Spectroelectrochemical and spectrophotochemical properties of N-tetradecyl-N '-ethyl-viologen. Micellar effects

The results of Spectroelectrochemical studies in homogenous solutions have shown that below the cmc value the cation radical of N-tetradecyl-N '-ethyl viologen (TDEV) dimerizes. The TDEV and tetradecyltriethyl-ammonium bromide (TDEA) micelles were found to stabilize the cation radical TDEV^.+ and increase the rate constant for the reaction TDEV+TDEV²⁺ = TDEV^.+ as compared with the results obtained at concentrations below cmc. Based on the spectrophotochemical measurements for TDEV it was found that the quantum yield (Φ) of photoreduction in micellar evironment of TDEA was twice as large as Φ for reactions performed in homogenous solution. Moreover, in micellar solutions photoreduction of TDEV leads to a cation radical of reduced TDEV (TDEV⁺), but in homogenous solution to the dimer of TDEV [TDEV]₂. Therefore, the process of dimerization of TDEV^.+ cation radical is inhibited by micellar catalysis.