Search results for "Optical rotation"
showing 4 items of 24 documents
Ferrochirality: a simple theoretical model of interacting, dynamically invertible, helical polymers, 2. Molecular field approach: supports and the de…
1995
Using a molecular field approach, the effect of interaction between reversibly invertible, helical polymers is investigated theoretically. The helices are modelled by nearest-neighbour statistical thermodynamics. If the interaction energy between two helices of common handedness is lower than that of oppositely handed ones, a critical temperature Tc exists, below which the system spontaneously must leave the racemic state, though there is no contact to any chiral centre or force. This is analogous to the second-order phase transition of ferromagnets. The critical point increases with molecular weight and optical persistence of the helices. At the critical point the system is highly sensitiv…
Unusual interaction extended between the pyranose ring oxygen and Zn(II) center in the complexes derived from 4,6-O-butylidene/ethylidene-N-(α-hydrox…
2003
The Zn(II) complexes of 4,6-O-butylidene/ethylidene-N-(α-hydroxynaphthylidene/o-hydroxybenzylidene)-β-Image -glucopyranosylamine have been synthesized and characterized using spectral and analytical methods and structure for one of the products was established. The geometry of the complexes vary from unusual distorted trigonal bipyramidal to pseudo-bicapped tetrahedron depending upon the extent of binding of pyranose ring oxygens to the Zn(II) ion, as evidenced from crystal structures. Such interaction is also reflected on the optical rotation and CD spectral properties of these complexes in solution.
Modification of Chiral Properties Due to Interaction of Polymers and Small Molecules or Ions
1979
The first part of this report deals with changes in the optical rotatory dispersion and circular dichroism resulting from the chemical modification of optically active polymers. Amylose derivatives have very different chiroptical properties compared with cellulose derivatives. Variations in glucosidic bonds and differing secondary structures are described and suggested as causes for this. The N-chlorination of synthetic optically active polyamides is also described, which in all probability proceeds without changing the configuration at the asymmetric C atoms. Reactions of inactive polymers with low molecular weight chiral reagents usually give optical rotation values proportional to the de…
Preparation of 2,3-seco-5α-cholestane-2,3-diol and 4α-methyl-2,3-seco-5α-cholestane-2,3-diol and its reactions with o-nitrophenyl selenocyanate
1984
The reaction of 2,3-seco-5 alpha-cholestane-2,3-diol and 4 alpha-methyl-2,3-seco-5 alpha-cholestane-2,3-diol with o-nitrophenyl selenocyanate was studied. The diols were synthesized from cholesterol.