Aspects of Small-sized Cyclophanes in Terms of Weak Interactions Involving π Electron System

Abstract

Cyclophanes can provide the intriguing cyclic structure built by the aromatic components. In small–sized [2.n]metacyclophanes their unique physical and chemical properties are mainly due to transannular electronic effects in the forced proximity and particular orientation of two π systems. In order to gain deeper insight concerning this π electronic interaction we have carried out investigation of the diazo coupling reaction of the cyclophanes, estimation of the cationic character of the cyclophane diazonium salts, comparison of the cyclophane skeleton toward the spectral properties and reactivity, and introduction of the stilbene and oligothiophene units into the cyclophane structure. Conformations and molecular packing of the cyclophanes have been examined in terms of some weak interactions based on π electron system. We also have studied the cyclophanes having the anthracene, pyrene and fluorene moieties as the component in viewpoints of their spectral properties, reactivities and formation of the charge–transfer complexes. Conformations of flexible cyclophanes have been investigated by considering intramolecular weak interaction involving the π electron system.