Synthesis discotics

Meier et al. have also contributed to the field of cyclic PAV oligomers with the synthesis of cyclic dl -trans (all- ) trimers (e.g. 113) containing alkoxy-substituted 1,7-naphthylene and 1,9-phenanthrylene building blocks, via a Siegrist-type trimerizing olefination [134,135]. Suitable substitution at the periphery of the cyclic trimers allows for the formation of stable, thermotropic discotic mesophases [134]. 

Approaches used to the development of LC materials with valuable luminescent properties include the synthesis of rod-like mesogens from fluorescent moieties, e.g. benzopyrans, " and discotic LCs with a fluorescent polyaromatic core. ... 

The formation of liquid crystals (LC) from suitably functionalized acetylenic SPMs has often been the motivation for their synthesis. A number of groups have sought to capitalize on the planar or nearly planar disk-like geometry of SPMs to promote the formation one-dimensional columnar stacks based on a combination of n-n stacking, van der Waals, dipole, and hydrophobic interactions. For example, Heiney, Moore, and coworkers have reported the high-resolution X-ray diffraction analysis (XRD) of a tubular, discotic LC based on SPM 133, which has been synthesized via a Sonogashira reaction [106]. These studies reveal an unanticipated distortion and... 

Figure 23 Synthesis of twin discotic dimer and branched oligomers from CTTV-7 mesogens connected with a hexadecane spacer. (From Ref. 76.)...

Isocyanides are excellent ligands for Pd(n) and Pt(ll), to the point that they can be nsed in the synthesis of thermotropic liqnid crystals. Some [MX2(isocyanide)2] complexes are liqnid crystals (discotic) at room temperatnre. The thermal properties depend very mnch on the cis or trans geometry of the complex. For X = I, the trans geometry is favored, whereas for X = Cl, cis complexes are formed. 

Kumar S, Pal SK (2005) Ionic discotic liquid crystals synthesis and characterization of pyridinium bromides containing a triphenylene core. Tetrahedron Lett 46 4127-4130... 

A surprisingly efficient intermolecular photochemical [2 + 2] dimerization was achieved in the synthesis of belt-shaped cyclophanes by irradiation of arenoannelated [18]annulenes like 176 [116]. The highly selective threefold [27t+27t] cycloaddition yields dimers 177 in up to 68%. The efficiency of this dimerization process even at high dilution can be explained with the perfect preorganization of the discotic mesogenes 176. 

The synthesis of discotic, mercury-bridged, triphenylene dimers (166 R = OC5Hu, 0(CH2)2CHMe(CH2)3-CHMe2) was reported by Kumar et The bis(2,3,6,7,10-pentapentyloxy-triphenylene-l l-ethynyl)mercury(ll)... 

There are relatively few reports of liquid crystal dimers containing discotic mesogenic units [105-112] and this has been due in large part to the difficulties in preparing monofunctionalised discotic precursors. Without such monofunctional precursors the preparation of discotic dimers often involves laborious separation procedures involving several isomers of the discotic core. In recent years, however, there have been many advances in the synthesis of triphenylene-... 

Discotic liquid crystals (particularly, heterocyclic compounds) and their applications from tailor-made synthesis to plastic electronics 07AG(E) 4832. 

A discotic LCE containing triphenylene group was also synthesized by the two-step process (Disch et al., 1995). Samples with a chemically fixed macroscopic alignment of the director (monodomains) was prepared by application of a uniaxial mechanical field during the synthesis of the LCEs. 

S. Laschat, A. Baro, N. Steinke, F. Giesselmaim, C. Hagele, G. Scalia, R. Judele, E. Kapatsina, S. Sauer, A. Schreivogel, M. Tosoni, Discotic liquid crystals from tailor-made synthesis to plastic electronics. Angew. Chem. Int. Ed. 46, 4832-4887 (2007)... 

T. Kamei, T. Kato, E. Itoh, K Ohta, Discotic liquid crystals of transition metal complexes 47 synthesis of phthalocyanine-fullerene dyads showing spontaneous homeotropic alignment. J. Porphyrins Phthalocyanines 16, 1261-1275 (2012)... 

H.K. Bisoyi, S. Kumar, First examples of monodisperse discotic liquid crystal pentamers synthesis and mesomorphism. Tetrahedron Lett. 49, 3628-3631 (2008)... 

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