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•A new synthesis of redox-active bis-chelate Ru(II) complex Ru(ONO)2.•The RuIII/RuII conversion through the formation of RuIII (ONO)3 intermediate.•Ru(ONO)2 enters into ligand ...substitution only via its radical-anion form.•The structure of Ru(ONO)Py3 is X-ray established.
The redox-active bis-chelate hexacoordinate ruthenium complex 2 Ru(ONO)2 comprising two redox-active 2,4,6,8-tetrakis(tert.-butyl)-9-hydroxyphenoxazin-1-one ligands 1 was synthesized by coupling ruthenium trichloride with 1 or its thallium salt. Reduction of 2 with zinc amalgam produces its radical-anion 2a, which readily reacts with pyridine in aerobic conditions resulting in substitution of one of the tridentate hydroxyphenoxazinone ligand by three pyridine molecules and the formation of a salt of tris(pyridine)(tetra-(tert.-butyl)oxyphenoxazin-1-onate) Ru(II) cation 5. The structure of this salt was established by X-ray crystallography and its redox activity investigated using cyclic voltammetry. The mechanism of the RuIII/RuII conversion observed in this reaction was suggested based on the data of ESR, UV-Vis spectra and DFT B3LYP/6-311++G(d,p)/SDD calculations.
The present study proposes a general method for constructing pharmaceutical fingerprints in the analysis of HPLC trace organic impurity patterns. The approach considers signals in phase space and ...accounts for two different types of noise: additive and perturbative. The first type, additive noise, contributes to distortion of the absolute values of signal peaks. The second type, perturbative noise, contributes to variations of the retention times of signal peaks and distorts the time scale of the trace organic impurity patterns. The ability of the proposed approach to consider both types of noise significantly distinguishes it from existing methods of data analysis that are usually designed to treat only the additive noise. Analysis of the HPLC signals in phase space eliminates the problem of perturbation noise and enables detection and comparison of similar signal segments recorded at different retention times. The current study analyzes the chromatographic trace organic impurity patterns collected from six different manufacturers of L-tryptophan using three HPLC columns. For five manufacturers the variability of data recorded with the same column are in perfect agreement with the proposed model. A significant variance of parameters is detected for one manufacturer, thus indicating a possible change in its product consistency. The analysis in phase space is also used to explain the previously detected variability of HPLC signals across columns. The accompanying paper reports an application of the proposed approach for the pattern recognition of HPLC data.
A technique for the experimental high-precision measurement of the surface-material erosion profile caused by ion bombardment is proposed. It is based on the preliminary deposition of a coating ...consisting of submicron layers of different materials with different colors. The erosion profile is determined using multilayer copper and aluminum coatings. An important advantage of the proposed procedure is that the erosion profile of the surface treated with an ion beam can be estimated preliminarily without using complex measuring instruments.
A series of 2‐(hydroxyphenyl)‐1H‐benzodimidazols bearing readily oxidizable 2,6‐di‐tert‐butyl‐phenol substituents and bis‐chelate Cu(II) complexes based on these ligands were synthesized. The ...structure of the compounds was characterized by NMR, IR, mass spectroscopy and X‐ray crystallographic analysis and redox behavior explored using ESR spectra and cyclic voltammetry. Under oxidation with PbO2 in toluene solution both the ligands and Cu(II) complexes form stable phenoxyl‐type radicals. As shown by ESR measurements and DFT calculations, no exchange interaction exists between unpaired electrons located on metal and oxygen centers in the biradical Cu (II) complexes. The ligands and complexes reveal antioxidant radical scavenging activity measured spectrophotometrically and using ESR and DPPH‐tests.
A series of 2‐hydroxyphenyl‐1H‐benzodimidazols bearing readily oxidizable 2,6‐di‐tert‐butyl‐phenol substituents and bis‐chelate Cu(II) complexes based on these ligands were synthesized. Under oxidation both the ligands and Cu(II) complexes form stable phenoxyl‐type radicals. As shown, no exchange interaction exists between unpaired electrons located on metal and oxygen centers in the Cu(II) complexes.
In 2001-2002 and 2006-2007, the author conducted two comparative surveys among the students of a number of higher educational institutions in Moscow. The main purpose of the surveys was to study ...processes of the modernization of higher education and also to determine what attitudes students hold toward these processes. Of the many aspects of modernization the author focused on the following: (1) college and university education on a tuition basis and nontuition basis; (2) stipends and benefits for students; (3) students' attitudes toward the unified state examination; and (4) how well informed college students are about the Bologna Convention on Higher Education. This article presents the analysis of the author on the findings of her surveys. (Contains 1 note.)
This article develops an expert-analytical model for assessing the quality of process-oriented management of construction companies. The model differs in a two-tier approach to object evaluation by ...pre-evaluating the characteristics of objects and their parameters. Assessments were made in connection with the time and financial costs of resources that allow to forming an expert group, conduct a survey and analyzing its results. These results were conducted by the method of written questionnaires, which are divided into three groups: general information about the expert (age, experience, specialty, etc.), the main questions related to the problems being analyzed or evaluated, additional questions to determine the rationale for answers , competence of experts, etc. The list of possible linguistic estimations of characteristics and parameters and their numerical equivalents is formed that will give the chance to provide quality of process-oriented management on the basis of the analyzed integrated indicators of quality of management of the building enterprise. A generalized assessment of the characteristics of each of the experts of the formed group in the expert-analytical model is also formed. The list of objects, parameters and their components which are intended for an estimation of quality of management at the building enterprise is generalized. The dynamic analysis of the integrated indicator of management quality allows the institutional level of contractors to rationally plan the activities of the construction company and adjust the work in sectors (financial, production, resource, etc.) for which negative evaluations were obtained.
A series of 2‐(hydroxyphenyl)‐1H‐benzodimidazols bearing readily oxidizable 2,6‐di‐tert‐butyl‐phenol substituents and bis‐chelate Cu(II) complexes based on these ligands were synthesized. The ...structure of the compounds was characterized by NMR, IR, mass spectroscopy and X‐ray crystallographic analysis and redox behavior explored using ESR spectra and cyclic voltammetry. Under oxidation with PbO2 in toluene solution both the ligands and Cu(II) complexes form stable phenoxyl‐type radicals. As shown by ESR measurements and DFT calculations, no exchange interaction exists between unpaired electrons located on metal and oxygen centers in the biradical Cu (II) complexes. The ligands and complexes reveal antioxidant radical scavenging activity measured spectrophotometrically and using ESR and DPPH‐tests.
Reducing the water content of crude oil is a necessary step in preparing oil for transportation and processing. This task is complicated by the presence of stable water-in-oil emulsions. The most ...widely used approach to oil demulsification is exploring chemical demulsifiers. However, the high cost and impossibility of regenerating the latter require the search for new ways to destroy water-oil emulsions. One of the promising areas is the use of ultrasound. This paper presents the results of studies on the ultrasonic treatment of four samples of emulsions with different water content (8.74; 15; 25 and 30 vol.%) based on oil from the Kumkol oilfield (Kazakhstan). Samples of emulsions were subjected to ultrasonic action at a frequency of 40 kHz for 5-60 min at a temperature of 70±1°C, followed by settling for 40 min at the indicated temperature. The influence of the initial water content in the emulsion, the acoustic intensity, as well as the duration of ultrasonic treatment on the dewatering ratio was investigated. It was found that the residual water content in the oil was 5.04- 7.82 vol.%. Ultrasonic treatment of crude oil from the Kumkol oilfield can be used for preliminary dewatering, to subsequently reduce the consumption of chemical demulsifiers.
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