Synthesis And Characterization Of Water-souble Polymer Based-on D-mannose With Aggregation-induced Emission Effect

In recent years,water-soluble fluorescent polymers have attracted extensive attention in the fields of biological imaging,sensors and fluorescent probes due to their good excellent luminescence performance and water-solubility.In this paper,the water-soluble fluorescent polymer P3 with aggregation-induced emission?AIE?effect was synthesized by“one-pot method”,water-soluble fluorescent polymers P5 and P7 with AIE effect were synthesized by atom transfer radical polymerization?ATRP?.Compounds M12 and M13 with AIE effect and red flourescence were synthesized by Buchwald-Hartwig coupling reaction.The main research contents and results of this paper are as follows.1.Compound?,?'-bis-?p-hydroxybenzylidene?-p-benzenediacetonitrile?M1?was synthesized by Knoevenagel condensation reaction using p-benzenediacetonitrile and p-hydroxybenzaldehyde as raw materials.Compound ?,?'-bis-[p-?2,3-epoxypropoxy?-benzylidene]-p-benzenediacetonitrile?M2?was synthesized from M1 and epichlorohydrin by Williamson reaction.Polymer P1 was synthesized by using2-?2',3',4',6'-tetra-O-acetyl-?-D-mannopyranosyloxy?ethyl methacrylate?M4?as monomer and 2-cyano-2-propyl benzodithioate as reversible addition-fragmentation transfer agent.Polymer P2 with defined structure was synthesized via one-pot reaction with P1 and M2?the reduction reaction of dithioester?P1?and click reaction between the thiol group and epoxy group?M2?were simultaneously conducted in one pot with high conversion?.The water-soluble fluorescent polymer P3 was obtained in a high yield after the deacetylation protection reaction of P2.The chemical structures and optical properties of compounds and polymers were characterized and tested by nuclear magnetic resonance spectrum,Fourier transform infrared spectroscopy,gel permeation chromatography,ultraviolet-visible spectroscopy and fluorescence spectroscopy,et al.These results showed that the ultraviolet-visible absorption peak and the fluorescence emission peak of P3 were 368 nm and440 nm,fluorescence intensity of P3 gradually increased with the increase of DMSO fraction?f_D?in DMSO/H₂O system,when f_D was over 80%,which indicated the AIE characteristic of P3.The fluorescence quantum yield of P3 in DMSO was 11.88%.Polymer P3 had good thermal stability,and the phase transition temperature was 118 ^oC.2.ATRP initiators M6 and M7 were synthesized from M1 through a series of reactions,and then oil-soluble polymers P4 and P6 were synthesized by using M4 as monomer and M6and M7 as ATRP initiator,and the acetyl group was removed to produce water-soluble fluorescent polymers P5 and P7.A series of characterizations of P5 and P7 showed that the maximum ultraviolet-visible absorption peak wavelengths of P5 and P7 were 361 nm and 371nm,and the maximum fluorescence emission peak wavelengths were 496 nm and 433 nm,respectively.The critical micelle concentration of P5 was 3.72?M.It was found that the fluorescence of P5 was weaken by Fe³⁺,and the fluorescence intensity decreased with the increase of Fe³⁺concentration by testing the selectivity of P5 for metal ions.The detection limit of Fe³⁺by P5 was 10?M.The fluorescence intensity of P5 gradually decreased with the increace of time after the addition of Fe³⁺and stabilized after 70 min.3.Compound M8 was synthesized from 4-aminophenone and diphenylketone by McMurry coupling reactions and then M8 was conjugated with bromobenzene and1-bromonaphthalene by Buchwald-Hartwig reactions to synthesize compounds M9 and M10,respectively.2,6-diisopropylaniline and 4-bromo-1,8-naphthalene dimethyl anhydride underwent nucleophilic substitution reaction to form compound M11 under acidic conditions,and then compound M11 was conjugated with M9 and M10 by Buchwald-Hartwig reactions to synthesize compounds M12 and M13,respectively.A series of tests on M12 and M13showed that M12 and M13 had both AIE and TICT?Twisted Intramolecular Charge Transfer?effects.The maximum ultraviolet-visible absorption peak wavelengths of M12 and M13 were474 nm and 475 nm,and the maximum fluorescence emission peak wavelengths were 600 nm and 610 nm.The maximum absorption and fluorescence emission peak wavelengths of M12and M13 had red-shifted 138 nm,139 nm and 110 nm,120 nm contrast to those of M8,respectively.M12 and M13 emitted red fluorescence,and the maximum fluorescence emission peak wavelength was close to the near-infrared region.In this paper,three water-soluble fluorescent polymers P3,P5 and P7 with AIE effect,and two compounds M12 and M13,which emitted red light with AIE effect.P3 had a specific recognition effect for Con A,and was expected to be applied to detect Con A.P5 had good selectivity for Fe³⁺,which can be used as a fluorescent probe to detect Fe³⁺in water environment.M12 and M13 had AIE effect,and the maximum fluorescence emission peak wavelengths of two compounds were closed to the near-infrared region which were expected to be used as a fluorescent probe to track cells in vitro for a long time.