Electrochemical insight on the nitrogen-rich, weakly aromatic cyclic triimidazole multifunctional system expanded with pyridine or thiophene terminals

Abstract

Cyclic triimidazole TT and its derivatives are gaining increasing attention for their multifaceted properties spanning from photoluminescence to supramolecular chemistry and biological activity. TTs structure-property relationships can be rationalized with the aid of electrochemical techniques that can also afford a precious tool to transfer molecular properties to molecular materials. An attracting study case is provided by TT derivatives with an increasing number of heteroaromatic terminals, either pyridine (popular protonation-sensitive capping agent) or thiophene/bithiophene ones (promoting coupling processes). An exhaustive voltammetry investigation, integrated by (and in some cases combined with) absorption and emission spectroscopy and supported by theoretical calculations, highlights the modulation of the electronic/redox properties as a function of the terminal nature and multiplicity. Moreover, a couple of first examples of TT derivatives successfully electrooligomerizable into electrochemically and spectroscopically highly active films, is reported. This can be regarded as an attractive first step in the perspective of electrochemically developing molecular materials endowed with TT functional properties combined with high electroactivity.