Electronic spectra of α,β-unsaturated carbonyl compounds—III : β-alkylamino and β-dialkylamino acrylamides

Several β-alkylamino, β-dialkylamino and β-aziridino acrylamides have been synthesized and their configuration and conformation established by means of NMR and IR. Cis and trans isomers have been isolated in some cases, and their respective π → π* absorption maxima assigned. Configuration does not appreciably affect the frequency of this transition.     

Symmetrically bifurcate hydrogen bonding—III (sym-o,o′ diacyl)-diphenylamines

Symmetrically bifurcate three-centre hydrogen bonding,

, was found in several (sym-o,o′-diacyl)-diphenylamines, [o(RCOC₆H₄)]₂NH.     

Mesomorphous Properties of Azo- and Azoxyarylethanes as Potential Stationary Phases in Gas Chromatography

Two series of compounds have been synthesized: 1,2-bis(4′-butoxybenzeneazobenzene-4)ethanes and 1,2-bis(4′-butoxybenzeneazoxybenzene-4)ethanes. The effects of lateral substituents (CH₃, Cl, CN) on temperature are tested as well as the molar enthalpies and entropies of their phase transitions determined. The application of those compounds as liquid-crystalline stationary phases in gas chromatography is suggested.     

Influence of low concentration silver nanoparticles on the electrical and electro-optical parameters of nematic liquid crystals

Thermodynamical, optical, dielectric and electro-optical characterisation of nematic liquid crystals (LCs) and silver nanoparticle (NP) composites have been carried out. Transition temperatures of pure and composites systems have been measured. Thermodynamical studies suggest increase of clearing temperature of the composite material as compared to the pure material. Threshold voltage for switching from bright to dark state and splay elastic constant of the pure and composite materials have been determined. From frequency dependence of dielectric measurements, permittivity, loss, relaxation frequency and dielectric strength of flip-flop mechanism of LC molecules in the nematic phase have been calculated. Dielectric properties of composites have been explained in reference of Maier and Meier theory. The effects of doping of NPs on dielectric and electro-optic properties of LC-NP composites have been discussed.