Preparation And Performance Of Tin-based Chalcogenide Cluster Based Open Frameworks

The crystalline materials of metal chalcogenide clusters（MCCs）have similar composition and semiconductor properties to metal chalcogenide semiconductors.MCCs not only have their unique performance advantages,but also can be regarded as an ideal model for the study of metal chalcogenide semiconductors.The clear composition information and structural characteristics of MCCs can provide a very valuable theoretical guidance for the study of the"structure-performance"relationship of metal chalcogenide semiconductors.In addition,due to semiconducting and porous properties of MCCs,open framework materials constructed from MCCs show attractive application prospects in many fields,such as catalysis,ion exchange,fast ion conduction,and gas adsorption.Among them,the metal-sulfur-oxygen clusters constructed by introducing oxygen into MCCs not only possess the properties of MCCs,but also have the stability of oxide materials,showing broad application prospects in the field of ion exchange.However,compared with other crystalline porous materials,such as zeolite,MOFs and COFs,the types of MCCs and their open frameworks are still relatively few,and the research on their structural types and performance development is not enough.In addition,when using MCCs or metal oxysulfur cluster open frameworks for ion exchange,the main exchanged protic amines are limited to small-sized amine,such as methylamine and dimethylamine.These have become urgent problems to be solved in the research of MCCs,metal oxysulfide clusters and their open framework.In this paper,seven compounds were synthesized from the perspective of the synthesis of MCCs and metal sulfuroxygen clusters,as well as the optimization of their photocatalytic and ion exchange properties.The full text is divided into the following 3 parts:1.The presence of metals in the material in mixed valence states can bring many properties to the material,such as superconductivity,metal conductivity,and magnetism.However,MCCs constructed with mixed valence metals and their open frameworks are very rare.Herein,we synthesized two isostructural chalcogenide cluster based mixed valence Sn3D open framework 1 and 2 by solvothermal method.The structural unit is a pseudo-T2-Sn Se cluster with one terminal interrupted,and Sn atoms show Sn ^IISe₃triangular pyramid and Sn ^IVSe₄tetrahedron two types of coordination modes.The valence states of Sn were further determined to be+2 and+4 by XPS.Photocatalytic studies reveal that the compound 1 has obvious photocatalytic degradation properties for various organic dyes such as methyl orange,methylene blue,and crystal violet（CV）,and the degradation rate is as high as 99%.2.Due to the strong reducibility of Sn（II）,it is difficult to introduce Sn（II）into the structure under the influence of complex synthesis conditions.The transition metal doping can also well adjust the electronic structure of MCCs,which is of great significance to improve their photoelectric properties.Herein,we synthesized Tn cluster open-frameworks 3 and 4constructed with the involvement of transition metals.Compound 3 is a quaternary chalcogenide with the participation of Zn,Ga and Sn.Its structure is a 3D open framework with double interpenetration assembled by T4-Zn Ga Sn S supertetrahedral clusters through corner sharing.The structure of compound 4 contains two types of clusters,T4-Zn Sn Se and T3-Sn Se,which are alternately connected by corner sharing and assembled into a 3D open framework with double interpenetration.Compounds 3 and 4 both have suitable visible optical band gaps.And the corresponding potentials of their LUMO orbitals are-1.07 e V and-1.00 e V by Mott-Schottky test,respectively,which suggests that they can be used as catalysts for photocatalytic decomposition of water in theory.3.Compared with the MCCs containing low oxidized Sn or transition metals,the open framework of MCCs constructed only by high oxidized Sn can show better stability and lower biological toxicity.Although such composition limits the application of MCCs in the field of optoelectronics,some of them have shown excellent removal ability of radioactive metals and rare earth metal ions in water.In addition,the introduction of oxygen into the structure is helpful to further improve chemical stability and ion exchange properties of MCCs open frameworks.Herein,we synthesized a series of open-frameworks 5-7,which constructed from metal oxysulfide cluster.Compounds 5 and 6 are open frameworks constructed by T3 or T2metal oxygen sulfur clusters,and their molecular formulas are T3-[Sn₁₀O₄S₁₈]^4-and T2-[Sn_2.6Ga_2.4O_1.3S₁₀]^5-,respectively.Notably,compound 7[Sn₃S₅O₆]^10-exhibits a novel open framework of metal oxysulfur clusters,which is different from the traditional Tn supertetrahedral cluster structural unit.The structural unit of compound 7 is composed of three Sn atoms combined with four surrounding oxygen and four sulfur atoms in an8-coordination manner,and the adjacent structural units are further assembled into a 2D layered structure.In addition,compound 5 exhibited excellent ion-exchange performance of radioactive metal ion Cs⁺,and the experimental adsorption capacity was as high as 162 mg/g.