Chirality-preserving growth of helical filaments in the B4 phase of bent-core liquid crystals.

The growth of helical filaments in the B4 liquid-crystal phase was investigated in mixtures of the bent-core and calamitic mesogens NOBOW and 8CB. Freezing-point depression led to nucleation of the NOBOW B4 phase directly from the isotropic phase in the mixtures, forming large left- and right-handed chiral domains that were easily observed in the microscope. We show that these domains are composed of homochiral helical filaments formed in a nucleation and growth process that starts from a nucleus of arbitrary chirality and continues with chirality-preserving growth of the filaments. A model that accounts for the observed local homochirality and phase coherence of the branched filaments is proposed. This model will help in providing a better understanding of the nature of the B4 phase and controlling its growth and morphology for applications, such as the use of the helical nanophase as a nanoheterogeneous medium.

[1]  N. Clark,et al.  Pretransitional orientational ordering of a calamitic liquid crystal by helical nanofilaments of a bent-core mesogen. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[2]  Elisabetta A. Matsumoto,et al.  Helical nanofilaments and the high chirality limit of smectics A. , 2009, Physical review letters.

[3]  K. Ishikawa,et al.  Enhanced optical activity by achiral rod-like molecules nanosegregated in the B4 structure of achiral bent-core molecules. , 2009, Journal of the American Chemical Society.

[4]  N. Clark,et al.  Chiral Isotropic Liquids from Achiral Molecules , 2009, Science.

[5]  N. Clark,et al.  Helical Nanofilament Phases , 2009, Science.

[6]  Michel Leeman,et al.  Emergence of a single solid chiral state from a nearly racemic amino acid derivative. , 2008, Journal of the American Chemical Society.

[7]  Y. Takanishi,et al.  Appearance of a liquid crystalline nematic-isotropic critical point in a mixture system of rod- and bent-shaped molecules. , 2006, Physical review letters.

[8]  Y. Takanishi,et al.  Intrinsic chirality in a bent-core mesogen induced by extrinsic chiral structures. , 2006, Angewandte Chemie.

[9]  C. Tschierske,et al.  Bent-core liquid crystals: polar order, superstructural chirality and spontaneous desymmetrisation in soft matter systems , 2006 .

[10]  Y. Takanishi,et al.  Circular-polarization-induced enantiomeric excess in liquid crystals of an achiral, bent-shaped mesogen. , 2006, Angewandte Chemie.

[11]  Y. Takanishi,et al.  Bent-Core Liquid Crystals: Their Mysterious and Attractive World , 2006 .

[12]  Junji Watanabe,et al.  Observation of very large chiral domains in a liquid crystal phase formed by mixtures of achiral bent-core and rod molecules , 2005 .

[13]  Y. Takanishi,et al.  Finite enantiomeric excess nucleated in an achiral banana mesogen by chiral alignment surfaces. , 2005, Angewandte Chemie.

[14]  J. Watanabe,et al.  Chiral memory on transition between the B2 and B4 phases in an achiral banana-shaped molecular system , 2004 .

[15]  N. Clark,et al.  Polarization-Modulated Smectic Liquid Crystal Phases , 2003, Science.

[16]  Y. Takanishi,et al.  Electrogyration effect in a chiral bent-core molecular system , 2003 .

[17]  R. Kamien.  The Geometry of Soft Materials: A Primer , 2002, cond-mat/0203127.

[18]  L. Chien,et al.  Macroscopic chirality of a liquid crystal from nonchiral molecules. , 2001, Physical review. E, Statistical, nonlinear, and soft matter physics.

[19]  T. Rasing,et al.  A shear cell for aligning and measuring birefringence of bow-shaped (banana) liquid crystals , 2000 .

[20]  N. Clark,et al.  A Ferroelectric Liquid Crystal Conglomerate Composed of Racemic Molecules , 2000, Science.

[21]  Clark,et al.  Spontaneous formation of macroscopic chiral domains in a fluid smectic phase of achiral molecules , 1997, Science.

[22]  D. Kondepudi,et al.  Chiral Symmetry Breaking in Sodium Chlorate Crystallizaton , 1990, Science.

[23]  N. Clark,et al.  Nanophase segregation in binary mixtures of a bent-core and a rodlike liquid-crystal molecule. , 2010, Physical review. E, Statistical, nonlinear, and soft matter physics.

[24]  J. McBride,et al.  Physical chemistry: Did life grind to a start? , 2008, Nature.

[25]  J. Watanabe,et al.  Distinct ferroelectric smectic liquid crystals consisting of banana shaped achiral molecules , 1996 .