Multifuntional Silver(?)-Chalcogenide/Chalcogenolate Cluster-Based MOFs Constructed Via The Aggregation-induced Emission Ligand

Silver(I)chalcogenide/chalcogenolate cluster-based metal-organic frameworks(SCC-MOFs)are a new category of metal-organic frameworks with aesthetic structures and luminescent properties built on the silver cluster-based secondary building unit.SCC-MOFs combine the excellent photophsical properties of silver cluster and the porosity of MOFs,which not only enhance the stability of silver chalcogenolate cluster but also exhibit excellent performance in chemical sensing and become a new series of luminescent materials.Integration of ligands with specific functions into SCC-MOFs endows them with various performance.In this thesis,a typical AIE ligand,1,1,2,2-tetrakis(4-(pyridin-4-yl)phenyl)-ethene(tppe),was used to assemble a series of multifunctional SCC-MOFs.On one hand,silver(1)chalcogenolate cluster with large size,various configurations and coordination modes can assemble with multidentate ligand,and are likely to form the rigid framework with open cavity.On the other hand,rigid skeletons can efficiently restrict the pathway of nonradiative transition of tppe molecules in the excited state,which will improve luminescence properties of SCC-MOFs.Most importantly,the porosity of SCC-MOFs makes it possible to effectively encapsulate a variety of guest molecules;Thus various choices can be used to adjust the luminescence performance of SCC-MOFs through the interaction between guest molecules and the frameworks.This thesis includes three parts as follows:In part 1,the first SCC-MOFs with dual-node was synthesized,with formula of{[Ag12(StBu)6(CF3CO2)6]0.5[Ag8(StBu)4(CF3CO2)4](tppe)2(DMAC)10}n(1(?)DMAC).The tppe ligands connect Ag8 and Ag12 clusters forming a new type of three-dimensional(3D)network with 2-fold interpenetration.This compound 1(?)DMAC exhibits strong blue emission with the fluorescence quantum yield of 51.1%in the solid state.Upon exposed in the atmosphere,its fluorescence gradually changed from blue to green.Interestingly,this fluorescence change was reversible,it turned back to blue immediately when treated with DMAC.The transformation of the conformation of the tppe was restricted via the interaction between guest molecules and the rigid skeletons.After desorption of the guest molecules,the large aperture of the material makes AIE ligand change its conformation flexibly,resulting in tunable luminescence of compound 1:DMAC which can be triggered by guest molecules.This work provides a unique visualized prototype to understand the mechanism of guest-triggered aggregation-induced emission in MOFs.In part 2,exploying dodenuclear silver as nodes,a non-interpenetrated 3D mesoporous SCC-MOFs {[Ag12(StBu)6(CF3CO2)6(tppe)1.5](DMAC)39}n(2(?)DMAC)was synthesized.Free effection volume of 2(?)DMAC is as high as 74.2%,and it contains the cubic cage with the diameter of 32 A.The highly symmetrical non-interpenetrating structure endows the compound larger pore cavities and open pore channels,which makes it possible to encapsulate large functionalized guest molecules besides small solvent molecules.Through encapsulating molecules of yellow light dye,menthol,room-temperature phosphorescence,room-temperature phosphorescence(RTP),white-light emission(WLE),and circularly polarized luminescence(CPL)are realized in the SCC-MOF.This work not only enriches the type of SCC-MOFs but also provided a versatile strategy for customizing luminescence in crystalline porous materials.In part 3,a novel SCC-MOF{[Ag8(StBu)4(CF3COO)4](tppe)2(DMAC)16}n(3(?)DMAC)with high luminous efficiency was synthesized by one-pot method.The compound exhibits bright green luminescence at room temperature,with the fluorescence quantum yield as high as 94.2%.Compared to the ligands,the luminescence efficiency of the compound was significantly improved.In the compound,the ligands possess two types of coordination mode with the uncoordinated pyridine rings angling in the channels.Due to the ligand is fixed in SCC-MOFs,the rotation of benzene rings in tppe is restricted,which can reduce the loss of energy during thermal vibration,then the rigidity of the structure is enhanced,and the luminescence efficiency is greatly improved.In summary,this thesis mainly focusses on the research of the photoluminescence properties of a series of silver-chalcogenolate cluster MOFs constructed by tppe ligands.Luminescence properties of intrinsic SCC-MOFs or regulation through encapsulation/removal of guest molecules are both studied,which not only provides a feasible method for the preparation of multifunctional luminescent materials but also enriches the application of host-guest chemistry.