Structural, spectroscopic and electrochemical investigations on fluorinated meso-tetraaryl porphyrins

Two series of meso-phenyl fluorinated porphyrins and their metal complexes, 5,10,15,20-tetrakis(2', 4', 6'-trifluorophenyl) porphyrin, MT(2', 4', 6'-TFP) Ps (2a-2d) and 5,10,15,20-tetrakis[ 3', 5'-bis(trifluoromethylphenyl)] porphyrin, MT(3', 5'-BTFMP) Ps (3a-3d); where M = 2H; Ni(II); Cu(II) and Zn(II) have been synthesized and characterized using various spectroscopic techniques including UV-visible, fluorescence and H-1 NMR and mass spectrometry. Electronic absorption spectra of porphyrins show the typical Soret (B) and visible (Q) bands. Free ligands and zinc(II) derivatives display two well-defined emission bands around 600-660 nm and 650-720 nm upon exciting the Soret band. Porphyrins, 1d, 2a, 2b, 2c, 3a and 3d were structurally characterized by single crystal XRD analysis, and various intermolecular interactions present in them were quantified on the basis of Hirshfeld surfaces and 2D fingerprint plots. Electrochemical studies were performed and the HOMO-LUMO energy gap is high for all the porphyrins compared to MTPPs.