Circular Dichroism of the Liquid Crystals of Poly (γ-benzyl-L-glutamate) Under Static Electric Fields
11
Citation
11
Reference
10
Related Paper
Abstract:
Abstract Liquid crystals of poly(γ-benzyl-L-glatamate) show circular dichroism (CD) from the benzyl chromophores. In an electric field the shape, magnitude and sign of the spectrum depend on the angle between the applied field and the direction of polarization. The inherent CD is restored after subtraction of the linear dichroism component.Keywords:
Chromophore
Dichroism
Linear dichroism
Linear dichroism
Dichroism
Dichroic glass
Principal axis theorem
Cite
Citations (5)
Linear dichroism
Polarizer
Dichroic glass
Dichroism
Cite
Citations (14)
Abstract Circular dichroism ( CD ) is the difference in absorption, , of left and right circularly polarized light: For randomly oriented systems such as solutions, only chiral molecules will show any CD intensity corresponding to their absorption bands. Chiral is derived from the Greek word χϵιρ meaning hand and describes something that cannot be superposed on its mirror image by rotation. Two molecules that are mirror images of each other are often referred to as enantiomers and equimolar mixtures of two enantiomers form a racemic mixture which has no net CD intensity in solution. CD can be used to analyze chiral structures, such as a protein secondary structure, and to probe interactions between chiral molecules and other molecules. Linear dichroism ( LD ) is the difference in absorption of light linearly polarized parallel and perpendicular to an orientation axis: LD can be used to provide orientation information about subunits of a molecular system such as small molecules absorbed onto stretched films, flow‐oriented DNAs and fibrous proteins, and lipid bilayer systems. Both circular and LD are absorbance techniques and most CD instruments will also measure LD. Both CD and LD can also be enhanced by fluorescence detection with either incident circularly or linearly polarized light (fluorescence detected circular and linear dichroism) and/or measurement of the circular or linear nature of the emitted light.
Linear dichroism
Dichroism
Vibrational Circular Dichroism
Cite
Citations (2)
Abstract Extrinsic optical activity was observed for symmetric side chain chromophores in helical polypeptides. Poly-β-benzyl-l-aspartate, poly-β-p-nitrobenzyl-l-aspartate and poly-γ-p-nitrobenzyl-l-glutamate gave induced circular dichroism in the wavelength regions corresponding to the absorption bands of the benzyl and the p-nitrobenzyl chromophores of the side chains in their dilute solutions. Moreover, poly-γ-benzyl-d-glutamate gave induced circular dichroism due to the benzyl chromophore in its concentrated solutions which formed a liquid crystalline phase. The extrinsic optical activity thus observed was explained as the consequence of the loss of the rotational freedom of the chromophores relative to the α-helical structure and to the cholesteric helical structure of the polypeptides.
Chromophore
Side chain
Cite
Citations (20)
We report a method to obtain a light-controllable dichroism. The main effect is achieved using spiropyran-doped (SP-doped) nematic liquid crystal mixtures. SP molecules exhibit a high solubility in the liquid crystal host, which can vary between 1% and 4% in weight, without destroying the liquid crystalline phase. Due to their elongated shape, SP molecules are oriented along the nematic liquid crystal director. The obtained linear dichroism was measured to be 1.08 with a dichroic ratio of 7.12. Further, a two-direction linear dichroism was obtained by adding a dichroic dye to the mixture. The angle between the two dichroic axes was found to be 11°. Two-direction linear dichroism is also light controllable and can be switched back to one-direction dichroism.
Dichroic glass
Dichroism
Linear dichroism
Cite
Citations (2)
Circular dichroism (CD) was used to study the structure of oxyblepharismin (OxyBP), the photoreceptor chromophore for the photophobic response of the blue form of Blepharisma japonicum. Both the chromophore associated to its native protein and the free chromophore in ethanol solution were investigated. CD spectra in the far-UV range indicate that OxyBP induces a slight increase in the alpha-helix content of the protein matrix. CD spectra in the near-UV and visible region of the spectrum show that OxyBP adopts a chiral conformation with a preferential geometry not only when associated to its protein matrix, but also when isolated and dissolved in ethanol. This experimental result is related to the existence of a high-energy interconversion barrier between two enantiomeric structures of the molecule and discussed on the basis of an asymmetric biosynthesis of its precursor, blepharismin.
Chromophore
Matrix (chemical analysis)
Cotton effect
Cite
Citations (11)
Liquid nitrogen
Cite
Citations (36)
Specific induced circular dichroism (ICD) for Z-DNA is produced by chromophore-linked alkynyldeoxyribose skeletons that exist at the 5′ ends of CG-repeated oligonucleotides. In their Full Paper on page 2401 ff., K. Fujimoto, M. Inouye et al. describe the CD spectra of the CG-repeated oligonucleotides labeled with the chromophore-linked alkynyldeoxyriboses as an ICD probe for their B to Z transitions.
Chromophore
Cite
Citations (0)
Abstract This book provides an introduction to all those who wish to use the complementary spectroscopic techniques of optical activity (circular dichroism, CD) and optical anisotropy (linear dichroism, LD) for the study of the structure of molecules and interactions between molecules in solution. It emphasizes these techniques and how to use them for both low and high molecular weight molecules. The book begins by describing the principles behind CD and LD and how these techniques can be used in the laboratory without using advanced maths or quantum mechanics. The next chapters describe how both techniques may be applied to the study of biological macromolecules and give a detailed description of how they may be used on small molecules to investigate molecular and electronic structure. The final part contains theoretical derivations of all the equations required for the applications described previously. Specific molecular examples are used to illustrate concepts and to show the reader how to use the techniques in chemical and biological systems. Circular Dichroism and Linear Dichroism is an easy guide to what a prospective user of CD needs to know and explains how LD is not merely an exotic technique only to be practiced by experienced spectroscopists, but may be routinely and usefully employed as an aid to molecular structure determination.
Linear dichroism
Dichroism
Vibrational Circular Dichroism
Cite
Citations (742)
Dichroic glass
Dichroism
Linear dichroism
Chromophore
Cite
Citations (75)