Thermochromic and Piezochromic Effects of CoII-Imidazole-Based Supramolecular Gels as Logic Gates.

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. [ABSTRACT FROM AUTHOR]