Synthesis,Structure And Properties Of Indium-based Chalcogenide Supertetrahedral Clusters And Their Open Frameworks

Metal chalcogenide supertetrahedral clusters（MCSCs）can be regarded as sulfide“quantum dot”,which not only show excellent potential for application,but also have important value for studying the"structure-property"relationship of sulfide semiconductors due to clear structure and composition information of MCSCs.In addition,the open frameworks assembled by MCSCs as building blocks have both the properties of semiconductor materials and porous materials,and show excellent application prospects in many fields such as photoelectric catalysis,gas adsorption,fast ion conductors,and ion exchange.At present,it is one of the research hotspots to improve the synthesis accuracy of such materials,expand their structural diversity,and finally obtain metal sulfide materials with excellent performance and high application value.However,the composition of MCSCs needs to strictly follow the Paulin electrostatic valence rule,which helps to regulate the reaction conditions to build the target compounds,but limits the diversity of metal composition in cluster.The sulfide of indium（In）not only has rich semiconductor properties,but also In often exhibits a moderate oxidation state（+3）when constructing MCSCs,which is conducive to adjusting the charge balance of bonded chalcogenide elements（-2）.Therefore,as an important metal choice for the construction of MCSCs,In has been used to develop a large number of chalcogenide cluster materials with novel structure and outstanding properties.Unfortunately,there are still great challenges to improve the synthetic controllability and structural diversity of indium-based MCSCs and their open frameworks.In this paper,we manily focused on the structure design,controllable synthesis and their performance optimization of metal chalcogenide cluster and their open frameworks,and 15compounds were synthesized.The main content of the full text includes the following four parts:1.The high negative charge of MCSCs makes them have a strong tendency to self-assemble to form multi-dimensional materials,so dicrete MCSCs are often difficult to obtain in synthesis.Herein,we prepared a third class of discrete MCSCs（HDBN）₆[In₂₀S₃₃（DBN）₆]1 by choosing high charge density organic superbase DBN as a template.It is composed of two T3-In S clusters through corner sharing and the six terminal S^2-are all replaced by DBN molecule,and the overall skeleton exhibits quasi-D₃ symmetry.The structural characteristics and intramolecular host-guest interaction were studied by DFT theory.This work provides new ideas for the design and preparation of novel discrete MCSCs and expands the structural diversity of chalcogenide molecular chemistry.2.The successful preparation of compound 1 shows that MCSCs have rich combination possibilities in the synthesis process.Slight changes in synthetic parameters during the preparation of MCSCs often lead to huge differences in compound structures,which indicates that there is competition for multiple metastable crystal nuclei in the synthesis of such compounds.The orientational selection and controllable regulation of crystal nuclei of different metastable phases is the crucial to realize the precise synthesis of MCSCs and their multidimensional compounds.Herein,we used the ligand-free T3-In S cluster 2 as a precursor,and achieved its diversity transformation by adjusting the reaction conditions.These include a series of ligand-substituted discrete T3-In S clusters 3-5,as well as 1D chain compounds 6 and 3D open framework compounds 7 with T3-In S cluster as building block.Subsequently,the transformation processes were studied by means of HRMS,DFT calculation and comparative experiment,and the possible transformation mechanism of T3-In S clusters was proposed.The proton transfer between the active-SH group at the terminal of discrete T3-In S cluster and its counterions may be an important driving force for the transformation.This result provides an important theoretical and experimental guidance for the controllable synthesis of MCSCs and their open frameworks,and is helpful to the directional development of target compounds with unique structure and composition.3.Compared with discrete mcscs,the three-dimensional open framework built by it shows attractive application prospects in many fields.Among them,the open frameworks of MCSCs connected by transition metal can not only enrich thier structure,but also adjust their photoelectric performance.However,the construction of MCSCs needs to follow the Paulin electrostatic valence rule to realize the local charge matching in the clusters,which is not conducive to the diversity regulation of metal composition and site distribution in the structures of MCSCs.Herein,we prepared T5 cluster open frameworks 8-12 assembled with transition metal linker M₂OS₂（M=Cu,Zn,Mn）for the first time.The study of their semiconductor properties shows that the introduction of M₂OS₂ promotes the transfer of electrons through the metal linker between clusters and significantly improves the photoelectric response of the compound.In addition,the study of their photoluminescence performance shows that the introduction of the linker also helps to improve the photoluminescence performance of the compound,and it is helpful to reduce the low-temperature sensitivity of the luminescence performance of the compound by enhancing the rigidity of the skeleton.This work is helpful to reduce the restriction of Pauling electrostatic valence rule on the composition and distribution of transition metals in the construction of MCSCs,and provides an effective way to enrich the metal composition and site distribution.4.Due to the specific composition and cluster size of MCSCs,its assembly mode and structural aperture change monotonously,which is not conducive to the enrichment of their structure and the improvement of their performance.In contrast,non-Tn clusters can obtain structural units of different shapes and sizes through more flexible metal composition and coordination modes,and then assemble into multi-dimensional compounds with rich structural characteristics.Herein,we prepared three compounds,i.e.,1D chain compounds13 and 14 and 2D layered compound 15,which composed of In³⁺or In³⁺/Sn⁴⁺mixtures.Interestingly,In and Sn in the compound structure are still dominated by the tetrahedral coordination of In S₄ and Sn S₄,but they do not further form Tn cluster structure.In fact,these In S₄ and Sn S₄ tetrahedra assemble into Tn-cluster-free 1D or 2D compounds through corner-sharing and edge-sharing.Notably,the coordination mode of In S₅ trigonal bipyramid appears in compound 14 is very rare in chalcogenide clusters constructed by In³⁺cation.The electrocatalytic ORR performance of the three compounds shows that they all have obvious ORR electrocatalytic activity.In addition,the introduction of Sn⁴⁺into the structure can improve the catalytic performance of the materials,and the ratio between Sn⁴⁺and In³⁺can adjust the catalytic path of the material.This work not only enriches the structural diversity of metal chalcogenide compounds,but also brings new idea for the use of IIIA metals to construct non-Tn cluster materials.