Two metal-organic frameworks (MOFs) containing rigid bis(triazole) ligand, namely {[Zn₂(L)(TP)₂(H₂O)·H₂O]}_n (1) and [Zn(L)(HTMA)]_n (2), where L=4, 4'-(3, 3'-dimethyl-(1, 1'-biphenyl)-4, 4'-diyl)bis(4H-1, 2, 4-triazole), H₂TP=terephthalic acid, H₃TMA=1, 3, 5-benzenetricarboxylic acid, were synthesized by using acid-base mixed ligands strategy and structurally characterized by X-ray single-crystal diffraction. Structural analysis reveals that MOF 1 displays a 3, 6-connected 2D structure with a new topological point symbol of (4²·6)₂(4⁸·6⁶·8), while MOF 2 presents a 2D sql topology structure. The catalytic studies reveal that 2 exhibits excellent catalytic activity for the cycloaddition reaction of CO₂ with epoxides under mild conditions. Furthermore, 2 can be reused at least three times while maintaining its catalytic ability.

Two new viologen-polyoxometalate hybrid crystalline materials: (MV)₂[HPW₂^ⅤW₁₀^ⅥO₄₀] ·2H₂O (1) and (EV)₂[Mo₈O₂₆] (2) have been synthesized by using the cations of 1, 1'-dimethyl-4, 4'-bipyridinium dichloride (methyl viologen, MV) and 1, 1'-diethyl-4, 4'-bipyridinium dibromide (ethyl viologen, EV) as the electron acceptors, and the electron-rich polyoxometalate anions as the electron donors. The structures of compounds 1 and 2 have been determined by single-crystal X-ray crystallography. Hydrogen bond interactions exist between the cations and the anions in 1 and 2. Interestingly, 2 has a photochromic performance with a light response time within 1 min. The photochromic mechanism of compound 2 has been investigated by solid-state diffuse reflection, electron paramagnetic resonance and theoretical calculation. 1 and 2 show good catalytic performance in the photocatalytic degradation of several organic dyes (methylene blue, pararosaniline hydrochloride and rhodamine 6G).