Synthesis, crystallographic characterization and homogeneous catalytic activity of novel unsymmetric porphyrins

Abstract

Unsymmetric porphyrins, containing both pentafluorophenyl (PFP = A) and 3,4-dimethoxyphenyl (DMP = B) substituents at the meso positions, were prepared using Lindsey's methodology. The isomeric trans-A₂B₂ (P1) and cis-A₂B₂ (P2) porphyrins together with the tris(pentafluorophenyl)porphyrin A₃B (P3) were isolated using chromatography. The porphyrins were characterized by UV-VIS, ¹H NMR spectroscopy, mass spectrometry, elemental analysis (C, H, N) and cyclic voltammetry (CV), and their molecular structures were confirmed by single crystal XRD. Their manganese complexes, MnP1, MnP2 and MnP3, were also synthesised and used as catalysts in cyclooctene and cyclohexane oxidation reactions under homogeneous conditions. The catalytic studies were supported by electrochemical measurements and showed that the number of electron-withdrawing substituents on the porphyrins rings influences the catalytic activity. These porphyrins may be used as precursors for the design of new materials, such as Polymers of Intrinsic Microporosity (PIMs).