Photo-induced secondary assembly of bis(terpyridyl)dibenzo-24-crown-8/Zn2+ supramolecular polymer

A crown ether-based supramolecular gel with a three-dimensional network structure was successfully constructed via a hierarchical induced assembly strategy and characterized by UV/vis NMR, viscometry and DLS. Therein, the coordination linkage of bis(terpyridyl)dibenzo-24-crown-8 1 with Zn 2+ produces the 1 /Zn 2+ supramolecular polymer as the primary assembly. Then, the anthryl-dibenzylammonium guest 2 was grafted to the 1 /Zn 2+ supramolecular polymer via the non-covalent association of dibenzylammonium moieties on guests with the dibenzo-24-crown-8 rings on supramolecular polymer. Furthermore, the supramolecular polymer with anthryl grafts underwent a photo-induced secondary assembly to produce the supramolecular gel, which could be reversibly disassembled by a thermo-induced dissociation of anthracene dimers. These photo/thermo-induced hierarchical assembly/disassembly behaviors will provide a potential way to construct degradable hierarchical supramolecular assemblies employing environment-friendly external stimuli, such as light and heat, as controlling method.