Functional Porphyrinoids from a Biomimetically Decorated Bipyrrole

Graphical Abstract

Functional analogues for hemes and phytofluors, a Mn corrole and a bis(bodipy) carrying two adjacent propionate substituents, are available in two steps from a simple bipyrrolic precursor. Hydrolysis of the ester groups to the free acid is successful for the corrole and yields buffer-soluble material, while for the dinuclear bis(bodipy), hydrolysis of B–F bonds is observed.

Abstract

The known 5,5′-diformyl-3,3′-bis(methoxycarbonylethyl)-4,4′-dimethyl-2,2′-bipyrrole was employed in the preparation of biomimetic functional porphyrinoids. Tetrapyrrolic 2,2′-bidipyrrins could be obtained from condensations with two equivalents of 3,4-dialkyl-2-methylpyrroles. From these compounds, a manganese(III) corrole as well as a boron-containing bis(bodipy) fluorophor are accessible as functional species in one-step reactions. Both products were investigated by means of X-ray crystallography. Attempts to hydrolyze the methyl ester moieties were successful only for the manganese corrole and yielded a buffer–soluble, heme-analogous corrole complex. The dinuclear BF₂ chelate [bis(bodipy)], on the other hand, decomposes unselectively under the applied conditions. A rationale for this decomposition was derived from crystallographic work on a related hydrolysis product with a F–B–O–B–F moiety. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)