Hydrothermal Syntheses of Metal–Organic Frameworks Constructed from Aromatic Polycarboxylate and 4,4′-Bis(1,2,4-triazol-1-ylmethyl)biphenyl

Six new metal–organic frameworks, namely, {[Co(btmb)(HBTC)]·2H2O}n (1), {[Co3(btmb)3(BTC)2(H2O)2]·6H2O}n (2), {[Co3(btmb)3(BTC)2(H2O)4]·2H2O}n (3), {[Ni3(btmb)3(BTC)2(H2O)4]·2H2O}n (4), [Cu(btmb)(HBTC)]n (5), and [Cu(btmb)(NDC)]n (6) (H3BTC = 1,3,5-benzenetricarboxylic acid, H2NDC = 1,2-benzenedicarboxylic acid, and btmb = 4,4′-bis(1,2,4-triazol-1-ylmethyl)biphenyl), have been synthesized under hydrothermal conditions. The structure of 1 is a 6-connected self-penetrating three-dimensional (3D) framework with 44·610·8 topology. Complex 2 exhibits a trinodal (3,4)-connected topology with a Schläfli symbol of (62·84)(64·82)(63). Both complexes 3 and 4 possess 3D pillar-layered structures with a Schläfli symbol of (62·8·103)(64·8·10)(6·102). Complex 5 is also a 3D polymer with a pillar-layered framework, which can be simplified as the (63)(69·8) topology. Complex 6 shows a 4-connected 3D framework with a Schläfli notation of (65·8)2. Furthermore, complexes 1–6 as heterogeneous catalysts were studied in the green catalysis process of the oxidative coupling of 2,6-dimethylphenol (DMP) to poly(1,4-phenylene ether) (PPE) and diphenoquinone (DPQ). The results show that these complexes exhibit different catalytic activities; both the Cu complexes are catalytically active by showing high conversion of DMP and high selectivity of PPE, and they exhibit great potential as recyclable catalysts.