Molecular Design And Performance Of AIE-active Polymers Based On Multi-component Reaction

Multi-component reactions can be used to prepare natural products with complex structures through simple processes,they have been widely used in combinatorial chemistry and medicinal chemistry.Until recent years,multi-component polymerizations(MCPs)in the field of polymer science have attracted increasing interest from researchers.MCPs have obvious advantages in synthesis,such as mild reaction conditions,high atomic efficiency,simple operation steps and so on.At the same time,AIE active polymer has become one of the important research contents in the field of AIE,especially the non-traditional inherently luminescent AIE active polymer has good processability,structure controllability,good modeling,and biocompatibility.AIE active polymer has a wide range of applications in the optoelectronics and biology fields.In this study,we used Ugi and MALI multi-component polymerization to prepare a series of polymers containing 4-thiazolidinone heterocycles and amide groups on the main chain.This kind of polymer cannot be obtained by any traditional polymerization method,which brings new opportunities and possibilities for the design and preparation of polymer materials with new structures and properties.1.The multi-component reaction,AIE phenomenon,AIE polymer,its classification,preparation methods,and applications in chemical sensing,biosensing,cell imaging,and optoelectronic devices are respectively introduced.2.We selected four diamines,glutaraldehyde,thioglycolic acid,and tert-butyl isonitrile to form the MALI and Ugi polymerization system.The Ugi polymerization system includes all four components,and the three components except tert-butyl isonitrile constitute the MALI polymerization system.During the reaction,the polymerization of MALI and Ugi occurred at the same time,and the main chain of poly(4-thiazolidinone-amide)(PTZA)contained4-thiazolidinone heteroatom ring and amide/thiol group.We optimized the synthesis conditions and selected DMSO and anhydrous methanol,which are widely used in MALI reactions and Ugi reactions.The results show that anhydrous methanol is the preferred reaction medium.We also briefly discussed the influence of precipitant,reaction temperature,reaction time,amine/aldehyde reaction time,and the feeding sequence of thioglycolic acid and tert-butyronitrile on polymerization.In addition,the feed ratio of tert-butyl isonitrile was used to control the polymer structure.As the feed amount of tert-butyl isonitrile increased,the content of the amide portion of PTZA increased,and the contact angle test results also confirmed this result.3.Based on the above research results,we further studied the AIE characteristics and applications of PTZAs.Because the thiazolidinone and amide groups"aggregate"within the molecule through chemical bonding,PTZA with highly negatively charged heteroatoms(including O,N,and S)exhibits strong fluorescence emission at 500 nm.More interestingly,Fe³⁺ions can effectively quench the fluorescence of PTZA,and the detection limit(LOD)of PTZA for Fe³⁺ions is 10^-6 mol/L.In addition,we also explored the detailed mechanism of PTZA luminescence and Fe³⁺quenching.All in all,the strategy of two simultaneous polymerization reactions in one-pot process provides powerful feasibility for preparing polymers with unique structures and properties.4.Polyallylamine derivatives(PATZD)containing thiazolidinone ring were obtained by functional modification of polyallylamine in MALI multi-component reaction.In the experiments,the influence of different aldehydes,reaction medium,reaction temperature,and reaction time on the structure and properties of PATZD are briefly discussed.The study indicated that only H₂O/DMSO mixed solvent is more conducive to the reaction and the product is more soluble in water.The fluorescence spectrum tests present that PATZD has strong increased fluorescence emission at 430 nm,after adding poor solvents into the system,showing the AIE feature.In short,the introduction of heterocycles has realized the effective conversion of non-AIE polymers to AIE active polymers,giving them more extensive practical applications in the fields of chemical sensing,biosensing,and cell imaging.