Manganese oxides are often highly reactive and easily reduced, both abiotically, by a variety of inorganic chemical species, and biologically during anaerobic respiration by microbes. To evaluate the reaction mechanisms of these different reduction routes and their potential lasting products, we measured the sequence progression of microbial manganese(IV) oxide reduction mediated by chemical sp...

A dominant feature of the inorganic chemistry of manganese is the variety of complexes that can be made with different oxidation levels ( + 11+ IV) of the manganese, and living systems have utilized this property in that manganese-containing en­ zymes are involved in many diverse redox func­ tions [1]. The biological function that has generat­ ed most interest is the photosynthetic oxygen evolv...

Redox-inactive metal ions can modulate the reactivity of redox-active metal ions in a variety of biological and chemical oxidations. Many synthetic models have been developed to help address the elusive roles of these redox-inactive metal ions. Using a non-heme manganese(II) complex as the model, the influence of redox-inactive metal ions as a Lewis acid on its catalytic efficiency in oxygen at...

A method was developed to determine whether microorganisms mediate the precipitation of manganese(II) in the marine environment. Radioactive Mn(II) was used as a tracer to measure the precipitation (binding and oxidation) of Mn(II) [i.e., the Mn(II) trapped on 0.2-mum membrane filters] in the presence and absence of biological poisons. A variety of antibiotics, fixatives, and metabolic inhibito...

Oxidative tissue damage is considered an early sign of cadmium (Cd) toxicity and has been linked with carcinogenesis. Manganese(II)-at low doses, was found to act as a potent antioxidant against oxidative stress in different in vitro systems producing lipid peroxidation conditions. The present study investigates in vivo antioxidant effects of Mn(2+) pretreatment in acute Cd intoxication with re...

A recent femtosecond X-ray diffraction study produced the first high-resolution structural model of the oxygen-evolving complex of photosystem II that is free of radiation-induced manganese reduction (Protein Data Bank entries 4UB6 and 4UB8 ). We find, however, that the model does not match extended X-ray absorption fine structure and QM/MM data for the S1 state. This is attributed to uncertain...

In the natural environment, manganese is found as reduced soluble or adsorbed Mn(II) and insoluble Mn(III) and Mn(IV) oxides. Mn oxidation has been reported in various microorganisms. Several possible pathways, indirect or direct, have been proposed. A wider variety of Mn-reducing microorganisms, from highly aerobic to strictly anaerobic, has been described. The mechanisms of Mn reduction can b...

in this research, a pvc membrane electrode for manganese (ii) ions based on n-(2-picolinamidoethyl)picolinamide as neutral carrier was prepared. the electrode exhibits a nemstian responseover mn(ii) concentration range of (1.0 x10-5 t01.0 x 10-1m) with a slope of 29.3±0.5 mv perdecade of concentration with a working ph range of 4.0-9.0. it has a fast response time (

A new two-dimensional manganese(II) coordination polymer, [Mn(μ-DEP)(μ-Cl)(H2O)2]n (1) (DEP is diethyl phosphate), was prepared from the reaction of MnCl2.4H2O and TEP (TEP is triethyl phosphate) ligand in mixture of H2O/CH3OH (1:10) at 40 °C. Suitable crystals of this complex for crystal structure determination were obtained by slow evaporation of the produced colorless solution at room temper...