Application of capillary electrophoresis technique for the enantioseparation of bioactive ferrocene-based compounds versus DFT calculated data

Herein, a series of bioactive ferrocene-modified N-heterocycles with alkyl linkers was prepared in good to quantitative yields starting from easy accessible ferrocene alcohols and heterocycles under acidic or neutral (for imidazole) conditions in racemic forms. The analytical resolution of a number of bioactive racemic ferrocene azoles 1 – 6 (where azole = imidazole, pyrazole, and benzotriazole derivatives) into enantiomers was first carried out by CE using sulfobuthylether-β-CD (captisol) as a chiral selector. The analytical approaches to highly enantiomeric-enriched ferrocene derivatives are based on the formation of their inclusion complexes. The best chiral separation was achieved using zone CE in a quartz capillary. The ACE was used to evaluate the stability constants of captisol complexes with enantiomeric forms of two ferrocene derivatives 1 , FcCHMe-imidazole, and 6 , FcCHMe-benzotriazole. The optimal conditions for the resolution of the studied (R, S)-ferrocene compounds 1 , 2 , and 6 were predicted on the basis of the performed quantum chemical calculations and then implemented by the electrophoretic method. A high correlation between density functional theory calculation results and experimental electrophoresis data were obtained. Successful enantioseparation of racemic mixtures is of great importance for the characterization and further applications of drug candidates in enantiopure forms and in the development of clinical treatment. The advantages of the CE procedure make it possible to have important practical value and significance for determining the purity and enantiomeric excess of other ferrocene-containing compounds.     

Time-gated measurements of electron beam generated Kα emission lines from brass planar wire array implosions

The relative amount of Kα radiation emitted by partially ionized copper and zinc from planar wire arrays on the 1 MA Zebra generator at the University of Nevada, Reno, does not correspond to the composition (70% copper, 30% zinc) of the array's brass wires. For example, the copper Kα line at 8 keV was observed to be much stronger than would be expected from zinc's Kα radiation at 8.6 keV, but this ratio also reversed, more emission from zinc than from copper, during the X-ray pulse. An excess of Kα photons from copper is consistent with a beam of electrons with energies above copper's K-edge but below that of zinc, but the opposite case is perplexing. Preferential ablation of Zn over Cu early in the current pulse could be a contributing factor, but opacity effects are not. Synthetic spectra for brass computed by a non-LTE collisional-radiative model that includes an electron beam component compare well with observed K-shell spectra, and suggest the parent ions of the Kα emission. These ionization stages are consistent with L-shell spectra. This comparison also indicates that the total energy in the electron beam increases towards the end of the radiation pulse while the electron temperature decreases. The crucial diagnostic in this measurement is a time-resolved X-ray spectrometer based on a LiF crystal.     

Electric dipole moment enhancement factor of thallium

The goal of this work is to resolve the present controversy in the value of the electric dipole moment (EDM) enhancement factor of Tl. We carry out several calculations by different high-precision methods, study previously omitted corrections, as well as test our methodology on other, parity conserving, quantities. We find the EDM enhancement factor of Tl to be equal to -573(20). This value is 20% larger than the recently published result of Nataraj et al. [Phys. Rev. Lett. 106, 200403 (2011)], but agrees very well with several earlier results.     

Non-local symmetries of first-order equations

It is shown how one can transform scalar first-order ordinarydifferential equations which admit non-local symmetries of theexponential type to integrable equations admitting canonicalexponential non-local symmetries. As examples we invoke theAbel equation of the second kind, the Riccati equation and naturalgeneralizations of these. Moreover, our method describes howa double reduction of order for a second-order ordinary differentialequation which admits a two-dimensional Lie algebra of generatorsof point symmetries can be affected if the second-order equationis first reduced in order once by a symmetry which does notspan an ideal of the two-dimensional Lie algebra.     

Thermodynamic characteristics of neodymium and terbium pyrazolonate complexes

The sublimation of 1-phenyl-3-methyl-4-isobutyryl-5-pyrazolonate complexes of neodymium and terbium was studied by the Knudsen effusion method with mass spectrometric gas phase monitoring. The gas phase was shown to contain only monomeric molecular species. The sublimation enthalpy (kJ/mol) for Nd complex is 205.9 ± 2.7 and that for the Tb complex is 208.0 ± 4.0.     

Influence of maturation conditions of hydroxyapatite gel on the composition of xerogel

The influence exerted by conditions of the secondary maturation of hydroxyapatite gel on the composition of a xerogel was determined. It was found that the prolonged stage of the secondary maturation within pH 7.6–7.1, the low pH value of distilled water or a solution of the acid (HCl, H₃PO₄) and the long time of contact of the hydoxyapatite gel with the acid solution assist the formation of α-tricalcium phosphate impurity. A singlephase hydroxyapatite is formed in the presence of distilled water with pH 5.3–5.6, as the time of the secondary stage of maturation of hydroxyapatite gel within pH 7.6–7.1 is decreased and the total washing time is decreased up to 34–40 days.     

Efficient tandem synthesis of 3-alkylaminoprop-2-enamides from 3-trimethylsilylprop-2-ynamides

A tandem synthetic approach to previously unknown 3-aminoprop-2-enamides has been developed. It is based on Si-C _sp desilylation of 3-trimethylsilylprop-2-ynamides and subsequent addition of an amine to the triple bond of intermediate terminal propynamides. The effects of the reaction conditions and amine nature on the efficiency of the process have been studied.     

Direct one-index transformations in multiconfiguration response calculations

The evaluation of gradient vectors of a general operator with one-index, double-one-index, or higher-order one-index transformed integrals is a key operation in multiconfiguration response theory calculations. We describe an integral-driven direct algorithm that carries out this operation efficiently without pretransforming the integrals. The use of this algorithm leads to a considerable reduction in disk space and timing. © 1994 by John Wiley & Sons, Inc.