Three metalloporphyrin frameworks containing imidazole groups: synthesis, characterization and properties

Abstract

In this paper, we designed and synthesized three novel free-base imidazolyl porphyrins via the Macdonald [2 + 2] method, and their reactions with different metal ions afforded three new metalloporphyrin frameworks (MPFs) [Co(tBu-Ph)₂(Im-Ph)₂Por]·2DMF (1), [Co(F₃-Ph)₂(Im-Ph)₂Por]·1.5DMF (2), and [Fe(Me₂N, F₄-Ph)₂(Im-Ph)₂Por]·3DMF (3), which display rich structural diversity. Complexes 1 and 2 are isostructural two-dimensional (2D) grid layers, which feature the rare rotaxane-like bilayer and an offset-stacking ABCD fashion of layers, as well as the significantly saddled porphyrin macrocycles. Differently, complex 3 forms a 4-connected lvt 3D framework with the slightly ruffled porphyrin macrocycles, which contains not only interesting helical channels but also uncommon tetrahedral cages. Gas adsorption studies of three complexes reveal the moderate CO₂ adsorption capacity. Meanwhile, all three complexes exhibit preferable catalytic activity for ethylbenzene oxidation.