Zai-Lai Xie

Crystalline Open‐Framework Selenidostannates Synthesized in Ionic Liquids

Ionic liquids (ILs) receive ever growing attention owing to their ability to be an alternative of conventional organic solvents in many processes, as well as other fascinating applications. The preparation of advanced functional materials making use of ILs, in particular ionothermal synthesis, has been shown to be very promising. As such, the benefits of using ILs in materials synthesis have been put forward and discussed extensively. However, such applications for chalcogenide chemistry is still in an early stage. To date most of the chalcogenides prepared in ILs are nanomaterials of known binaries. Though recently there were reports of new crystalline chalcogenides obtained in ILs containing Lewis acids or strong acceptors, for example, EmimBr-AlCl3, [5] the resulting products were limited to compounds featuring discrete clusters or cationic two-dimensional (2D) layer structure. Crystalline microporous chalcogenides are desirable for applications such as ion exchange, photocatalysis, and fast ion conductivity. Normally such materials contain an anionic framework with organic amine or alkali (or alkaline-earth) metal cations as the structure-directing agent (SDA) and charge compensating agent, and are synthesized by solvothermal or solid-state reactions. Our aim is to develop a general preparative route in ILs for crystalline microporous chalcogenides with anionic three-dimensional (3D) or 2D structures. It is anticipated that the unique solvent properties of ILs and the structure-directing effect of their cations (e.g. imidazolium cations) would favor the formation of novel microporous chalcogenides that are inaccessible using traditional SDAs and traditional synthetic routes. However, our initial ionothermal reaction trials using imidazolium-based ILs always led to known binary chalcogenides or poor-crystalline powders/gels. Hydrazine and hydrazine monohydrate (N2H4·H2O) have unique solvent properties, and have recently been widely used as efficient solvents or co-solvents in the synthesis and crystallization of inorganic solids, especially for chalcogenides. We thought that the addition of a small quantity of N2H4·H2O to an IL may change the solvent properties of the IL, and thus promote crystal growth. To explore the feasibility of this strategy, we chose selenidostannates as a model system, imidazolium chlorides as reactive ILs, and N2H4·H2O as the auxiliary solvent. By changing the varieties of ILs and adjusting the weight fraction of IL and N2H4·H2O, four open-framework selenidostannates (see Scheme 1) with high crystallinity have been obtained, namely 3D-[bmim]4[Sn9Se20] (1) (bmim = 1-butyl-3-methyl imidazolium), 3D-[bmmim]4[Sn9Se19(Se2)0.9Se0.1] (2) (bmmim = 1-butyl-2,3-dimethyl imidazolium), 3D-[pmmim]4[Sn9Se19(Se2)0.93Se0.07] (3) (pmmim = 1-pentyl-2,3-dimethyl imidazolium), and 2D-[pmmim]8[Sn17Se38] (4). Compounds 1–3 represent the first examples of IL-directed 3D open-frameworks based on binary selenidostannates and compound 4 features 2D microporous structure composed of inorganic selenidostannate nanotubes. The crystals of compound 1 were obtained by the reaction of tin, selenium, [bmim]Cl and N2H4·H2O in a molar ratio of 1:2.5:5.7:8.0 at 160 8C for 5 days. Single-crystal X-ray diffraction analysis reveals that the structure of 1 features a 3D open-framework of anionic [Sn9Se20]n 4n with multi-directional channels filled by [bmim] cations, Figure 1. In the structure, the [Sn3Se4] semicubes are linked together by two additional Se atoms that bridge one Sn atom from each cube to form [Sn6Se10] units (Figure 1a), but which link to each other through [SnSe4] tetrahedra to form an infinite wavy chain running along the 1⁄210 1 direction (Figure 1b). The chain further connects four adjacent such chains through [Sn2Se6] units through corner-bridging to result in a 3D network. Compound 2 was obtained in the reaction of tin, selenium, [bmmim]Cl, and N2H4·H2O in a molar ratio of 1:2.5:5.3:1.6 at 160 8C for 5 days. Its structure features a 3D open-framework of [Sn9Se19(Se2)0.9Se0.1]n 4n with multi-directional channels filled by [bmmim] cations, Figure 2. In the structure, the alternating [SnSe4] and [SnSe3(Se2)0.9Se0.1] tetrahedra connect one [Sn3Se4] semicube by corner-bridging and another [Sn3Se4] semicube by edge-bridging, respectively, to form an infinite chain along the a-axis. Then two such chains are linked by [SnSe4] tetrahedra via corner-bridging to form a double-chain, Figure 2b. Each double-chain further connects four adjacent double-chains by edge-bridging the [Sn3Se4] semicubes through two Se atoms, resulting in a 3D network. Dark-red thin brick-like crystals of 3 accompanied by red rod-like crystals of 4 were obtained by the reaction of tin, selenium, [pmmim]Cl, and N2H4·H2O in a molar ratio of 1:2.5:4.9:1.0 at 160 8C for 5 days. Simply by increasing the weight fraction of N2H4·H2O to a 4.9:1.6 molar ratio of [pmmim]Cl:N2H4·H2O, pure phase of 4 could be obtained in a [*] Dr. J.-R. Li, Z.-L. Xie, X.-W. He, Dr. L.-H. Li, Prof. X.-Y. Huang State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou, Fujian 350002 (P. R. China) E-mail: xyhuang@fjirsm.ac.cn

