Research On The Synthesis Of Pyrazolinyl Polymer From Olefin And Diazocompound

Fluorescent polymers are materials that can be visibly labeled and identified.Because of their unique photophysical and photochemical properties,they have broad application prospects in biology,medicine and fields requiring localization and identification,and are now widely used in many fields such as fluorescent dyes,fluorescent detection,chemical sensors,fluorescent probes,and biochemistry.However,traditional fluorescent polymers often contain large rigid conjugated groups such as benzene rings,which to a certain extent limit the flexibility,solubility,biocompatibility and degradability of polymer molecular chains.This does not meet the need for designing and synthesizing fluorescent polymers with flexible chains.Therefore,there is an urgent need to design a new carbon chain polymer with unique structure and excellent performance.Diazo compounds are a class of organic molecules with high reactivity and stable structure,which are widely used in organic reactions.They can form highly reactive carbine intermediates after the removal of nitrogen under light or heat conditions,and can be effectively synthesized into carbon chain polymers by carbine polymerization.As a new type of polymerization,carbine-based polymerization makes it possible to synthesize new polymers with excellent properties by making each carbon atom in the polymer main chain with a substituent group and a well-organized structure.Olefin polymerization is one of the main methods used to synthesize carbon-chain polymers,and it has a relatively mature theoretical development and practical application system.The 1,3-dipolar cycloaddition reaction of diazo compounds with olefins can be carried out without catalysis and at room temperature under relatively mild conditions,which is suitable for many types of olefins containing electron-absorbing groups,and this reaction provides a new route for the synthesis of pyrazoline derivatives.The main studies and results of the article are as follows:（1）Firstly,methyl diazoacetate+1,6-hexanediyl diacrylate（1a+2a）,methyl diazoacetate+1,4-butanediyl diacrylate（1a+2b）,ethyl diazoacetate+1,6-hexanediyl diacrylate（1b+2a）and ethyl diazoacetate+1.4-hexanediyl diacrylate（1b+2a）were synthesized by the 1,3-dipolar cycloaddition reaction of diazo compounds with diolefins.Four different structures of pyrazoline based olefin monomers（1b+2b）were used to obtain four fluorescent polymers with pyrazoline side groups,poly（1a+2a）,poly（1a+2b）,poly（1b+2a）,poly（1b+2b）and poly（1b+2b）,by their own polymerization reactions.The structures of the fluorescent polymers were characterized by Fourier transform infrared spectroscopy（FTIR）,nuclear magnetic resonance（NMR）,time-of-flight mass spectrometry（MALDL-TOF-MS）,ultraviolet-visible absorption spectroscopy（UV-Vis）,differential scanning calorimetry（DSC）,thermogravimetric analysis（TG）,fluorescence spectroscopy（PL）,gel permeation chromatography（GPC）,etc.The results of GPC showed that the molecular weights of the four polymers gradually increased with the increase of temperature,and the highest average molecular weight of the polymer was obtained by the 16 h polymerization reaction at 110℃with5%AIBN as the catalyst,reaching 5943 g/mol.The results of NMR,FTIR and time-of-flight mass spectrometry showed that all four monomers underwent polymerization;the fluorescence spectroscopy showed that the maximum excitation wavelength of poly（1a+2b）was 340 nm,and the fluorescence intensity of the polymer was higher than that of poly（1b+2a）when the reaction time was 21 h and the reaction solvent and fluorescence solution were both Toluene.The relative fluorescence quantum yield of the polymer was up to 21%when quinine sulfate was used as the standard.（2）By the 1,3-dipolar cycloaddition reaction of the bisdiazo compounds,two fluorescent polymers with pyrazoline side groups were synthesized by the carbene polymerization reaction of the 1,3-propanediol bisdiazo diacetate+methyl acrylate（1a+2a）1,6-hexanediol propanediol bisdiazo diacetate+methyl acrylate（1b+2a）,and two fluorescent polymers with pyrazoline side groups were obtained by their own carbene polymerization,respectively The GPC results showed that the molecular weights of the two polymers with different structures gradually increased with increasing temperatures,with the average molecular weight of the polymers produced by the 16-h reaction at 115℃with 0.1%Rh₂（OAc）₄ as catalyst reaching 2555 g/mol for 1b+2a and 2555 g/mol for 1a+2a.The molecular weight of poly（1a+2a）was higher than that of poly（1b+2a）,and the NMR,FTIR and time-of-flight mass spectrometry results showed that both monomers contained diazo groups and both of them underwent carbene polymerization.The fluorescence spectra showed that the maximum excitation wavelength of poly（1a+2a）was 356 nm,and the fluorescence intensity of the polymer obtained by carabine polymerization was stronger than that of the monomer,in which when the reaction time was 16 h,the reaction solvent was BUAC,and the fluorescence solution was THF,the fluorescence intensity of the polymer obtained was the strongest.When the reaction time was 16 h,the reaction solvent was BUAC and the fluorescent solution was THF,the fluorescence intensity of the polymer was the strongest;the relative fluorescence quantum yield of the polymer was measured up to 23%using quinine sulfate as the standard.The pyrazolyl polymers obtained by the above two methods improve the disadvantages of conventional fluorescent polymers which generally contain large rigid conjugate groups and have important applications in the field of fluorescent materials.