Nonlinear wave motion in magnetoelasticity

Archive for Rational Mechanics and Analysis -     

Adsorption of CO2, CH4, and N2 on Zeolitic Imidazolate Frameworks: Experiments and Simulations

Experimental measurements and molecular simulations were conducted for two zeolitic imidazolate frameworks, ZIF‐8 and ZIF‐76. The transferability of the force field was tested by comparing molecular simulation results of gas adsorption with experimental data available in the literature for other ZIF materials (ZIF‐69). Owing to the good agreement observed between simulation and experimental data, the simulation results can be used to identify preferential adsorption sites, which are located close to the organic linkers. Topological mapping of the potential‐energy surfaces makes it possible to relate the preferential adsorption sites, Henry constant, and isosteric heats of adsorption at zero coverage to the nature of the host–guest interactions and the chemical nature of the organic linker. The role played by the topology of the solid and the organic linkers, instead of the metal sites, upon gas adsorption on zeolite‐like metal–organic frameworks is discussed.     

Perhalogenated thiazoles. Their synthesis,reactions and mass spectra

The synthesis of six new mixed perhalogenaled thiazoles ane reported. Three of these contain a 2-fluoro substituent one of which includes the novel 5-bromo-4-chloro-2-fluorothiazole. The mass spectral fragmentation pattern of the perhalogenated thiazoles was used to elucidate the orientation of the halogen suhstituents. A novel halogen migration from carbon to nitrogen in the mass spectrum was observed for several of the perhalogenated thiazoles. Nucleophilie displacement of fluoride ion in 4,5-diehloro-2-flurothiazile ( 7 ) by cyano, hydroxyl and methoxyl unions and by diclhyl amine produced the respective 2-substituted dichlorothiazoles. The ease of electrophilic substitution on carbon in the polyhalogenated thiazoles was observed to be 2 > > 5 > 4. Sulfur tetrafluoride fluorinalion of 2-earboxy-4,5-dichlorothiazole, formed by lilhiation and eurbonation of tricblorolhiazole, yielded 4,5-dicbloro-2-trifluoromethylthiazole.