Synthesis and Characterization of New porphyrins and Porphyrin Derivatives with Fluorine.

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5, 10, 15, 20-Tetrakis (trifluoromethyl) porphyrin, 1, was obtained by oxidative cyclization of 2-(2-trifluoro-1-hydroxyethyl) pyrrole in moderate yield.Meso-(trifluoromethyl) octaethylporphyrin, 5, was readily prepared by photochemical trifluoromethylation of octaethylporphyrin with trifluoromethyl iodide in DMF.No pertrifluoromethylation products have been detected in the present reaction. Similarly, δ-(trifluoromethyl)-octaethylchlorin, 6, and meso-(trifluoromethyl) mesoporphyrin IX dimethyl ester were obtained in moderate yields. ^1H-NMR and ^<19>F-NMR of the latter products indicated formation the four regioisomers, 9-12.These compounds showed a variety of unusual properties due to steric constrain and electronic effect of the meso-trifluoromethyl group. Both electrochemical studies and energy calculations of molecular orbitals indicated that the HOMO and LUMO of 1, 5, and 6 were markedly stabilized than those of trifluoromethyl group unsubstituted compounds. Moreover, for 5 the stabilization is much greater for the LUMO.This difference is attributable to the partial distortion of the porphyrin ring by interaction between the ethyl and trifluoromethyl groups.