Gear Alignments Due to Hydrogen-Bonded Networks in a Crystal Structure of Resorcyltriptycene Hydrate and Its Transformation to a Nongearing Anhydrate Crystal by Heating

摘要

Construction of hydrogen-bonded networks among hydroxyl groups has often been utilized to synthesize specific structures on the basis of supramolecular chemistry. In this study, resorcyltriptycene was designed as a possible component of a crystalline molecular gear, because the molecule has a triptycyl wheel and a resorcyl linker which can be involved in intermolecular alignments in a crystal, as mediated by hydrogen-bonded networks. The synthesis and crystal structure of resorcyltriptycene are reported here. The gear alignment among triptycyls in a crystalline state was achieved in a crystal structure of resorcyltriptycene containing water in the intermolecular spaces. However, rotations of triptycyls in the crystalline state was suppressed by steric interaction with the water molecules. This crystal structure was stabilized by O-H center dot center dot center dot C-pi(phenyl) interactions between triptycyl and the hydrated water. Moreover, single crystals without solvent and with methanol were obtained from a dry toluene solution and a methanol solution, respectively. Transformations among the single crystals were observed by heating or drying or soaking in a solvent. It is significant that various crystal structures dependent on the condition were observed. The observed phenomena should aid the design of functional crystals.