Infrared linear dichroism

I. Noda, A.E. Dowrey and C. Marcott, Characterization of polymers using polarization-modulation infrared techniques Dynamic infrared linear dichroism (DIRLD) spectroscopy. 

If peptide chains can be oriented in a regular fashion, it may be useful to measure infrared linear dichroism.24 25 Absorption spectra are recorded by passing plane polarized light through the protein in two mutually perpendicular directions, with the electric vector either parallel to the peptide chains or perpendicular to the chains. Such a pair of spectra is shown in Fig. 23-3A for oriented fibrils of insulin. In this instance, the insulin molecules are thought to assume a P conformation and to be stacked in such a way that they extend transverse to the fibril axis (a cross-P structure). When the electric vector is parallel to the fibril axis, it is perpendicular to the peptide chains. Since the amide I band is dominated by a carbonyl stretching motion that is perpendicular to the... 

Figure 4.6-5 Infrared linear dichroism of a nematic sample (EBBA/MBBA equimolar mixture of N-(p-ethoxybenzylidene)-//- -butylaniline and its methoxy analogue 2 of Table 4.6-1 Riedel-de Haen) expressed as the difference of the absorption indices k and ke (imaginary part of the complex refractive index) for the ordinary and the extraordinary beam, resp. the temperature increases and thus, the degree of order decreases from spectrum a to spectrum d, the latter was taken close to the clearing point F, where the order and consequently the anisotropy vanishes (Reins et al., 1993).

Infrared linear dichroism measurements may be performed on unidirectionally oriented samples. In the case of DNA, the favored axis of orientation is the axis of the double helix. Films are prepared by unidirectional stroking while the sample is gently dried. Two spectra are recorded with the electric field of the incident light oriented parallelly... 

The second class of drugs (intercalating drugs) involves interaction of the two anthra-cycline derivatives aclacinomycin A and violamycin B1 with DNA, which has recently been investigated by infrared linear dichroism (Fritzsche and Rupprecht, 1990). The restriction of the B —> A transition as a consequence of drug binding turns out to be only slightly dependent on the DNA base composition. 

Bindee, H., et al.. Hydration of the dionic lipid dioctadecadienoylphos-phatidylcholine in the lamellar phase. An infrared linear dichroism and X-ray study on headgroup orientation, water ordering, and bilayer dimensions, Biophys. J., 1998, 74, 1908-1923. 

The interaction with small molecules such as metal ions and intercalating molecules has been investigated. Both the molecular nature of the interaction and the influence on the conformation have been addressed. " Infrared linear dichroism has also been applied to the study of intercalating drugs interacting with oriented films of DNA. In many of the cited references normal mode calculations have been performed to provide a molecular basis for the interpretation of the spectra in terms of the different conformers. 

S. A. Champion, P.M. Determination of CO orientation in myoglobin by single-crystal infrared linear dichroism. J. Am. Chem. Soc. 1994. 116. 4139-4140. 

Poly(phenoxy phenylene vinylene)(PO-PPV) is synthesized via the chlorine precursor route as shown in Figure 3. The CPR is preferred for preparation of precursor polymers with large substituents such as phenoxy. The precursor film is quite flexible and dynamic infrared linear dichroism (DIRLD) studies (stretching the polymer while recording the dynamic infrared spectra) are in progress. 

Noda, L Dowrey, A. E. Marcott, C., Characterization of Polymers Using Polarization-Modulation Infrared Techniques Dynamic Infrared Linear Dichroism (DIRLD) Spectroscopy. In Fourier Transform Infrared Characterization of Polymers, Ishida, H., Ed. Plenum Press New York, 1987 pp 33-57. 

Figure 1-3. Schematic diagram of the dynamic infrared linear dichroism (DIRLDi experiment 23], A small-amplitude sinusoidal strain is applied to a sample, and submolecular level reorientation responses of chemical moieties are monitored with a polarized IR beam.

Ultimate dichroic ratio Dynamic infrared linear dichroism Observation period Time... 

Attenuated total reflection (ATR) FTIR is one of the most useful tools for characterising the chemical composition and physical characteristics of polymer surfaces [53]. One useful application is the measurement of molecular orientation using polarised infrared ATR spectroscopy [54,55]. The polarised infrared ATR spectra normally include three-dimensional (e.g., machine, transverse, and thickness direction) orientational information in contrast to the polarised transmission infrared linear dichroism. In addition, band absorbance of less than 0.7 au is easily achieved, even with the strong absorption bands, because the penetration depth of ATR from sample surfaces can be adjusted to a few micrometers by changing the internal reflection element and/or the angle of incidence. If successful combination of the dynamic infrared spectroscopy and the ATR methods can be achieved, more useful dynamic orientational information can be obtained. 

Schoonover, J. R., Thompson, D. G, et al. (2001), Infrared linear dichroism study of a hydrolytically degraded poly(ester Urethane). Polymer Degradation and Stability, 74, 87-96. 

Y. Wang, C. Pellerin, C. G. Bazuin, M. Pezolet, Molecular orientation and relaxation in uniaxially stretched segmented ptmo zwitterionomers by polarization modulation infrared linear dichroism. Macromolecules 38(10), 4377-4383 (2005). 

DYNAMIC INFRARED LINEAR DICHROISM MEASURED WITH A MONOCHROMATOR... 

I. Noda, A. E. Dowrey, and C. Marcott, Characterization of polymers using polarization-modualtion infrared techniques dynamic infrared linear dichroism (DIRLD) spectroscopy, in Fourier-Tran orm Infrared Characterization of Polymers, H. Ishida, Ed., Plenum Press, New York, 1987, p. 33. 

Marcott, C. and Noda, I. (2002) Dynamic infrared linear dichroism spectroscopy. In Handbook of Vibrational Spectroscopy, Vol. 4 (eds J.M. Chalmers and PR. Griffiths), John Wiley Sons, Ltd, Chichester, pp. 2576-2591. 

Buffeteau, T. and Pezolet, M. (2007) Infrared Linear Dichroism of Polymers, in Vibrational Spectroscopy of Polymers, Principles and Practice (eds N. Everall, P.R. Griffiths, and J.M. Chalmers), Wiley-VCH, Weinheim, p. 255. 

Spanget-Larsen, J., and N. Fink. 1990. Molecular symmetry of 2,5-dimethyl-1,6,6a. lambda.4-trithiapentalene Infrared linear dichroism in stretched polyethylene. J. Phys. Chem. 94 8423-8425. 

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