Linear Circular Dichroism

In order to describe the problems of the nonlinear optical response from biological systems, the question of chirality must be addressed. Linear circular dichroism (CD) has been investigated extensively for biological compounds and a wealth of data are available on... 

Equally important is the sensitivity to spin ordering referred to as x-ray magnetic linear/circular dichroism [5]. 

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. 

A. Rodger and B. Norden, Circular Dichroism and Linear LHchmism, Oxford University Press, Oxford, U.K.. 1997. 

The redox potentials of zinc-substituted phthalocyanines are shown to be linearly dependent on the total Hammett substituent constant.837 In 1987, Stillman and co-workers used the absorption and magnetic circular dichroism spectra of the zinc phthalocyanine and its 7r-cation-radical species to assign the observed bands on the basis of theoretical calculations. The neutral and oxidized zinc phthalocyanine complexes with cyanide, imidazole, and pyridine were used with the key factor in these studies the stability of the 7r-cation-radical species.838 The structure of zinc chloro(phthalocyaninato) has been determined and conductivity investigated.839... 

Figure 5.32 Circular dichroism spectra of tubules made from mixtures of opposite enantiomers of DCg.gPC in 80 20 methanol-water. Spectra shown correspond to mixtures of (a) 100 0, (b) 75 25, (c) 50 50, (d) 25 75, and (e) 0 100 L-/D-DC89PC. Inset shows dependence of peak molar ellipticity on enantiomeric excess along with linear fit of data. Reprinted with permission from Ref. 125. Copyright 1998 by the American Chemical Society.

UVSOR storage ring in the Institute for Molecular Science. Circular dichroism for LB films was measured by a JASCO spectropolarimeter (J-600) with rotating the film sample to remove the influence of linear dichroism. 

Linear dichroism data with DNA oriented by an electric field [53, 54] or a linear flow [55, 56], under linearly polarised light, lead to determinations of the angle between the absorbing transition dipole moment of the chromophore in the molecule and the DNA helix axis conclusions concerning intercalation may thus be drawn from this technique. Finally, with chiral compounds, circular dichroism is also an attractive method to determine the enantioselectivity in the binding of the molecule [48, 57,58]. 

Probing Metalloproteins Electronic absorption spectroscopy of copper proteins, 226, 1 electronic absorption spectroscopy of nonheme iron proteins, 226, 33 cobalt as probe and label of proteins, 226, 52 biochemical and spectroscopic probes of mercury(ii) coordination environments in proteins, 226, 71 low-temperature optical spectroscopy metalloprotein structure and dynamics, 226, 97 nanosecond transient absorption spectroscopy, 226, 119 nanosecond time-resolved absorption and polarization dichroism spectroscopies, 226, 147 real-time spectroscopic techniques for probing conformational dynamics of heme proteins, 226, 177 variable-temperature magnetic circular dichroism, 226, 199 linear dichroism, 226, 232 infrared spectroscopy, 226, 259 Fourier transform infrared spectroscopy, 226, 289 infrared circular dichroism, 226, 306 Raman and resonance Raman spectroscopy, 226, 319 protein structure from ultraviolet resonance Raman spectroscopy, 226, 374 single-crystal micro-Raman spectroscopy, 226, 397 nanosecond time-resolved resonance Raman spectroscopy, 226, 409 techniques for obtaining resonance Raman spectra of metalloproteins, 226, 431 Raman optical activity, 226, 470 surface-enhanced resonance Raman scattering, 226, 482 luminescence... 

Of course, as with any spectroscopic technique, FTIR should not be used in isolation but always in conjunction with other techniques. FTIR is most usefully paired with circular dichroism in both the UV (i.e., ECD) and, if possible, also in the IR (i.e., VCD))64 70 73 110-112 Coupling IR to NMR studies can usefully aid interpretation of spectra from fluctional structures and can lead to some site-specific insight)113-1151 Even the generality of X-ray diffraction results (especially for linear oligopeptides whose conformation can be strongly influenced by intermolecular interactions in the crystal) can be tested by comparison of solid-state and solution-phase IR data with solution-phase CD data.1"6 "71... 

Thulstrup, E. W. Aspects of Linear and Magnetic Circular Dichroism of Planar Organic Molecules , Springer Berlin, 1980 No. 14 In Lecture Notes in Chemistry. 

Vacuum-ultraviolet, circular dichroism (v.u.c.d.) measurements have been made on films and solutions of linear D-glucan in a study of the conformation of dextran and its oligomers.123 Film formation of the linear dextran was accompanied by crystallization, and the v.u.c.d. band was observed at 165 nm, in contrast to nonlinear dextran films displaying a band at 177 nm. The difference was ascribed to hydrogen bonding of the ring-oxygen atom in the crystalline state. 

The circular dichroism of polynucleotides at 275 nm is a linear function of both the helix winding angle and the base pair twist.103 Measurement of CD spectra on large polynucleotides or large molecular aggregates... 

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