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Chiral Side Chains (chiral + side_chain)
Selected AbstractsSelf-Assembly of m -Diethynylbenzene Macrocycles Containing Exoannular Chiral Side Chains,ADVANCED FUNCTIONAL MATERIALS, Issue 12 2006Y. Tobe Abstract Induced circular dichroism (CD) spectra of the m -diethynylbenzene macrocycles (S)- 2 and (R)- 2 that have exoannular chiral side chains are observed in a methanol/chloroform (8:2) solution, indicating the formation of chiral, helical aggregates in solution. Solid films prepared on the surface of quartz substrates by spin-coating solutions of (S)- 2 also exhibit CD signals that are remarkably dependent on the solvent used for the spin-coating. The relationship between the CD spectra and the morphology of the solid films observed by atomic force microscopy is discussed. [source] Luminescent chiral organoboron 8-aminoquinolate-coordination polymersAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 8 2010Yuichiro Tokoro Abstract We have successfully synthesized optically active organoboron aminoquinolate-based coordination polymers bearing the chiral side chain derived from L -alanine, and studied their optical behavior by UV,vis and photoluminescence spectroscopies. Higher absolute quantum yields (,F) of the obtained polymers, measured by integrating sphere method, were observed with electron-withdrawing substituent (,F = 0.80) than with electron-donating substituent (,F = 0.52). The circular dichroism (CD) study in the mixed solvents of CHCl3 and DMF showed that the secondary structures of the obtained polymers were stabilized by hydrogen-bonding interaction in the side chain. From concentration dependence on the CD spectra, the chirality of the obtained polymers originated from the nature of one molecule. Copyright © 2009 John Wiley & Sons, Ltd. [source] Self-Assembly of m -Diethynylbenzene Macrocycles Containing Exoannular Chiral Side Chains,ADVANCED FUNCTIONAL MATERIALS, Issue 12 2006Y. Tobe Abstract Induced circular dichroism (CD) spectra of the m -diethynylbenzene macrocycles (S)- 2 and (R)- 2 that have exoannular chiral side chains are observed in a methanol/chloroform (8:2) solution, indicating the formation of chiral, helical aggregates in solution. Solid films prepared on the surface of quartz substrates by spin-coating solutions of (S)- 2 also exhibit CD signals that are remarkably dependent on the solvent used for the spin-coating. The relationship between the CD spectra and the morphology of the solid films observed by atomic force microscopy is discussed. [source] Chiral polymers for resolution of enantiomersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2009Yoshio Okamoto Abstract In 1979, the formation of one-handed helical poly(triphenylmethyl methacrylate) (PTrMA) was found through the helix-sense-selective polymerization of methacrylate using chiral anionic initiators, and the existence of a stable helical polymer without chiral side chains was proved. The chiral polymer exhibited unexpected high chiral recognition of various racemic compounds when used as the chiral packing material (CPM) for HPLC, which was commercialized in 1982 as the first chiral column based on an optically active polymer. This success encouraged us to develop further useful commercial chiral packing materials (CPMs) based on polysaccharides, cellulose, and amylose. By using these polysaccharide-based CPMs, particularly phenylcarbamate derivatives, nearly 90% of chiral compounds can be resolved not only analytically but also preparatively, and several chiral drugs have been produced using the CPMs. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1731,1739, 2009 [source] Cyclic ,-Tetra- and Pentapeptides: Synthesis through On-Resin Cyclization and Conformational Studies by X-Ray, NMR and CD Spectroscopy and Theoretical CalculationsCHEMISTRY - A EUROPEAN JOURNAL, Issue 21 2005Frank Büttner Dr. Abstract The solution-phase synthesis of the simplest cyclic ,-tetrapeptide, cyclo(,-Ala)4 (4), as well as the solid-phase syntheses through side chain anchoring and on-resin cyclization of the cyclic ,3 -tetrapeptide cyclo(-,3hPhe-,3hLeu-,3hLys-,3hGln-) (14) and the first cyclic ,3 -pentapeptide cyclo(-,3hVal-,3hPhe-,3hLeu-,3hLys-,3hLys-) (19) are reported. Extensive computational as well as spectroscopic studies, including X-ray and NMR spectroscopy, were undertaken to determine the preferred conformations of these unnatural oligomers in solution and in the solid state. cyclo(,-Ala)4 (4) with no chiral side chains is shown to exist as a mixture of rapidly interchanging conformers in solution, whereas inclusion of chiral side chains in the cyclo-,3 -tetrapeptide causes stabilization of one dominating conformer. The cyclic ,3 -pentapeptide on the other hand shows larger conformational freedom. The X-ray structure of achiral cyclo(,-Ala)4 (4) displays a Ci -symmetrical 16-membered ring with adjacent CO and N-H atoms pointing pair wise up and down with respect to the ring plane. CD spectroscopic examinations of all cyclic ,-peptides were undertaken and revealed results valuable as starting point for further structural investigations of these entities. [source] | |||||||||||||