Supramolecular chain-like aggregates and polymeric sandwich complexes constructed from p-sulfonatocalix[4,6]arenes with (8-hydroxy)quinoline guests

Abstract

Three crystalline complexes were prepared by the inclusion complexation of p-sulfonatocalix[4]arene with quinoline (1), p-sulfonatocalix[6]arene with quinoline (3) and 8-hydroxyquinoline (4), respectively. These crystals were compared to the reported p-sulfonatocalix[4]arene complex with 8-hydroxyquinoline (2). The results obtained show that p-sulfonatocalix[4]arene forms 1 : 1 included complexes for (8-hydroxy)quinoline guests with the pinched-cone conformation, whereas p-sulfonatocalix[6]arene forms 1 : 2 complexes with the centrosymmetric ‘up–down’ double partial cone conformation. Furthermore, the aggregation structures of complexes 1–4 are diverse from the common bilayer array for 2 to the chain-like aggregation for 1 and to the polymeric sandwich complexes for 3 and 4. These observations are carefully discussed from the viewpoints of host conformation, host–guest binding structure and stoichiometry, and the effect of counterion.