Supramolecular Assembly of Tris(4-carboxyphenyl)arenes: Relationship between Molecular Structure and Solid-State Catenation Motifs

The crystal structures of seven 1,3,5-tris­(4-carboxyphenyl)­arenes with functionalized central arene rings are reported. The formation of (6,3) hcb hexagonal sheets as a result of carboxylic acid dimer formation was observed in most of the crystal structures, with the exception of two compounds with functional groups capable of forming hydrogen bonds, namely, 2,4,6-tris­(4-carboxyphenyl)-1,3-diaminobenzene and 2,4,6-tris­(4-carboxyphenyl)-3-methylaniline. These structures were found to incorporate THF solvent molecules in their hydrogen-bonding motif, giving rise to distorted pseudohexagonal arrays. Functional groups on the central ring were found to influence stacking distances, stacking offsets, inclination angles, degree of catenation, and dimensions of solvent-occupied channels. To better understand and appreciate these complicated crystal structures, they were categorized into four distinct stacking/catenation families: simple stacking, single-layer offset catenation, double-layer offset catenation, and rotated-layer catenation. The unique structure of the unfunctionalized parent compound 1,3,5-tris­(4-carboxyphenyl)­benzene is rationalized in light of the structural behavior of its derivatives.