Journal ArticleDOI
Dielectric and Thermodynamic Study on the Liquid Crystal Dimer α-(4-Cyanobiphenyl-4′-oxy)-ω-(1-pyreniminebenzylidene-4′-oxy)undecane (CBO11O·Py)
Nerea Sebastián,M. R. de la Fuente,David López,David López,M. A. Perez-Jubindo,Josep Salud,S. Diez-Berart,María Blanca Ros +7 more
TLDR
The nematic-to-isotropic phase transition has been exhaustively studied and it has been concluded that the transition is first order in nature and follows the tricritical hypothesis.Abstract:
Broadband dielectric spectroscopy (103 to 1.8 × 109 Hz) and specific heat measurements have been performed on the odd nonsymmetric liquid crystal dimer α-(4-cyanobiphenyl-4′-oxy)-ω-(1-pyreniminebenzylidene-4′-oxy)undecane (CBO11O·Py), as a function of temperature. The mesogenic behavior is restricted to a nematic mesophase which can be supercooled down to its corresponding glassy state if the cooling rate is fast enough (no less than 15 K·min–1). Dielectric measurements enable us to obtain the static permittivity and information about the molecular dynamics in the nematic mesophase as well as in the isotropic phase and across the isotropic-to-nematic phase transition. Two orientations (parallel and perpendicular) of the molecular director with regard to the probe electric field have been investigated. In the nematic mesophase, the dielectric anisotropy is revealed to be positive. Measurements of the parallel component of the dielectric permittivity are well explained by means of the molecular theory of di...read more
Citations
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Journal ArticleDOI
Understanding the twist-bend nematic phase: the characterisation of 1-(4-cyanobiphenyl-4′-yloxy)-6-(4-cyanobiphenyl-4′-yl)hexane (CB6OCB) and comparison with CB7CB
Daniel A. Paterson,Min Gao,Young-Ki Kim,Afsoon Jamali,Kirsten L. Finley,Beatriz Robles-Hernández,S. Diez-Berart,Josep Salud,M. Rosario de la Fuente,Bakir A. Timimi,Herbert Zimmermann,Cristina Greco,Alberta Ferrarini,John Storey,David López,Oleg D. Lavrentovich,Geoffrey R. Luckhurst,Corrie T. Imrie +17 more
TL;DR: A complementary extended molecular field theory was found to be in suggestive accord with the (2)H-NMR studies of CB6OCB-d2, and those already known for CB7CB-d4, including the reduced transition temperature, TNTBN/TNI, and the order parameter of the mesogenic arms in the N phase close to the NTB-N transition.
Journal ArticleDOI
Liquid crystal dimers and the twist-bend nematic phase. The preparation and characterisation of the α,ω-bis(4-cyanobiphenyl-4′-yl) alkanedioates
TL;DR: In this article, the α,ω-bis(4-cyanobiphenyl-4′-yl) alkanedioates have been synthesized and their transitional properties characterised.
Journal ArticleDOI
Dielectric, calorimetric and mesophase properties of 1′′-(2′,4-difluorobiphenyl-4′-yloxy)-9′′-(4-cyanobiphenyl-4′-yloxy) nonane: an odd liquid crystal dimer with a monotropic mesophase having the characteristics of a twist-bend nematic phase
Nerea Sebastián,David López,Beatriz Robles-Hernández,Beatriz Robles-Hernández,M. R. de la Fuente,Josep Salud,M. A. Perez-Jubindo,D. A. Dunmur,Geoffrey R. Luckhurst,D. J. B. Jackson +9 more
TL;DR: It is concluded that the low temperature mesophase exhibits the characteristics of a twist-bend nematic phase, and the nematic-to-isotropic phase transition has been exhaustively studied from the accurate evolution of the heat capacity and the static dielectric permittivity data.
Journal ArticleDOI
Liquid‐Crystalline Hybrid Materials Based on [60]Fullerene and Bent‐Core Structures
Jorge Vergara,Joaquín Barberá,José Luis Serrano,M. Blanca Ros,Nerea Sebastián,Rosario M. de la Fuente,David López,Gustavo Fernández,Luis Sánchez,Nazario Martín +9 more
TL;DR: By the appropriate combination of promesogenic bent-core structures and the C(60) unit, lamellar polar liquid-crystal phases were induced and the supramolecular organization of the functional fullerene-based assemblies, the temperature range of the soft phase, the stabilization of the mesophase-like order at room temperature, and the molecular switching under an electric field can be tuned, depending on the molecular structure.
Journal ArticleDOI
Novel luminescent phenothiazine-based Schiff bases with tuned morphology. Synthesis, structure, photophysical and thermotropic characterization
TL;DR: In this article, a Schiff base dimer based on phenothiazine heterocycle has been obtained with high yield and purity by condensation of 3-formyl-10-methyl-phenothiazines with various amines.
References
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Journal ArticleDOI
Eine einfache molekulare Theorie des nematischen kristallinflüssigen Zustandes
W. Maier,Alfred Saupe +1 more
Journal ArticleDOI
Liquid crystal ‘blue phases’ with a wide temperature range
TL;DR: It is proposed that the unusual behaviour of these blue phase materials is due to their dimeric molecular structure and their very high flexoelectric coefficients, which sets out new theoretical challenges and potentially opens up new photonic applications.
Journal ArticleDOI
Liquid crystal dimers and higher oligomers: between monomers and polymers
TL;DR: The underlying theme of this Critical Review is the relationship between molecular structure and liquid crystalline behaviour in a class of materials referred to as liquid crystal oligomers, and how this molecular architecture has been exploited to address issues in a range of quite different areas and has given rise to potential applications for these materials.
Journal ArticleDOI
Liquid crystal dimers and oligomers
TL;DR: In this article, the most recent developments in the understanding of structure-property relationships in liquid crystal dimers and higher oligomers are discussed, including trimers and tetramers.