Inclusion complex of calix[8]arene-C₆₀: Photophysical properties and its behaviour as singlet molecular oxygen sensitiser in the solid state

The inclusion complex calix[8]arene-C60 has been studied in the solid state by means of nanosecond laser flash photolysis with diffuse reflectance (DRLFP) and NIR luminescence (TRNIR) detection techniques. The recorded transient absorption spectrum and its kinetics are similar to those showed by the inclusion complex of γ-cyclodextrin-C60 in solid state. Contrarily, the new complex shows a very different behaviour against oxygen: the deduced deactivation quenching constant by molecular O2 is kq(O2) = (1.1±0.1) × 108 dm3 mol-1 s-1 in solid state, while the deactivation of triplet γ-cyclodextrin-C60 by molecular O2 in solid state had been reported as negligible. Consistent with this, TRNIR shows unequivocally that the solid calix[8] arene complex photosensitises the formation of singlet molecular oxygen. O2(1Δg), while the γ-cyclodextrin complex does not. O2(1Δg) has a lifetime of 16 μs in the heterogeneous solid calix[8] arene complex-air system. Both complexes seem to show complementary properties to be used in the area of new materials. © 1998 Elsevier Science S.A. All rights reserved.