Abstract
AbstractStimuli responsive helical polymers have attracted wide attention and many polymers responsive to the external stimuli have been synthesized. But, only a few examples have been reported regarding the redox-induced helicity inversion helical polymers. The polyisocyanide including thioether pendant (poly-MBTIP) was synthesized by polymerization of methyl (R)-3-(benzylthio)-2-isocyanopropanoate (MBTIP) monomer using NiCl2·6H2O as catalytic agent in dry DCM. The chiroptical and oxidation properties of the poly-MBTIP are investigated. The poly-MBTIPs exhibit intense specific optical rotations and Cotton effects compared to the monomer, strongly suggesting a helical conformation of the polymer backbone. Additionally, the thioether pendant of poly-MBTIP backbone was oxidized to sulfoxide group by H2O2. Interestingly, the specific optical rotations and Cotton effects of poly-MBTIP oxidized are reversed, probably suggesting a helical conformation inversion.
Highlights
The synthesis of methyl (R)-3-(benzylthio)-2isocyanopropanoate (MBTIP) was performed a four-step synthetic route, the last step of which was the conversion of the formamide to the isocyanide by dehydration in dry CH2Cl2 with triphosgene
The IR spectrum of poly-MBTIP has signal disappear at 2149 cm-1 corresponding to the isocyanide moiety in MBTIP, and showed a broad band at approximately 1650 cm-1 from the imine groups attached to the polymer backbone. 1H-NMR and 13C-NMR spectra of the poly-MBTIP show broad resonances
These spectra confirm that the monomer was polymerized and the polyisocyanide was obtained
Summary
Let A, A∗ denote TahLeehoenliacradl poaliyrmoenrsVo.bWtaeinceadnadretveerrmyisneenswithiveethtoereAd,oAx ∗ is self-dual i By [13, Lemma 1.3] eascthimeuiglie, nmsposatcoefowf hAi,chA∗arheatshdeimreednoxsiotrnigogenree.dLcehti{raθlii}tydi= denote an o. The thioether group can be easyly oxidized to sulfoxide and sulfone. Guo et al.: Synthesis and characterization of a polyisocyanide with thioether pendant transition hasn’t been reported. The helical structures and oxidation-responsive behavior of the polyisocyanides were checked. The phenomenon was found that the helix sense of polyisocyanide with thioether pendant was probably inversion when it was oxidized
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