• Title/Summary/Keyword: Chirality

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Synthesis of Novel H8-Binaphthol-based Chiral Receptors and Their Applications in Enantioselective Recognition of 1,2-Amino alcohols and Chirality Conversion of L-Amino acids to D-Amino acids

  • Jung, Hye-In;Nandhakumar, Raju;Yoon, Hoe-Jin;Lee, Sang-Gi;Kim, Kwan-Mook
    • Bulletin of the Korean Chemical Society
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    • v.31 no.5
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    • pp.1289-1294
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    • 2010
  • Novel $H_8$-binaphthol-based chiral receptors appended with an uryl moiety (2a) and a guanidinium moiety (2b) have been designed and synthesized for the enantioselective recognition of 1,2-amino alcohols via reversible imine formation. The selectivities ($K_R/K_S$ = 9.8 ~ 19.4) of 2b in imine formation with 1,2-amino alcohols are higher than those of 2a ($K_R/K_S$ = 1.8 ~ 4.5). Similar efficiency trend have been observed in the conversion of L-amino acids to D-amino acids, i.e., the efficiency of the receptor 2b (D/L ratio: 4.3 ~ 10.1) is superior to 2a (D/L ratio: 4.0 ~ 8.7).

Induction of Single Helical Screw Sense in Poly (n-Hexyl Isocyanate) by End-capping with a Chiral Moiety

  • Nath G. Yogendra;Samal Shashadhar;Park, Sang-Yoon;Murthy C.N.;Lee, Jae-Suk
    • Proceedings of the Polymer Society of Korea Conference
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    • 2006.10a
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    • pp.334-334
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    • 2006
  • Helical polymers like polyisocyanates with single screw sense are essential to exhibit sophisticated functions like molecular recognition, self-replication, chirality memory and catalytic activity. One approach that has not been explored is the effect on handedness of the polyisocyanates through end-capping with a chiral residue. Induction of chirality in poly(n-hexyl isocyanate) was studied by end-capping with chiral (R and S) 2-bromo-3-methylbutyryl chloride(R-BMBC and S-BMBC). We have shown that a control over living anionic polymerization of HIC by using a suitable initiator affords an opportunity to introduce chiral end-groups with 100% yield and in high purity. This has resulted in helicity induction through extended lengths several orders of magnitude.

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Free vibration analysis of chiral double-walled carbon nanotube using non-local elasticity theory

  • Rakrak, Kaddour;Zidour, Mohamed;Heireche, Houari;Bousahla, Abdelmoumen Anis;Chemi, Awda
    • Advances in nano research
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    • v.4 no.1
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    • pp.31-44
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    • 2016
  • This article is concerned with the free vibration problem for chiral double-walled carbon nanotube (DWCNTs) modelled using the non-local elasticity theory and Euler Bernoulli beam model. According to the governing equations of non-local Euler Bernoulli beam theory and the boundary conditions, the analytical solution is derived and two branches of transverse wave propagating are obtained. The numerical results obtained provide better representations of the vibration behaviour of double-walled carbon nanotube, where the aspect ratio of the (DWCNTs), the vibrational mode number, the small-scale coefficient and chirality of double-walled carbon nanotube on the frequency ratio (${\chi}^N$) of the (DWCNTs) are significant. In this work, the numerical results obtained can be used to predict and prevent the phenomenon of resonance for the forced vibration analyses of double -walled carbon nanotubes.