Synthesis, spectroscopic and crystallographic analysis of the Zn-complex of a di( β, β′-sulfoleno)pyrrin: model for Zn-complexes of bilirubin and of phylloxanthobilins

Abstract

Abstract

A high yield preparation, spectroscopic and crystallographic investigation of the crystalline Zn-complex of a di( β, β′-sulfoleno)pyrrin are reported here. In the brightly green fluorescent Zn-complex of the hardly luminescent di( β, β′-sulfoleno)pyrrin, the metal ion is bound by two di( β, β′-sulfoleno)pyrrin ligands, as revealed first by its mass spectra. The crystal structure of this Zn-complex of the di( β, β′-sulfoleno)pyrrin confirmed a regular 2:1 composition of the bidentate di( β, β′-sulfoleno)pyrrin ligand and the metal ion. The latter was coordinated in a distorted tetrahedral fashion, as found in other dipyrrin Zn-complexes. The here studied Zn-complex of a designed di( β, β′-sulfoleno)pyrrin ligand provides insights into the coordination properties of the proposed (2:1)- and (2:2)-complexes of phylloxanthobilin and bilirubin, respectively, which are two abundant natural bilin-type tetrapyrroles.

Graphical abstract