Cation Sensing by a Calix[4]arene-Cycloparaphenylene Hybrid Host

Calixarenes are considered as a versatile platform for developing macrocyclic hosts with novel and intriguing supramolecular features. Among the calixarene hosts, a main role has been played by the hybrid systems which are composed by calixarene skeleton and portion of different macrocyclic that combine the supramolecular features of both the hosts. 1 Carbon nanorings are a class of macrocyclic compounds constituted by arene rings linked by single bonds. Among, these, the [n]CycloParaPhenylenes ([n]CPPs) 2 are fully conjugate macrocycles constituted by para-linked benzene that exhibit interesting optical, electronic 3 and supramolecular properties. 4 Thus, based on these considerations, we have designed the CPP-Calix[4] hybrid system 1, which combines perfectly the recognition abilities of the calix-skeleton with the optoelectronic features of CPP derivatives and shows an unexpected selectivity for the Li+ cation over Na+, as a result of more favorable cation···π interactions of Li+ with the CPP-bridge and its better size-complementarity.