[14]Heterophane prototypes containing azolium and/or azole anion-binding motifs

Abstract

Revisiting a ‘3 + 1’ convergent stepwise strategy permitted the synthesis of [1₄]imidazoliophane 2·2Br in excellent yield for a macrocyclization. The new [1₄]triazoliophane 3 and bis(1,2,3-triazolium) counterpart 4·2Cl were less synthetically accessible and the hybrid derivative 5·Cl proved troublesome to prepare. Triazolophane 3 was devoid of anion-binding affinities, while charged [1₄]heterophane prototypes showed a particular preference for acetate. When association constants were compared, dicationic systems 2·2PF₆ and 4·2PF₆ showed greater values than monocationic macrocycle 5·PF₆, and the highest affinities corresponded to the bis(imidazolium) receptor 2·2PF₆.