Nonradiative Deactivation of Singlet Oxygen (1O2) by Cubane and Its Derivatives

The bimolecular quenching rate constants of singlet oxygen (O-1(2)) by cubane and cubane derivatives were determined and found to be in the order of 10(3)-10(4) M-1 s(-1). These values represent larger values than expected for aliphatic alkanes as a model for C-H vibrational deactivation. This result is explained by the occurrence of two different deactivation mechanisms: energy transfer to cubane C-H vibrational modes and the formation of a charge-transfer complex between O-1(2) and cubane (O-1(2)center dot-center dot center dot center dot cubane(center dot+)).