Abstract
The use of simple Mn-II ions as efficient catalyst precursors for the oxidation of different highly stable organic dyes using H2O2 as an environmentally benign oxidant under mild reaction conditions, is presented. The role of a series of aromatic dyes in the in situ formation and stabilisation of the active catalyst was studied in detail using stopped-flow techniques and UV-Vis detection. DFT calculations were employed to predict the nature of the role of the substrate in the stabilisation of highly reactive Mn-II intermediates. Furthermore, low-temperature EPR measurements were performed in order to characterize the in situ formed catalytically active Mn-IV=O intermediate responsible for the fast and versatile oxidation of organic dyes in aqueous solution. (C) 2009 Elsevier B.V. All rights reserved.