Synthesis And Properties Of Aromatic Amine Modified Cyclometallated Iridium Complexes And Water-soluble Iridium Complexes

With the advancement of science and technology,people’s desire for a better life has become stronger.Mobile phones,tablets,computers and other electronic products have entered thousands of households,adding luster to our lives;at the same time,people’s pursuit of high-performance electronic products has never stopped.To develop more compact and intelligent electronic products,it is particularly important to design conductive components at the molecular level.In order to optimize various molecular-scale ultramicro devices,complex molecules have attracted extensive attention.Through the theoretical study of the basic complex molecules,and then to understand the principle of its conductivity,we can better explore the mysteries of molecular electronic devices.Transition metals have excellent properties,by combining with organic ligands,they can exhibit wonderful electrochemical properties.Unlike homonuclear complexes,the electron distribution and transfer of heteronuclear complexes are more complex and more challenging.Through the construction of different molecular configurations,the combination of metal cores and bridging ligands,we can systematically study the factors that affect the electron transport performance of metal organic complexes,and lay a solid foundation for the design of excellent molecular-level devices.The special structure of triarylamine makes it have good redox properties.At the same time,the complex of iridium has good photoelectric properties and is very suitable for development as a molecular device.Therefore,in this thesis,we try to design arylpyridine as the bridged ligand,use arylamine and iridium center as the redox active end groups,change the relative position of iridium center and arylamine,and the substituents on arylamine to synthesize a new type of organic molecular wire compounds,and explore the electron transportability of these compounds by electrochemical,ultraviolet-visible-near-infrared spectroscopy,and crystal structure methods.At the same time,we designed and synthesized a series of water-soluble compounds based on the existing research in the group on aggregation-induced luminescent materials,with iridium as the center,arylpyridine as the ligand,and Schiff base as the auxiliary ligand,and try to explore their photophysical properties.The specific research content is as follows:(1)Diarylamine or triarylamine modified cyclometallated iridium complexesⅡ-1～Ⅱ-8 were designed and synthesized,and their structures were characterized by NMR,carbon and high resolution mass spectrometry.The cyclic voltammetry,square wave voltammetry,ultraviolet-visible-near infrared spectroscopy electrochemical method and theoretical calculation methods were used to study the electron coupling between iridium and aromatic amines in the target compound.The results showed that:The electronic effect has a certain effect on the oxidation potential of the molecule,the reversibility of the redox process,and the electron coupling between iridium and aromatic amines.Pushing electron groups such as-OCH3 can reduce the oxidation potential of the molecule and make the redox process reversible and enhance the electronic coupling between iridium and aromatic amine;the position of iridium and aromatic amine on the benzene ring has a certain effect on the electronic coupling between iridium and aromatic amine in the molecule,and those whose iridium and aromatic amine on the para position of benzene ring are more conducive to the electronic coupling between iridium and aromatic amine than those on the meta position.(2)We designed and synthesized trifluoromethyl-modified water-soluble iridium complexes Ⅲ-8 and Ⅲ-9 and the corresponding non-carboxyl reference compound III-7,and characterized them by NMR,carbon and high resolution mass spectrometry.The structure of those compounds were further confirmed.By studying their photophysical properties and their response to acids and bases,we found that the solutions of compounds Ⅲ-8 and Ⅲ-9 have a weak emission at about 400 nm,and their maximum emission wavelength in the solid phase are 632 nm which produces strong red fluorescence,showing a significant aggregation-induced fluorescence enhancement effect;compounds Ⅲ-8 and Ⅲ-9 respond significantly to acid,and show strong red fluorescence.When pH=5,the emission of Ⅲ-8 and Ⅲ-9 at 620 nm is the strongest,and their intensities are 15 times and 50 times of that at pH=7,respectively,while the control compound Ⅲ-7 without carboxyl group has no obvious response to acid and alkali.