نتایج جستجو برای: achiral

تعداد نتایج: 1375  

Journal: :Advanced Materials 2021

Achiral mesogenic molecules are shown to be able spontaneously assemble into liquid crystalline smectic phases having either simple or double-helical structures. At the transition between these phases, structure unwinds. As a consequence, in some temperature range, pitch of helix becomes comparable wavelength visible light and selective reflection range is observed. The photonic bandgap phenome...

Journal: :Electrophoresis 2003
Cevdet Akbay Nicole L Gill Rezik A Agbaria Isiah M Warner

An achiral monomeric surfactant (sodium 10-undecenyl sulfate, SUS) and a chiral surfactant (sodium 10-undecenoyl L-leucinate, SUL) were synthesized and polymerized individually to form poly-SUS and poly-SUL. These surfactants were then copolymerized at various molar ratios to produce a variety of copolymerized surfactants (CoPSs), possessing both achiral (sulfate) and chiral (leucinate) head gr...

2017
Dong Yang Pengfei Duan Li Zhang Minghua Liu

Transfer of both chirality and energy information plays an important role in biological systems. Here we show a chiral donor π-gelator and assembled it with an achiral π-acceptor to see how chirality and energy can be transferred in a composite donor-acceptor system. It is found that the individual chiral gelator can self-assemble into nanohelix. In the presence of the achiral acceptor, the sel...

Journal: :Soft matter 2016
Dong Yang Yin Zhao Kai Lv Xiufeng Wang Wei Zhang Li Zhang Minghua Liu

A general strategy to tune the achiral main chain polymers into helical nanoassemblies was proposed based on the co-gelation approach. As an example, two achiral main chain polymers, PCz8 and PSi8, were selected, and their co-assembly with an amphiphilic l- or d-glutamide gelator was investigated. Although the polymers could not form gels individually, they could form co-gels with the gelator a...

Journal: :iranian journal of science and technology (sciences) 2007
a. jarrahpour

synthesis of some new monocyclic β-lactams containing a quaternary carbon center via a [2+2]cycloaddition reaction is described. the reaction of achiral diphenyl ketene with chiral aldimines derivedfrom chiral 2, 3, 4, 6-tetra-o-acetyl-β-d-galactopyranosylamine, 2, 3, 4, 6-tetra-o-acetyl-β-dglucopyranosylamine and different benzaldehydes resulted in the formation of β-lactams as singlediastereo...

Journal: :Helvetica Chimica Acta 2003

Journal: :Physical review letters 2003
Ralf Stannarius Jianjun Li Wolfgang Weissflog

We report electro-optic experiments in liquid crystalline freestanding films of achiral hockey stick shaped mesogens with a straight aromatic core. The material forms two smectic mesophases. In the higher temperature phase, a spontaneous polarization exists in the smectic layer plane and the films show polar switching in electric fields. It is the first example of a ferroelectric phase formed b...

1999
Helmut R. Brand Harald Pleiner P. E. Cladis

Liquid crystal phases (LCs) formed by achiral bent-core molecules (banana LCs) are distinguishable from those of their classical (i.e., rod/disc-shaped) counterparts with only quadrupolar order. We argue that the interplay between tetrahedratic (octupolar) and quadrupolar order clarifies the physics of banana LCs sufficiently to account for two effects only observed in achiral banana LCs: a 100...

2007
WEIHUA MU ANTHONY NICKOLAS VAMIVAKAS YAN FANG BOLIN WANG

The method to obtain phonon dispersion of achiral single-wall carbon nanotubes (SWNTs) from 6× 6 matrix proposed by Mahan and Jeon has been extended to chiral SWNTs. The number of calculated phonon modes of a chiral SWNT (10, 1) is much larger than that of a zigzag one (10, 0) because the number of atoms in the translational unit cell of chiral SWNT is larger than that of an achiral one even th...

Journal: :Physical review letters 2008
Fangyong Yan Christopher Adam Hixson David J Earl

We explore the phase behavior of a rigid achiral bent-core model system. Nematic and smectic phases form at higher densities, whereas micelles and columns composed of chiral clusters of these molecules self-assemble at lower densities. No nucleation mechanism requiring transient chirality is possible in the formation of these chiral superstructures due to the rigid achiral nature of the substit...

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