Interesting pH-Responsive Behavior in Benzothiadiazole-Derived Coordination Polymer Constructed via an in Situ Click Synthesis

In this work, two new benzothiadiazole-derived complexes, namely, [Zn0.5(TBC)(H2O)] (1, TBC = 4-cyano-7-(1H-tetrazol-5-yl)benzothiadiazole) and [Cd(TBC)(N3)(H2O)]n (2), were successfully obtained by the in situ click synthetic methods in hydrothermal conditions. While complex 1 shows a mononuclear structure that can be extended to the three-dimensional (3D) supramolecular network by the intermolecular hydrogen bonds and N–S interactions, for 2, it is a coordination polymer comprised of undulated two-dimensional layers with a (8)(84•122) topological network, where the adjacent layers are stacked to form a 3D supramolecular framework sustained by interlayer N–S interactions. Comparing to the single emission of 1 centered at 570 nm, 2 showed the dual emissions, which were centered at 490 and 568 nm, respectively. Such phenomenon resulted from the different decay procedures for the π → π* states of monomeric benzothiadiazole species (ππ* state) between 1 and 2. Significantly, on the one hand, because of the d...