Experimental data on synthesis and characterization of chiral dinuclear manganese (II-II) compounds as biomimetic models of the active center of catalase

Abstract

Dinuclear manganese (II– III) compounds, which are potential models of the active center of catalase, were synthetized. This type of metalloenzymes presents biological importance due to three factors: they are redox catalyst centres, they are able to carry out hydrolytic reactions and they participate in activated processes via Lewis acids. Structurally, their active centre is composed by dinuclear manganese compounds, linked to nitrogen and oxygen donor atoms. An octahedral geometry around the metal ions were found, with acetate, hydroxy and aquo ligands; which can work as molecule bridges between them. The acid medium favours the electronic transfer between Mn3+ - Mn2+ as redox centre at 1.559 V and the consequent oxidation of hydrogen peroxide or organic molecules. The work also reports the data of two chiral novel compounds, [Mn2(S,S(+)Hcpse)4(NaClO4)2(NaOH)(CH4O)]n·[(C2H6O)2]n·[(CH4O)2]n and its respective enantioisomer, in which μ-oxo being as bridge metal centre. The X-ray structural was obtained as well as the optical and magnetic properties using Circular Dichroism, Electronic Paramagnetic Resonance, Magnetic Susceptibility and X-ray photoelectron spectroscopy.

Synthesis and Evaluation of Structural and Functional Biomimetic Models of Oxidase-Type Metalloenzymes Based on Polynuclear Compounds with Copper (II) and Manganese (II) Ions

“…Additionally, these mimetic models facilitate understanding in biological systems with similar helically arrangements such as the structure of DNA. ) ligands that adopt a facial arrangement, in which the equatorial plane is formed by the nitrogen atoms N1(N3) and N2(N4), and the O5(O7) and O6(O8) oxygen atoms from the carboxylic groups while the apical position are occupied by the hydroxyls groups O1(O3) and O2(O4) for Mn1 and Mn2 atoms respectively, Figure 5; selected bond lengths and bond angles are reported previously [36]. 1D-chains run along the vector [0 0 1] with the phenyl and methyl groups as pendants toward the outside surface of the endless chain generating a lipophilic surface.…”

“…This charge transfer would generate a decreasing of the catalytic sites available for oxidation of the hydrogen peroxide. Furthermore, the manganese (III) ion presents an absorption in the visible region due to electronic transition in octahedral geometry (t2g 3 eg → t2g 2 eg 2 ) [36]. In contrast, the manganese (II) has no transitions in high spin configuration for this geometry, which shows the structural differences between solid and solution state.…”

“…However, the EPR spectra in solution at 2.03 mM, T=110 K; showed the non-Kramers doublet near 1500 G. This behavior is related with manganese (III), with four unpaired electrons resulting in a 5Eg ground state, and a Jahn-Teller distortion. Consequently, is indicating that there is a dissociation of the binuclear unit in solution and a subsequent stabilization of manganese (III) species [36].…”

“…In order to corroborate this idea, an analysis of the electrochemical behavior with respect to the scan rate was carried out. Before any mechanistic analysis, it is necessary to investigate whether the electroactive species diffuse from solution or adsorb on the electrode surface [36]. For this reason, the variation of anodic peak current with respect to the scan rate (Log Ipa-Log v plot) was constructed, figure 8.…”

Enantioselective Biomimetic Structures Inspired by Oxi-Dase-Type Metalloenzymes, Utilizing Polynuclear Compounds Containing Copper (II) and Manganese (II) Ions as Building Blocks

“…Among the basidiomycetes that colonize wood and cause white rot, manganese peroxidase is the most prevalent peroxidase involved in modifying lignin. This enzyme relies on hydrogen peroxide as a co-substrate to oxidize Mn 2+ ions present in wood and soil into Mn 3+ ions (Equation (1)), with stabilization achieved through fungal chelates like oxalic acid [ 18 ]. Manganese peroxidase, a plant, and fungal enzymes utilize hydrogen peroxide to oxidize and transform various phenolic substrates, including lignin.…”