ABSTRACT
4-Cyano-1,1'-biphenyl derivatives bearing ω-hydroxyalkyl substituents were reacted with methyl 3-chloro-3-oxopropionate or cyanoacetic acid, giving liquid-crystalline linear malonates and cyanoacetates. These compounds formed monotropic nematic phases at 62 °C down to ambient temperature upon cooling from the isotropic liquid. The mesomorphic properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction (WAXS).
ABSTRACT
The last five years' achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.
ABSTRACT
Di(mesityl)cyclohexenylphosphine undergoes hydroboration with Piers' borane [HB(C(6)F(5))(2)] to yield the cyclohexylene-anellated frustrated Lewis pair 5. This P/B pair splits H(2) with the formation of the product 4 and adds to the C=O double bond of phenyl isocyanate to yield 6. In the crystal, compound 5 features a puckered four-membered heterocyclic core structure with a long P-B bond (av. 2.197(5) Å). The activation energy of the P-B cleavage of the frustrated Lewis pair 5 was determined by dynamic (19)F NMR spectroscopy at ΔG(≠)(298 K)=12.1±0.3 kcal mol(-1).
ABSTRACT
The bis(arylimino-Cp)ZrCl2 complex (I) forms an "antagonistic" Lewis pair with B(C6F5)3. Treatment with dihydrogen yields the aminomethyl-Cp hydrogenation product (II) by means of a quasi-autocatalytic process. The salt III is an efficient catalyst for the hydrogenation of bulky imines and of silyl enolethers.
