A comparative experimental and theoretical investigation of hydrogen-bond, halogen-bond and π-π interactions in the solid-state supramolecular assembly of 2- and 4-formylphenyl arylsulfonates.

To explore the operational role of noncovalent interactions in supramolecular architectures with designed topologies, a series of solid-state structures of 2- and 4-formylphenyl 4-substituted benzenesulfonates was investigated. The compounds are 2-formylphenyl 4-methylbenzenesulfonate, CHOS, 3a, 2-formylphenyl 4-chlorobenzenesulfonate, CHClOS, 3b, 2-formylphenyl 4-bromobenzenesulfonate, CHBrOS, 3c, 4-formylphenyl 4-methylbenzenesulfonate, CHOS, 4a, 4-formylphenyl 4-chlorobenzenesulfonate, 4b, CHClOS, and 4-formylphenyl 4-bromobenzenesulfonate, CHBrOS, 4c. The title compounds were synthesized under basic conditions from salicylaldehyde/4-hydroxybenzaldehydes and various aryl sulfonyl chlorides. Remarkably, halogen-bonding interactions are found to be important to rationalize the solid-state crystal structures. In particular, the formation of O...X (X = Cl and Br) and type I X...X halogen-bonding interactions have been analyzed by means of density functional theory (DFT) calculations and characterized using Bader's theory of `atoms in molecules' and molecular electrostatic potential (MEP) surfaces, confirming the relevance and stabilizing nature of these interactions. They have been compared to antiparallel π-stacking interactions that are formed between the arylsulfonates.