Hydrogen bonded network of 1,1-cyclobutanedicarboxylic acid (CBD) salts: Effect of amine backbone on supramolecular assembly

Abstract

A new series of salts containing 1,1-cyclobutanedicarboxylic acid (CBD) and amines with a diverse backbone (aliphatic, alicyclic, aromatic, and heterocyclic) were designed and synthesized. Twelve new salts (CBD-1 to CBD-12) were prepared and characterized by various physicochemical techniques such as FT-IR, 1H NMR, and X-ray crystallography (9 out of 12 salts). Various hydrogen-bonded motifs present in CBD salts were assigned graph set representation and compared with the known CBD salts (using CSD search) to discover the similarity/dissimilarity between packing in these salts and to understand the role of amine backbone on the hydrogen-bonded network in these salts. The quantitative analysis of non-covalent interaction in CBD salts was carried out using Hirshfeld surface analysis. Hydrogen bonded network of salts (CBD-1 to CBD-3, CBD-5, CBD-6, CBD-9 to CBD-12) displayed a plethora of supramolecular synthons and graph set representation ranging from conventional graph set representation R22(8) and R44(12) frequently observed in PAM (Primary ammonium monocarboxylate) and PAD (Primary ammonium dicarboxylate) salts to unconventional R44(16), R22(14),R12(6), etc. Hirshfeld surface analysis establishes the van der Waals interaction as the most significant non-bonded interaction to control the overall supramolecular assembly in CBD salts.