SYNTHESIS, SPECTRAL AND ELECTROCHEMICAL PROPERTIES OF β-FUNCTIONALIZED PORPHYRINS AND THEIR METAL COMPLEXES

Abstract

π-Extended porphyrins are widely utilized in solar cells, nonlinear optics, catalysis and photodynamic therapy. A family of β-substituted metalloporphyrins with extended conjugation viz. MTPPMN, where M= NiII, CuII, ZnII, 2H were synthesized in excellent yields using Knoevenagel reaction from β formyl porphyrin. These porphyrins were characterized by various spectroscopic techniques such as UV-Vis, fluorescence, NMR and cyclic voltammetric studies. Red shift was observed in absorption bands of synthesized porphyrins. Also, the HOMO-LUMO band gaps were found to be lowered compared to their respective precursors. Sensing application was observed in the synthesized porphyrin ((MTPPMN), M= Ni(II), Cu(II), Zn, 2H). Cyanide ion and hydroxide ion were detected efficiently. These porphyrins detect cyanide ions at very low concentration of porphyrin (0.12 ppm). Significant shifts in both oxidation and reduction potentials was observed in electrochemical studies. Resultant dipole was observed to be significantly large as compared to precursor H2TPP. Dipole moment of 3.23 D was observed for H2TPPMN due to ‘pull’ effect of β-substituents. The bromination of NiTPPMN to form NiTPPMNBr6 were found to have interesting results.