Formation and optical absorption of clusters of the p-tert-butylcalix[8]arene: C-60 complex

Depending on the initial concentrations of fullerene (C-60) and p-tert-buty l calix[8]arene (C[8]A) in toluene, two regimes of their interaction were d istinguished. The changes in optical absorption of C-60:C[8]A mixed solutio ns observed over a period of time suggest that the following consecutive pr ocesses take place upon interaction between C-60 and C[8]A in toluene: (1) molecular inclusion, and (2) growth and sedimentation of the insoluble C-60 /C[8]A clusters. At increased concentrations of the components, process (2) is suppressed and stable C-60/C[8]A colloids can be formed. Spectral featu res of these colloids in different solvents clearly indicate the difference between self-aggregated C-60 and small clusters of the complex. A specific influence of the C[8]A cage on the entrapped C-60 molecules is also confir med by IR spectroscopy of the complex in the solid state.