Complexation Based Voltammetric Determination of Pantoprazole Sodium in Pharmaceutical Formulations and Rabbit Plasma

Square wave adsorptive stripping voltammetric (SQWASV) method has been utilized to confirm and elucidate the possible complexation reaction between pantoprazole sodium and cobalt as a transition metal in Britton‐Robinson buffer (pH=7.0). The current signal due to the oxidation process was a function of the amount of pantoprazole sodium, pH of the medium, cobalt concentration and accumulation time at the electrode surface. The oxidation peak current has varied linearly with the concentration over the range of 0.1–9.0 nM. The limit of detection was found to be 0.04 nM. The validity of the method was successfully applied for the determination of pantoprazole sodium in pharmaceutical formulations with a pharmacokinetic study in rabbit plasma. The simplicity, rapidity, sensitivity and selectivity of this method make it a very attractive alternative to the other existing methods in the quality control laboratories.     

CRYSTAL STRUCTURE AND THERMAL ANALYSIS OF A 4,4′-BIPY-BRIDGED BINUCLEAR ZINC(II) COMPLEX, 2[R2NCS2]2 · Zn(4,4′-BIPY) (R=PIPERIDYL)

Abstract

The crystal structure of the title complex 2[R₂NCS₂]₂ · Zn(4,4′-bipy) (R = Piperidyl), 1, revealed that it consists of dimers made up from two crystallographically independent molecules. Each zinc atom in 1 forms a 5-coordinate pseudo-square-based pyramidal arrangement (with four Zn-S and one Zn-N interactions). Bondlengths to Zn with the coordinating atoms are comparable to those in other Zn(II) dithiocarbamate complexes. The piperidine ring has a chair conformation. To allow improved packing, the title complex molecules form an approximately linear arrangement extending along both a and b. TGA showed that 1 is decomposed in two close steps to produce ZnS as identified by residual weight. The complex 1 crystallizes in the monoclinic space group C2/c with cell parameters: a = 22.021(5), b = 22.215(3), c = 17.537(2) Å, β = 93.49(2)°, V = 8563(3) ų and Z = 8. The structure was refined by full-matrix least-squares methods to R = 0.067, R_w = 0.114.     

State of the art and research development prospects of energy and resource-efficient environmentally safe chemical process systems engineering

In this focus overview, the main types and directions of engineering, methods and techniques of intensification of chemical process systems (CPS) and process optimization of energy- and resource-efficient processes for the representative production of titanium compounds, mining waste processing systems, electrochemical coating technologies, combined technologies for the treatment of industrial effluents and energy-and resource-efficient technologies for cleaning soils from petroleum and chemical pollution products are reviewed. The following issues have been discussed: methods of complex assessment of production energy efficiency and software and information support for automated synthesis of optimal energy-efficient regenerative heat exchange systems using pinch analysis; methods and algorithms for fractal-statistical characteristics analysis of nonstationary gas flows in complex gas pipelines; methods of ecological and economic optimization of production, infrastructure supply chains; methods for assessing and preventing the dangerous environmental impact assessment of chemical pollution; organization and logistics management of business processes engineering for improving the energy efficiency of plants; engineering of problem oriented computer systems, heuristic-computational models and algorithms for intelligent integrated logistics support of the equipment life cycle; engineering developments in the field of digital transformation of energy-efficient CPS and technological production systems; application of methods for optimizing reliability factors optimization, digitalized risk and safety management in the engineering of energy- and resource efficient CPS.     

Design and characterization of guided mode resonance filters with the improved structure for facile fabrication

In this study, a guided mode resonance filter with the improved structure for facile fabrication is designed; the properties of the designed filters are simulated by rigorous coupled wave analysis. It is found that the resonance wavelength and spectral linewidth are slightly increased with the increasing of the grating thickness, and seldom changed with the thickness of the grating filling factor, as the parameter error of the grating thickness and the grating filling factor are deviated from the designed value by ±10%, respectively, which are very favorable for simplifying preparation process of the GMR filter.     

In Silico Design of Heteroaromatic Half‐Sandwich RhI Catalysts for Acetylene [2+2+2] Cyclotrimerization: Evidence of a Reverse Indenyl Effect

A mechanistic density functional theory study of acetylene [2+2+2] cyclotrimerization to benzene catalyzed by Rh^I half metallocenes is presented. The catalyst fragment contains a heteroaromatic ligand, that is, the 1,2‐azaborolyl (Ab) or the 3a,7a‐azaborindenyl (Abi) anions, which are isostructural and isoelectronic to the hydrocarbon cyclopentadienyl (Cp) and indenyl (Ind) anions, respectively, but differ from the last ones on having two adjacent carbon atoms replaced with a boron and a nitrogen atom. The better performance of either the classic hydrocarbon or the heteroaromatic catalysts is found to depend on the different mechanistic paths that can be envisioned for the process. The present analyses uncover and explain general structure–reactivity relationships that may serve as rational design principles. In particular, we provide evidence of a reverse indenyl effect.     

Studies of phase transitions and ferroelastic domain walls in Pb5Al3F19 crystals by optical measurements

Three phase transitions between 100 and 400 K were previously shown by X-ray diffraction measurements. Such results have been confirmed by optical measurements on crystals. The thermal dependence of the birefringence has been determined. A new phase transformation has been shown at around 590 K not only by optical study but also by dielectric measurements. Ferroelastic domain-walls have been visualized. The sequence transition has been discussed taking into account the various space groups.     

Aharonov–Bohm effects in magnetohydrodynamics

It is shown that an Aharonov–Bohm (AB) effect exists in magnetohydrodynamics (MHD). This effect is best described in terms of the MHD variational variables (Kats, 2004; Yahalom and Lynden-Bell, 2008; Yahalom, 2010) [1], [10], [12]. If a MHD flow has a non-trivial topology some of the functions appearing in the MHD Lagrangian are non-single-valued. These functions have properties similar to the phases in the AB celebrated effect (Aharonov and Bohm, 1959; van Oudenaarden et al., 1998) [2], [3]. While the manifestation of the quantum AB effect is in interference fringe patterns (Tonomura et al., 1982) [4], the manifestation of the MHD Aharonov–Bohm effects are through new dynamical conservation laws.     

The Conformation of Sterically Congested Seven-Membered Rings Containing Tetracoordinate Germanium(IV): A First X-Ray Crystallographic Structure Determination

The X-ray crystallographic analysis of 6,6-dimethyl-2,4,8,10-tetra-tert-octyl-dibenzo[d,f][1,3,2]dioxagermepin, 1 is reported. In the solid-state conformation of 1, the dihedral angle about the C─C sp²-sp ² σ bond connecting the two aryl rings is 50.1°. The observed C₂ symmetry in the solid-state conformation of 1 is consistent with the previously suggested solution conformation.     

3,4-Thienylene-ethynylene Oligomers

Several well-defined 3,4-thienylene-ethynylene oligomers with different chain lengths have been synthesized and characterized. X-Ray crystallographic analyses proved their unique, totally helical conformations.     

Sigmatropic Rearrangements in Phosphorylated 2-Azaallylic Systems

Abstract

Allylic and heteroallylic compounds are classical objects of organic chemistry and can serve as models in the investigation of various theoretical problems. The anions and 1,3-dipoles generated from azaallylic derivatives are widely used in the synthesis of cyclic and acyclic nitrogen-containing compounds.