Observation of optical activity in polythiourethane obtained by the controlled cationic ring‐opening polymerization of chiral cyclic thiourethane derived from serine

Nagai, Atsushi; Ochiai, Bungo; Endō, Takeshi

doi:10.1002/pola.20624

Cited by 8 publications

(6 citation statements)

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“…Furthermore, the inversed carbonyl peaks of the block copolymer were in good agreement with those of poly(S L ) and racemic polymer [poly(S DL )] in DMSO solution. 13 The absorptions resulted from NH and carbonyl groups of the ester and thiourethane moieties in copolymers which were also observed by the IR spectrum, in which the absorptions attributable to the NH moiety of copolymers except poly(S L51 -co-BzS In conclusion, we inversed the chiroptical behavior of optically active polythiourethane segments by sandwiching segments, which would have originated from the conformational inversion confirmed by the NMR spectroscopic study. We think this phenomenon is similar to the manner in which a white piece in the board game 'Othello' flips to black when sandwiched by black pieces.…”

supporting

confidence: 64%

“…A successful example is the helical inversion of chiral polymers (e.g., polysilane, 1,2 polyacetylene, [3][4][5][6][7][8] and polyisocyanate 9,10 ), whose secondary structures depend on low energy interactions. [12][13][14] As compared with the inescapable steric regulation, the regulation by hydrogen-bonds may be reorganizable due to its lability, i.e., if a chiral polythiourethane comprises both hydrogen-bonding and sterically regulating sequences, the properties of the labile hydrogen-bonding sequence may vary along with the steric regulation. In contrast to synthetic polymers, drastic changes in the high-order structure stabilized by hydrogen-bonds are often observed in mutated proteins.…”

mentioning

confidence: 99%

“…We recently reported the chiroptical behavior of chiral polythiourethanes, which are analoguous to c-peptides, 11 obtained by the living polymerization of cyclic thiourethanes derived from L-serine, depending on the substituents on the nitrogen atoms that would regulate the secondary structures by either hydrogen-bonds or steric controls. [12][13][14] As compared with the inescapable steric regulation, the regulation by hydrogen-bonds may be reorganizable due to its lability, i.e., if a chiral polythiourethane comprises both hydrogen-bonding and sterically regulating sequences, the properties of the labile hydrogen-bonding sequence may vary along with the steric regulation. Accordingly, various chiral polythiourehanes were prepared from a chiral cyclic thiourethane (S L ) and its N-benzoyl derivative (BzS L ) (Scheme 1), and the chiroptical behavior of the obtained polymers was investigated.…”

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confidence: 99%

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Chiroptical inversion induced by sandwiching units in chiral polythiourethane

2006

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Chiroptical inversion induced by sandwiching units in chiral polythiourethane

2006

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“…The fact that polymer was optically active had been confirmed by the specific rotation of −233.3° at a M n of 13.300 g·mol −1 . As an additional advantage, it was observed that hydrogen bonding between the carbonyl and NH groups in the thiourethane group constrained the main chain of the chiral polythiourethane precisely under the direction of chirality; as a consequence the polythiourethane took a secondary structure …”

Section: Chemistrymentioning

confidence: 99%

Sulfur Chemistry in Polymer and Materials Science

Mutlu

Ceper

et al. 2018

Macromol. Rapid Commun.

