Low temperature route towards new materials: solvothermal synthesis of metal chalcogenides in ethylenediamine

Novel Materials through Non-Hydrolytic Sol-Gel Processing: Negative Thermal Expansion Oxides and Beyond

Low temperature methods have been applied to the synthesis of many advanced materials. Non-hydrolytic sol-gel (NHSG) processes offer an elegant route to stable and metastable phases at low temperatures. Excellent atomic level homogeneity gives access to polymorphs that are difficult or impossible to obtain by other methods. The NHSG approach is most commonly applied to the preparation of metal oxides, but can be easily extended to metal sulfides. Exploration of experimental variables allows control over product stoichiometry and crystal structure. This paper reviews the application of NHSG chemistry to the synthesis of negative thermal expansion oxides and selected metal sulfides.

Small organic molecule templating synthesis of organic-inorganic hybrid materials: their nanostructures and properties

The design and synthesis of organic-inorganic hybrid materials has developed over the last two decades as chemists and materials engineers have maintained their attention on these materials. In the synthetic process of organic-inorganic hybrid materials, the organic components usually act as templates for directing the connectivity and arrangement of inorganic building blocks. Specifically, according to the size and scale of inorganic building blocks, these organic-inorganic hybrid materials can be divided into molecular scale and nanoscale organic-inorganic hybrid materials. In this review, we highlight the recent advances in using small organic molecules as the templates for the synthesis of organic-inorganic hybrid nanomaterials with interesting properties. The synthetic techniques, hybrid crystal structures, templating roles, crystal growth mechanism, control of sizes and morphologies, and novel properties of organic-inorganic hybrid materials will be discussed.

A low band gap iron sulfide hybrid semiconductor with unique 2D [Fe(16)S(20)](8-) layer and reduced thermal conductivity

A low band gap iron sulfide hybrid semiconductor with unique layered structure and unusual iron coordination exhibits significantly reduced thermal conductivity.

Sonochemical synthesis of nanocrystalline mercury sulfide, selenide and telluride in aqueous solutions

Nanocrystalline mercury chalcogenides HgE (E=S, Se, Te) were synthesized in a single step by a convenient, simple sonochemical method. Mercury nitrate, Hg(NO3)2, dissolved in 0.1 M ethylenediamine tetraacetic acid (EDTA), was used as the source of mercury and elemental chalcogenes, dissolved in a NaOH solution, as the sources of chalcogenide. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDAX). The synthesis procedure is simple and uses less toxic reagents than the previously reported methods. The results showed that the complexing agent EDTA plays a crucial role in the process.

Toward a facile one-step construction of quantum dots containing Zn8S cores

Three neutral nanoclusters Zn 8S(SC 6H 5) 14L 2 [L = 3-aminopyridine ( 1), 4-(dimethylamino)pyridine ( 2), 4-methylpyridine ( 3)] featuring a wurtzite-like core have been assembled by a controlled one-step hydrothermal reaction. Their detailed photoluminescence properties depend upon the ligand substituents. Cluster 1 exhibited a narrow, symmetric emission spectrum and has a potential application as a fluorescence quantum dot.

Direct solvothermal growth, crystal structures, and optical properties of one-dimensional lanthanide selenidoarsenate(v) polymers [Ln(dien)2(µ3-AsSe4)] (Ln = Nd, Sm): the first example of an AsSe43−anion acting as a ligand to a lanthanide complex

Two novel lanthanide selenidoarsenates(v) [Ln(dien)2(micro(3)-AsSe(4))] (Ln = Nd 1, Sm 2, dien = diethylenetriamine) were synthesized by the reactions of As(2)O(3) and Se with Nd(2)O(3) or Sm(2)O(3) in dien under solvothermal conditions. 1 and 2 are in the orthorhombic crystal system with Iba2 and Pbca space groups, respectively. The [AsSe(4)](3-) anion acts as a tridentate micro(3)-AsSe(4) ligand to bridge the lanthanide [Ln(dien)2](3+) complexes leading to one-dimensional neutral [Ln(dien)(2)(micro(3)-AsSe(4))](infinity) chains. The chains contact through hydrogen bonding to form network structures. The lanthanide center lies within a nine-coordinated environment involving six N atoms of two dien ligands and three Se atoms of two different tetrahedral [AsSe(4)](3-) anions forming a distorted monocapped square antiprism. The novel coordination polymers [Nd(dien)2(micro(3)-AsSe(4))](infinity) and [Sm(dien)2(micro(3)-AsSe(4))](infinity) are the first examples of solvothermally synthesized selenidoarsenates with [AsSe(4)](3-) anion acting as a ligand in lanthanide complexes. The band gaps of 2.11 eV for 1, and 2.18 eV for 2 have been derived from optical absorption spectra. TG-DSC curves show that two compounds remove coordinated dien ligands in a single step.

