Quenching of oxygen (1. DELTA. 8) by amines

The electronic relaxation of the lowest singlet state of molecular oxygen has been studied in the presence of a number of aliphatic amines. Rate constants have been obtained for quenching by mono-, di-, and trimethyland ethylamines and 1,4-diazabicyclo[2.2.2]octane (DABCO). The constants range between 2 X lo5 1. mol-’ sec-l (for monomethylamine) and 1.9 x lo7 1. mol-’ sec-1 (for triethylamine) and display a good correlation with the ionization energy of the quencher. Temperature and pressure dependency studies indicate that no bound intermediate is formed, and the results can be rationalized in terms of a “contact charge-transfer” interaction