Suprareceptors emerging from click chemistry: Comparing the triazole based scaffolds of calixarenes, cyclodextrins, cucurbiturils and pillararenes

Rapid, reliable, and unbiased detection and quantification of important analytes have drawn rising attention because of the dire need to understand the environmental and the biomedical conditions better. Macrocyclic platforms, such as, calix[n]arenes (C[n]A), pillar[n]arenes (P[n]A), cyclodextrins (CD) and cucurbiturils (CB[n]) have been reported recently to build sensitive receptors to selectively recognize the relevant species of importance by primarily eliciting appropriate fluorescence, absorbance, and or colorimetric signals. This review highlights the examples of such suprareceptors based on these four types of macrocyclic scaffolds wherein the attachment of triazole moiety played either a structural or a functional or both the roles in recognizing an ion or a molecule or a species of importance. Notably, the common cations, anions, amino acids and other species having importance in the environmental and biomedical fields were chosen as the guest species of interest for discussion. In addition, this review article emphasizes the role of the pre-defined molecular structures of selected macrocyclic scaffolds, which allows suitable modification to incorporate molecular linkers, ligating groups, and signaling units for selective and sensitive recognition of species of chemical, biological, medical and ecological importance. The article also focusses on their relative utility and importance and thereby provides some futuristic growth potential and dimensions of these four supramolecular platforms. It is to be noted that the integration of triazole moieties into the arms of these supramolecular platforms has been possible with the advent of Click chemistry which revolutionalized the application domains of such conjugates and thereby transformed the Nobel prize winning “Click Chemistry” into “Click Technology” and hence the present article.