Study of Host-Guest Interaction of [70]Fullerene with Substituted Calix[6]arenes by Absorption Spectrometric Method

摘要

The host-guest interaction of various mono O-substituted calix[6]arenes,namely,(i) 37-benzyl-38,39,40,41,42-pentahydroxy-5,11,17,23,29,35-hexa(4-tert-butyl)calix[6]arene (1),(ii) 37-ethylester-38,39,40,41,42-pentahydroxy-5,ll,17,23,29,35-hexa(4-tert-butyl)calix[6]arene (2),and (iii) 37-allyl-38,39,40,41,42-penta-hydroxy-5,11,17,23,29,35-hexa(4-tert-butyl)calix[6]arene (3) with [70]fullerene has been studied in a CCl_4 medium by the absorption spectroscopic method.All of the complexes are found to be stable with 1:1 stoichiometry.An absorption band due to a charge transfer (CT) transition is observed in the visible region;with increasing ionization potential of the mono O-substituted calix[6]arenes,the peak energy shifts to the higher energy side and the oscillator strength of CT transition increases.Degrees of CT have been estimated by analyzing the CT transition energy as a function of ionization potential.Thermodynamic parameters for the supramolecular complex formation of [70]fullerene with 1,2,and 3 receptors are reported.The high formation constant value for the [70]fullerenecentre not2 complex indicates that 2 forms an inclusion complex with [70]fullerene.