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Supramolecular Columnar Liquid Crystals with Tapered‐Shape Simple Pyrazoles Obtained by Efficient Henry/Michael Reactions
Author(s) -
Blanco Hugo,
Iguarbe Verónica,
Barberá Joaquín,
Serrano José Luis,
Elduque Anabel,
Giménez Raquel
Publication year - 2016
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.201504779
Subject(s) - supramolecular chemistry , antiparallel (mathematics) , mesogen , hydrogen bond , molecule , materials science , liquid crystal , crystallography , pyrazole , crystal structure , chemistry , stereochemistry , liquid crystalline , organic chemistry , optoelectronics , physics , quantum mechanics , magnetic field
A straightforward synthesis of mesogenic pyrazoles starting from benzaldehydes by a combination of efficient Henry and Michael reactions led to novel supramolecular liquid crystals. The mesogens are fluorescent 3,5‐dimethyl‐4‐(di or trialkoxyphenyl)pyrazoles and, in spite of the tapered shape of these molecules and their structural simplicity (only one phenyl ring), columnar liquid‐crystal phases were formed that are stable at room temperature. The self‐assembled structure was studied by XRD and the columnar cross section contains two molecules on average with an antiparallel arrangement of pyrazoles interacting through hydrogen bonds. In contrast, the single‐crystal structure of a trimethoxy analog did not show hydrogen‐bonded pyrazoles but chains of head‐to‐tail arranged molecules.