Nan-Nan Shen

Syntheses, Crystal Structures, Ion-Exchange, and Photocatalytic Properties of Two Amine-Directed Ge-Sb-S Compounds.

Among numerous heterometallic chalcogenidoantimonates, relatively a few amine-directed Ge-Sb-S compounds have been synthesized. Presented here are the solvothermal syntheses, crystal structures, and ion-exchange, optical, and photocatalytic properties of two novel amine-directed Ge-Sb-S compounds, namely, [CH3NH3]20Ge10Sb28S72·7H2O (1) and [(CH3CH2CH2)2NH2]3Ge3Sb5S15·0.5(C2H5OH) (2). The structure of 1 features an unprecedented two-dimensional Ge-Sb-S double-layer composed of two twofold rotational symmetry-related thick [Ge8Sb28S72]n(28n-) single layers adhered via vertex-sharing [GeS4] tetrahedra. Compound 2 features a unique [Ge3Sb5S15]n(3n-) slab perforated with large elliptic-like windows. Remarkably, compound 1 exhibited excellent Cs(+) ion-exchange property despite the presence of excess competitive cations, such as Na(+), K(+), Mg(2+), and Ca(2+) ions. In addition, compound 1 displayed visible-light-driven photocatalytic activity for degradation of rhodamine B.

Varied forms of lamellar [Sn3Se7]n2n− anion: the competitive and synergistic structure-directing effects of metal–amine complex and imidazolium cations

Presented are the syntheses, characterizations and properties of a series of selenidostannate compounds directed by metal-amine complex (MAC) cations and/or [Bmmim](+) (Bmmim = 1-butyl-2,3-dimethylimidazolium). Mixtures of the ionic liquid (IL) (Bmmim)Cl and amines, such as ethylenediamine (en) and diethylenetriamine (dien), in various ratios were used to ionothermally/solvothermally prepare four selenidostannates, namely, [Mn(en)3]Sn3Se7 (1), [Mn(dien)2]Sn3Se7·H2O (2), (Bmmim)3[Mn(en)3]2[Sn9Se21]Cl (3) and (Bmmim)6[Mn(dien)2]2Sn15Se35 (4). Single-crystal X-ray diffraction analyses revealed that these compounds exhibit lamellar anionic [Sn3Se7]n(2n-) structures. [Sn3Se7]n(2n-) layers in all 1-4 possess a {6(3)} net, considering [Sn3Se10] semi-cube unit as a 3-connected node; however, diverse multi-membered rings exist there. In compounds 1 and 2, all the [Sn3Se10] units are 3-connected nodes interlinking with each other via edge-sharing two Se atoms to produce six-membered rings. However, in compound 3, the insertion of two [Sn3Se9] units into a six-membered ring results in a novel eight-membered heart-shaped ring, which has never been observed before in the family of chalcogenidostannates. More interestingly, the [Sn3Se7]n(2n-) layer in compound 4 consists of mixed six- and eight-membered rings. The phase composition is strongly dependent on the ratio of IL to MAC in the syntheses, e.g., 1 and 2 were obtained with IL:MAC ratios less than 3:1 and 4:1, while 3 and 4 were obtained when the ratios were increased to 4:1 and 5:1, respectively. The structural variation from 1 to 4 clearly indicates the competitive and synergistic effects between MAC and IL cation on the formation of lamellar selenidostannates. A synthetic approach via varying the ratio of IL to MAC cation as solvent and structure-directing agent will be attractive in the synthesis of novel chalcogenidometallates.

From T2,2@Bmmim to Alkali@T2,2@Bmmim Ivory Ball-like Clusters: Ionothermal Syntheses, Precise Doping, and Photocatalytic Properties

Presented here are the syntheses, structures, and properties of an In-Sn-Se compound based on a ternary super-supertetrahedral T2,2 cluster nested by Bmmim cations and two of its alkali-doped quaternary analogues. By means of a one-pot ionothermal method, an alkali metal ion (Cs(+) or Rb(+)) could be precisely doped into the central cavity of the cluster, forming an alkali@T2,2@Bmmim quaternary cluster. Remarkably, the undoped compound exhibited excellent stability and visible light photodegradation ability over a wide range of pH, especially in acidic conditions.

Synthesizing 2D and 3D Selenidostannates in Ionic Liquids: The Synergistic Structure-Directing Effects of Ionic Liquids and Metal–Amine Complexes

Presented are the ionothermal syntheses, characterizations, and properties of a series of two- and three-dimensional selenidostannate compounds synergistically directed by metal-amine complex (MAC) cations and ionic liquids (ILs) of [Bmmim]Cl (Bmmim=1-butyl-2,3-dimethylimidazolium). Four selenidostannates, namely, 2D-(Bmmim)3 [Ni(en)3 ]2 [Sn9 Se21 ]Cl (1, en=ethylenediamine), 2D-(Bmmim)8 [Ni2 (teta)2 (μ-teta)]Sn18 Se42 (2, teta=triethylenetetramine), 2D-(Bmmim)4 [Ni(tepa)Cl]2 [Ni(tepa)Sn12 Se28 ] (3, tepa=tetraethylenepentamine), and 3D-(Bmmim)2 [Ni(1,2-pda)3 ]Sn8 Se18 (4, 1,2-pda=1,2-diaminopropane), were obtained. Single-crystal X-ray diffraction analyses revealed that compounds 1 and 2 possess a lamellar anionic [Sn3 Se7 ]n (2n-) structure comprising distinct eight-membered ring units, whereas 3 features a MAC-decorated anionic [Ni(tepa)Sn12 Se28 ]n (6n-) layered structure. In contrast to 1-3, compound 4 exhibits a 3D open framework of anionic [Sn4 Se9 ]n (2n-) . The structural variation from 1 to 4 clearly indicates that on the basis of the synergistic structure-directing ability of the MACs and ILs, variation of the organic polyamine ligand has a significant impact on the formation of selenidostannates.

Supramolecular Organization of [TeCl6]2– with Ionic Liquid Cations: Studies on the Electrical Conductivity and Luminescent Properties

A series of hybrid tellurium chlorides based on ionic liquids (ILs), namely, α-[Bmim]2TeCl6 (1, Bmim = 1-butyl-3-methyl imidazolium), β-[Bmim]2TeCl6 (2), [HOOCMim]2TeCl6 (3, HOOCMim = 1-carboxymethyl-3-methyl imidazolium), [Bzmim]2TeCl6 (4, Bzmim = 1-benzyl-3-methyl imidazolium), [EPy]2TeCl6 (5, EPy = 1-ethylpyridinium), [Bmmim]2TeCl6 (6, Bmmim = 1-butyl-2,3-dimethyl imidazolium), have been synthesized and characterized. Different kinds of supramolecular networks have been obtained via self-assemblies of isolated [TeCl6]2- anions and various ionic liquid cations. Interestingly, all the title compounds exhibit semiconducting behaviors: their optical absorption edges calculated from reflectance spectra are in the range of 2.54-2.68 eV; their electrical conductivities measured by using two-probe direct current (DC) method indicate values from 2.06 × 10-9 to 4.65 × 10-6 S/cm, which are typical for semiconductors and comparable to the reported crystalline hybrid metal halides. The luminescent property studies reveal that only compounds 3 and 6 exhibit intense emissions both at 77 and 298 K, probably owing to the minimum distortion of the TeCl6 octahedra in 3 and 6.