Meso-nitro substitution as a means of Mn-octaethylporphyrin redox state controlling

• Mono, di, tri and tetra-nitro substituted Mn-porphyrins were synthesized. • Their NBO analysis and structure optimization was performed by DFT method. • Obtained materials electrochemical properties were investigated. • It was shown that nitro substitution determines Mn-porphyrin redox state. Mn(II,III)- and Cd(II)-complexes of 5-mononitro-2,3,7,8,12,13,17,18-octaethylporphyrin, 5,15-dinitro-octaethylporphyrin, 5,10,15-trinitro-2,3,7,8,12,13,17,18-octaethylporphyrin and 5,10,15,20-tetranitro-2,3,7,8,12,13,17,18-octaethylporphyrin have been synthesized and identified. A comparative study of the coordination reactions of the corresponding porphyrin ligands with manganese (II) chloride and metal exchange of their cadmium complexes with manganese (II) chloride in dimethylformamide was carried out to find the optimal conditions for the synthesis of Mn(II, III)-porphyrins. The obtained compounds were identified by UV-vis, 1 H NMR spectroscopy and mass spectrometry. The structural parameters of the synthesized compounds were calculated by the DFT method and their NBO analysis was carried out. The electrochemical properties of the synthesized manganese complexes were studied by the cyclic voltammetry method. It is shown that nitro substitution determines Mn-porphyrin redox state.