Synthesis and applications of conjugated pillararenes

Pillar[n]arenes, as a new class of macrocyclic hosts, show bright prospect due to their rigid cavity structures, rich host-guest interactions, and easy functionalization. How to improve the host-guest recognition selectivity, signal report sensitivity and host-guest assembly properties of the pillar[n]arene-based hosts by rational functionalization is an attractive issue. Among various of functionalization approaches for pillar[5]arenes, constructing conjugated systems through the A, A'-sites of pillar[5]arenes is a very crucial method. In contrast to conventional alkoxy chain-functionalized pillar[5]arenes, conjugated pillar[5]arenes exhibit superior charge transfer and signal response capabilities, as well as a rigid structure that facilitates the construction of framework materials. Furthermore, they readily facilitate collaborative effects through functionalized groups within the cavity of the pillar[5]arenes. There are many nice works on design synthesis and applications of conjugated pillar[5]arenes in various fields. This minireview presents a systematic introduction on the synthesis of conjugated pillar[5]arenes and their applications in different fields.