TY - JOUR
T1 - Stereochemical control of nonamphiphilic lyotropic liquid crystals
T2 - Chiral nematic phase of assemblies separated by six nanometers of aqueous solvents
AU - Yang, Sijie
AU - Wang, Bing
AU - Cui, Dawei
AU - Kerwood, Deborah
AU - Wilkens, Stephan
AU - Han, Junjie
AU - Luk, Yan Yeung
PY - 2013/6/13
Y1 - 2013/6/13
N2 - Unlike conventional thermotropic and lyotropic liquid crystals, nonamphiphilic lyotropic liquid crystals consist of hydrated assemblies of nonamphiphilic molecules that are aligned with a separation of about 6 nm between assemblies in an aqueous environment. This separation raises the question of how chirality, either from chiral mesogens or chiral dopants, would impact the phase as the assemblies that need to interact with each other are about 6 nm apart. Here, we report the synthesis of three stereoisomers of disodium chromonyl carboxylate, 5′DSCG-diviol, and the correlation between the molecular structure, bulk assembly, and liquid crystal formation. We observed that the chiral isomers (enantiomers 5′DSCG-(R,R)-diviol and 5′DSCG-(S,S)-diviol) formed liquid crystals while the achiral isomer 5′DSCG-meso-diviol did not. Circular dichroism indicated a chiral conformation with bisignate cotton effect. The nuclear Overhauser effect in proton NMR spectroscopy revealed conformations that are responsible for liquid crystal formation. Cryogenic transmission electron microscopy showed that chiral 5′DSCG-diviols form assemblies with crossings. Interestingly, only planar alignment of the chiral nematic phase was observed in liquid crystal cells with thin spacers. The homeotropic alignment that permitted a fingerprint texture was obtained only when the thickness of the liquid crystal cell was increase to above ∼500 μm. These studies suggest that hydrated assemblies of chiral 5′DSCG-diviol can interact with each other across a 6 nm separation in an aqueous environment by having a twist angle of about 0.22 throughout the sample between the neighboring assemblies.
AB - Unlike conventional thermotropic and lyotropic liquid crystals, nonamphiphilic lyotropic liquid crystals consist of hydrated assemblies of nonamphiphilic molecules that are aligned with a separation of about 6 nm between assemblies in an aqueous environment. This separation raises the question of how chirality, either from chiral mesogens or chiral dopants, would impact the phase as the assemblies that need to interact with each other are about 6 nm apart. Here, we report the synthesis of three stereoisomers of disodium chromonyl carboxylate, 5′DSCG-diviol, and the correlation between the molecular structure, bulk assembly, and liquid crystal formation. We observed that the chiral isomers (enantiomers 5′DSCG-(R,R)-diviol and 5′DSCG-(S,S)-diviol) formed liquid crystals while the achiral isomer 5′DSCG-meso-diviol did not. Circular dichroism indicated a chiral conformation with bisignate cotton effect. The nuclear Overhauser effect in proton NMR spectroscopy revealed conformations that are responsible for liquid crystal formation. Cryogenic transmission electron microscopy showed that chiral 5′DSCG-diviols form assemblies with crossings. Interestingly, only planar alignment of the chiral nematic phase was observed in liquid crystal cells with thin spacers. The homeotropic alignment that permitted a fingerprint texture was obtained only when the thickness of the liquid crystal cell was increase to above ∼500 μm. These studies suggest that hydrated assemblies of chiral 5′DSCG-diviol can interact with each other across a 6 nm separation in an aqueous environment by having a twist angle of about 0.22 throughout the sample between the neighboring assemblies.
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U2 - 10.1021/jp401382h
DO - 10.1021/jp401382h
M3 - Article
C2 - 23688325
AN - SCOPUS:84879063617
SN - 1520-6106
VL - 117
SP - 7133
EP - 7143
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 23
ER -