3073-05-0Relevant articles and documents
Synthesis of cyclopentadienyl iron complexes with substituted phenylene ligands via Suzuki coupling
Shved, Andrei M.,Nelyubina, Yulia V.,Perekalin, Dmitry S.
, (2020)
Cationic cyclopentadienyl iron complexes of substituted phenylenes [CpFe(p-CH3-C6H4-Ar)]PF6 and [CpFe(p-Ar-C6H4-Ar)]PF6 were obtained in 37–73% yields by Pd-catalyzed Suzuki coupling reactions of [CpFe(p-CH3-C6H4-Cl)]PF6 and [CpFe(p-Cl-C6H4-Cl)]PF6 with polyarylboronic acids Ar-B(OH)2 (Ar = biphenyl, naphthyl, phenanthryl, bithienyl). The complex [CpFe(p-CH3-C6H4-Cl)]PF6 also underwent Sonogashira-type coupling with phenylacetylene to give the compound [CpFe(p-CH3-C6H4-C[tbnd]C-Ph]PF6 in 26% yield. Such coupling reactions represent an alternative approach to [CpFe(arene)]PF6 complexes, which are typically obtained from ferrocene via Bolesova-Nesmeyanov reaction under harsh conditions (AlCl3, >100 °C). The structures of the products of Suzuki reaction were established by single-crystal X-ray diffraction analysis.
Synthesis of p-Quinquephenyl from E,E-1,4-Bis(4-bromophenyl)-1,3-butadiene
Davis, Matthew C.,Groshens, Thomas J.
, p. 206 - 218 (2011/03/18)
p-Quinquephenyl was synthesized in five steps from E,E-1,4-bis(4- bromophenyl)-1,3-butadiene in 34% overall yield. The butadiene was prepared in six steps from 4-bromobenzaldehyde in 35% overall yield. Copyright Taylor & Francis Group, LLC.
Javelin-, hockey stick-, and boomerang-shaped liquid crystals. Structural variations on p-quinquephenyl
Dingemans, Theo J.,Murthy, N. Sanjeeva,Samulski, Edward T.
, p. 8845 - 8860 (2007/10/03)
The ramifications of changing molecular geometry in a series of all-aromatic liquid crystals derived from p-quinquephenyl are reported. Substituting heterocyclic rings such as thiophene, oxadiazole, oxazole, or 1,3-phenylene into the p-quinquephenylene core affects molecular shape changes via the substituent's exocyclic bond angle. In general, we found that introducing nonlinearity into molecules depresses the melting transition temperature. The symmetric (boomerang-shaped) molecules, 2,5-bisbiphenyl-4-yl-1,3,4-oxadiazole, 2,5-bisbiphenyl-4-yl-oxazole, and 1,3-bisbiphenyl-4-yl-benzene, melt into isotropic phases showing small monotropic mesophases. By contrast, the asymmetric (hockey stick-shaped) mesogens, 2-terphenyl-4-yl-5-phenyl thiophene and 2-terphenyl-4-yl-5-phenyl-1,3,4-oxadiazole, exhibit more stable enantiotropic liquid crystalline phases. The hockey stick-shaped mesogens exhibit a smectic phase as well as a nematic phase. High-temperature X-ray determination of the smectic layer spacing gives an unambiguous picture of interdigitated, bilayerlike supramolecular architecture in the smectic phase. There are associated changes in the mesogen's electrostatic profile when a heterocycle is introduced into the quinquiphenylene framework (e.g., conjugation is perturbed). Our findings suggest that steric packing considerations dominate the phase preferences (nematic versus smectic phases). However, electronic considerations (conjugation) appear to control the range of mesomorphism in this new family of nonlinear liquid crystals.