Incorporation of a New Type of Transition Metal Complex into the Thioarsenate Anion: Syntheses, Structures, and Properties of Two Novel Compounds [Mn3(2,2‘-bipy)3(AsVS4)2]n·nH2O and Mn2(2,2‘-bipy)As2IIIS5

The incorporation of [Mn(2,2'-bipy)2]2+ with thioarsenate resulted in the formation of two novel compounds, [Mn3(2,2'-bipy)3(As(V)S4)2]n.nH2O (1) and Mn2(2,2'-bipy)As2(III)S5 (2), in which the main-group chalcogenide framework is incorporated with a [tm(2,2'-bipy)m]n+ complex. Meanwhile, the tetrathioarsenate(V) anion acts as a new mu3-1kappaS:1,2kappaS':2,3kappaS":3kappaS'" ligand in 1, in which all four S atoms of the [As(V)S4]3- anion are coordinating to metal. As a result, the two compounds exhibit semiconducting properties (Eg = 2.18 eV (1) and 1.83 eV (2)) and strong blue photoluminescence, with the emission maximum occurring at about 440 nm. Magnetic measurements show that both compounds have AF ordered states with Néel temperatures of 19 and 24 K for 1 and 2, respectively.

Copper tellurolate clusters in trimethylsilylated MCM-41 — Preparation and condensation

The copper tellurolate cluster [(Cu6(TePh)6(PEtPh2)5] (1) has been loaded into the pores of a trimethylsilylated MCM-41 (TMS–MCM-41) framework. Solutions of 1 in tetrahydrofuran lead to good impregnation weight % (~10 wt%, 1). The resulting material was analysed by powder X-ray diffraction (PXRD), nitrogen sorption isotherms, thermogravimetric analysis (TGA), energy dispersive X-ray (EDX) analysis, 31P CP MAS NMR spectroscopy, and transmission electron microscopy (TEM). It was observed that the loading process proceeds with the intact cluster 1 being present within the hexagonal architecture. The intact nature of 1 makes it an ideal candidate for condensation by photochemical or thermal means. Both of these condensation treatments increase the Cu:Te ratio of 1 to approach that observed in binary semiconductor Cu2Te. The condensation process was analysed by GC–MS spectrometry and characterization of the condensed, isolated composites was performed by TGA, EDX analysis, 31P CP MAS NMR spectroscopy, nitrogen adsorption, and TEM measurements. Thermal condensation results in the formation of Cu2Te particles, whereas photochemical condensation yields larger copper-tellurolate nanoclusters.Key words: copper, tellurium, cluster, MCM-41, trimethylsilylated, photolysis, thermolysis, Cu2Te, composite, mesoporous material.

Room temperature synthesis of coinage metal (Ag, Cu) chalcogenides

Coinage metal chalcogenides in their nanoregime have been synthesized in aqueous medium at room temperature by mixing the nanoparticles of silver or copper with selenium nanoparticles which are authenticated by UV-vis, XRD and TEM analyses.

The First Example of Solvothermally Synthesized Thioantimonates(V) with Ethylenediamine Coordinated Lanthanide(III): [Sm(en)4]SbS4·0.5en and [Sm(en)3(H2O)(μ-SbS4)]∞

Under mild solvothermal conditions two novel thioantimonates(V) [Sm(en)4]SbS4 x 0.5en (1) and [Sm(en)3(H2O)(micro-SbS4)]infinity (2) were synthesized; the structure of 1 contains discrete [Sm(en)4]3+ and [SbS4]3 ions, while 2 consists of neutral [Sm(en)3(H2O) (micro-SbS4)] one-dimensional chains.

Incorporating Transition Metal Complexes into Tetrathioarsenates(V): Syntheses, Structures, and Properties of Two Unprecedented [Mn(dien)2]n[Mn(dien)AsS4]2n·4nH2O and [Mn(en)3]2[Mn(en)2AsS4][As3S6]

Two transition-metal tetrathioarsenate complexes, [Mn(dien)(2)](n)[Mn(dien)AsS(4)](2n).4nH(2)O (1) with one-dimensional water chain and [Mn(en)(3)](2)[Mn(en)(2)AsS(4)][As(3)S(6)] (2) with mixed-valence As(3+)/As(5+) character, have been synthesized and structurally characterized. The tetrathioarsenate(V) anion acts as a novel mu(2)-eta(1),eta(2) ligand in 1 and as a chelating ligand in 2. The two compounds exhibit intriguing semiconducting properties (E(g) = 2.18 eV (1), 2.48 eV (2)) and strong photoluminescence with the emission maximum occurring around 440 nm.

