Design,Synthesis And Application Of Conjugated Functional Materials Based On Non-Covalent Interaction

The Nobel Prize in Chemistry 1987 was awarded jointly to C.J.Pedersen,J.M.Lehn and D.J.Cram,for their pioneering work in the theory of supramolecular chemistry.Since then,supramolecular chemistry has attracted considerable attention as an emerging edge discipline,and has gradually penetrated into various fields of chemistry,materials,biology and other scientific community.Supramolecular chemistry is also called host-guest chemistry,which mainly uses van der Waals forces,hydrogen bonds,halogen bonds,electrostatic interactions,??stacking,hydrophobic interactions,homo radical pairing interactions,and coordination of metal-ligands,to form a“super molecule”with specific functions and properties.For example,supramolecular chemistry can be used to construct fascinating three-dimensional(3D)architectures,efficiently catalyze organic reactions,selectively recognize and detect guest molecules(including molecules,ions,and radicals),and capture and stabilize some unstable intermediates,even determine the absolute conformation of certain non-crystalline compounds.This thesis focuses on the application of supramolecular chemistry and supramolecular interactions in related fields.Firstly,we were briefly introduced the concept of supramolecular chemistry,supramolecular forces(non-covalent forces),and some common supramolecular host.After that,we summarized the application of supramolecular chemistry and supramolecular forces in different fields,like material,biology,physic,medicine and so on.Taking this as a starting point,the design ideas of this thesis were then proposed.In the second chapter,we report that spin-pairing interactions could take place between two different?-electron radicals,namely a bipyridinium radical cation(BPY^+·)and a naphthalene-1,8:4,5-bis(dicarboximide)radical anion(NDI^-·).The occurrence of this type of previously unreported hetero radical-pairing interactions is attributed to the enhancement effect of coulombic attraction between these two radicals bearing opposite charges.The coulombic-enhanced hetero radical pairing interactions were employed to drive the reversible switching of a bistable[2]rotaxane.However,since such materials are constructed by irreversible chemical bonds,their synthesis yields are usually low.Therefore,in the third chapter,using reversible hydrazide bond(?C=N-N?),we self-assembled a purely organic 3-dimensional prismatic cage(namely C⁶⁺)in water in almost quantitative yield,which not only simplifies the synthesis route but improves the synthesis efficiency.Compared to the traditional imine bond(?C=N?),this novel reversible chemical bond overcomes the unstable fact of schiff base in water,thus obtaining the very first organic imine-based cage in pure water without template.Owing to the hydrophobic cavity and electron-deficient nature of C⁶⁺,it could act as a“molecular flask”to accommodate suitably paired donor–acceptor substrates with the assistance of??stacking,hydrophobic interaction and hydrogen bonding such as guests containing either dihydroxynaphthalene or naphthalene diimide.The intermolecular donor–acceptor interactions between these two guests are remarkably enhanced within the cage cavity.In Chapter Four,we further utilize dynamic reversible imine chemistry,as well as combines with??stacking interaction and van der Waals interaction,to efficiently lock aggregate-induced luminescence(AIE)materials into rigid dimers(TPE-3-stack),which can effectively inhibit their non-radiative transitions.As a result,compared to the traditional AIE luminescent material(TPE-3-model),the stack exhibits high emission efficiency both in the dilute solution and the condensed state,and the strong solution luminescence can be used in cell imaging,while the solid-state luminescence can be used in electroluminescent materials.More importantly,our results indicate that such cage(or stack)-based pure organic compounds are promising emitting materials,and may open up an interdisciplinary in the fields of supramolecular chemistry and organic fluorescence chemistry.In Chapter Five,by using intramolecular??stacking interaction,a thermally activated delayed fluorescence(TADF)material with simultaneous through-space and-bond charge transfer(TSCT and TBCT)effects was achieved.Meanwhile,we constructed this TADF molecule into multi-(donor/acceptor)characteristic.Therefore,the non-doped solution processed device based on the three-(donor/acceptor)molecule T-CNDF-T-tCz exhibited great electroluminescent characteristics:the maximum brightness(B_max)was 5200 cd/m²,the maximum current efficiency(CE_max)was 46.4 cd/A,the maximum power efficiency(PE_max)was 20.8 lm/W,and the maximum external quantum efficiency(EQE_max)was 21.0%.The reason for the high EL performance of the multi-(donor/acceptor)system may stem from the existence of both TSCT and TBCT,which can simultaneously impart a small single-triplet gap(?E_ST)and a high transition dipole moment,as well as light up more reverse inter-system crossing(RISC)channels through degenerating molecular orbitals.According to the literature research,the efficiency of the multi-(donor/acceptor)-based device was evidently superior to those reported previously.In contrast,the peformance of the reference molecules with weaker TSCT effects or fewer D/A fragments are much inferior.In Chapter Six,with the assistance of the biological macromolecules(such as protein),the organic fluorescent probe NIM-7 could be encapusulated into its cavity by the hydrophobic interaction.On the one hand,the luminescence efficiency of NIM-7 with CT properties can be enhanced in the hydrophobic cavity of the protein;on the other hand,the good biocompatibility of the protein can help NIM-7 penetrate the cell membrane,and then improve its imaging performance.Therefore,a hydrophobic fluorescent probe was designed and synthesized,namely NIM-7,which allowed lipid droplets and lysosomes to be labelled simultaneously with high specificity under the aid of protein.Due to the different microenvironment polarity of these two organelles,NIM-7 showed two different color within cell.Moreover,NIM-7 was able to track lipid droplets and lysosomes dynamics concurrently in real-time.In contrast,the comparative experiments without addition of protein showed significantly worse imaging results.To the best of our knowledge,this is the first small-molecule fluorescent probe that can simultaneously label two different organelles.