Thermochromic and Piezochromic Effects of CoIIImidazole- Based Supramolecular Gels as Logic Gates

Abstract

We demonstrate that the imidazole-based ligand 1 efficiently produces a coordination polymer gel by simple mixing with Co2+ ion. When the molar ratio of CoCl2 to ligand 1 was less < 1, a red sol was obtained, indicating the formation of an octahedral (O-h) complex species as occurs with Co(NO3)(2). In contrast to G1, when the amount of CoCl2 employed was more than 1 equiv., the color of the gel changed from red to blue (G2), indicating the formation of mainly a tetrahedral (T-d) complex species. The ionochromic and the piezochromic effects of imidazole-based suprmolecular gel with Co2+ were investigated. These effects of supramolecular gel were controlled by various anions of cobalt, which are due to coordination geometric change of gels. Interestingly, the ionochromic and piezochromic effects of G1 act as AND and OR logic gates in the solid and the gel state.