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991.
Scandium,yttrium, and ytterbium bisalkyl complexes stabilized by monoanionic amidopyridinate ligands
D. M. Lyubov V. Yu. Rad’kov A. V. Cherkasov G. K. Fukin A. A. Trifonov 《Russian Chemical Bulletin》2016,65(11):2594-2600
A reaction of Sc, Y, and Yb amidopyridinate dichlorides with the corresponding amount of LiCH2SiMe3 was used to synthesize bis(trimethylsilylmethyl) complexes (Ap)Ln(CH2SiMe3)2-(THF) (Ap is N-mesityl-6-(2,4,6-triisopropylphenyl)pyridine-2-amide (Ap9Me), Ln = Y (2); Ap is N-(2,6-diisopropylphenyl)-6-(2,4,6-triisopropylphenyl)pyridine-2-amide (Ap*), Ln = Sc (3), Yb (4)). An exchange reaction of yttrium amidopyridinate dichloride derivative 1 with 4 equiv. of ButLi in hexane gave the corresponding di-tert-butyl derivative Ap9MeY(But)2(THF) (5). Molecular structures of complexes 3 and 4 were established by X-ray diffraction. A method of the ligand solid angles was used to calculate the completion degree of the metal atom coordination sphere for the series of isomorphic derivatives (Ap*)Ln(CH2SiMe3)2(THF) containing the central metal ions with different ionic radii (Sc, Y, Yb, Lu). According to this method, the amidopyridinate ligand solid angle in these complexes virtually does not vary, while the solid angles of coordinated THF molecule and alkyl ligands vary within a wide range. 相似文献
992.
The stability (affinity, association, binding, complexation, formation) constant characterizes binding interaction between the analyte and the complexing agent. Knowledge of the stability constant makes possible the prediction and estimation of the binding behavior of constituents (amino acids, peptides, proteins, drugs, antibiotics, enzymes, enantiomers) to their partners, and the finding of a suitable partner for the given analyte to form a stable complex. The present paper summarizes the stability constant determination methods and the approaches used to evaluate the experimental data. Further, the paper recapitulates the published stability constant values determined, mainly, by capillary electrophoretic methods, taken from the Web of Science database covering the last decade. Details of the experimental conditions employed for the determination of the stability constants are also given. The review attempts to give a critical evaluation of the problems that accompany the determination of stability constant and discusses their solution. 相似文献
993.
The depository effects that occur in slowly metabolized proteins (typically glycation) are very difficult to assess, owing to their extremely low concentration in the protein matrix. Collagen accumulates reactive metabolites through reactions that are not regulated by enzymes. A typical example of these non-enzymatic changes is glycation (the Maillard reaction, the formation of advanced glycation end products), resulting from the reaction of the oxo-group of sugars with the epsilon-amino group of lysine and arginine. Collagen samples (type I) as a test protein were incubated separately with glucose, ribose and malondialdehyde. Collagen was fragmented with cyanogen bromide and then digested with trypsin. This peptide digest was separated by CE, CE-MS/MS, and HPLC-MS/MS. An ion trap MS was used and MS conditions were optimized for both methods. These on-line CE-MS/MS and HPLC-MS/MS couplings made it possible to discover specific modifications such as (N(epsilon)-(carboxymethyl)-lysine) in the precise location in the structure of collagen corresponding to posttranslational non-enzymatic modifications. A new CE-MS/MS technique for peptide analysis was developed, and applied in the identification of posttranslational modifications in slowly metabolized test proteins. 相似文献
994.
Shmelev N. Yu. Gongola M. I. Malysheva S. F. Belogorlova N. A. Artem’ev A. V. Fomenko Ya. S. Komarov V. Yu. Sopov K. V. Kompan’kov N. B. Sheven’ D. G. Sokolov M. N. Gushchin A. L. 《Russian Journal of Coordination Chemistry》2021,47(3):209-218
Russian Journal of Coordination Chemistry - The reaction of [Mo3S4(Tu)8(H2O)]Cl4·4H2O (Tu is thiourea) with (PhCH2CH2)2-PCH2CH2SeC5H11) (PSe) followed by purification on a chromatographic... 相似文献
995.
