Circular dichroism using

Borisov V, Arutyunyan AM et al (1998) Magnetic circular dichroism used to examine the interaction of Escherichia coli cytochrome Bd with ligands. Biochemistry 38 740-750... 

Circular dichroism, used to derive absolute configuration. 

Bruhat defined circular dichroism using a differential extinction coefficient, Ae, cl-... 

Ragunathan N, Lee N-S, Freedman TB, Nafie LA, Tripp C and Buijs H (1990) Measurement of vibrational circular dichroism using a polarizing Michelson interferometer. Applied Spectroscopy 44 5-7. 

There has been considerable interest in the development of new methods of chemical sensing to recognize molecules or ions as important application of supramolecular chemistry [1-3]. Our group has prepared many kinds of chro-mophore-modified cyclodextrins (CD) as chemosensors for detecting molecules [4-8]. Colorless neutral molecules can be detected as changes in the intensities of the fluorescence, absorption, or circular dichroism using chemosensors based on chromophore-modified CD. 

CDAD Circular dichroism photo- Uses circularly polarized Orientation of adsorbed... 

FiaaHy, the use of photoreversible change of the circular dichroism for optical data storage is of iaterest. This technique offers an advantage over photochromic materials ia that the data can be read ia a way that does not damage the stored information. These chirooptic data storage devices have been demonstrated with the example of chiral peptides with azobenzene side groups (155). 

Although the usual absorption and scattering spectroscopies caimot distinguish enantiomers, certain techniques are sensitive to optical activity in chiral molecules. These include optical rotatory dispersion (ORD), the rotation by the sample of the plane of linearly polari2ed light, used in simple polarimeters and circular dichroism (CD), the differential absorption of circularly polari2ed light. 

Circular dichroism employs standard dispersive or interferometric instmmentation, but uses a thermal source that is rapidly modulated between circular polari2ation states using a photoelastic or electro-optic modulator. Using phase-sensitive detection, a difference signal proportional to the absorption difference between left- and right-polari2ed light, AA is recorded as a function of wavenumber. Relative differential absorptions... 

The circular dichroism curves for a variety of penicillanic acid derivatives have been published and discussed (B-77MI51100) and have been used to support extended Hiickel MO calculations (77T711). 

Freeing a solution from extremely small particles [e.g. for optical rotatory dispersion (ORD) or circular dichroism (CD) measurements] requires filters with very small pore size. Commercially available (Millipore, Gelman, Nucleopore) filters other than cellulose or glass include nylon, Teflon, and polyvinyl chloride, and the pore diameter may be as small as 0.01 micron (see Table 6). Special containers are used to hold the filters, through which the solution is pressed by applying pressure, e.g. from a syringe. Some of these filters can be used to clear strong sulfuric acid solutions. 

Infrared, nuclear magnetic resonance, ultraviolet, optical rotary dispersion and circular dichroism measurements have been used for the spectral analysis of thiiranes. A few steroidal thiiranes have been reported to possess infrared absorption in the range from 580 to 700 cm The intermediate thiocyanate derivatives (RSCN) have a strong sharp peak at 2130-2160 cm the isomeric isothiocyanate (RNCS) shows a much stronger but broad band at 2040-2180 cm. ... 

In a few instances the technique of magnetic circular dichroism (MCD) spectroscopy has been used to corroborate assignments based on UV-visible spectroscopy. For example, the assignment of the intense 360 nm band for [S,N,Y to a r (2e") r (2a2") (HOMO LUMO) excitation has been confirmed by the measurement of the MCD spectrum of The MCD spectrum of [S4N3] indicates that each of the... 

Results from an array of methods, including X-ray absorption, EXAFS, esr and magnetic circular dichroism, suggest that in all ureases the active sites are a pair of Ni" atoms. In at least one urease,these are 350 pm apart and are bridged by a carboxylate group. One nickel is attached to 2 N atoms with a fourth site probably used for binding to urea. The second nickel has a trigonal bipyramidal coordination sphere. 

Incorporation of chiral units into polymers generates optically active polymers.27 Two types of optically active polymers could be obtained according to where the chiral units reside optically active polymers with chirality derived from chiral side chains and optically active polymers with chirality derived from tire chiral main chain. The circular dichroism (CD) measurement of 32, an optically active polymer with chiral side chains, showed that the chiral substituents have induced main-chain chirality. The induced main-chain chirality disappeared at higher temperature and appeared upon cooling. This type of chiral conjugated polymer is potentially useful in reversing optical recording28 ... 

Optical rotation and circular dichroism have been used for die characterization of optically active polymers. They have been used to determine whether polymers are optically active and whether a secondary structure such as a helix exists. 

Optically active molecules show circular dichroism. Their extinction coefficients f l and are different and change as a function of wavelength. Using a suitable spectroelectrochemical cell, Af = fl -which is usually small compared to conventional extinction coefficients, can be measured. Combined with the special properties of a thin layer cell kinetic data can be extracted from CD-data [01 Liu]. (Data obtained with this method are labelled CD.)... 

Small-angle X-ray scattering (SAXS), circular dichroism (CD), and UV spectroscopy at different temperatures were used to investigate the nature of calf-thymus DNA in aqueous solution, in the presence of [Me Sn] " (n = 1-3) species. The results demonstrate that the [MeSn(IV)] moiety does not influence the structure and conformation of the DNA double helix, and does not degrade DNA, as indicated by agarose gel electrophoresis. Inter alia, the radii of gyration, Rg, of the cross section of native calf-thymus DNA, determined by SAXS in aqueous solution in the presence of [Me Sn] " (n = 1-3) species are constant and independent of the nature and concentration of the [Me Sn] species. 

Other methods have also been used, including optical rotatory dispersion, circular dichroism (CD), and asymmetric synthesis (see p. 147). 

Recently, peptoid-based mimics of both SP-C and SP-B have been designed to adopt helical secondary structures, and also mimic (to varying degrees) the sequence patterning of hydrophobic and polar residues found in the natural surfactant proteins. Peptoid-based SP-C mimics of up to 22 monomers in length, were synthesized and characterized by in vitro experimental methods [67, 68] (Fig. 1.8). The secondary structure of all molecules was assessed by circular dichroism and found to be helical. The surface activities of these peptoids, in comparison to the actual SP peptides described above, were characterized by surfactometry using... 

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