Anion sensing by rhenium(I) carbonyls with polarized N–H recognition motifs

This article describes our recent research results on several rhenium(I) carbonyls complexes with polarized N–H recognition motifs as anion receptors. Structurally simple and easily synthesized luminescent anion receptors containing an amide-type anion binding site and a rhenium(I) tricarbonyl pyridine signaling unit have been developed, and they display outstanding sensitivity and selectivity toward a variety of anionic species. Moreover, thioamides and thiourea derivatives of 2,6-pyridinedicarbonyl dichloride, isophthaloyl dichloride and terephthaloyl dichloride have been synthesized. These ligands have been incorporated in dinuclear rhenium(I) diimine tricarbonyl complexes and provide anion recognition properties in these complexes. Furthermore, the related rhenium(I) complex featuring sulfonamide interacting sites that incorporate the highly chromophoric π-conjugated quinoxaline moiety has been prepared, characterized, and its photophysical properties were also studied.

Graphical abstractAnion recognition and sensing has been explored by luminescent rhenium(I) carbonyls containing ligands imparted with polarized N–H groups to serve as the anion recognition motifs. The interactions between rhenium(I) carbonyls and different anions resulted in various degrees of colorimetric and/or luminescent responses that has been attributed to either hydrogen-bonding interactions or proton transfer in some extreme cases.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Several rhenium(I) carbonyls complexes with polarized N–H recognition motifs have been synthesized. ► Anion recognition properties of the complexes have been studied by UV–Vis and luminescence spectroscopy. ► Hydrogen-bonding interactions and proton transfer processes have been investigated.