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

Abstract

Six new metal–organic frameworks, namely, {[Co(btmb)(HBTC)]·2H₂O}_<i>n</i> (<b>1</b>), {[Co₃(btmb)₃(BTC)₂(H₂O)₂]·6H₂O}_n (<b>2</b>), {[Co₃(btmb)₃(BTC)₂(H₂O)₄]·2H₂O}_n (<b>3</b>), {[Ni₃(btmb)₃(BTC)₂(H₂O)₄]·2H₂O}_n (<b>4</b>), [Cu(btmb)(HBTC)]_<i>n</i> (<b>5</b>), and [Cu(btmb)(NDC)]_<i>n</i> (<b>6</b>) (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 <b>1</b> is a 6-connected self-penetrating three-dimensional (3D) framework with 4⁴·6¹⁰·8 topology. Complex <b>2</b> exhibits a trinodal (3,4)-connected topology with a Schläfli symbol of (6²·8⁴)(6⁴·8²)(6³). Both complexes <b>3</b> and <b>4</b> possess 3D pillar-layered structures with a Schläfli symbol of (6²·8·10³)(6⁴·8·10)(6·10²). Complex <b>5</b> is also a 3D polymer with a pillar-layered framework, which can be simplified as the (6³)(6⁹·8) topology. Complex <b>6</b> shows a 4-connected 3D framework with a Schläfli notation of (6⁵·8)₂. Furthermore, complexes <b>1</b>–<b>6</b> 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.