Evidence of Reverse Micellization of a Calix[4]arene through a Study of Its Charge Transfer and Host−Guest Complexation with [60]Fullerene

By UV−vis absorption and fluorescence spectroscopy it has been established that 25,27-dihydroxy-26,28-dimethoxycalix[4]arene (1) forms reverse micelles in CCl4 and n-hexane media. The new feature of this compound as a surfactant is that even before micelle formation it can incorporate water molecules and the critical micellization concentration (cmc) in nonaqueous media increases with increase in ω (=water:1 mole ratio). The inclusion complex of 1 with [70]fullerene has a CT absorption band that, in conjunction with those of some quinone complexes of 1, leads to the determination of the vertical ionization potential of 1. 1H NMR spectrometric determination of the formation constant (K) of the inclusion complex of [60]fullerene with 1 in CCl4 has revealed that K increases on addition of microquantities of water. This has been rationalized by assuming that the −OH groups of the calix[4]arene molecules attach themselves to the water micropool of the reverse micelles by forming H-bonds and the individual cali...