Synthesis of an alternating copolymer of the dense 1,2,3‐triazole backbone carrying t‐butyl ester and nitrile side chains

Abstract

In these decades, synthesis of polymers with controlled monomer sequences has been of increasing importance in polymer chemistry. When we tested synthesis of a heterodimer of 4‐azido‐5‐hexynoic acid derivatives carrying t‐butyl (tBu) ester and tBu amide side chains for preparation of an alternating copolymer, we unexpectedly obtained a heterodimer precursor carrying tBu ester and nitrile side chains, in a high yield. Since dense 1,2,3‐triazole polymers carrying nitrile side chains are expected as a new functional polymer, the heterodimer is polymerized by copper(I)‐catalyzed azide–alkyne cycloaddition polymerization to obtain an alternating copolymer carrying tBu ester and nitrile side chains in this study. Since 1,2,3‐triazole and nitrile moieties are known to be ligands for metal ions, the complex formation of the alternating copolymer with PdCl2 is also investigated by NMR. In the presence of PdCl2, 1H NMR spectra show broad and separated signals due to the free and complexed copolymers, indicative of slow exchange. Pulse‐field‐gradient spin‐echo NMR data indicated that the coordination of alternating copolymer to PdCl2 made the copolymer chains take a more compact conformation under dilute conditions. The density functional theory calculations indicated that the alternating copolymer coordinated to PdCl2 preferentially through the 1,2,3‐triazole nitrogen and nitrile nitrogen atoms.

Interaction of Cyclodextrins with Amphiphilic Alternating Cooligomers Possessing the Dense Triazole Backbone

“…CuAAC has been utilized as one of the most popular reactions in click chemistry because of its excellent tolerance to various functional groups. − Since AH derivatives can be connected by stepwise CuAAC using their precursors that possess a silyl-protected alkyne or hydroxy group that can be converted to azide, it is feasible to synthesize structure-controlled polymers, e.g., stereoregular and sequence-controlled polymers, of AH derivatives with the dense 1,2,3-triazole backbone. Alternating copolymers, i.e., the simplest sequence-controlled polymers, can be synthesized by CuAAC polymerization of heterodimers possessing different side chains. , In this study, alternating amphiphilic cooligomers of N -alkyl-4-azido-5-hexynamide and AH (oligoC n AH, where n is the carbon number of the alkyl group) were synthesized by CuAAC polymerization of heterodimers carrying N -alkylamide and t -butyl (tBu) ester side chains, followed by hydrolysis of the tBu ester, to study the interaction of CDs with oligoC n AH.…”

“…Alternating copolymers, i.e., the simplest sequence-controlled polymers, can be synthesized by CuAAC polymerization of heterodimers possessing different side chains. 85,86 In this study, alternating amphiphilic cooligomers of N-alkyl-4-azido-5-hexynamide and AH (oligoCnAH, where n is the carbon number of the alkyl group) were synthesized by CuAAC polymerization of heterodimers carrying N-alkylamide and t-butyl (tBu) ester side chains, followed by hydrolysis of the tBu ester, to study the interaction of CDs with oligoCnAH.…”