Supramolecular synthons in the guanidine-terephthalic acid system: Experimental and quantum chemical studies

Hydrogen bonds come in a wide range of lengths, strengths and geometries and are one of the major driving forces for supramolecular cohesion in solids. Predictable Hydrogen-bonding synthons are important tools for crystal structure prediction, a computational prediction of the arrangement of molecules in the unit cell, knowing just the molecular structure. Three new crystal structures containing the guanidinium cation and terephthalic acid derivatives are described and inspected for the existence of predominant synthons. The Cambridge Structural Database was surveyed looking for the prevalence of the main synthons in similar systems. Hirshfeld surface analysis and fingerprint plots were computed to identify and analyse the significant intermolecular interactions in the crystal assembling and to distinguish the contribution of the distinct moieties in the crystal structure construction. This study was complemented with molecular electrostatic potential surface calculations. Finally Mulliken population analyses were performed using density functional theory (B3LYP and 311++G(d,p) basis set) to reveal the partial atomic charges of the anions functional groups.