نتایج جستجو برای: achiral

تعداد نتایج: 1375  

2005
M. Nilsson A. Brandenburg A. C. Andersen S. Hoefner

The differences between unidirectional and bidirectional polymerization are considered. The unidirectional case is discussed in the framework of the RNA world. Similar to earlier models of this type, where polymerization was assumed to proceed in a bidirectional fashion (presumed to be relevant to peptide nucleic acids), leftand right-handed monomers are produced via an autocatalysis from an ac...

2013
Ting Chen Wen-Hong Yang Dong Wang Li-Jun Wan

Understanding the chirality induction and amplification processes, and the construction of globally homochiral surfaces, represent essential challenges in surface chirality studies. Here we report the induction of global homochirality in two-dimensional enantiomorphous networks of achiral molecules via co-assembly with chiral co-absorbers. The scanning tunnelling microscopy investigations and m...

Journal: :Nature chemistry 2015
Jos C M Kistemaker Peter Štacko Johan Visser Ben L Feringa

Control of the direction of motion is an essential feature of biological rotary motors and results from the intrinsic chirality of the amino acids from which the motors are made. In synthetic autonomous light-driven rotary motors, point chirality is transferred to helical chirality, and this governs their unidirectional rotation. However, achieving directional rotary motion in an achiral molecu...

Journal: :Electrophoresis 2004
Cevdet Akbay Jepkoech Tarus Nicole L Gill Rezik A Agbaria Isiah M Warner

One disadvantage of amino acid-based chiral selectors for micellar electrokinetic chromatography (MEKC) is that either they have very low solubility or are insoluble at acidic pHs. In order to increase solubilities at lower pHs, we have synthesized a highly water-soluble achiral surfactant and copolymerized it with an amino acid-based chiral surfactant. These two surfactants were polymerized ei...

2013
Hernán Santos M. C. Muñoz M. P. López-Sancho Leonor Chico

We study the electronic structure of chiral and achiral graphene nanoribbons with symmetric edges, including curvature and spin-orbit effects. Curved ribbons show spin-split bands, whereas flat ribbons present spin-degenerate bands. We show that this effect is due to the breaking of spatial inversion symmetry in curved graphene nanoribbons, while flat ribbons with symmetric edges possess an inv...

2012
Matthew A. Windsor Daniel J. Hermanson Philip J. Kingsley Shu Xu Brenda C. Crews Winnie Ho Catherine M. Keenan Surajit Banerjee Keith A. Sharkey Lawrence J. Marnett

Cyclooxygenase-2 (COX-2) oxygenates arachidonic acid and the endocannabinoids 2-arachidonoylglycerol (2-AG) and arachidonoylethanolamide (AEA). We recently reported that (R)-profens selectively inhibit endocannabinoid oxygenation but not arachidonic acid oxygenation. In this work, we synthesized achiral derivatives of five profen scaffolds and evaluated them for substrate-selective inhibition u...

2018
Wei Zhang Yin Zhao Lu Yin

To date, liquid crystal chirality, mechanophysical chirality, circularly polarized photon chirality, gelation and chiral solvation are all feasible candidates to generate optically active polymers and supramolecular chirality when employing achiral molecules as start‐ ing substances. Among this, chiral‐solvation‐induced chirality is one of the dominant methods for construction of chirality from...

Journal: :Chemical communications 2008
Yoshio Hayashi Thomas Regnier Shigenobu Nishiguchi Magne O Sydnes Daisuke Hashimoto Junya Hasegawa Takahiro Katoh Tetsuya Kajimoto Masataka Shiozuka Ryoichi Matsuda Manabu Node Yoshiaki Kiso

Herein, we describe an efficient strategy for the total synthesis of (+)-negamycin using commercially available achiral N-Boc-2-aminoacetaldehyde as starting material with 42% overall yield for a limited number of steps.

Journal: :Chemical communications 2012
Jiaxi Cui Jie Zhang Xinhua Wan

A small change in chemical structure causes a remarkable influence on the stereostructure stability and mutarotational rate of helical vinyl polymers bearing laterally attached p-terphenyl pendants with an achiral butoxy terminal and a chiral galactosyloxy terminal.

Journal: :Journal of the American Chemical Society 2009
Zhi-Yong Han Han Xiao Xiao-Hua Chen Liu-Zhu Gong

Consecutive hydroamination/asymmetric transfer hydrogenation under relay catalysis of an achiral gold complex/chiral Brønsted acid binary system has been described for the direct transformation of 2-(2-propynyl)aniline derivatives into tetrahydroquinolines with high enantiomeric purity.

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