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Article
Fluorine Containing Nonsymmetrical Five-Ring Achiral Banana-Shaped Compounds with Columnar and Synclinic Antiferroelectric Layered Phases
Soft Matter
  • Channabasaveshwar V. Yelamaggad
  • Indudhara Swamy Shashikala
  • Uma S. Hiremath
  • Guangxun Liao, Kent State University - Kent Campus
  • Antal Jakli, Kent State University - Kent Campus
  • Doddamane S. Shankar Rao
  • Subbarao Krishna Prasad
  • Quan Li, Kent State University - Kent Campus
Publication Date
7-27-2006
Document Type
Article
DOI
10.1039/b608278e
Keywords
  • bent-core molecules,
  • liquid-crystals,
  • mesomorphic properties,
  • lateral substituents,
  • helical superstructures,
  • mesophase behavior,
  • homologous series,
  • direct transition,
  • mesogenic units,
  • polar order
Disciplines
Abstract
The phase transitional behavior of two homologous series of five-ring banana-shaped compounds comprising fluorine substituents synthesized through covalent linking of two chemically dissimilar rod-like anisometric cores (arms) to central 1,3-phenylene is reported. The novelty of these molecules originates from the fact that the molecules are highly nonsymmetrical. One of the arms, which is either salicylaldimine or Schiff base core, possesses two vicinal fluorine atoms at the terminal ring having a n-decyloxy tail; while the n-alkyl tail attached to the other arm was varied to realize a homologous series of compounds. The mesophases have been characterized by several complementary studies. The banana-shaped systems having short or medium alkyl chain lengths form apolar columnar (two-dimensional) structures, while on ascending the series, a polar smectic phase is stabilized. Detailed electro-optical investigations on one of the polar smectic phases revealed a synclinic antiferroelectric (racemic) ground state structure, which switches, as expected, to an anticlinic ferroelectric state by the application of an electrical field. At higher field strengths applied for an extended time interval, the anticlinic ferroelectric state switches to a synclinic ferroelectric (chiral) state. Upon field removal, these domains switch to an anticlinic antiferroelectric (chiral) state, which eventually nucleates to the original antiferroelectric synclinic (racemic) state. Remarkably, the associated spontaneous polarization value exceeds 800 nC cm(-2), which is among the highest reported hitherto.
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Available on publisher's site at http://dx.doi.org/10.1039/b608278e.

Citation Information
Channabasaveshwar V. Yelamaggad, Indudhara Swamy Shashikala, Uma S. Hiremath, Guangxun Liao, et al.. "Fluorine Containing Nonsymmetrical Five-Ring Achiral Banana-Shaped Compounds with Columnar and Synclinic Antiferroelectric Layered Phases" Soft Matter Vol. 2 Iss. 9 (2006) p. 785 - 792
Available at: http://works.bepress.com/quan_li/8/