Newstar like oligomers are presented characterized by the chemical linkage of a defined number of disc-shaped multialkynylbenzene moieties via a central linking unit. The compounds exhibit a nematic mesophase which can be quenched into a glassy state. The molecular orientation of the discotic oligomesogens on rubbed polyimide layers has been investigated.
作者:Paul H. J. Kouwer、Wolter F. Jager、Wim J. Mijs、Stephen J. Picken
DOI:10.1039/b208923h
日期:2003.2.20
A series of novel mesogens have been prepared by a five-fold Sonogashira reaction of terminal acetylenes with a functionalized pentabromophenol derivative. The corresponding side-chain substituted polymers were prepared by an analogous polymer substitution reaction. The mesogens differ in the nature of the substituents, i.e. CH2, O, S, SO2 and CONH groups, linking five hexyl tails to the core. A wide range of mesophases and corresponding transition temperatures have been detected, varying from low melting nematic phases to highly stable columnar phases. The wide spread in phase behaviour is described in terms of specific intermolecular interactions. The addition of planar electron deficient molecules resulted in the formation of charge transfer complexes. The observed stabilisation or destabilisation of the mesophases is explained by considering the complexation strength of the complex as well as steric factors.
A series of novel mesogens have been prepared by a five-fold Sonogashira reaction of terminal acetylenes with a functionalized pentabromophenol. The corresponding side chain polymers were prepared by a polymer analogous substitution reaction. The mesogens differ in the nature of the substituents, linking five hexyl tails to the aromatic core, i.e. CH2, O, S, SO2 and CONH groups. A wide range of mesophases
Charge Transfer Complexes of Discotic Liquid Crystals: A Flexible Route to a Wide Variety of Mesophases
作者:Paul H. J. Kouwer、Wolter F. Jager、Wim J. Mijs、Stephen J. Picken
DOI:10.1021/ma0118567
日期:2002.5.21
We have prepared a new discotic nematogen, bearing one functional tail and five methoxy substituents. The corresponding side chain polymers, prepared via a polymer analogous esterification reaction, exhibited ND phases from 50 °C until degradation above 200 °C. Addition of equimolar amounts of various trinitrofluorenone-based acceptors to the mesogen resulted in the formation of charge transfer complexes
Investigation of the Complete Miscibility of Disc-rod Mesogens in the Nematic Phase
作者:Daniela Apreutesei、Georg Mehl
DOI:10.1080/15421400600582523
日期:2006.7
The synthesis and the phase behaviour of nematic dimers, built up from rod and disc shaped mesogens, separated by extended spacers is described. Miscibility studies with the rod as well as disc shaped mesogens were performed and OPM data of contact samples and the results of detailed DSC experiments of mixtures are presented. Full miscibility in the nematic phase was observed.