These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Constructions of 1D helical chains with left-handed/right-handed helicity: a correlation between the helicity of 1D chains and the chirality of building blocks.
    Author: Zheng XD, Jiang L, Feng XL, Lu TB.
    Journal: Dalton Trans; 2009 Sep 14; (34):6802-8. PubMed ID: 19690692.
    Abstract:
    The reactions of [Ni(alpha-SS-L)](ClO(4))(2)/[Ni(alpha-RR-L)](ClO(4))(2) with dca(-) gave two enantiomers of [Ni(SS-L)](dca)(2) (S-) and [Ni(RR-L)](dca)(2) (R-) in acetonitrile/water, and two supramolecular stereoisomers of {[Ni(SS-L)](2)(dca)(3)(ClO(4)).DMF}(n) (Delta-) and {[Ni(RR-L)](2)(dca)(3)(ClO(4)).DMF}(n) (Lambda-) in acetonitrile/DMF, respectively (L = 5,5,7,12,12, 14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, dca = dicyanamide, N(CN)(2)(-)). While the reaction of racemic [Ni(alpha-rac-L)](ClO(4))(2) (containing an equal amount of SS and RR enantiomers) with dca(-) in acetonitrile/water or acetonitrile/DMF produced a trimer of [Ni(rac-L)(dca)](3).(dca).(ClO(4))(2).MeCN () rather than S-/R- or Delta-/Lambda-. X-ray single-crystal analysis reveals that S-/R- and Delta-/Lambda- crystallize in a chiral space group P2(1), while crystallizes in a centrosymmetric space group C2/c. In S-/R-, the [Ni(SS-L)](dca)(2)/[Ni(RR-L)](dca)(2) monomers are linked through intermolecular hydrogen bonds to form a two-dimensional sheet. While the intermolecular hydrogen bonding linking of {[Ni(SS-L)](2)(dca)(3)}(+)/{[Ni(RR-L)](2)(dca)(3)}(+) leads to the formation of a 1D right-handed helical chain of Delta- and 1D left-handed helical chain of Lambda-, respectively, demonstrating there is a correlation between the helicity of 1D chains and the chirality of building blocks. Complex forms a triangular structure of {[Ni(rac-L)(dca)](3)}(3+), in which the macrocyclic ligand L adopts unsymmetrical RR/RR/SS or RR/SS/SS configurations. The homochiral nature of S-/R- and Delta-/Lambda- are confirmed by the results of solid circular dichroism (CD) spectra measurements. The magnetic properties of chiral Delta-/Lambda- and achiral were investigated.
    [Abstract] [Full Text] [Related] [New Search]