Synthesis and crystal structure of a new MOF-type indium pyromellitate (MIL-117) with infinite chains of unusual cis connection of octahedra InO_4(OH)_2

摘要

A new MOF-type indium pyromellitate (MIL-117) was hydrothermally synthesized at 483 K for 24 h. The structure of MIL-117 with structural formula In_6(OH)_6(btec)_3(H_4btec)-8-14H_2O (btec = 1,2,4,5-benzenetetracarboxylate), orthorhombic (Pnmm) symmetry and unit cell parameters a = 8.2390(8), b = 22.251(2), c = 37.791(4) A, V = 6928.2(11) A~3 was solved from single-crystal diffraction data. The three-dimensional open framework structure consists of infinite chains of unusual cis sharing In-centered octahedra linked to each other through the pyromellitate ligands. The three distinct In(III) cations are coordinated to four oxygen atoms from carboxyl groups and two μ_2-hydroxyl groups in cis positions. The MIL-117 network delimits one-dimensional channels of 7.7 x 8.0 A running along the a axis, where occluded water molecules are located. Although water species can be easily removed from the pore, no significant N_2 or CO_2 sorption was observed.