Vida Július Ilčíková Martina Přibyl Roman Homola Tomáš 《Plasma Chemistry and Plasma Processing》2021,41(3):841-854
Plasma Chemistry and Plasma Processing - Activation of polymeric surfaces, i.e. formation and/or modification of the functional groups on the surface of a material, is essential prior to the... 相似文献
996.
UV-absorbing neutral substances are commonly used as markers of mean electroosmotic flow in capillary electrophoresis for their zero electrophoretic mobility in an electric field. However, some of these markers can interact with background electrolyte components and migrate at a different velocity than the electroosmotic flow. Thus, we tested 11 markers primarily varying in their degree of methylation and type of central atom in combination with five background electrolyte cations differing in their ionic radii and surface charge density, measuring the relative electrophoretic mobility using thiourea as a reference marker. Our results from this set of experiments showed some general trends in the mobilization of the markers based on the effects of marker structure and type of background electrolyte cation on the relative electrophoretic mobility. As an example, the effects of an inadequate choice of marker on analyte identification were illustrated in the electrophoretic separation of glucosinolates. Therefore, our findings may help electrophoretists appropriately select electroosmotic flow markers for various electrophoretic systems. 相似文献
997.
Zdeněk Wagner Magdalena Bendová Jan Rotrekl Petr Velíšek Jan Storch Petr Uchytil Katerina Setnickova Jiřina Řezníčková 《Journal of solution chemistry》2017,46(9-10):1836-1853
Two novel imidazolium based ether-functionalized room temperature ionic liquids were synthesized to study the temperature dependence of the isobaric heat capacity in the temperature range 298.15–348.15 K. In-house synthesized ionic liquids are often available in small amounts only, owing to the high cost of the precursors and difficulties during the synthesis itself. It is therefore impossible to repeat measurement many times so that a statistically significant data sample can be obtained. In addition, to obtain at least several values of the measured property, the ionic liquid must be recycled and reused. In this work two recycling techniques were used and their influence on the values of the experimental isobaric heat capacity was analyzed. Advantages of a modern nonstatistical data analysis technique, namely mathematical gnostics, were demonstrated. 相似文献
998.
Selected rhenium complexes with pyrogallol (1,2,3-trihydroxybenzene) and catechol (1,2-dihydroxybenzene) as strongly bound ligands were prepared by a reaction of rhenium precursor tetrabutylammonium-tetrachlorooxorhenate with twofold molar excess of ligand in presence of various amounts of triethylamine. The structures of formed complexes and their consequent reaction products were estimated by means of mass spectrometry with electrospray ionization. The kinetics of reactions in course of complex formation and consequent decomposition were primarily followed by UV–Vis absorption spectra measurement, complemented by single or continuous electrospray mass spectrometry analyses. 相似文献
999.
D Rahmadani E T Baskoro M Bača H Assiyatun A Semaničová-Feňovčíková 《Proceedings Mathematical Sciences》2017,127(5):779-786
For any given two graphs G and H, the notation \(F\rightarrow \) (G, H) means that for any red–blue coloring of all the edges of F will create either a red subgraph isomorphic to G or a blue subgraph isomorphic to H. A graph F is a Ramsey (G, H)-minimal graph if \(F\rightarrow \) (G, H) but \(F-e\nrightarrow (G,H)\), for every \(e \in E(F)\). The class of all Ramsey (G, H)-minimal graphs is denoted by \(\mathcal {R}(G,H)\). In this paper, we construct some infinite families of trees belonging to \(\mathcal {R}(P_3,P_n)\), for \(n=8\) and 9. In particular, we give an algorithm to obtain an infinite family of trees belonging to \(\mathcal {R}(P_3,P_n)\), for \(n\ge 10\). 相似文献
1000.
D O Haryeni E T Baskoro S W Saputro M Bača A Semaničová-Feňovčíková 《Proceedings Mathematical Sciences》2017,127(5):755-767
In this paper, we continue investigating the partition dimension for disconnected graphs. We determine the partition dimension for some classes of disconnected graphs G consisting of two components. If \(G=G_1 \cup G_2\), then we give the bounds of the partition dimension of G for \(G_1 = P_n\) or \(G_1=C_n\) and also for \(pd(G_1)=pd(G_2)\). 相似文献