278

220

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The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/marc.201800650. ChemistryBefore moving to the recent advances within the last 5 years in the diverse applications of sulfur chemistry in polymer and Sulfur-Containing PolymersSulfur and its functional groups are major players in an area of exciting research taking place in modern polymer and materials science, both in academia and industry. In fact, manifold sulfur-based reactions that are both exceptionally versatile as well as tremendously useful have been implemented, and further utilized for the design and preparation of polymeric materials that lead to a plethora of applications ranging from medicine to optics and nanotechnology to separation science. Hence, within this review, an overview of strategies and developments used over the last 5 years to reinforce the importance of the sulfur functional group in modern polymer and materials science is presented. In particular, many important references in the primary literature of sulfur chemistry are referred to, including thiol-ene, thiol-yne, thiol-Michael addition, disulfide cross-linking, and thiol-disulfide exchange, among others, by explaining and illustrating the important principles. Last but not least, the grand aim to underpin the importance of sulfur in modern polymer and materials science is achieved by presenting selected examples in diverse fields and postulating the respective potential for real-world applications. he is now a full professor at KIT.sulfur atoms, and tetraphenylethene-bearing di(alkyl bromide) (Scheme 3). The yield of the polymerization was dependent on the di(alkyl bromide) monomer; the longer spacer between the aromatic moiety and the reactive bromide end groups Scheme 1. The discussion henceforth focuses on the synthesis of polymers possessing the depicted sulfur functional groups. Scheme 2.Representative examples of polythioethers prepared via A) the nucleophilic substitution reaction between an electrophilic dihalide with nucleophilic derivatives of dithiols under alkaline conditions; B) the thiol-ene/yne addition reaction between AA and BB type monomers (i.e., dithiols and dienes/diynes); and C) radical or ionic ring-opening of sulfurcontaining strained rings.Scheme 3. The thiol-bromo polymerization of conformationally fixed monomers to provide multifunctional polymers. [19] Macromol. Rapid Commun. 2019, 40, 1800650 Scheme 4. The regioselective selective nucleophilic aromatic substitution between thiol and fluorinated aromatic compounds, the para-fluorothiol reaction (PFTR).Scheme 5. Synthesis of a linear polymer via PFTR-reaction. [21]

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“…9,10 Recently, polyurethanes and polythiourethanes with main-chain chirality were synthesized by self-polyaddition followed by ring-opening polymerization. 11 The enantiopure polymers formed higher order structures, which were stabilized by much stronger internal hydrogen bonds, compared to the internal hydrogen bonds formed in the unordered racemic polymer.…”

Section: Introductionmentioning

confidence: 99%

Secondary structure formation of main-chain chiral poly(2-oxazoline)s in solution

Bloksma¹,

Rogers²,

Schubert³

et al. 2010

Soft Matter

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The synthesis and microwave-assisted polymerization of new 2,4-disubstituted-2-oxazoline monomers, namely R-2-butyl-4-ethyl-2-oxazoline, RS-2-butyl-4-ethyl-2-oxazoline and S-2-butyl-4-ethyl-2oxazoline, are reported. A kinetic investigation of the polymerization of the enantiopure and racemic monomers revealed comparable polymerization rates and in all cases a living mechanism. The difference in solubility between the racemic polymer and the enantiopure polymer gave a first indication that the enantiopure polymers might form ordered, most likely helical, structures in solution, while the racemic polymer forms a random coil. The dichroic Cotton effects obtained with circular dichroism (CD) confirmed the formation of a secondary structure of the enantiopure polymers in trifluoroethanol (TFE) and hexafluoroisopropanol (HFIP), while the racemic polymer did not show a CD signal. In addition, CD revealed that the ordered structures in HFIP exhibit a unique temperature dependent change in the secondary structure presumably due to HFIP hydrogen bonding to the polymeric amide groups. However, small angle neutron scattering (SANS) data contradict the CD results. When the polymers are dissolved in trifluoroethanol-d 3 , a good solvent, SANS indicated the presence of a random coil for both the enantiopure polymers and the racemic polymer. These observations indicate the formation of a flexible and dynamic structure of the chiral polymers so that only a certain fraction of the polymer adopts an ordered secondary structure in this good solvent. When the polymers are dissolved in a bad solvent like methanol-d 4 , the SANS data reveal that the enantiopure polymers do form a more compact elongated structure compared to the racemic polymer, implying that the ordered structure of the enantiopure polymer is better preserved in a 'bad' solvent, i.e. the persistence length of the ordered segments increases. As such, these synthetic polymers form a dynamic secondary structure similar to polyproline type II helices.

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Observation of optical activity in polythiourethane obtained by the controlled cationic ring‐opening polymerization of chiral cyclic thiourethane derived from serine

Cited by 8 publications

References 25 publications

Chiroptical inversion induced by sandwiching units in chiral polythiourethane

Chiroptical inversion induced by sandwiching units in chiral polythiourethane

Sulfur Chemistry in Polymer and Materials Science

Secondary structure formation of main-chain chiral poly(2-oxazoline)s in solution

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