Quenching of singlet oxygen in dimethylformamide

in the last two decades, many singlet oxygen quenching constants of organic solvents (k(Delta)) were published. In the early years these rates often varied significantly because of indirect O-1(2) detection methods or insensitive experimental setups. Currently, published k(Delta) values are usually consistent with the corresponding values in the literature of recent years. However, k(Delta) of dimethylformamide, a commonly used solvent, is an exception to this trend. Published (K-Delta)(-1) values are 25 mu S, 19 mu S and 14 mu s. In this study the reasons for these inconsistent values are examined. (C) 2000 Elsevier Science S.A. All rights reserved.