| Atomically precise silver-chalcogenide nanoclusters have attracted extensive attention from researchers due to their fascinating molecular structures and excellent photophysical properties.However,the instability under heating or illumination seriously hinders the research and exploration of their potential applications.In order to make up for the deficiency of silver-chalcogenide nanoclusters,researchers have constructed a series of silver-chalcogenide cluster-based metal-organic frameworks using different types of nitrogen-containing ligands,and studied their applications in luminescence regulation,heterogeneous catalysis,biological activity,etc.Combined with the current research progress,the structural diversity and versatility of such silver-chalcogenide metal-organic frameworks remain to be developed.Therefore,this thesis is the directional assembly of atomically precise silver-chalcogenide secondary units into highly ordered silver-chalcogenide metal-organic frameworks via different multi-carboxylic acid organic ligands,thereby realizing organic combination of framework materials from silver-chalcogenide secondary units and metal-organic frameworks.Such assembly greatly improves the stability of silver-chalcogenide framework materials,and integrates the porosity of metal-organic framework materials to increase the active sites of silver-chalcogenide unit site,which will be applied on gas adsorption and separation,molecular response and recognition,and heterogeneous catalysis,etc.This paper mainly includes the following three parts of research work:1.Two examples of metal-organic frameworks based on Ag–S layer were obtained by solvothermal technique,[Ag4（iPr S）3（CF3COO）]n（1）and[Ag6（iPr S）4（BTEC）0.5]n（2）.Compound 1 is a supramolecular structure formed by interlayer van der Waals interactions,while compound 2 is a three-dimensional metal-organic framework formed by coordination interaction between pyromellitic acid（H4BTEC）ligand and the Ag-S layer.Due to the semiconducting character of the Ag-S layer,both compounds 1 and 2 show temperature-dependent electronic conductivities,and density functional theory（DFT）calculations further reveal the electron transport paths of the compounds along the silver-sulfur layer.Compared with compound 1,which has a relatively large specific surface area,compound 2 has a smaller activation energy and its electronic conduction properties are less affected with temperature.Furthermore,the partial charge transfer from the Ag–S layer to the BTEC ligands in compound 2 renders unique temperature-variable photoluminescence phenomenon.This work provides a new route for the synthesis of multifunctional semiconducting metal chalcogenide 2D materials,and provides a theoretical basis and experimental basis for their applications in thermoelectric materials,electrocatalysis,and energy storage.2.Two examples of metal-organic frameworks based on Ag–S rods,namely[Ag16（iPr S）9（BTC）（HBTC）2（CH3CN）2]n（3）and{（NH2Me2）[Ag14（iPr S）6（BTB）3]}n（4）,were successfully assembled by solvothermal method using two tricarboxylic acid linkers with different sizes.Both compounds are crystallized in the cubic P3-1c space group,and two different types of silver-sulfur rods are presented in the frameworks which arranged in a perfect hexagonal array.The increase in the size of the tricarboxylic acid linker expands the framework of the compound and increases its porosity.The anisotropic electronic conductivity of compound 3 proves that electrons are mainly transported along the direction of the silver-sulfur rods.This work successfully assembled silver-sulfur rod-based metal-organic frameworks using carboxylic acid linkers,which enriched the structural diversity of silver-sulfur rod-based frameworks,and its anisotropic semiconductor properties provided research basic and experimental models for multifunctional metal rod-based frameworks.3.Using two photosensitive porphyrin carboxylic acid ligands（H2TCPP and Zn TCPP）as organic linkers,two silver-sulfur cluster-based metal-organic frameworks were successfully constructed by an anionic template strategy,namely[（HPO4）4（H2PO4）2@Ag54（iPr S）32（CF3COO）6（CH3CN）2（H2TCPP）（TCPP）]3n（5）and[（HPO4）2@Ag18（iPr S）8（H2PO4）4（H2Zn TCPP（Et OH））]2n（6）.Compound 5 is a double interpenetrating three-dimensional structure formed by the assembly of phosphate-aggregated Ag54 cluster nodes and H2TCPP linkers.Compound 6 is composed of Ag18 cluster nodes assembled into a two-dimensional structure through Zn TCPP linkers,and further assembled into a three-dimensional supramolecular framework through intramolecular and intermolecular hydrogen bonds.Both silver cluster-based framework materials exhibited good chemical stability in conventional organic solvents,which provided the basic conditions as heterogeneous catalysts.The two materials displayed effective degradation efficiency in photooxidizing the chemical warfare agent simulant 2-chloroethylethyl sulfide（CEES）and hydrolyzing diethyl cyanophosphonate（DECP）.This work demonstrates that the anionic templating strategy can efficiently synthesize silver-sulfur cluster-based frameworks,and also helps to stabilize metal cluster-based frameworks and explore their practical applications.The above results show that the silver-chalcogenide metal-organic frameworks constructed by carboxylic acid ligands not only enriches the possibility of multiple changes of silver-chalcogenide secondary unit nodes from two-dimensional layers,one-dimensional rods and discrete clusters,but also improves the overall stability of the silver-chalcogenide framework materials.On the other hand,the structural features such as silver-sulfur rods and silver-sulfur layers formed by the aggregation of silver ions are beneficial to expand the potential semiconductor properties of silver-sulfur framework materials,and presented Lewis acid sites through silver-chalcogenide nodes to promote silver-chalcogenide framework materials to have a place in the field of heterogeneous catalysis. |
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