Efficient and Regioselectivity‐Tunable Metal‐Free Polycycloaddition of Activated Azide and Alkynes

Abstract

The transition-metal catalyzed and metal-free click polymerizations have been developed as powerful tools for the construction of functional polymers with linear and hyperbranched structures. The latter provides a thorough solution for the completely removing metallic residues from the products encountered in the former. Compared to the activated alkyne-azide metal-free click polymerization, the activated azide-alkyne one is rarely studied. In this Communication, a perfluorophenyl-activated azide of hexane-1,6-diyl-bis(4-azido-2,3,5,6-tetrafluorobenzoate) is rationally designed and facilely prepared. Through systematical optimization of the reaction conditions, an efficient metal-free perfluorophenylazide-alkyne polycycloaddition is established, and polytriazoles with high molecular weights (up to 166 000) and excellent solubility are obtained in excellent yields (up to 93%) under mild reaction conditions. Interestingly, the regioselectivity of the reaction could be fine-tuned by the solvents and diyne monomers. Therefore, this work provides not only a powerful tool for the preparation of functional polytriazoles, but also an attractive method for fine-tuning their regioregularity.

Metal‐Free Poly‐Cycloaddition of Activated Azide and Alkynes toward Multifunctional Polytriazoles: Aggregation‐Induced Emission, Explosive Detection, Fluorescent Patterning, and Light Refraction

“…Using the same method, a F 1,4 value of 40% was obtained for P Ib (Figures S5 and S6, Supporting Information). These results support our previous explanation that the regioselectivity of metal‐free poly‐cycloaddition could be fine‐tuned by the arene–perfluoroarene (Ar–Ar F ) interaction between PFPA (activated diazide 1) and aromatic solvents or aromatic diynes . In this case, the Ar–Ar F interaction between the perfluorophenyl groups of 1 and the phenyl groups of 2a or 2b favors the formation of 1,5‐regioisomers during the polymerization.…”

“…The activated diazide of hexane‐1,6‐diyl‐bis(4‐azido‐2,3,5,6‐tetrafluorobenzoate) ( 1 ), and TPE and silole‐containing diynes of 2a and 2b , were facilely synthesized according to the reported procedures . Under the reaction conditions optimized in our previous work, diazide 1 and diynes 2a and 2b were readily polymerized (Scheme ), and PTAs P Ia and P Ib with high molecular weights ( M w up to 32 000) were obtained in high yields (up to 90%), respectively (Table ).…”

“…Recently, we successfully solved these problems by alternating the activated azide from rigid 4,4′‐diazidoperfluorobenzophenone to flexible perfluorophenyl azide (PFPA), and a new poly‐cycloaddition reaction was established . PTAs with high molecular weights ( M w up to 166 000) and excellent solubility were obtained in excellent yields (up to 91%) under mild reaction conditions.…”

“…The AIE‐active moieties of tetraphenylethene (TPE) and silole‐containing diynes of 1,2‐bis(4‐ethynylphenyl)‐1,2‐diphenylethene ( 2a ) and 1,1‐dimethyl‐2,5‐bis(4‐ethynylphenyl)‐3,4‐diphenylsilole ( 2b ) were designed and synthesized, respectively. Then, they were reacted with activated azide of hexane‐1,6‐diyl‐bis(4‐azido‐2,3,5,6‐tetrafluorobenzoate) ( 1 ), a representative of PFPA, in DMF ( N , N ‐dimethylformamide) at 100 °C in air . Delightfully, polytriazoles of P Ia and P Ib with high molecular weights ( M w up to 32 000) were produced in excellent yields (up to 90%).…”

Progress on Catalytic Systems Used in Click Polymerization

“…Soluble polytriazoles with high molecular weights ( M w up to 160 000) were readily produced in high yields (up to 93%) ( Scheme ). Interestingly, the regioregularities of the polymers could be fine‐tuned by the solvents and diyne monomers . In addition, TPE and silole moieties could be easily incorporated into the backbones of PTAs to render them with novel properties, such as AIE, high refractive indices and fluorescent photopatterning …”