Ag(I)-π interactions with pyrrolic derivatives

Whereas Ag-pi interactions with alkenes, alkynes and arenes have been thoroughly explored, assembly with pyrrolic derivatives has been much less investigated. This is surprising given the prominent place that species such as BODIPYs, corroles or porphyrins occupy in chemistry and biology and given that these compounds are actually prone to this mode of complexation of Ag(I) cations in solution as well as in the solid state. Indeed, studies in the liquid phase by NMR, UV-visible and Raman spectroscopy with bis-dipyrrin based helicates or systems incorporating porphyrinic units have demonstrated their ability to interact with silver(I) centers. Furthermore, a variety of homo- and hetero-metallic architectures featuring this binding mode, especially with beta-pyrrolic carbon atoms, based on a diversity of ligands comprising one, two, three or more pyrrole moieties have been characterized in the crystalline state by X-ray diffraction. Whereas the presence of these interactions is difficult to promote and control a priori, recent work has shown their recurrence with 2,2'-bis-dipyrrin based helicates. All these aspects are reviewed in this contribution aiming at highlighting the importance and potential of Ag-pi interactions with pyrrolic systems. (C) 2018 Elsevier B.V. All rights reserved.