Polarimetry and Circular-dichroism Studies

Studies of the rotational strengths of 5-thio- and l,S-dithio-D-glucopyranosides have shown how they can lead to deductions of anomeric configurations and molecular conformations.  

Satsumabayashi, Y. Nomoto. and H. Nakahara, Nippon Shika Daigaku Kiyo, 1977, 

Sticzay, S. Bystricky, C. Peciar, and J. Hirsch, CoU. Czech. Chem. Comm., 1978, 43, 1496. 

A review on the importance and realization of defined wavelengths in saccharimetry has appeared. + 

of over forty bis-, tris, and tetrakis p-bromobenz-oates of methyl pyranosides have been recorded. The amplitudes of the maxima at 235 and 253 nm were additive, based on diester pairs allowing stereochemical relationships to be determined. This formed the basis for an ingenious method for determining oligosaccharide structures on a microscale (See Vol. 15, p.237, ref. 

and was also applied to complex carbohydrate antibiotics, allowing the position of glycosidic linkages in deoxy sugars to be assessed.  

spectra have been recorded for 1-deoxy-1-nitro-heptitols.  

Electroanal. Chem. Interfacial Electrochem., 1980, 114, 179 (Chem. Abstr. 

The complexings of D-glucose, D-fructose, and maltose with borate anions have been studied by polarimetric, conductivity, and pH measurements, and circular dichroism methods have been used to investigate the complexing of cuprammonium ions with carbohydrate diols and amino-alcohols. An examination of the c.d. spectra of fifteen methyl 3-acetamido-3,6-dideoxyhexopyranoside derivatives measured in methanol, 2,2,2-trifluoroethanol, and acetonitrile su ests that the amide group is not completely planar and may show chirality. The n it transition of the carboxylic acid carbonyl groups at 

Boruch and J. Makuch, Zesz. Nauk. Politech. Lodz., Chem. Spozyw., 1977, 32, 19 (Chem. Abs., 1979, 90, 23 428r). 

Bystricky, I. Erie, J. Stanek, K. Capek, J. Jary, and K. Blaha, Collect. Czech. Chem. Commun., 1979, 44, 174. 

A helicity rule has been proposed for 1-thio-D-glucopyranosides which allows the c.d. band at 220 nm n a of sulphur) to be interpreted in terms of the stereochemical relationship at C-1 and C-2. The o.r.d. and c.d. characteristics of the thioanhydro-compound (6) and the disulphides (7) and (8) have been measured at different temperatures and discussed. 

Chapter 6 contains references to the o.r.d., c.d., and u.v. studies of gluco-pyranosyl xanthates. 

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The rotary dispersion and circular dichroism spectra of enantiomeric acylglycerols have been studied by Gronowitz et al, (1975). Some of the data from their experiments are discussed by Buchnea (1978). Again, as with polarimetry, there are distinct solvent effects - the highest rotations being obtained with benzene and chloroform. 

Polarimetry, circular dichroism (CD) and optical rotatory dispersion (ORD) are the most important tools for the study of properties arising from optical activity. Although many chiral thiophenes have been prepared, there is no secure basis for a systematic discussion of the special effects of thiophene or annelated thiophene rings. For the purpose now at hand it is more expedient to discuss three different areas in which thiophene containing molecules and the related chiroptical techniques are central features. 

The fundamental requirement for the existence of molecular dissymmetry is that the molecule cannot possess any improper axes of rofation, the minimal interpretation of which implies additional interaction with light whose electric vectors are circularly polarized. This property manifests itself in an apparent rotation of the plane of linearly polarized light (polarimetry and optical rotatory dispersion) [1-5], or in a preferential absorption of either left- or right-circularly polarized light (circular dichroism) that can be observed in spectroscopy associated with either transitions among electronic [3-7] or vibrational states [6-8]. Optical activity has also been studied in the excited state of chiral compounds [9,10]. An overview of the instrumentation associated with these various chiroptical techniques is available [11]. 

Polarimetry, Circular Dichroism, Calorimetry and Related Studies... 

In the previous decades, the optical activity of these synthetic polymers were studied by polarimetry. Presently, advances in Optical Rotatory Dispersion (ORD) and in Circular Dichroism (CD) allow more detailed investigations in the far UV essential to interpret chiroptical properties. Explaining observed ORD and CD changes and establishing relationships between spectra and structures of backbones and side-chains are two of the problems which arise when synthetic optically active polymers are studied. 

Theory Induced Circular Dichroism Macromolecule-Ligand Interactions Studied By NMR Magnetic Circular Dichroism, Theory Nucleic Acids and Nucleotides Studied Using Mass Spectrometry Nucleic Acids Studied Using NMR ORD and Polarimetry Instruments Proteins Studied Using NMR Spectroscopy Peptides and Proteins Studied Using Mass... 

Unfortunately, in the VUV region no polarimetry data are available, but calculations indicate the degree of circular polarization achieved by the wiggler may be 80%, estimated to be no worse than 70% delivered at the experimental chamber [95, 96]. In PECD experiments, we have calibrated the polarization state by deduction from cross-comparison of results at a few fixed energies previously studied on the SU5 beamline where accurate polarimetry data was available [36]. Because the horizontal magnetic field array in the insertion device is electromagnetic, fast current reversal to switch left- and right-handed elliptical polarizations is possible, with the usual potential benefit for dichroism measurements. 

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