Two Gallium Antimony Sulfides Built on a Novel Heterometallic Cluster

Two gallium antimony sulfides, [Ni(en)(3)][Ga(2)Sb(2)S(7)] (1) and [(Me)(2)NH(2)](2)[Ga(2)Sb(2)S(7)] (2), have been prepared under mild solvothermal conditions. Both structures feature a two-dimensional network in which two GaS(4) tetrahedra and two SbS(3) trigonal pyramids are combined to form a heterometallic cluster of {Ga(2)Sb(2)S(9)} as a new secondary building unit. The thermal properties of 1 and 2 have been studied by thernogravimetric analysis, and the optical properties of 1 and 2 have been characterized by UV-vis spectra.

Ionothermal syntheses, crystal structures and properties of three-dimensional rare earth metal–organic frameworks with 1,4-naphthalenedicarboxylic acid

Twelve isostructural rare earth metal-organic frameworks, namely, [Hmim][RE(2)Cl(1,4-NDC)(3)] (RE = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Ho (10), Er (11), Y (12), Hmim = 1-hexyl-3-methylimidazolium, 1,4-NDCH(2) = 1,4-naphthalenedicarboxylic acid), have been ionothermally synthesized and structurally characterized. The structures feature three-dimensionally anionic frameworks of [RE(2)Cl(1,4-NDC)(3)](n)(n-) with channels in which the Hmim(+) cations are located. The current results are the first ionothermal synthesis of rare earth metal-organic frameworks based on 1,4-NDCH(2) which possess a previously unknown (4,7)-connected 3-nodal network with the Schläfli symbol of (3(2)·4(2)·5(2))(3(2)·4(9)·5(2)·6(8))(2)(4(3)·6(3))(2). Luminescent and magnetic properties of some of the title compounds have been studied. Thermogravimetric analyses indicated that all these compounds were thermally stable up to ca. 250 °C.

The multifunctional roles of the ionic liquid [Bmim][BF4] in the creation of cadmium metal–organic frameworks

This work addresses the application of ionic liquid [Bmim][BF4] with multiple functions, including as a solvent, structure-directing agent, fluoride source and catalyst promoter, for the creation of F-center Cd3F metal–organic frameworks (MOFs) via an in situ ionothermal oxidation and hydrolysis process. We thus report the syntheses, structures and characterizations of three novel three-dimensional MOFs based on the Cd3F cluster, namely, [Cd3F(ina)4(4-pic)3]·BF4 (1), [Cd3F(ina)3(4,4′-bpy)2(4-pic)2]·2BF4·(4,4′-bpy)·2H2O (2) and [Cd3F(ina)3(4,4′-bpy)3]·2BF4·(4,4′-bpy)·2H2O (3) (ina = isonicotinate, 4,4′-bpy = 4,4′-bipyridine, 4-pic = 4-methylpyridine), in which the ina ligand was produced in situ from ligand precursors, such as 4-pic and 4,4′-bpy. Compounds 1, 2 and 3 present cationic frameworks, in which the BF4− anions and the guest molecules, including the non-coordinating 4,4′-bpy and the lattice water, fill in the holes and/or channels. A thermal analysis shows that 1–3 are stable up to 200 °C. A study on the luminescence property indicates that 1–3 exhibit strong emission bands in the blue region. The current study opens an avenue for the use of ionic liquids in the formation of crystalline materials.