation of O–H···O, O–H···N, and N − H···O intermolecular contacts. From the graph set analysis, it was noted that the supramolecular architecture was maintained by the homosynthon dimer and one-dimensional O–H···O anionic chain built by R22(12)and C(7) motifs. Additionally, the cage type assembly was formed by additional hydrogen bonds present in between the chains with H2O as a linker. The 2D fingerprint plots confirmed the maximum percentage contribution of -O–H (59%) towards the Hirshfeld surface. Hence, a full analysis of crystal packing and discussions in the context of the supramolecular chemistry of the salt hydrate is presented.