Optical rotatory dispersion definition

Salvwkm, P. and Ciaidelli, F. An Introduction to Chiroptical Technique Basic Principles, Definitions and Applications," In Optical Rotatory Dispersion and Circular Dichroism Ciaidelli, F. Savadori, P., Eds. Heyden London, 1973 pp. 3-24. 

Optical rotatory dispersion and circular dichroism (83, 84) can often be of great value, and the spectra are particularly sensitive to the conformation of the protein. Much work remains to be done in this field before the results can be definitely interpreted in terms of the electronic structure of the metal. Magneto-optical rotation and magnetic circular dichroism (MOR and MCD), which are beginning to be applied to porphyrins and haemoproteins, offer much greater promise (30, 85). 

Palytoxin is a white, amorphous, hydroscopic solid that has not yet been crystallized. It is insoluble in nonpolar solvents such as chlorophorm, ether, and acetone sparingly soluble in methanol and ethanol and soluble in pyridine, dimethyl sulfoxide, and water. The partition coefficient for the distribution of palytoxin between 1-butanol and water is 0.21 at 25°C based on comparison of the absorbance at 263 nm for the two layers. In aqueous solutions, palytoxin foams on agitation, like a steroidal saponin, probably because of its amphipathic nature. The toxin shows no definite melting point and is resistant to heat but chars at 300°C. It is an optically active compound, having a specific rotation of -i-26° 2° in water. The optical rotatory dispersion curve of palytoxin exhibits a positive Cotton effect with [a]25o being -i-700° and [a]2,j being +600° (Moore and Scheuer 1971 Tan and Lau 2000). 

Figure 3 The Faraday Effect within magnetic optical rotatory dispersion (MORD) spectroscopy. A plane polarized beam is rotated by a magnetic field applied parallel to the axis of propagation. The rotation is defined as positive if the beam is rotated to the right in a clockwise direction when viewed toward the source (a). The original definition of Icp and rep within CD spectroscopy—fight plane polarized in the yz-plane can be described in mathematical terms as being comprised of left or right circularly polarized components of equal phase and amplitude (b). The perspective is depicted schematically toward the source. (Reprinted from Mack, Stillman and Kobayashi, Elsevier 2007)...

ABA is a C, organic acid with one asymmetric carbon atom at C-1 (Fig. 1). The naturally occurring form is 5-( + )-ABA the side chain of ABA is by definition 2-cis,4-trans [2]. The optical rotatory dispersion (ORD) spectrum of ABA exhibits an intense Cotton effect. This property was initially exploited to identify and measure ABA in purified extracts of a number of plants [11]. ABA in organic solvents can be photo-isomerized by ultraviolet radiation to give a mixture of approximately 50% ABA and 50% 2-trans,4 trans-ABA (f-ABA) (Fig. 1). The latter compound is biologically inactive. 

II. DEFINITIONS OPTICAL ROTATORY DISPERSION AND CIRCULAR DICHROISM... 

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