Solvent-Induced Manipulation of Supramolecular Organic Frameworks

Supramolecular organic frameworks based on C-alkylresorcin­[4]­arenes (RsCn) and the conformationally flexible spacer 1,2-bis­(4-pyridyl)­ethane (bpea) are discussed here. The conformational flexibility of bpea was predetermined with the help of electronic structure calculations of bpea in the gas and solution phases. The architectures of these frameworks are primarily governed by O–H···O and O–H···N intermolecular hydrogen-bonding interactions between the components of the frameworks. The unique arrangement of the bpea spacer around RsCn yields continuous 1D wavelike and 1D lateral hydrogen-bonded frameworks. The cocrystals of RsCn with bpea show conformational variation as a function of a change in the solvent of crystallization. In acetonitrile, the bpea spacer exists in the trans form, whereas in ethanol it adopts both gauche and trans forms. RsCn, on the other hand, adopts a pinched-cone conformation in both solvents. The extended frameworks of RsCn–bpea in ethanol enclose continuous channels filled with arrays of hydrogen-bonded gauche-bpea molecules.