Abstract
The bis-sulfonamide TAML activator of peroxides [Fe{4-NO2C6H3-1,2-(NCOCMe2NSO2)2CHMe}]- (2) catalyzes the H2O2 oxidation of microcystin-LR (m-LR), a common surface water contaminant produced by cyanobacteria that is toxic at very low concentrations. The major reaction product is by 16 Da heavier than m-LR, suggesting that the first oxidative step involves addition of oxygen to one of m-LRs three C = C units to form an epoxide. The kinetic data suggest that the m-LR → m + 16 conversion occurs without any kinetically meaningful intermediate with the catalytic rate constant kII of 2.5 × 105 M−1 s−1, which characterizes the interaction of m-LR with the oxidized, active form of the catalyst. The primary m + 16 product undergoes much slower further catalytic oxidation in the aqueous reaction medium. This communication describes a potential utility of TAML/H2O2 catalysis for microcystin detoxification that calls for further research.
Graphical Abstract
Acknowledgement
The assistance from Liam Dugan (Center for Molecular Analysis of Carnegie Mellon University) is gratefully acknowledged.
Disclosure statement
There are no competing interests.