Premium
Homochiral Helices of Oligonaphthalenes Inducing Opposite‐Handed Cholesteric Phases
Author(s) -
Pieraccini Silvia,
Ferrarini Alberta,
Fuji Kaoru,
Gottarelli Giovanni,
Lena Stefano,
Tsubaki Kazunori,
Spada Gian Piero
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200500683
Subject(s) - helix (gastropod) , materials science , chemistry , biology , ecology , snail
The helical structure of the chiral nematic phases (cholesterics) obtained by doping nematic solvents with chiral non‐racemic compounds is a macroscopic proof of the solute chirality. Oligonaphthalene (tetra‐, hexa‐, octa‐) derivatives linked at the 1,4‐positions have been used as chiral dopants: When the chirality axes are configurationally homogeneous (that is, all‐ S ), the molecular structures correspond to right‐handed helices. Yet, we have found series of derivatives with the surprising property that the handedness of the induced cholesteric phase alternates from positive to negative and to positive again, on passing from tetra‐ to hexa‐ and to octanaphthalene. A comparison with oligonapthalene derivatives, which do not exhibit this twisting ability, points to the importance of the substitution pattern. Both the possibility of inducing oppositely‐handed cholesteric phases by homochiral helices of different length, and the role played of substituents, are confirmed by calculations performed with the surface chirality model.