Determination of Cerium in Filtrates After Sorption by Stripping Voltammetry on Solid Electrodes

Разработана методика определения церия (III) в водных растворах методом инверсионной вольтамперометрии на графитовом электроде в виде малорастворимого соединения. Зависимость аналитического сигнала церия (III) от его концентрации в растворе линейна в диапазоне 0.5–10 мг/л и описывается уравнением I = (0.56±0.03)с + (0.54±0.10) [коэффициент корреляции > 0.99]. Предел обнаружения церия (III) составляет 0.1 мг/л. Методом «введено-найдено» показано отсутствие значимой систематической погрешности. С использованием разработанной методики определено содержание церия в фильтратах после его сорбцииА stripping voltammetry method was developed for the determination of cerium (III) on graphite electrode as a poorly soluble compound in filtrate after sorption. The cerium (III) concentration presents a good linear relationship over the range of 0.5–10 mg/l. Its linear equation is I = (0.56±0.03)с + + (0.54±0.10), with a correlation coefficient >0.99. The detection limit of cerium (III) is 0.1 mg/l. The absence of a significant systematic error is shown by the added-found method. Using the developed technique, the concentration of cerium (III) in the filtrates after sorption has been determine

13C NMR spectrum of crystalline [Rh(Acac) (CO)2]: A contribution to the discussion on [Rh(Acac) (CO)2] molecular structure in the solid state

13C MAS NMR spectrum of polycrystalline [Rh(Acac) (CO)2] (1) displays separate signals from all 7 carbon atoms: 2 doublets from CO ligand carbons along with 5 singlets from Acac carbons. GIPAW calculation of 13C shielding tensor values also revealed non-equivalence of all carbon atoms in molecule 1 in the anisotropic medium of the crystal lattice. Apparently, the C2v symmetry of molecule 1 is broken owing to the asymmetry of its contacts to the neighboring molecules. For example, the contacts O⋯HC of two CO ligands of molecule 1 to the CH group of the closest molecule in the adjacent stack are markedly different: the distances OH are 2.72 and 4.38 Å, the distances OC are 3.65 and 5.00 Å, the angles OHC are 164.9° and 126.4°

INFLUENCE OF THE MEDICAL OZONE ON INTENSITY OF PHENOL MIGRATION FROM PVC MEDICAL INFUSION SET INTO WATER SOLUTION

In article the results of investigating the phenol migration from polyvinyl chloride medical infusion set into contacting water solution were presented. The perfusion of ozonized, physiologic solutions through the medical infusion set extended, in clinical practice can be accompanied, by migration of phenol from a polymeric material with concentration up to 1 mg/l

Solubility Study of Betulonic Acid in the Presence of Hydroxypropyl-γ-cyclodextrin by Capillary Electrophoresis

Методом капиллярного электрофореза изучена растворимость бетулоновой кислоты в 40 мМ растворе гидроксипропил-γ-циклодекстрина. Показано, что равновесие реакции комплексообразования между бетулоновой кислотой и гидрокиспропил-γ-циклодекстрином (ГП-γ-ЦД) устанавливается в течение трех суток. Найдено, что присутствие или отсутствие кислорода в растворе ГП-γ-ЦД не влияет на динамику растворения бетулоновой кислоты. Определена растворимость бетулоновой кислоты в 40 мМ водного раствора гидроксипропил- γ-циклодекстрина, которая составляет (410±20) мг/л.Solubility of betulonic acid in 40 mM hydroxypropyl-γ-cyclodextrin solution was studied by capillary electrophoresis. It was shown that the equilibrium of complexation reaction between betulonic acid and hydroxypropyl-γ-cyclodextrin was established for three days. The oxidation of betulonic acid by atmospheric oxygen was shown not to occur during the long stirring. The solubility of betulonic acid in 40 mM aqueous cyclodextrin solution was 410±20 mg/l

Syntheses and Physical-Chemical Properties of Phenylvinylidene Complexes with MnPt Core, Containing Diphenylphosphine Ligand at the Platinum Atom

