Synthesis Of D-A Type Terpyridine-Metal Complexes And Their Photoelectric Property

In recent years,tripyridine（TPY）and its derivatives combined with transition metals and rare earth metal ions to form complexes have been widely used in chemical/biological sensing,electrochromic and supramolecular aggregation due to their unique photophysical,electrochemical,catalytic and magnetic properties.In this thesis,a series of2,2’:6’,2’’-tripyridine（TPY）derivatives and the corresponding Zn and Eu complexes were designed and synthesized,and the relationship between the molecular structure and the photoelectric function of the complexes was comparatively studied,with the main work as follows.1.A series of benzene（ph-）,4-methoxybenzene（CH₃Oph-）,4-（3,6-tert-butyl carbazolyl）benzene（2^tBu CZph-）,dimethylaniline（2CH₃N-）,N-butyldiphenylamine（DPA-）,triphenylamine（TPA-）and dimethoxytriphenylamine（2CH₃O-TPA-）were selected as different electron-donating groups and chemically modified to TPY at the 4’s position,a series of D-A type ligands L₁～L₇ were synthesized,followed by coordination with Zn（II）to synthesize the complexes 1～7 with D-A-D interactions,and the effects of push-pull electron effects on the photophysical and electrochemical properties of the complexes were systematically investigated.The results show that the modulation of Zn complexes from deep blue to red light emission can be achieved by the modification of peripheral electron-donating groups;the complexes can be used for multicolor fluorescence imaging of He La cells due to their good biocompatibility;the complexes present multiple emission properties in different polar organic films that are different from the solution state and can be used as multicolor fluorescent coatings;the TPA-modified complexes 6 have excellent electrofluorescence enhancement（～26-fold）effect,as well as its electropolymerized films with low-voltage driven（+1.0 V）electrochromic behavior from orange to dark blue,with a coloring response time of 5.7 s,a bleaching response time of 2.9 s,and an optical contrast of43.9%.2.Benzene（ph-）,4-methoxybenzene（CH₃Oph-）,N-butyldiphenylamine（DPA-）,triphenylamine（TPA-）and dimethoxytriphenylamine（2CH₃O-TPA-）with different electron-pulling abilities were chemically coupled with TPY,2,6-bis（pyrazinyl）pyridine（PYDPZ）and N,N’-dimethyl-2,6-bis（pyrazinyl）pyridine（PYDPZ-2CH₃-2I）groups with different electron-pulling abilities to synthesize a series of D-A ligands molecules with different intramolecular interactions 1～15,and the effects of D-A interactions on the photophysical properties of the ligands were systematically investigated.The results showed that the ICT absorption and emission peaks of TPY series ligands in CH₂Cl₂ solution were significantly red-shifted and the quantum yields were significantly increased with the enhanced electron donating ability of the modified groups.By replacing TPY with the more electron-pulling PYDPZ,the ICT absorption peaks of the ligands were further red-shifted,and thus the N,N-dimethylation sharply increased the intramolecular D-A interactions and molecular polarity,leading to their non-emitting nature in CH₂Cl₂ solution.However,when CH₂Cl₂ was changed to a polar ethanol solvent and Zn²⁺was added,their PL intensity was restored.Among them,the ligands TPAPYDPZ-2CH₃-2I exhibited good Zn²⁺-induced green fluorescence in ethanol solution.The stoichiometric ratio of the formed complexes was confirmed by successive titration experiments.The method has a good selectivity factor(I_Zn/I_Cd=23)and a low detection limit（32 ng/m L）,and was used for the quantitative determination of Zn²⁺in water samples under optimized experimental conditions with an average recovery of 97.5%.Due to the good biocompatibility of the TPAPYDPZ-2CH₃-2I probe,it was also successfully used for the quantitative determination of Zn²⁺in water samples was also successfully applied to the imaging of Zn²⁺ions in He La cells due to its good biocompatibility.Meanwhile,its low membrane surface adsorption and transport energy barriers were verified using molecular dynamics simulations,showing the potential of the probe for studying Zn²⁺uptake,bioaccumulation and bioavailability in living organisms.3.Three new terpyridine Eu（Ⅲ）complexes,[(L^1-3)Eu（HFA）₃]（where L¹=4’-phenyl-2,2’:6’,2’’-terpyridine,L²=4’-{[p-（N-butyl-N-phenyl）amino]-phenyl}-2,2’:6’,2’’-terpyridine},L³=4’-{p-[p-（N,N′-dibutyl-N′-phenyl）-phenyldiamino]-phenyl}-2,2’:6’,2’’-terpyridine,and HFA=hexafluoroacetylacetone）,have been successfully synthesized and characterized by UV-vis absorption spectrum,FTIR,MALDI-TOF MS and elemental analysis.The X-ray crystallography of complex[（L²）Eu（HFA）₃]shows that the europium（Ⅲ）ion is nine-coordinated with N₃O₆ donors in normal ranges.Owing to the antenna effect,complex[（L¹）Eu（HFA）₃]（Ф=0.44）possesses ca.3 times enhancement of the metal-centered red emission intensity compared to that of precursor Eu（HFA）₃（Ф=0.16）.The most interesting is that complex[（L³）Eu（HFA）₃]displays an unique electrofluorochromic behavior with the ternary absorption（orange/dark-blue/pale-yellow）and PL emission（red/deep-blue/greenish-blue）conversions,in which the ICT,cation radicals-related and Eu（Ⅲ）-centered electronic transitions are involved.