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Induced Chirality (induced + chirality)
Selected AbstractsControl of Induced Chirality in Optically Active Poly(N-propargylcarbamate) Films by Solvent VaporMACROMOLECULAR RAPID COMMUNICATIONS, Issue 15 2009Toshiyuki Fukushima Abstract Chiral polyethyne derivatives with lyotropic liquid-crystalline properties are found to be able to self-assemble, forming two chiral organizations with opposite handedness in solid thin films by selection of the casting solvent and its concentration. After the film preparation, chiral organization could also be induced by simple exposure to an appropriate organic solvent's vapor for several minutes without thermal treatment. Furthermore, irreversible inversion of the handedness of the chiral organization in the film could be achieved by exposure to solvent vapor. [source] Raman optical activity of an achiral element in a chiral environmentJOURNAL OF RAMAN SPECTROSCOPY, Issue 9 2009Andrew M. Smith Abstract Raman optical activity (ROA) is a relatively new technique used to determine the structure of chiral molecules and is proving useful in the study of biological molecules such as proteins and DNA/RNA. Here, for the first time, we demonstrate the applicability of ROA as a technique to study achiral groups in chiral environments, detecting the induced chirality of N -(fluorenyl-9-methoxycarbonyl) (Fmoc) in a chiral self-assembled structure of Fmoc-dipeptides. This technique is therefore of interest to those studying self-assembled systems that adopt a chiral structure. Copyright © 2009 John Wiley & Sons, Ltd. [source] A VCD robust mode analysis of induced chirality: The case of pulegone in chloroform,CHIRALITY, Issue 1E 2009Valentin Paul Nicu Abstract Vibrational modes in an achiral molecule may acquire rotational strength by complexation to a chiral molecule, as happens for achiral solvent molecules complexed to a chiral solute. We investigate this transfer of chirality in vibrational circular dichroism for the pulegone molecule in CDCl3 solvent from the point of view of the robustness concept introduced recently. It turns out that the transfer of chirality yields nonrobust modes, which means that, although they are observed in vibrational circular dichroism (VCD) experiments, the sign of these modes cannot be predicted reliably with standard (Density Functional Theory) VCD calculations. This limits the usefulness of the induced chirality phenomenon for obtaining information on the intermolecular interactions that give rise to it. Chirality 21:E287,E297, 2009. © 2010 Wiley-Liss, Inc. [source] Self-assembly of multinuclear complexes with enantiomerically pure chiral binaphthoxy imine ligands: Effect of the alkyl spacer connecting two binaphthyl units on the metal bindingCHIRALITY, Issue 9 2006Takeshi Maeda Abstract Metal complexing behavior of enantiomerically pure ,,,-diiminoalkanes possessing the two terminal binaphthyl units (L1 and L2) was studied. The ligands L1 and L2 were prepared by the reaction of optically pure 2,-butoxy-3-formyl-2-hydroxy-1,1,-binaphthyl with propane and pentane diamines. Reactions of L1 and L2 with equimolar amount of Cu(OAc)2 afforded quantitatively multinuclear complexes 1. The structure of 1 was confirmed by MALDI,TOF MS spectroscopy, X-ray single-crystal-structure analysis, and UV/vis and CD spectroscopic analyses. The reaction of L1 having a 1,3-propanediyl spacer resulted in the formation of a self-assembled product, which was assigned as enantiopure trinuclear circular helicate 1a, while the ligand having a 1,5-pentanediyl spacer L2 gave a different self-assembled product, dinuclear side-by-side complex 1b. The circular dichroism (CD) spectrum of 1a in solution showed intense Cotton effects in both the ,,,* transition of the naphthalene units and the LMCT region of the N,O -chelate moieties. The CD spectrum of 1b was completely different from that of 1a; in particular the Cotton effects in the LMCT region were very weak, contrary to those of 1a. These results suggest that 1a retains some chirality induced on the N,O -chelating moieties even in solution, while the induced chirality on the N,O -chelating moieties in 1b is not very significant, being consistent with the consequences of the X-ray single-crystal-structure studies. Chirality, 2006. © 2006 Wiley-Liss, Inc. [source] | ||||||||||