Effect of the coordination of π-acceptor 4-cyanopyridine ligand on the structural and electronic properties of<i>meso</i>-tetra(<i>para</i>-methoxy) and<i>meso</i>-tetra(<i>para</i>-chlorophenyl) porphyrin cobalt(<scp>ii</scp>) coordination compounds. Application in the catalytic degradation of methylene blue dye

Abstract

To examine the influence of both the important π-acceptor character of the 4-cyanopyridine ligand and the nature of the <i>para</i>-substituted phenyls of <i>meso</i>-porphyrins on the electronic, electrochemical and structural properties of cobaltous metalloporphyrins, we prepared and fully characterized two coordination compounds: the (4-cyanopyridine)[<i>meso</i>-tetra(<i>para</i>-methoxyphenyl)porphyrinato]cobalt(ii) and the (4-cyanopyridine)[<i>meso</i>-tetra(<i>para</i>-chlorophenyl)porphyrinato]cobalt(ii) with the [Co^II(TMPP)(4-CNpy)] and [Co^II(TClPP)(4-CNpy)] formulas (complexes 1-2). The solution structures of compounds 1-2 were confirmed by ¹H NMR spectroscopy and mass spectrometry methods. They were further characterized by cyclic voltammetry and photoluminescence studies. The X-ray molecular structure data show that the Co-TClPP-4-NCpy derivative (2) exhibits high ruffling deformation compared to that of the Co-TMPP-4-CNpy species (1). Notably, the crystal packing of complex 1 shows the formation of Co⋯Co supramolecular dimers with a distance of 5.663 Å. As an application of our two cobaltous compounds, an investigation involving complexes 1-2 in the degradation of the methylene blue dye in the presence and absence of H₂O₂ in aqueous solutions was carried out. These promising results show that 1-2 can be used as catalysts in the degradation processes of dyes.