A sonochemical method for the selective synthesis of alpha-HgS and beta-HgS nanoparticles

A novel sonochemical method for the selective synthesis of alpha-HgS (cinnabar) and beta-HgS (metacinnabar) nanoparticles in aqueous solutions is reported in this paper. alpha-HgS and beta-HgS nanoparticles have been selectively prepared by choosing sodium thiosulfate and thiourea as the sulfur source respectively. To study the crystalline structure, size, morphology and composition of the products, characterization techniques including X-ray powder diffraction, transmission electron microscopy, selected area electron diffraction, X-ray photoelectron spectroscopy and energy-dispersive X-ray analysis are employed. The optical properties of the nanoparticles are investigated by UV-visible absorption spectroscopic measurements. The direct band gap of the as-prepared alpha-HgS nanoparticles with an average size of 12 nm is calculated to be 2.8 eV according to the absorption spectrum. In the case of the beta-HgS nanoparticles with an average size of 13 nm, a broad absorption peak is observed in the UV-visible absorption spectrum, which can be ascribed to the special surface state of this sample. Probable mechanisms for the sonochemical formation of alpha-HgS and beta-HgS nanoparticles in aqueous solutions are presented. The optimum pH value of the stock solutions and the effect of sonication time on the particle size are also investigated.

Templated Synthesis of the Novel Layered Silver−Antimony Sulfides [H3NCH2CH2NH2][Ag2SbS3] and [H3NCH2CH2NH2]2[Ag5Sb3S8]

Two new silver-antimony sulfides, [C(2)H(9)N(2)][Ag(2)SbS(3)] (1) and [C(2)H(9)N(2)](2)[Ag(5)Sb(3)S(8)] (2), have been prepared solvothermally in the presence of ethylenediamine and characterized by single-crystal X-ray diffraction, thermogravimetry, and elemental analysis. Compound 1 crystallizes in the space group Pn (a = 6.1781(1) A, b =11.9491(3) A, c = 6.9239(2) A, beta =111.164(1) degrees ) and 2 in the space group Pm (a = 6.2215(2) A, b = 15.7707(7) A, c = 11.6478(5) A, beta = 92.645(2) degrees ). The structure of 1 consists of chains of fused five-membered Ag(2)SbS(2) rings linked to form layers, between which the template molecules reside. Compound 2 contains honeycomb-like sheets of fused silver-antimony-sulfide six-membered rings linked to form double layers. The idealized structure can be considered to be an ordered defect derivative of that of lithium bismuthide, Li(3)Bi, and represents a new solid-state structure type.

Rb(4)Hg(5)(Te(2))(2)(Te(3))(2)Te(3), [Zn(en)3](4)In(16)(Te2)4(Te3)Te22, and K2Cu2(Te2)(Te3): novel metal polytellurides with unusual metal-tellurium coordination

Three novel metal polytellurides Rb(4)Hg(5)(Te(2))(2)(Te(3))(2)Te(3) (I), [Zn(en)(3)](4)In(16)(Te(2))(4)(Te(3))Te(22) (II), and K(2)Cu(2)(Te(2))(Te(3)) (III) have been prepared by solvothermal reactions in superheated ethylenediamine at 160 degrees C. Their crystal structures have been determined by single-crystal X-ray diffraction techniques. Crystal data for I: space group Pnma, a = 9.803(2) A, b = 9.124(2) A, c = 34.714(7) A, Z = 4. Crystal data for II: space group C2/c, a = 36.814(7) A, b = 16.908(3) A, c = 25.302(5) A, beta = 128.46(3) degrees, Z = 4. Crystal data for III: space group Cmcm, a = 11.386(2) A, b = 7.756(2) A, c = 11.985(2) A, Z = 4. The crystal structure of I consists of 1D infinite ribbons of [Hg(5)(Te(2))(2)(Te(3))(2)Te(3)](4-), which are composed of tetrahedral HgTe(4) and trigonal HgTe(3) units connected through the bridging Te(2-), (Te(2))(2-), and (Te(3))(2-) ligands. II is a layered compound containing InTe(4) tetrahedra that share corners and edges via Te, Te(2), and Te(3) units to form a 2D slab that contains relatively large voids. The [Zn(en)(3)](2+) template cations are filled in these voids and between the slabs. The primary building blocks of III are CuTe(4) tetrahedra that are linked by intralayer (Te(3))(2-) and interlayer (Te(2))(2-) units to form a 3D network with open channels that are occupied by the K(+) cations. All three compounds are rare polytelluride products of solvothermal reactions that contain both Te(2) and Te(3) fragments with unusual metal-tellurium coordination.