Self-Sensitized Photooxidation of Protoporphyrin IX Derivatives in Aqueous Surfactant Solutions: Product and Mechanistic Studies

Article abstract of DOI:10.1021/ja00389a008

The photooxidation of protoporphyrin IX and its dimethyl ester has been investigated in several aqueous surfactant media including neutral micelles (Brij 35) and vesicles (dipalmitoylphosphatidylcholine) and charged micelles (SDS and DTAB).The results obtained indicate that while the same products are formed in these media as in homogeneous organic solvents such as methylene chloride, the product distributions are quite different.At least two major reaction paths are indicated.The first involves singlet oxygen generation and attack on ground-state porphyrins.This path can be shown by studies with H2O vs.D2O and the use of the aqueous phase quencher N3^- to consist of two components, an intramicellar path and an intermicellar reaction.The second path appears most likely to involve electron transfer from excited porphyrin to generate superoxide and porphyrin ?-cation.This path appears to be exclusively intramicellar and is much more prominent in the organized media than in homogeneous solution.Quenching of ¹O2^* by azide appears to enhance the "superoxide-derived" products in SDS and Brij 35 supporting recent studies indicating that azide quenching occurs at least in part of electron transfer.

Full text of DOI:10.1021/ja00389a008

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.