Structural And Stimulus-responsive Properties Of Dye/Coordination Polymers

Coordination polymers（CPs）are new inorganic organic hybrid materials that exhibit many excellent properties.The loading of guest molecules such as dyes into CP matrix to form composites and thus enhance the properties of CPs is a current research topic,but the mechanism of the guest molecules’influence on the structure and properties of the target composites is still unclear.Many CP compounds exhibit Mechanochromic Luminescence（MCL）properties,but there is still a problem of precise modulation of the luminescence color of the material under mechanical force stimulation.Accordingly,we modified different types of CPs by forming composites using dyes as guest molecules and investigated the mechanism of the influence of dye guest molecules on the structure and MCL properties of the composites.The detailed work is as follows:（1）A novel CP[Cd L¹（DMF）₂]（1）with a two-dimensional layered structure was synthesized.When 1 is immersed in water,a dissolution recrystallization process occurs to produce a novel CP with a one-dimensional chain-like structure,[Cd L¹（H₂O）₃]·H₂O（2）.Both1 and 2 have MCL properties.A series of Dye@2 composites were conveniently prepared by doping the dye in 2 using the same solvent-mediated structure conversion reaction method.Detailed studies show that dyes exhibiting a significant aggregation-caused quenching（ACQ）effect in the matrix are suitable for modulating the luminescence color of the ground phase,while dyes exhibiting a significant solid solvent dilution（SSD）effect in the matrix are suitable for modulating the luminescence color of the unground phase.Therefore,by modulating the type and amount of dyes,we can achieve full-spectrum precision modulation of the luminescence color of the Dye@2 composite before and after mechanical grinding stimulation.In addition,the composites of 1,2 and Dye@2 also have thermoluminescent（TL）properties.The combination of Hill cipher encryption principle and the MCL/TL properties of Dye@2 can be used for information encryption applications.（2）We synthesized a series of Dye@3 composites using in situ approach by loading different dye molecules into a 3D CP with a rhombic pore,（Me₂NH₂）[Zn₂L²（H₂O）]·6DMF4H₂O（3）.The topology of the series of composites is the same as that of 3,all of which are of the binodal（4⁶.6⁴）（4⁶.6⁴）type.The pore shape of the Dye@3 skeleton under the influence of different types and amounts of dyes would be between rhombic and square,i.e.,the pore would undergo similar respiratory effect type changes.Structural analysis shows that the flexibility of SBU nodes in the skeleton plays an important role in affecting the structures.Moreover,there is a significant increase in the volume of the cell volume of the composites,but it is not simply proportional to the size and amount of the dye molecules,but shows more of a stochastic nature.In addition,we synthesized a new composite（DSM⁺）[Zn₂L²]DMF·H₂O（DSM⁺@4）;4-[p-（dimethylamino）styryl]-1-methyl-pyridinium,DSM⁺)whose matrix has a uninodal bnn-type topology.Single crystal structural analysis reveals an ordered stacking of DSM⁺cations in the channel of the composite,as well as strong C-H-πinteractions and hydrogen bonds between the dye guest molecule and the matrix.