The effect of a chiral nematic solvent on the orientational order and conformational distribution of a flexible prochiral solute

2004 ◽  
Vol 6 (23) ◽  
pp. 5331 ◽  
Author(s):  
J. W. Emsley ◽  
Philippe Lesot ◽  
Jacques Courtieu ◽  
Denis Merlet
Keyword(s):  
Orientational Order ◽  
Chiral Nematic ◽  
Nematic Solvent ◽  
Conformational Distribution

scholarly journals Cover Feature: Helicity Control of Supramolecular Gel Fibers Consisting of an Achiral NiII Complex in a Chiral Nematic Solvent (Chem. Eur. J. 48/2018)

2018 ◽  
Vol 24 (48) ◽  
pp. 12445-12445
Author(s):  
Takatoshi Maeda ◽  
Yuuki Kuwajima ◽  
Takuya Akita ◽  
Yosuke Iwai ◽  
Naruyoshi Komiya ◽  
...  
Keyword(s):  
Supramolecular Gel ◽  
Chiral Nematic ◽  
Niii Complex ◽  
Nematic Solvent

Organic reactions in liquid crystalline solvents. 4. Nanosecond laser flash photolysis studies of intramolecular motions of rod-like solutes in liquid crystals

1986 ◽  
Vol 64 (6) ◽  
pp. 1130-1139 ◽  
Author(s):  
William J. Leigh
Keyword(s):  
Nematic Phase ◽  
Liquid Crystalline ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Orientational Order ◽  
Laser Flash ◽  
Viscous Drag ◽  
Nanosecond Laser ◽  
Nanosecond Laser Flash Photolysis ◽  
Nematic Solvent

The rates of triplet decay of a series of β-aryl-(4-alkoxypropiophenone)s in the smectic, nematic, and isotropic phases of 4′-butyl- and 4′-ethylbicyclohexyl-4-carbonitrile (BCCN and ECCN, respectively) have been measured over the 30–95 °C temperature range by nanosecond laser flash photolysis. The rates of triplet decay for these probe molecules in fluid solution are governed by the rates of Cα—Cβ bond rotation, which allows intramolecular quenching of the carbonyl triplet state by the β-aryl ring. The ketones are substituted with alkyl groups of varying length, shape, and flexibility in the para positions of the β-phenyl (H, n-hexyl, cyclohexyl) and benzoyl (meth-, n-pent-, and n-octoxy) rings. With the exception of β-phenyl-(4-methoxypropiophenone), for each ketone the Arrhenius parameters for triplet decay in the smectic phase of BCCN are similar to those in the nematic phase of the same solvent, and in all cases, the Arrhenius plots exhibit perfect continuity at the S—N transition temperature. A solvation model is tentatively advanced to explain these results. In the nematic phase of BCCN, the Arrhenius activation energy and entropy are significantly more positive than those in isotropic ECCN for all the ketones studied, but variations in the energetics of triplet decay in the nematic phase as a function of solute structure are parallelled in the isotropic solvent. Thus, the inhibiting effect of the nematic solvent on the bond rotations leading to intramolecular triplet quenching in these probes is attributed to the predominant influence of microviscosity (viscous drag) effects; the presence of solvent orientational order appears to have little or no effect on the intramolecular mobility of these ketones. The results and conclusions of earlier studies of unimolecular reactions in nematic solvents are discussed in light of these results.

Helicity Control of Supramolecular Gel Fibers Consisting of an Achiral NiIIComplex in a Chiral Nematic Solvent

2018 ◽  
Vol 24 (48) ◽  
pp. 12546-12554 ◽  
Author(s):  
Takatoshi Maeda ◽  
Yuuki Kuwajima ◽  
Takuya Akita ◽  
Yosuke Iwai ◽  
Naruyoshi Komiya ◽  
...  
Keyword(s):  
Supramolecular Gel ◽  
Chiral Nematic ◽  
Nematic Solvent

Orientational order of 1,3-dichloro-2-ethenylbenzene in liquid-crystal solvents

1997 ◽  
Vol 75 (8) ◽  
pp. 1156-1161 ◽  
Author(s):  
J.C.T. Rendell ◽  
D.S. Zimmerman ◽  
A.J. van der Est ◽  
E.E. Burnell
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Moment Tensor ◽  
Orientational Order ◽  
Mean Field ◽  
Field Potential ◽  
Intermolecular Forces ◽  
Sample Tube ◽  
Average Electric Field ◽  
Nematic Solvent

The order parameter matrices of a molecule that has no symmetry, 1,3-dichloro-2-ethenylbenzene, dissolved in two different nematic liquid-crystal solvents are analyzed in terms of various models for the intermolecular mean-field potential. In a mixture of liquid crystals for which the interaction between the molecular quadrupole moment tensor and the average electric field gradient of the nematic solvent has been minimized, the orientational order is best described by models for the short-range anisotropic potential. The most successful potentials are written in terms of anisotropic interactions between the solute surface and the liquid-crystal mean field. This represents a strong test of such models because they simultaneously fit the five independent orientational parameters obtained from the same solute, thus removing the problems associated with comparing results among different solutes in either the same or a different sample tube. Keywords: liquid crystals, intermolecular forces, order parameters, anisotropic.

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