A new indium metal-organic 3D framework with 1,3,5-benzenetricarboxylate, MIL-96 (In), containing μ3-oxo-centered trinuclear units and a hexagonal 18-ring network

A new indium trimesate In12O(OH)12({OH}4,{H2O}5)[btc]6·≈31H2O, called MIL-96, (btc = 1,3,5-benzenetricarboxylate or trimesate species) was hydrothermally synthesized under mild condition (210 °C, 5 h) in the presence of trimethyl 1,3,5-benzenetricarboxylate in water and characterized by single-crystal X-ray diffraction technique. The MIL-96 (In) structure exhibits a three-dimensional metal-organic framework containing isolated trinuclear μ3-oxo-bridged indium clusters and infinite chains of InO4(OH)2 and InO2(OH)3(H2O) octahedra generating a hexagonal network based on 18-membered ring. The two types of indium entities are connected to each other through the trimesate species which induce corrugated chains of indium octahedra, linked via μ2-hydroxo bonds with the specific –cis–cis–trans– sequence. The 3D framework of MIL-96 reveals three kind of cavities (two of them have estimated ≈ 400 Å3 volumes), in which are encapsulated free water molecules. The latter species are removed upon heating at 150 °C.