Structural characterization and solvent vapor sorption of two solvent-dependent Zn(ii) supramolecular architectures based on a flexible tripodal thioether-based pyridyl ligand and a dicarboxylate-based ligand†
Abstract
Two solvent-dependent 3D supramolecular architectures constructed by a doubly-interpenetrating layered 2D MOF of [Zn3(L1)2(L2)(Cl)4(CH3OH)2]·6CH3OH (1) and triply-interpenetrating 3D MOF of [Zn(L1)(L2)(H2O)]·2C2H5OH (2) (L1 = 1,3,5-tris(4-pyridylsulfanylmethyl)-2,4,6-trimethylbenzene and L2 = dianion of 2,5-dihydroxyterephthalic acid), were synthesized and structurally characterized using single-crystal X-ray diffraction method. In compound 1, there were two crystallographically independent Zn(II) ions with a distorted octahedral and a distorted tetrahedral geometries, respectively. L1 acted as a bridge ligand with a tris-monodentate coordination connecting two Zn(II) (Zn(1) and Zn(2)) ions to form a one-dimensional (1D) polymeric chain, genertating a [Zn2L12] metallocycle as the building unit. Adjacent chains were then connected via the bridge of Zn(II) and L2 with a bis-monodentate coordination mode to form a two-dimensional (2D) layered MOF. Two 2D layers mutually interpenetrated via the L2 ligands penetrating into the [Zn2L12] metallocycle rings to genetrate a 2D doubly-interpenetrating network. In 2, the Zn(II) ion was six-coordinate bonded to three nitrogen donors of three L1 and three oxygen donors of two crystallographically independent L2 and one H2O molecule to form a distorted octahedral grometry. L1 acted as a bridge ligand with a tris-monodentate coordination connecting Zn(II) ions to form a 2D honeycomb-like layered framework. Adjacent 2D layers were mutually connected via the bridge of Zn(II) and L2 with a bis-monodentate coordination mode to form a three-dimensional (3D) MOF. The much larger intraframework spaces were then occupied by the other two 3D crystallographically identical networks but independent to form a 3D triply interpenetrating supramolecular architecture. The reversible solvent vapor ad-/desorption behaviors were investigated by cyclic de-/rehydration TG analysis and the water vapor ad-/desorption isotherms of 1 and 2 were studied in detail.