Solvothermal Syntheses,Structures And Properties Of Multinary Metal Sulfides Containing Barium Ions

As a kind of important inorganic functional material,multinary metal sulfides not only possess rich structures,but also exhibit unique physical and chemical properties,and represent potential applications in photocatalysis,selective ion exchange,fast ion conduction,and so on.Therefore,the study on the syntheses and properties of these sulfides is an important field in inorganic chemistry.Because of the preferences to bond with sulfur and flexible coordination modes of late transition metal ions,multinary sulfides containing these ions have become the focus in inorganic synthesis.Mild hydro/solvothermal methods are commonly used for synthesizing these compounds.While the corresponding metal sulfides have small solubility,which leads to the failure of constructing the structures.Up to now,most of the solvothermally synthesized multinary sulfides were obtained using structure directing agents with lower charge density.such as protonated organic amines or alkali metal ions.The study of alkaline earth metal ions as structural guiding agents is seldom reported,which may be related to the higher charge density of such ions and the lower solubility of corresponding sulfide.In this thesis,effective mineralizers were selected to solve the insoluble problems of transition metal sulfides,Ba2+ion was used as structure directing agent,and a series of multinary sulfides were synthesized.The structures and properties of these compounds were studied.(1)In the system of Ba-Cu-M?/M?v-S,quaternary sulfides BaCu3InS4(1),BaCu3GaS4(2),BaCu2SnS4(3)and BaCu2GeS4(4)were obtained when using excess sulfur as a mineralizer.The CuS3 and CuS4 units in 1 form a 3D Cu-S framework by sharing corners and edges,and In3+ions are incorporated into the framework and generate a complex anionic[Cu3InS4]2-structure;the CuS4 tetrahedra in compound 2 polymerize by sharing corners and edges to form a Cu-S framework,in which Ga3+ions are decorated to generate a complex anionic[Cu3InS4]2-structure.Although the two compounds have the same chemical formula,the coordination modes of Cu+and their crystal structures are totally different.The Cu-S frameworks also exist in the structures of compounds 3 and 4,and Sn4+/Ge4+ions are incorporated into them to form complex frameworks.The generating structures have the same topological structures with compound 2.(2)In the system of Ba-Ag-M?/M?-S,quaternary sulfides Ba2AgInS4(5),Ba3Ag2Sn2S8(6),BaAg2SnS4(7)and BaAg2GeS4(8)were synthesized when using excess sulfur as a mineralizer.In compound 5,Ag+and In3+are located at the same crystallographic site,and the layered structure is formed by sharing corners of MS4(M=Ag,In)tetrahedra.In compound 6,AgS4 and SnS4 tetrahedra are linked by sharing corners to form a highly symmetric cubic framework,in which each kind of tetrahedra were not self-condensed.In compounds 7 and 8,the AgS4 tetrahedra are self-condensed to form AgS2 layers with Sn4+/Ge4+ions pillaring between them and finally generate 3D anionic[Ag2SnS4]2-and[Ag2GeS4]2-frameworks.Under simulated solar light illumination,compound 7 exhibits excellent photocurrent responsive property and remains good stability.(3)In the system of Ba-Cu-M?B-S,quaternary sulfides BaCu2Cd2S5(9)and Ba3Cu4Hg4S9(10)were obtained using thiophenol as a mineralizer.In compound 9,two[CdS3]4-chains and two[CuS2]3-chains are connected by sharing the comers of S atoms to form an infinite[Cu2CdS6]6-ribbon.Each[Cu2Cd2S6]6-ribbon is linked with two such ribbons by sharing two coordinated S atoms to generate novel anionic[Cu2Cd2S5]4-layer.In compound 10,the trigonal CuS3 and linear HgS2 units are corner-shared to generate a unique anionic[Cu4Hg4S9]6-layer.Interestingly,linear-coordinated sulfur and square-planar coordinated sulfur exist in the structures of 9 and 10,respectively.Both of the coordination modes have not been reported previously in multinary sulfides.Under simulated solar light illumination,compound 9 exhibits excellent photocurrent responsive property.(4)In the system of Ba-M?B/M?B-S,ternary sulfides BaCu2S2(11),BaCu4S3(12),Ba2Ag8S7(13)and BaHgS2(14)were prepared using thiophenol as a mineralizer.In compounds 11-13,CuSx/AgSx units possess higher negative charge,so these units polymerize by sharing corners or edges to decrease the negative charge.The structure of compound 14 is formed by Hg-S framework.In the research studies,we found that excess sulfur and thiophenol are good mineralizers for the syntheses of multinay sulfides containing late transition metals.In addition,comparing with other structure directing agents(alkali metals,protonated organic amines and transition metal complexes),Ba2+has a significantly different structure directing effect due to its smaller ion radius and higher charge density.