5-(2-pyridyl)tetrabenzoporphyrin and its complexes with zinc, cobalt, copper and iron. synthesis, spectral, electrochemical and electrocatalytic properties

Abstract

The interaction of phthalimide with 2-picoline in the presence of zinc oxide synthesized 3-(pyridin-2-ylmethylene)isoindolin-1-one. Heating its mixture with an excess of phthalimide and zinc acetate leads to the formation of zinc 5-(2-pyridyl)tetrabenzoporphyrinate, which, upon treatment with acid, is converted to 5-(2-pyridyl) tetrabenzoporphyrin. The latter, when interacting with cobalt(II), copper(II), and iron(III) chlorides in DMF, forms the corresponding metal complexes. The composition and structure of the obtained compounds were confirmed by mass spectrometry, vibrational, 1H NMR, and electron spectroscopy. The results of quantum-chemical calculations of complexes by the DFT method are presented. A correlation is established between the energy gap between the frontier orbitals and the positions of the first bands in the electronic absorption spectra. All the synthesized tetrabenzoporphyrins exhibit catalytic activity in the electroreduction of oxygen, the highest activity being exhibited by cobalt and copper complexes.