Structural, photophysical, and electrochemical redox properties of meso-tetrakis(pentafluorophenyl)porphyrins

This study delineates the synthesis and comprehensive characterization of metal complexes of meso-tetrakis(pentafluorophenyl)porphyrin (H2TPF(20)P, 1) with first-row transition metal ions (M = Mn(III) 2, Fe(III) 3, Co(II) 4, Ni(II) 5, Cu(II) 6, and Zn(II) 7) to elucidate their structural, electronic spectral, and electrochemical redox properties. Co, Ni, Cu and Zn Complexes exhibit planar structure (Delta 24 = 0.003-0.021 angstrom and Delta C-beta = 0.004-0.041 angstrom) which is also confirmed by the single crystal data of complex ZnTPF20P, 7 shows the planar geometry, while Fe and Mn complexes show the slightly nonplanar structure (Delta 24 = 0.101-0.143 angstrom; and Delta C-beta = 0.080-0.112 angstrom), which are distorted due to their occupied axial sites by -Cl ligand as revealed by density functional theory (DFT) calculations. Furthermore, electronic spectroscopy revealed a gradual bathochromic shift following the order of NiTPF20P < CoTPF20P < CuTPF20PCl < H2TPF(20)P = FeTPF20PCl < ZnTPF20P < MnTPF20PCl by appending different metal ions in the porphyrin core. MnTPF20PCl exhibited the most significant bathochromic shift (Delta lambda(max) = 63nm) in the Soret band compared to H2TPF(20)P. Also, MnTPF20PCl and FeTPF20PCl show a unique pattern of split Soret band at around 364 and 345 nm due to the interaction between the metal d-orbitals and the surrounding ligands. The electrochemical redox potentials of the filled 3d orbital of Zn endow ZnTPF20P (ring centered) with the lowest oxidation potential.