Crystallography and the liquid crystal phase: a new approach to structural studies on a thermo-tropic smectic Schiff base

In spite of the apparent contradiction between ‘liquid crystals’ (LC, materials exhibiting some degree of disorder) and ‘crystallography’ (a paradigmatic ordered kingdom), X-ray diffraction (XRD) studies make a substantial contribution to the field of LC. Focusing this review on smectic (Sm, lamella...

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Publicado:	2018
Materias:	Liquid crystals powder X-ray diffraction vs. temperature Schiff base single-crystal X-ray diffraction smectic mesophases Crystallography Liquids Single crystals X ray diffraction Liquid crystal phase Molecular organization Powder X ray diffraction Schiff-base Single crystal x-ray diffraction Smectic mesophases Topological changes Variable temperature X ray crystallography
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0889311X_v24_n1_p3_Piro http://hdl.handle.net/20.500.12110/paper_0889311X_v24_n1_p3_Piro
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_0889311X_v24_n1_p3_Piro
record_format	dspace
spelling	paper:paper_0889311X_v24_n1_p3_Piro2023-06-08T15:47:05Z Crystallography and the liquid crystal phase: a new approach to structural studies on a thermo-tropic smectic Schiff base Liquid crystals powder X-ray diffraction vs. temperature Schiff base single-crystal X-ray diffraction smectic mesophases Crystallography Liquid crystals Liquids Single crystals X ray diffraction Liquid crystal phase Molecular organization Powder X ray diffraction Schiff-base Single crystal x-ray diffraction Smectic mesophases Topological changes Variable temperature X ray crystallography In spite of the apparent contradiction between ‘liquid crystals’ (LC, materials exhibiting some degree of disorder) and ‘crystallography’ (a paradigmatic ordered kingdom), X-ray diffraction (XRD) studies make a substantial contribution to the field of LC. Focusing this review on smectic (Sm, lamellar) LC, we first describe how extremely careful XRD studies performed on mono-domain samples in the LC phase helped to elucidate the molecular structure of ordered Sm phases. Then, we describe selected examples in which single-crystal (SC) XRD on the solid-state phase of the mesogens provided information about their supra-molecular organization in the Sm phase. Finally, we present a different approach to this problem in the case of a thermo-tropic Schiff base (SB) which undergoes crystal ↔ LC ↔ isotropic liquid phase transformations. By combined SC and variable-temperature powder XRD, we show that the SB LC is a hexatic smectic B phase that derives from the crystal phase by relatively small topological changes promoted by the set-in of thermal rotational disorder around the long SB molecular axis. © 2017 Informa UK Limited, trading as Taylor & Francis Group. 2018 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0889311X_v24_n1_p3_Piro http://hdl.handle.net/20.500.12110/paper_0889311X_v24_n1_p3_Piro
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Liquid crystals powder X-ray diffraction vs. temperature Schiff base single-crystal X-ray diffraction smectic mesophases Crystallography Liquid crystals Liquids Single crystals X ray diffraction Liquid crystal phase Molecular organization Powder X ray diffraction Schiff-base Single crystal x-ray diffraction Smectic mesophases Topological changes Variable temperature X ray crystallography
spellingShingle	Liquid crystals powder X-ray diffraction vs. temperature Schiff base single-crystal X-ray diffraction smectic mesophases Crystallography Liquid crystals Liquids Single crystals X ray diffraction Liquid crystal phase Molecular organization Powder X ray diffraction Schiff-base Single crystal x-ray diffraction Smectic mesophases Topological changes Variable temperature X ray crystallography Crystallography and the liquid crystal phase: a new approach to structural studies on a thermo-tropic smectic Schiff base
topic_facet	Liquid crystals powder X-ray diffraction vs. temperature Schiff base single-crystal X-ray diffraction smectic mesophases Crystallography Liquid crystals Liquids Single crystals X ray diffraction Liquid crystal phase Molecular organization Powder X ray diffraction Schiff-base Single crystal x-ray diffraction Smectic mesophases Topological changes Variable temperature X ray crystallography
description	In spite of the apparent contradiction between ‘liquid crystals’ (LC, materials exhibiting some degree of disorder) and ‘crystallography’ (a paradigmatic ordered kingdom), X-ray diffraction (XRD) studies make a substantial contribution to the field of LC. Focusing this review on smectic (Sm, lamellar) LC, we first describe how extremely careful XRD studies performed on mono-domain samples in the LC phase helped to elucidate the molecular structure of ordered Sm phases. Then, we describe selected examples in which single-crystal (SC) XRD on the solid-state phase of the mesogens provided information about their supra-molecular organization in the Sm phase. Finally, we present a different approach to this problem in the case of a thermo-tropic Schiff base (SB) which undergoes crystal ↔ LC ↔ isotropic liquid phase transformations. By combined SC and variable-temperature powder XRD, we show that the SB LC is a hexatic smectic B phase that derives from the crystal phase by relatively small topological changes promoted by the set-in of thermal rotational disorder around the long SB molecular axis. © 2017 Informa UK Limited, trading as Taylor & Francis Group.
title	Crystallography and the liquid crystal phase: a new approach to structural studies on a thermo-tropic smectic Schiff base
title_short	Crystallography and the liquid crystal phase: a new approach to structural studies on a thermo-tropic smectic Schiff base
title_full	Crystallography and the liquid crystal phase: a new approach to structural studies on a thermo-tropic smectic Schiff base
title_fullStr	Crystallography and the liquid crystal phase: a new approach to structural studies on a thermo-tropic smectic Schiff base
title_full_unstemmed	Crystallography and the liquid crystal phase: a new approach to structural studies on a thermo-tropic smectic Schiff base
title_sort	crystallography and the liquid crystal phase: a new approach to structural studies on a thermo-tropic smectic schiff base
publishDate	2018
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0889311X_v24_n1_p3_Piro http://hdl.handle.net/20.500.12110/paper_0889311X_v24_n1_p3_Piro
_version_	1768546545762828288

Crystallography and the liquid crystal phase: a new approach to structural studies on a thermo-tropic smectic Schiff base

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