Phosphorescence and photochemical studies of some benzophenone dicarboxylic acid esters

Abstract Phosphorescence quantum yields and lifetimes in solution in carbon tetrachloride were measured for dimethyl esters of three benzophenone dicarboxylic acids. Curious features were noted. The triplet energies (in kilocalories per mole) varied with substitution ((3,3), 67.0; (3,4), 65.6; (4,4), 64.8), as did the phosphorescence lifetimes (14 μs, 26 μs and 45 μs respectively). The radiative rate constants k p = 165 ± 10 s −1 were identical. The triplets of all three ketones reacted with n -octane with a second-order rate constant of 1.14 × 10 6 M −1 s −1 at 22 °C.