A major challenge in synthetic polymer chemistry lies in achieving precise control over monomer sequence and chain length while maintaining high efficiency and functional versatility. This work presents a highly efficient strategy for constructing sequence-defined polytriazoles through an iridium-catalyzed azide–alkyne cycloaddition (IrAAC) reaction between internal 1-thioalkynes and azides. Unlike traditional copper-catalyzed click reactions that predominantly yield 1,4-disubstituted triazoles, IrAAC enables exclusive formation of 1,4,5-trisubstituted isomers with excellent regioselectivity, offering a unique opportunity to incorporate diverse functional groups at the C4 position of the triazole ring.
The synthesis begins with the facile preparation of functionalized 1-thioalkyne monomers from terminal alkynes and TBS-protected bis(2-hydroxyethyl) disulfide under mild conditions. These monomers are then subjected to iterative cycles of IrAAC followed by azidation, allowing stepwise chain extension with full control over sequence and composition. The use of [Ir(COD)Cl]₂ as a catalyst in THF/DCE mixtures ensures high reactivity and tolerance across various solvent systems, enabling solution-phase synthesis without compromising purity or yield. Reaction progress is monitored by NMR spectroscopy, which confirms complete conversion and absence of side products at each stage.
Size exclusion chromatography (SEC) analysis reveals sharp, single peaks for all synthesized oligomers, indicating high monodispersity and successful sequential growth. MALDI-TOF mass spectrometry provides definitive evidence of molecular weight and structural integrity, with observed signals matching theoretical values within ±0.1 Da. For example, the hexamer product shows clear [M + Na]⁺ and [M + K]⁺ ions consistent with its expected composition, confirming the accuracy of the iterative assembly process.
One of the most significant features of this architecture is its compatibility with tandem mass spectrometry (MS/MS) for sequence decoding. The presence of sulfur atoms in the backbone facilitates preferential cleavage of Csp³–S bonds during fragmentation, generating characteristic ion series that reflect individual monomer units. In addition, the adjacent Csp³–N bond also undergoes efficient rupture, yielding complementary fragments. This dual cleavage mechanism allows for unambiguous reconstruction of the original sequence, making these polymers ideal candidates for high-density digital information storage applications.
To demonstrate functional potential, we incorporated aggregation-induced emission (AIE) moieties—specifically tetraphenylethylene (TPE)—into the backbone by using TPE-functionalized 1-thioalkyne building blocks. Oligomers 21–23 were synthesized with increasing numbers of TPE units, and their photoluminescence behavior was evaluated in THF/water mixtures.ITGB5 Antibody web In dilute solutions, they remain non-emissive due to free rotation of phenyl rings; however, upon aggregation induced by water, strong emission is observed.PDHA1 Antibody Technical Information The intensity increases progressively with chain length and TPE content, confirming effective restriction of intramolecular motion—a hallmark of AIE behavior.PMID:34929591
This approach not only offers a streamlined route to well-defined macromolecules but also opens new avenues for designing advanced functional materials. The ability to precisely install multiple functionalities along the chain, combined with intrinsic readibility and tunable optical properties, positions this platform as a powerful tool in the development of smart polymers for data storage, sensing, imaging, and nanomedicine.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com