Does local chain conformation affect the chiral recognition ability of an amylose derivative? Comparison between linear and cyclic amylose tris(3,5-dimethylphenylcarbamate)

The full-text file will be made open to the public on 16 August 2021 in accordance with the publisher's policy.Akiyuki Ryoki, Yuto Kimura, Shinichi Kitamura, Katsuhiro Maeda, Ken Terao. Does local chain conformation affect the chiral recognition ability of an amylose derivative? Comparison between linear and cyclic amylose tris(3,5-dimethylphenylcarbamate). Journal of Chromatography A, 1599, 2019, pp. 144-151. https://doi.org/10.1016/j.chroma.2019.04.019

Coordination Asymmetry: Design of Asymmetric Coordination Sphere and Anisotropic Assembly for the Creation of Functional Molecules

金沢大学ナノ生命科学研究所本研究は、らせん高分子に特徴的な協同効果による不斉増幅現象を活用し、微量キラル源からの効率的なキラルナノ空間の形成を目指す。さらに、外部刺激によるらせんの巻き方向の可逆的な制御が可能である特長を利用することにより、固体状態でキラリティー制御が可能なスイッチングキラルナノ空間を創成する。本年度は以下の研究成果が得られた。1. らせん高分子集積キラルナノ空間の不斉反応への適用昨年度、らせん構造を記憶として保持した側鎖にカルボキシル基を有するポリ（ジフェニルアセチレン）を、中心金属にロジウムを有する二核金属錯体と混合することにより、らせん高分子を多座配位子とした集積型らせん高分子錯体を合成することに成功し、本錯体を不斉シクロプロパン化反応の触媒として用いると、らせんキラリティーのみに由来する不斉選択性を発現することを見出している。本年度は、本錯体を触媒に用いた不斉反応について反応条件の最適化を行い、最大48%ee の不斉選択性が発現することを明らかにした。２. キラルカチオンの配位によるポリアセチレンへのらせん誘起・記憶側鎖に動的軸性キラルなビフェニル基を有するポリアセチレン (poly-1)が、溶液中だけでなく固体状態でもキラルゲストとの非共有結合相互作用を介して、一方向巻きらせん構造の誘起・記憶の現象を示すことを見出し、この特徴的な性質を利用して溶出順序を自在にスイッチできるキラルカラムの開発に世界で初めて成功している。しかし、poly-1に一方向巻きらせん構造を誘起するには、大過剰量のキラルゲストが必要であった。そこで、poly-1のビフェニル基上の２つのメトキシメトキシ基によって形成される擬クラウンエーテル構造に着目し、キラルアンモニウム塩をキラルゲストに用いることによって、触媒量（0.1当量）でもほぼ完全な一方向巻きらせん構造の誘起と記憶が可能であることを明らかにした。研究課題/領域番号:17H05361, 研究期間(年度):2017-04-01 – 2019-03-3

Three-State Switchable Chiral Stationary Phase Based on Helicity Control of an Optically Active Poly(phenylacetylene) Derivative by Using Metal Cations in the Solid State

This is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, Copyright © 2019 American Chemical Society after peer review and technical edityng by the publisher. To access the final edited and published work see: https://pubs.acs.org/doi/10.1021/jacs.9b03177An unprecedented three-state switchable chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC) was developed using a helical poly(phenylacetylene) bearing a chiral (R)-α-methoxyphenylacetic acid residue as the pendant (poly-1). The left- and right-handed helical conformations were induced in poly-1-based CSP upon coordination with a catalytic amount of soluble sodium and cesium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate salts (MBArF), respectively, which are soluble in the HPLC conditions [hexane–2-propanol (95:5, v/v)]. The switch between the two different helical states of poly-1 can be easily achieved by rinsing the poly-1-based CSP with MeOH and the subsequent addition of the proper MBArF salt. Using this dynamic helical CSP, we demonstrate how changes on the orientation of the secondary structure of a chiral polymer (right-handed, left-handed, and racemic helices) can alter and even invert the elution order of the enantiomers. This study was done without adding chiral additives or changing the mobile phase, which could produce changes on the retention times and make it more difficult to determine the role of the secondary structure during the chiral recognition processThis work was supported by JSPS KAKENHI Grant No. 16H04154 (Grants-in-Aid for Scientific Research (B)) and 17H05361 (Coordination Asymmetry) (K.M.)S

Helical polymer brushes with a preferred-handed helix-sense triggered by a terminal optically active group in the pendant

Helical polymer brushes with a preferred-handed helix-sense composed of a poly(phenylacetylene) backbone and poly(phenyl isocyanate) pendants are synthesized. The helix-sense of the backbone is effectively controlled by the helical chirality of the pendants, which is triggered by an optically active group introduced at the pendant terminal. © The Royal Society of Chemistry 2012

The Quiescent Intracluster Medium in the Core of the Perseus Cluster

Clusters of galaxies are the most massive gravitationally-bound objects in the Universe and are still forming. They are thus important probes of cosmological parameters and a host of astrophysical processes. Knowledge of the dynamics of the pervasive hot gas, which dominates in mass over stars in a cluster, is a crucial missing ingredient. It can enable new insights into mechanical energy injection by the central supermassive black hole and the use of hydrostatic equilibrium for the determination of cluster masses. X-rays from the core of the Perseus cluster are emitted by the 50 million K diffuse hot plasma filling its gravitational potential well. The Active Galactic Nucleus of the central galaxy NGC1275 is pumping jetted energy into the surrounding intracluster medium, creating buoyant bubbles filled with relativistic plasma. These likely induce motions in the intracluster medium and heat the inner gas preventing runaway radiative cooling; a process known as Active Galactic Nucleus Feedback. Here we report on Hitomi X-ray observations of the Perseus cluster core, which reveal a remarkably quiescent atmosphere where the gas has a line-of-sight velocity dispersion of 164+/-10 km/s in a region 30-60 kpc from the central nucleus. A gradient in the line-of-sight velocity of 150+/-70 km/s is found across the 60 kpc image of the cluster core. Turbulent pressure support in the gas is 4% or less of the thermodynamic pressure, with large scale shear at most doubling that estimate. We infer that total cluster masses determined from hydrostatic equilibrium in the central regions need little correction for turbulent pressure.Comment: 31 pages, 11 Figs, published in Nature July