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Tetraphenylethene‐Derived Columnar Liquid Crystals and Their Oxidative Photocyclization
Author(s) -
Schultz Andreas,
Laschat Sabine,
Diele Siegmar,
Nimtz Manfred
Publication year - 2003
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200300118
Subject(s) - mesogen , mesophase , chemistry , liquid crystal , biphenyl , ether , crystallography , alkyl , differential scanning calorimetry , columnar phase , polymer chemistry , organic chemistry , materials science , liquid crystalline , phase (matter) , physics , optoelectronics , thermodynamics
The synthesis of novel tetraphenylethenes 9a − f , 13 , and 18a , b bearing ether, biphenyl, and 4‐cyanobiphenyl moieties via a McMurry reaction and Suzuki coupling as key steps is described. Mesogenic properties of these compounds were studied by differential scanning calorimetry (DSC), optical polarizing microscopy, and X‐ray diffraction. Ether‐substituted derivatives 9a , b with chain lengths C 8 or C 9 were non‐mesogenic. Compounds 9c − f with longer alkyl chains displayed hexagonal columnar mesophases. Whereas cyanobiphenyl derivative 13 was non‐mesogenic, the corresponding biphenyl systems 18a , b with decyloxy and dodecyloxy chains, respectively, formed hexagonal columnar mesophases. Oxidative photocyclization of compounds 1f , 9c , 13 , and 18a were investigated. Upon irradiation in the presence of iodine tetraphenylethenes 1f , 9c gave the corresponding phenanthrenes 22a , b . The mesomorphic properties of 22a , b were strongly dependent on the substituent. Whereas ether 22a displayed only isotropic melting, a hexagonal columnar mesophase was found for ester 22b . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)