Optical spectroscopy of C"6"0 complexes

Complexes of fullerene C"6"0 with different organic donors have been studied by optical absorption spectroscopy in solutions and in solid state. Charge transfer bands were found for C"6"0 complexes with tetrathiafulvalenes, pyranylidene and xantenyl in the 600-1300 nm range. It is shown that the energies corresponding to the maxima of charge transfer bands (hv"c"t) for C"6"0 complexes in solution are almost independent of solvent polarity. The hv"C"T values for the complexes in solid state are ~0.15-0.20 eV less than in solution. The dependence of the hv"C"T values on donor ionization potentials (Ip) for C"6"0 complexes with tetrathiafulvalenes in solid state was found to be hv"C"T= 0.82 i"p-3.93 eV. The lowering of the intensity was observed for the C"6"0 transitions at 420-540 nm in absorptoin spectra of single crystals of some C"6"0 complexes obviously due to isolation of C"6"0 molecules.