Synthesis And Self-assembly Behavior Of Conjugated Polymers With Aggregation-Induced Fluorescence Enhancement

The luminescent conjugated polymer can be efficiently synthesized,easily modified,and has a high fluorescence quantum yield.In many cases,these applications need to be formed in solid,concentrated solution and / or aggregated.However,due to the strong π-π interaction resulting from the aromatic ring structure and the emissive body,the aggregate form usually results in highly attenuated or completely quenched fluorescence.Thus,aggregation-caused quenching(ACQ)effect can partially limit their practical application.On the other hand,a luminous body having a propeller-like structure is significantly emissive in concentrated solution,solid and / or aggregated state,rather than in dilute solution.This photophysical phenomenon is opposite to the ACQ effect and is therefore referred as aggregation-induced emission(AIE)or aggregation-induced emission enhancement(AIEE).AIE emitters can be easily incorporated into the polymer backbone or side chains to form highly available conjugated polymers.In addition,AlE molecules with diyne or tetracyne can be polycyclic,poly-trimerized,clicked or copolymerized to produce high molecular weight hyperbranched polymers,all of which are weakly luminescent in solution,but their emission In the aggregation state is significantly enhanced.Based on the above discussion,this paper is discussed from the following two aspects.In the first part,we synthesized three completely hydrophobic polytetraphenylstyrene(PTPEs),o-TPE-1,m-TPE-1 and p-TPE-1,which are similar in composition but different in structure by Sonogashira cross-coupling polymerization.These conjugated polymers are significantly enhanced in the mass-weakened solvent,exhibiting typical AEE characteristics.But they exhibit different spectral behavior in different mixed solvents such as toluene / methanol,chloroform / n-hexane and chloroform / methanol.In order to further verify this nature,we explored their self-assembly behavior in different solution systems and found that self-supporting films were formed in the toluene / methanol system and gradually formed with nanospheres as the methanol content increased.In the chloroform / methanol system,self-assembled to form a uniform size of solid nano-sphere;and in chloroform / n-hexane system,it formed very beautiful hollow nanospheres.And we found that their morphology and fluorescence changes have dependency.In the second part,TPE molecules with AIE effect were introduced into Pt(II)complexes of dibenzimidazolopyridine,and they were characterized in detail,including NMR,IR,UV-Vis absorption spectra and fluorescence spectra.From the UV-Vis spectra,we found that the absorption wavelength of tetraphenyl ethylene appeared at 315 nm,and the characteristic absorption of imidazolidine occurred in the range of 310-390 nm.Then,the fluorescence changes in THF / H2 O were discussed.It was found that the fluorescence of TPE monomer was weakened with the increase of water content,and the fluorescence of the corresponding aggregation was gradually enhanced.At the same time,the emission of Pt · Pt interaction gradually increases with the increase of water content.We expect it to have good photophysical properties and to accompany morphological changes in the future of organic optoelectronics,molecular devices and fluorescence sensing and other potential values.