Разработан метод синтеза новых биядерных μ-винилиденовых комплексов типа Cp(CO)2MnPt(μ-C=CHPh)(PPh2H)(L) [L = PPh3 (1), P(OPri)3 (2)], содержащих дифенилфосфиновый лиганд PPh2H при атоме платины. Полученные соединения изучены методами ИК- и ЯМР-спектроскопии. На основе спектроскопических данных предложено строение комплексовA synthetic approach to the new heterobinuclear μ-phenylvinylidene complexes Cp(CO)2MnPt(μ- C=CHPh)(PPh2H)(L) [L = PPh3 (1), P(OPri)3 (2)], containing diphenylphosphine ligand at the platinum atom, was developed. The compounds were studied by IR- and NMR-spectroscopy. Their molecular structures were proposed based on IR, NMR spectroscopic dat

New Carbonyl β-diketonate Rhodium (I) Complexes Containing 1-adamantyl Isocyanide

Синтезирована серия новых β-дикетонатных комплексов родия (I), содержащих 1-aдамантилизоцианидный лиганд (acac)Rh(CO)(CNAd) (1а), (dbm)Rh(CO)(CNAd) (2а) и (hfac) Rh(CO)(CNAd) (3а) (acac = ацетилацетонат, dbm = дибензоилметан, hfac= гексафторацетилацетон, Ad = 1-адамантил). Строение полученных соединений предложено на основании данных ИК- и ЯМР‑спектров. Исследованы реакции новых комплексов с диэтиламиномA series of new β-diketonate rhodium (I) complexes (acac)Rh(CO)(CNAd) (1а), (dbm)Rh(CO)(CNAd) (2а) and (hfac)Rh(CO)(CNAd) (3а) (acac = acetylacetonate, dbm = dibenzoyl methane, hfac = hexafluoroacetylacetonate, Ad = 1-adamantyl) containing adamantyl isocyanide ligand were synthesized. The new complexes were characterized by IR- and NMR‑spectroscopy. These spectroscopy data allow us to propose their molecular structures. The reactions between the new complexes and diethylamine were studie

The New μ-Phenylvinylidene RePt Complexes Containing Platinum-Bound 1-(Isocyanomethylsulfonyl)- 4-Methylbenzene

Впервые получены биядерные μ-винилиденовые комплексы Cp(CO)2RePt(μ- C=CHPh)(TosMIC)(L) [ L = PPh3 (1), P(OPri)3 (2)], в которых изоцианидный лиганд, 1-(изоцианометилсульфонил)-4-метилбензол (TosMIC), координирован с атомом платины. Соединения 1 и 2 синтезированы путем замещения карбонильного лиганда при атоме платины в соединениях Cp(CO)2RePt(μ-C=CHPh)(CO)(L) [ L = PPh3 (1a), P(OPri)3 (2a)] на 1-(изоцианометилсульфонил)-4-метилбензол. Полученные комплексы изучены методами ИК, ЯМР спектроскопии и электрохимии. На основе спектроскопических данных предложено строение комплексовThe binuclear μ-vinylidene complexes containing an isocyanide ligand (1-(isocyanomethylsulfonyl)-4-methylbenzene) Cp(CO)2RePt(μ-C=CHPh)(TosMIC)(L) [L = PPh3 (1), P(OPri)3 (2)] were synthesized for the first time. The approach afforded 1 and 2 based on the substitution reactions of a platinum bound carbonyl group in Cp(CO)2RePt(μ-C=CHPh)(CO)(L) [L = PPh3 (1a), P(OPri)3 (2a)] upon addition of 1-(isocyanomethylsulfonyl)-4-methylbenzene. The complexes 1 and 2 were characterized by IR and NMR spectroscopy. Their redox properties were studie

Redox Properties of New Carbonyl β-diketonate Rhodium (I) Complexes Containing 1-adamantyl isocyanide Ligand

