1,3,4,5-Tetrasubstituted Poly(1,2,3-triazolium) Obtained through Metal-Free AA+BB Polyaddition of a Diazide and an Activated Internal Dialkyne

A tetra(ethylene glycol)-based 1,3,4,5-tetrasubstituted poly(1,2,3-triazolium) is synthesized in two steps including: i) the catalyst-free polyaddition of a diazide and an activated internal dialkyne and ii) the N-alkylation of the resulting 1,2,3-triazole groups. In order to provide detailed structure/properties correlations different analogs are also synthesized. First, parent poly(1,2,3-triazole)s are obtained via AA+BB polyaddition using copper(I)-catalyzed alkyne-azide cycloaddition or metal-free thermal alkyne-azide cycloaddition (TAAC). Poly(1,2,3-triazole)s with higher molar masses are obtained in higher yields by TAAC polyaddition. A 1,3,4-trisubstituted poly(1,2,3-triazolium) structural analog obtained by TAAC polyaddition using a terminal activated dialkyne and subsequent N-alkylation of the 1,2,3-triazole groups enables discussing the influence of the methyl group in the C-4 or C-5 position on thermal and ion conducting properties. Obtained polymers are characterized by 1H, 13C, and 19F NMR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, size exclusion chromatography, and broadband dielectric spectroscopy. The targeted 1,3,4,5-tetrasubstituted poly(1,2,3-triazolium) exhibits a glass transition temperature of -23 °C and a direct current ionic conductivity of 2.0 × 10-6 S cm-1 at 30 °C under anhydrous conditions. The developed strategy offers opportunities to further tune the electron delocalization of the 1,2,3-triazolium cation and the properties of poly(1,2,3-triazolium)s using this additional substituent as structural handle.

Aggregation-Induced Emission-Active Biomacromolecules: Progress, Challenges, and Opportunities

Biomacromolecules featuring aggregation-induced-emission (AIE) characteristics generally present new properties and performances that are silent in the molecular state, providing endless possibilities for the evolution of biomedical applications. Tremendous achievements based on the research of AIE-active biomacromolecules have been made in synthetic exploration, material development, and practical applications. In this Perspective, we give a brief account in the development of AIE-active biomacromolecules. Remarkable progresses have been made in the exploration of AIE-active biomacromolecule preparation, structure-property relationships, and the relevant biomedical applications. The existing challenges and promising opportunities, as well as the future directions in AIE-active biomacromolecule research, are also discussed. It is expected that this Perspective can act as a trigger for the innovation of AIE-active biomacromolecule research and aggregate science.

Catalyst-Free Four-Component Polymerization of Propiolic Acids, Benzylamines, Organoboronic Acids, and Formaldehyde toward Functional Poly(propargylamine)s

Multicomponent polymerizations (MCPs) are a group of fascinating polymer synthesis approaches that are developed rapidly in the recent decade. As a popular alkyne-based MCP, the A³ -polycouplings of alkynes, aldehydes, and amines are developed for the synthesis of poly(propargylamine)s under the catalysis of metal catalysts. In this work, through the design of carboxylic acid group-activated alkyne monomers, a catalyst-free, four-component polymerization of propiolic acids, benzylamines, organoboronic acids, and formaldehyde is reported under mild condition at 45 °C in dichloroethane. This four-component polymerization is applicable to different monomer structures, which can afford seven poly(propargylamine)s with up to 94% yields and molecular weights of up to 13 900 g mol^-1 . Moreover, the poly(propargylamine)s demonstrate good solubility and processibility, high thermal stability and light refractivity, unique photophysical property, and so on. The simple monomers, mild condition, low cost, high efficiency, and procedure simplicity of this catalyst-free four-component polymerization demonstrates an elegant example of functional polymer synthesis.