Solvothermal Syntheses, Structure And Properties Of Multinary Chalcogenidometalates

Multinary chalcogenides exhibit useful physical and chemical properties due to their diverse and interesting structures, which are promising for applications in many modern technologies fileds, such as nonlinear optics, catalysts, IR detection, photoelectronic conductors and solar energy conversion. Therefore, the synthesis of multinary chalcogenidometalates is becoming an active area of solid state chemistry. Majority of multinary chalcogenidometalates have been prepared by the method of high-temperature solid phase, intermediate-temperature. Solvothermal technique is motivated by their potential to provide access to metastable phases which may have markedly different structures and properties from those of materials prepared using high-temperature synthetic techniques. However, transition metal ions is prone to form the less solubility of transition metal sulfide in the process of synthesizing multinary chalcogenidometalates under solvothermal condition, therefore the number of known synthetic multinary chalcogenidometalates containing transition metal ions is limited. The key of successfully obtaining novel structure is to search for suitable mineralizer to increase the solubility of transition metal sulfide under mild solvothermal condition. We synthesized a series of multinary chalcogenides containing transition metal ions with alkali metals ions counterions in the presense of thiophenol as a mineralizer, and their reactions, structures, thermal stabilities and semiconductor proterties are discussed and studied in detail.1.In AgNO3/PhSH/en and AgSPh/HOCH2CH2OH/en systems, two 2D layered compounds KAg2SbS3(1)and K2Ag3Sb3S7(2) and three 3D framework compounds A3Ag9Sb4S12(A=K, Rb, Cs)(3,4,5) were prepared with alkali metals ions counterions. In the process of synthesizing these five compounds, the thiophenol play a mineralizing role. Compound 1 contains hexagonal net formed by condensation of Ag2SbS3 six-member rings. These sheets are linked through Ag-S bonds to obtain double layers [Ag2SbS3]-.The anion of 2 consists of infinite [Sb2S4]2- chains and [Ag6Sb2S10]∞8- columns linked to form layers with potassium ions between the adjacent layers. Compounds 1,2 and 3 are isostructural and contain infinite silver-sulfur chains [Ag9S12]15-. These chains are connected to one another by the antimony atoms to generate wide channels where the alkali metal cations reside. Although the distances of alkali metal with sulfur is different, the size of channels is nearly equivalent for compound 1-3. 2.In AgSPh/HOCH2CH2OH/en and Cu(Ac)2/PhSH/en systems, two 2D layered compounds KAg2AsS3(6) and KCu2AsS3(7) were solvothermally synthesized. But in Cu/S/HOCH2CH2OH/en system, two completely different compounds CsCu2AsS3(8) and KCu4AsS4(9) were obtained using different starting materials of arsenic and different structure-directing agents.In the process of synthesizing compounds 6 and 7, the thiophenol play an effective mineralizing role. The structure of 6 consists of helical chains [Ag2S3]4-linked by the arsenic atoms to form layers with potassium ions between the adjacent layers. The condensation of Cu2AsS3 six-member rings forms a single layer [Cu2SbS3]- anion, and two parallel [Cu2SbS3]- sheets are linked by Cu-S bands to form double layers [Cu2AsS3]- of 7. Compound 8 contain layered [Cu2AsS3]- anion constructed by the fusion of two kinds of [Cu2AsS3]∞- chains with cesium ions between the adjacent layers. The anion [Cu4AsS4]- of 9 are built by a series of [Cu2S2]∞2- chains linking parallel [Cu6As2S6]∞layers, and the anion is a 3D framework and contains channels where the potassium cations reside.3.In AgNO3/PhSH/en system, we extend mineralizing role of thiophenol from synthesizing sulfide to selenide, and obtained two chains K2Ag2GeSe4(10) and K3AgSn3Se8(12). When no adding thiophenol in the mixed solvents, two oligomers, Cs4Ge2Se6 (11)and K4Sn3Se8(13) were obtained, in which don't contain transition metal Ag. This demonstrates that thiophenol plays an effective mineralizing role in synthesizing multinary chalcogenides containing transition metal silver. Meantime, we firstly attempt to synthesize multinary chalcogenides containing transition metal mercury using thiophenol serving as a mineralizer, and obtained a Hg-containing selenidometlates K2HgSnSe4(14). Compound 10 contains isolated GeSe4 tetrahedra connected by linear-coordinated Ag+ ions to form an infinite anionic chains [Ag2GeSe4]2-, with potassium ions between the adjacent chains. Compounds 11 and 13 contain dimeric [Ge2Se6]4- and trimeric [Sn3Se8]4- anions, respectively. The building blocks [Sn3Se8]4- are linked by tetrahedral coordinated Ag+ ions to generate infinite chain [AgSn3Se8]3- of 12.The [HgSnSe4]2" anion of 14 is built by edge-sharing of SnSe4 and HgSe4 units. The linkage of tetrahedrally coordinated Sn and Ag atoms in compound 14 is the same as that in the structure of SiS2, in which tetrahedral SiS4 shares their edges to form a single chain, and the same linkage is also found in compound 12.4.We are firstly obtained chainlike selenidoindate compound Mn(en)3In2Se5(15) containing Se-Se bond in the presence of thiophenol under amine alkaline conditions. The [In2Se3(Se2)]2" anion of 15 is constructed by the alternate linkage of coplanar In2Se2 four-member ring and distorted In2Se3 five-member ring. When applying H2O/en instead of PhSH/pyridine/en, we obtained pillar-layered compound MnSe(en)(16), which is built by ethylenediamine molecule linking neutral [MnSe] layer. We attempt to extend the role of thiophenol to form selenidogallates compounds containing Se-Se bond, but we obtained Ga4Se7(en)2·(enH)2(17), which is constructed by the connection of [Ga4Se7(en)2]2- unit one another.Most of chalcogenidometalates were characterized by powder XRD,DSC-TG analyses and UV-vis diffusion reflectance spectrum, and the results showed that all of these compounds are in pure phase, and have relatively good stability and semiconductor properties.