Effect of the α-substituted chiral side chain on the helical conformation of N-substituted poly(p-benzamide)

Yokoyama, Akihiro; Saiki, Tomoaki; Masu, Hyuma; Azumaya, Isao; Yokozawa, Tsutomu

doi:10.1016/j.polymer.2017.11.066

Cited by 7 publications

(8 citation statements)

References 38 publications

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“…The difference of screw senses was probably due to the different driving forces to induce the helical structure of α-DPA and α-PA . As described in the previous report, the helical folding of α-PA needed solvophobic interactions. In contrast, as for α-DPA , the main chain and the side chain of α-DPA were solvated similarly in chloroform and THF, and the preference of left-handed helical conformation of α-DPA would be determined by the steric interaction between the main chain and the side chain, not by solvophobic interactions.…”

Section: Results and Discussionmentioning

confidence: 52%

“… Therefore, the CD spectrum of α-DPA can be interpreted in a similar manner to those of α-PA and β-PA . Because the CD spectrum of α-DPA was a mirror image of that of α-PA , α-DPA takes a left-handed helical structure, opposite to that of α-PA .…”

Section: Results and Discussionmentioning

confidence: 99%

“…Poly( p -benzamide) with ( S )-α-methyl-substituted TEG side chains ( α-PA ) was also synthesized in the expectation of a larger bias to one helical handedness, compared with β-PA . However, α-PA adopted a right-handed helical conformation in polar solvents, such as water and methanol, and a random structure in chloroform . These results indicate that the solvophobic effect plays a significant role in the helical folding of α-PA .…”

Section: Introductionmentioning

confidence: 88%

“…Pd(P t Bu 3 ) 2 (0.325 g, 0.636 mmol), t BuONa (3.00 g, 31.2 mmol), and 15 (3.70 g, 20.9 mmol) were placed in a round-bottom flask with a three-way stopcock, and the flask was degassed under reduced pressure and filled with argon. A degassed solution of 14 containing a small amount of 1-bromo-4-iodobenzene, (triisopropylsilyl)acetylene, and its dimer (7.06 g, 14 = 18.6 mmol) in dry toluene (64 mL) was added to the flask via syringes from the three-way stopcock with a stream of nitrogen.…”

Section: Methodsmentioning

confidence: 99%

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Development of Helical Aromatic Amide Foldamers with a Diphenylacetylene Backbone

et al. 2020

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We designed and synthesized aromatic polyamides with a diphenylacetylene backbone, α-DPA and β-DPA, bearing (S)-α-and (S)-βmethyl-substituted triethyleneglycol (TEG) side chains, respectively, and examined their conformations in solution. Both polymers exhibit strong, solvent polarity-dependent circular dichroism spectra, which indicated that they take helical conformations in low-polarity solvents. The spectra were mirror images, depending on the chiral position of the side chains. Thus, the polyamide α-DPA bearing (S)-α-methyl-substituted TEG groups takes a left-handed helical conformation, while the polyamide β-DPA with (S)-β-methyl-substituted TEG groups takes a right-handed helical conformation. The difference in the screw sense of α-DPA and β-DPA would be caused by the steric interaction between the main chain and the side chain, as observed in poly(p-benzamide) possessing (S)-βmethyl-substituted TEG side chains (β-PA) because the large cavity of the helical structure of DPA would disturb the solvophobically induced helical folding. Detailed conformational analyses of the oligoamides 6−12 with β-methyl-substituted TEG groups were conducted. Theoretical calculations indicated that the oligoamides with β-methyl-substituted TEG groups exist in a helical conformation with a cavity of 7 Å in diameter. The 1 H NMR spectra of the oligomers revealed interactions with small anions such as chloride and acetate anions and with pyridinium cations.

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Section: Results and Discussionmentioning

confidence: 52%

Section: Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 88%

Section: Methodsmentioning

confidence: 99%

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Development of Helical Aromatic Amide Foldamers with a Diphenylacetylene Backbone

et al. 2020

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“…Yokoyama et al investigated the effect of the -substituted chiral side chain on the helical conformation of N-substituted poly(pbenzamide). [91] The CD spectra demonstrated that the poly(pbenzamide) has a right-handed helical conformation in protic polar solvents, and a random structure in chloroform, which indicated that solvophobic interactions play a key role in the helical folding of the poly(p-benzamide). Tojo et al synthesized the pyrrole-containing amides and their oligomers, and investigated their conformations in solution and in the crystalline state.…”

Section: Helical Polyamidesmentioning

confidence: 95%

Preparation and Chiral Applications of Optically Active Polyamides

Zhong

Deng

2021

Macromol. Rapid Commun.

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Chirality is omnipresent in nature and plays vital roles in living organism, and has become a hot research topic across multidisciplinary fields including chemistry, biology, physics, and material science. Meanwhile, polyamides constitute an important class of polymers and have received significant attention owing to their outstanding properties and wide-ranging applications in many areas. Judiciously introducing chirality into polyamides will undoubtedly obtain attractive chiral polymers, namely, optically active polyamides. This review describes the preparation methods of chiral polyamides, including solution polycondensation, interfacial polycondensation, ring-open polymerization, and others; the newly emerging categories of chiral polyamides, i.e., helical polyamides, chiral polyamide-imides, are also presented. The applications of optically active polyamides in chiral research fields including asymmetric catalysis, membrane separation, and enantioselective crystallization are also summarized. In addition, current challenges in chiral polyamides are further presented and future perspectives in the field are proposed. Preparation of Chiral Polyamides Solution PolycondensationSolution condensation polymerization is one of the most common methods to prepare chiral polyamides. Yoshikawa and

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Control of Polycondensation

Yokozawa

Ohta

2022

Macromolecular Engineering

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Polycondensation is an important method of polymerization that affords polymers containing functional groups and/or aromatic rings in the backbone, which serve as fibers, engineering plastics, electrical materials, and so on by virtue of their strong intermolecular forces. Most research had been centered on how to increase the molecular weight of polymers and how to synthesize a variety of condensation polymers. Lately, however, polycondensation has developed in many controlled ways. This article describes (i) stoichiometric‐imbalanced polycondensation, in which high‐molecular‐weight polymers are obtained even when one of the two monomers are used in excess, (s) sequence control of monomer units in the backbone, (ii) molecular weight and dispersity control in polycondensation which proceeds in chain‐growth polymerization manner like living polymerization to afford aromatic polyamides, π‐conjugated polymers, and so on, (iii) chain topology control for linear, cyclic, and hyperbranched polymers, and (iv) architectures containing condensation polymer such as block copolymer, star polymer, and graft copolymer from a combination of controlled polycondensation and another polymerization method.

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Effect of the α-substituted chiral side chain on the helical conformation of N-substituted poly(p-benzamide)

Cited by 7 publications

References 38 publications

Development of Helical Aromatic Amide Foldamers with a Diphenylacetylene Backbone

Development of Helical Aromatic Amide Foldamers with a Diphenylacetylene Backbone

Preparation and Chiral Applications of Optically Active Polyamides

Control of Polycondensation

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