نتایج جستجو برای: achiral

تعداد نتایج: 1375  

Journal: :Symmetry 2018
Keiji Hirose Masaya Ukimi Shota Ueda Chie Onoda Ryohei Kano Kyosuke Tsuda Yuko Hinohara Yoshito Tobe

Rotaxanes consisting of achiral axle and achiral ring components can possess supramolecular chirality due to their unique geometrical architectures. To synthesize such chiral rotaxanes, we adapted a prerotaxane method based on aminolysis of a metacyclophane type prerotaxane that had planar chirality, which is composed of an achiral stopper unit and a crown ether type ring component. The prerota...

2008
Yukio Saito Hiroyuki Hyuga

A cluster growth model is proposed to study chiral symmetry breaking in stirred crystallization from an achiral element. Achiral monomers are assumed to coagulate to form chiral clusters from dimers to hexamers. Due to the stirring, the hexamers break into dimers. The coagulation of two dimers into a tetramer also occurs. The fixed point analysis of coupled rate equations of cluster densities a...

Journal: :Chemical science 2015
Miki Horie Naoki Ousaka Daisuke Taura Eiji Yashima

A series of novel PtII-linked double helices were prepared by inter- or intrastrand ligand-exchange reactions of the complementary duplexes composed of chiral or achiral amidine dimer and achiral carboxylic acid dimer strands joined by trans-PtII-acetylide complexes with PPh3 ligands using chiral and achiral chelating diphosphines. The structure and stability of the PtII-linked double helices w...

2013
Nathan Manville Hekla Alite Fredrik Haeffner Amir H. Hoveyda Marc L. Snapper

Catalytic enantioselective monosilylations of diols and polyols furnish valuable alcohol-containing molecules in high enantiomeric purity. These transformations, however, require high catalyst loadings (20-30 mol%) and long reaction times (2-5 days). Here, we report that a counterintuitive strategy involving the use of an achiral co-catalyst structurally similar to the chiral catalyst provides ...

2010
Tsuneomi Kawasaki Yuko Hakoda Hiroko Mineki Kenta Suzuki Kenso Soai

The enantioselective formation of chiral crystal of achiral nucleobase cytosine was achieved mediated by the crystal direction selective dehydration of crystal water in the achiral crystal of cytosine monohydrate (P2(1)/c). Heat transfer from the enantiotopic face of the single crystal of cytosine monohydrate afforded the enantiomorphous crystal of anhydrous cytosine.

Journal: :Chemical communications 2014
Zongxia Guo Inge De Cat Bernard Van Averbeke Jianbin Lin Guojie Wang Hong Xu Roberto Lazzaroni David Beljonne Albertus P H J Schenning Steven De Feyter

Here we report on the apparent reduction in surface chirality upon co-assembling a chiral and achiral molecule into a physisorbed self-assembled monolayer at the liquid/solid interface as revealed by scanning tunneling microscopy (STM). Chiral OPV with achiral thymine gives rise to surface-confined supramolecular diastereomers.

Journal: :Chemical communications 2016
Mohamed Alaasar Silvio Poppe Qingshu Dong Feng Liu Carsten Tschierske

Achiral supramolecular hydrogen bonded complexes between rod-like 4-(4-alkoxyphenylazo)pyridines and a taper shaped 4-substituted benzoic acid form achiral (Ia3[combining macron]d) and chiral "Im3[combining macron]m-type" bicontinuous cubic (I432) phases and a chiral isotropic liquid mesophase (Iso1[*]). The chiral phases, resulting from spontaneous mirror symmetry breaking, represent conglomer...

Journal: :Dalton transactions 2016
Zekiye P Guven Burcin Ustbas Kellen M Harkness Hikmet Coskun Chakra P Joshi Tabot M D Besong Francesco Stellacci Osman M Bakr Ozge Akbulut

Chiral mixed ligand silver nanoclusters were synthesized in the presence of a chiral and an achiral ligand. While the chiral ligand led mostly to the formation of nanoparticles, the presence of the achiral ligand drastically increased the yield of nanoclusters with enhanced chiral properties.

Journal: :Organic & biomolecular chemistry 2010
Tom W Anderson Jeremy K M Sanders G Dan Pantoş

Self-assembling naphthalenediimide (NDI)-based helical organic nanotubes display sergeants-and-soldiers behaviour, chiral monomers imposing a supramolecular structure upon achiral monomers. Several achiral NDI monomers were synthesised and their ability to incorporate into supramolecular nanotubes was studied. Nanotubes containing predominantly the most effective soldier, derived from 1-aminocy...

Journal: :journal of sciences islamic republic of iran 0

this paper considers the possibility of spontaneous transition of aracemic mixture (composed of equal amounts of two enantiomeric species, say l and d) into a monochiral state (in which only one enantiomer, say l, is present). transitions of this kind have been recently experimentally observed. a plausible approach to this phenomenon is a model put forward by frank, based on simple laws of chem...

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