Structural Diversity and Tunable Luminescent Properties of Zn(II) Metal–Organic Frameworks with Terephthalate and 4,7-Di(1,2,4-triazol-1-yl)-2,1,3-benzothiadiazole Linkers

A series of new coordination polymers (CPs) [Zn(tr2btd)(bdc)]n (compound 1), {[Zn2(tr2btd)2(bdc)2]·MeCN}n (compound 2), {[Zn3(tr2btd)4(H2O)2(bdc)3]·H2O}n (compound 3), and [Zn(tr2btd)2(bdc)]n (compound 4) were prepared from the same starting materials under different reaction conditions. Compounds 1–3 demonstrated luminescent sensing properties toward Ga3+ cations with the limits of detection in a low micromolar range, 1.6, 6.1, and 1.8 μM, respectively. Careful comparison of the crystal structures of the four synthesized CPs suggests that the packing features and intermolecular interactions strongly influence the luminescent and sensing properties. The luminescence sensing response was attributed to the absorption enhancement upon the interaction of metal–organic framework with Ga3+ via the nitrogen atoms at positions 4 of 1,2,4-triazole rings.