Электрохимическими методами изучены редокс-свойства новых карбонил β-дикетонатных комплексов родия (I), содержащих 1-адамантилизоцианидный лиганд, (β-diketonato) Rh(CO)(CNAd) [β-diketonato = ацетилацетонат (acac), дибензоилметан (dbm), гексафторацетилацетонат (hfac)] на платиновом, стеклоуглеродном и ртутном капельном электродах в ацетонитриле. Проведено сравнение электрохимического поведения новых комплексов с их родственными соединениями (β-diketonato) Rh(CO)(L) [L = CO, PPh3]. Показано, что механизм двухэлектронного окисления изученных комплексов зависит от природы хелатного лиганда. Одноэлектронное восстановление изоцианидных комплексов протекает при потенциалах, промежуточных между значениями Е1/2 восстановления дикарбонильных и карбонилфосфиновых комплексов родия (I), в соответствии с электронодонорной способностью терминальных лигандов CO, CNAd и PPh3The redox properties of new carbonyl β-diketonate rhodium (I) complexes containing 1-adamantyl isocyanide ligand (β-diketonato)Rh(CO)(CNAd) [β-diketonato = acetylacetonate (acac), dibenzoylmethane (dbm), hexafluoroacetylacetonate (hfac), Ad =1-adamantyl)] were studied by electrochemical methods at platinum, glassed carbon and dropping mercury electrodes in acetonitrile. The electrochemical behaviour of the new complexes and related rhodium compounds (β-diketonato)Rh(CO)(L) [L = CO, PPh3] were compared. The mechanism of two electron oxidation of the studied complexes was shown to depend on the nature of the chelate ligand. One electron reduction of the isocyanide complexes occurs at the Е1/2 values, that are found between the reduction potentials of dicarbonyl and carbonylphosphine rhodium (I) complexes. That is consistent with the electron-donating ability of the terminal CO, CNAd and PPh3 ligands at the Rh ato

Composition and stability constants of copper(II) complexes with succinic acid determined by capillary electrophoresis

The advantage of capillary electrophoresis was demonstrated for studying a complicated system owing to the dependence of direction and velocity of the electrophoretic movement on the charge of complex species. The stability constants of copper(II) complexes with ions of succinic acid were determined by capillary electrophoresis, including the 1 : 2 metal to ligand complexes which are rarely mentioned. The measurements were carried out at 25 °C and ionic strength of 0.1, obtained by mixing the solutions of succinic acid and lithium hydroxide up to pH 4.2–6.2. It was shown that while pH was more than 4.5 the zone of copper(II) complexes with succinate moves as an anion. It is impossible to treat this fact using only the complexes with a metal-ligand ratio of 1 : 1 (CuL0, CuHL+). The following values of stability constants were obtained: log β(CuL) = 2.89 ± 0.02, log β(CuHL+) = 5.4 ± 0.5, log β(CuL2 2−) = 3.88 ± 0.05, log β(CuHL2 −) = 7.2 ± 0.3

Determination of binding constants for strong complexation by affinity capillary electrophoresis: the example of complexes of ester betulin derivatives with (2-hydroxypropyl)-gamma-cyclodextrin

Complexation plays an important role in many biological phenomena, the analysis of different samples, optimization of separation processes. and increasing the pharmacological activity of drugs. This paper discusses the features of using mobility shift affinity capillary electrophoresis for studying strong complexation. Electrophoretic peaks for this case are often triangular. It was shown that the use of electrophoretic mobility obtained from the peak apex time to calculate binding constants leads to significant systematic and random errors, and the parameter a t of the Haarhoff-Van der Linde function should be used instead of the apex time. Distorted triangular peaks with dips were shown to be observed at too high a ratio of analyte concentration in the sample to ligand concentration in the background electrolyte. and the peaks and parameter at significantly shifted. It was found that the permissible excess of analyte concentration over ligand concentration was approximately 10-35, provided that the parameter a t was used, but the peak shape should be used as a landmark, and only triangular peaks without dips should be fitted with the function. The lowest possible analyte concentration should be utilized, which allows the use of a wider range of ligand concentration leading to higher precision of determining the binding constants values. Kinetically labile 1:1 complexes between (2-hydroxypropyl)-gamma-cyclodextrin (HP-gamma-CD) and betulin 3,28-diphthalate (DPhB) and betulin 3,28-disuccinate (DScB) were studied as an example. The binding constant logarithms at 25 degrees C are 7.23 +/- 0.03 and 7.13 +/- 0.10 for the HP-gamma-CD complexes of DPhB and DScB, respectively