نتایج جستجو برای: achiral
تعداد نتایج: 1375 فیلتر نتایج به سال:
Three Co(II) isomers assembled from D-, or L-, or DL-camphorate together with achiral isonicotinate exhibit a clear relationship between chirality and helicity even though chiral molecules are not in the backbone of the helix: the absolute sense of helix made of achiral components is controlled by chains of metal and enantiopure chiral ligands running perpendicular to helix in two enantiomeric ...
We examine and partially confirm some questions on properties of the the Alexander and HOMFLY polynomial of achiral knots. In particular we show that determinants of achiral knots are exactly the odd numbers representable as sums of two squares. Using the checkerboard coloring, then an analogous statement follows for the number of spanning trees in planar self-dual graphs.
Optically active materials could be generated by simple solidification of achiral materials without an external chiral source. When achiral cis-3,4-diphenylsuccinimides were solidified in the presence of a catalytic amount of DBU by evaporating the solvent with stirring, optically active trans-3,4-diphenylsuccinimides were obtained quantitatively with high enantiomeric excesses.
This paper considers the possibility of spontaneous transition of aracemic mixture (composed of equal amounts of two enantiomeric species, say L and D) into a monochiral state (in which only one enantiomer, say L, is present). Transitions of this kind have been recently experimentally observed. A plausible approach to this phenomenon is a model put forward by Frank, based on simple laws of ...
We outline the need for rigorous and consensual definitions in field of symmetry, particular about chirality. provide examples confusing use such terminology mathematical literature physics literature. In particular, we prove that an antisymmetric function is symmetric a wide class metrics. It may be either direct-symmetric or achiral both achiral.
The helix-sense selective polymerization of achiral monomers by homochiral catalysts was investigated. Polymerization of chiral carbodiimides (N-(R)-2,6-(dimethylheptyl)-N'-phenylcarbodiimide) by achiral catalysts yields polymers that undergo mutorotation at elevated temperatures, thus illustrating that these chains are formed under kinetic rather than thermodynamic control. Building on this ob...
The transfer of chirality from one set of molecules to another is fundamental for applications in chiral technology and has likely played a crucial role for establishing homochirality on earth. Here we show that an intrinsically chiral gold cluster can transfer its handedness to an achiral molecule adsorbed on its surface. Solutions of chiral Au38(2-PET)24 (2-PET=2-phenylethylthiolate) cluster ...
The global screw-sense preference of an achiral helical oligomer may be controlled by a single chiral monomer located at one terminus. Remarkably, maximal control is induced in oligomers of the achiral quaternary amino acid Aib by a single C-terminal alaninamide residue, probably because the Ala side chain, though small, is compatible with a 310 helical conformation. The presence or absence of ...
Extending a molecular field model for the orientational order in the nematic phase, we calculate the (2)H-NMR splittings for the achiral solute 8CB-d2 in the twist-bend nematic phase formed by the achiral liquid crystal dimer CB7CB. We give an explanation for the enantiotopic discrimination observed in the spectra and comparison with experimental data allows us to provide quantitative estimates...
Developing of alternative chiral thiol stabilizers from the assembly of achiral thiol (e.g. thioglycolic acid) and chiral ligand (e.g. arginine) via both hydrogen bonding and electrostatic interactions was proposed and successfully applied to an efficient preparation of chiral CdS quantum dots (QDs). Chiral CdS QDs capped mainly with achiral thioglycolic acid were also obtained that may allow t...
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