Three-dimensional structure of phosphorus-containing heterocycles. 48. 2-methoxy-5,6-benz-1,3,2-dioxaphosphepine oxide and sulfide

Using PMR spectroscopy and the dipole moment and Kerr effect methods it has been shown that 2-methoxy-5,6-benzo-1,3,2-dioxaphosphepine oxide and sulfide are characterized by solution equlibria involving two chair-like (C) conformers e-C ⇄ a-C, which are shifted in favor of the e-C form; in the case of an equatorial orientation of the methoxy group equilibrium involves the gauche and anti rotamers, while in the case of an axial orientation (of the methoxy group) the gauche rotamer of the methyl group relative to P=O or P=S bond is stabilized. The presence of a twist conformer in the case of the oxide cannot be precluded from consideration. © 1989 Plenum Publishing Corporation

Stereochemistry of Seven-membered Heterocycles. XXXVI. Unprecedented Solvent Effect on Thermodynamical Parameters of Conformational Equilibrium of Model 1,2,3-Trithia-5,6-benzocycloheptene: Donor-Acceptor Interactions of Conformers with the Medium

Medium effect on the conformational equilibrium of a model seven-membered trisulfide represented in solutions by chair and boat conformations is studied by dynamic 1H NMR spectroscopy. Thermodynamic equilibrium parameters (ΔG0, ΔH0, and ΔS0) in nine solvents substantially differing in polar, acceptor, and donor properties, as well as in 5 M solution of lithium perchlorate in acetone are obtained. A pronounced compensation effect is revealed. The difference in the ΔH0 values in the studied media are as high as 6.6 kcal/mol, magnitudes of ΔS0 differ by up to 22 e.u. Analysis of the solvation energy components led us to conclusion that the observed effect depends on the donor-acceptor interaction of two conformers with the medium. Increasing acceptor properties of solvent result in the enthalpy stabilization of the boat form

Methodological aspects of fractionation of humus substances

The separation of humus as a nonadditive entity comprising an indefinite multitude of high-molecular substances differing in molecular weight and chemical heterogeneity into homogeneous fractions is discussed, with the developed procedure of fractional dissolution as an example. The problem of humus fractionation is theoretically solvable, but kinetic limitations make it unfeasible under laboratory conditions because of long duration. Epistemological aspects of the problem are discussed. Copyright © 2004 by MAIK "Nauka/Interperiodica" (Russia)

1H NMR spectra, dipole moments, and conformations of 3-oxo-6,7-benzo-1,5,3-dioxaphosphepines

1H NMR spectroscopy, measurements of dipole moments, and the Kerr effect have been used to study the conformational structure in solutions of 3-X-3-oxo-6,7-benzo-1,5,3-dioxaphosphepines (X=Me, Et, Ph, Cl, NEt2, OEt, OPh). On the basis of x-ray diffraction data, by means of the Dillen-Geise method, possible conformers of the seven-membered ring have been described quantitatively: chair, twist, and twist-boat. It has been shown that the compounds are characterized by a three-component equilibrium of chair and flexible forms. The relative populations of the conformers depend on the nature of the substituent X. The relationships in internal rotation around the P-Ph and P-O(R) bonds are discussed. © 1991 Plenum Publishing Corporation

Application of low pressure capacitively coupled rf hydrogen plasma for low temperature reduction of iron clusters in structure of fe-pillared materials

© Published under licence by IOP Publishing Ltd.The unique properties of pillared materials determine their use in catalysis, purification and separation. The paper studies the reduction of composite catalysts, Fe-pillared materials. The authors compare their reduction in low temperature capacitively coupled RF hydrogen discharge of low pressure to their conventional direct hydrogen reduction in a tubular muffle furnace. X-ray diffraction analysis was used to characterize the iron-bearing phases. The results show that the reduction of iron hydro/oxide clusters associated with an aluminosilicate matrix to metallic iron is very challenging due to the degree of the pore space availability for hydrogen

Spatial structure of phosphorus-containing heterocycles. 49. Vibrational spectra, dipole moments, and conformations of 2-aroxy-1,3,2-dioxaphosphepines and their benzo analogs

1. On the basis of IR and Raman vibrational spectra,1H NMR spectra, and measurements of dipole moments of 4,7-dihydro-2-aroxy-1,3,2-dioxaphosphepines, their 5,6-dichloro analogs are conformationally homogeneous and have a flexible T conformation with anti orientation of the phenoxyl radical. 5,6-Benzo-2-phenoxy-1,3,2-dioxaphosphepine is characterized by a three-component equilibrium in which both chair conformations and the twist conformation participate, with predominance of the first two. 2. In phenoxy-substituted 1,3,2-dioxaphosphepines, the plane of the benzene ring is nearly orthogonal to the plane of the {Mathematical expression}. © 1989 Plenum Publishing Corporation

Molecular structure of 2-tert-butyl-2-oxo-1,3,2-dioxaphosphepine and its benzo derivative

X-ray structure investigation of the title compounds displays a chair form with equatorial alkyl substituent. 1H NMR and PM3 semiempirical calculations have been also applied and the effect of the planar fragment on the chair-twist-boat equilibrium has been observed. © 2004 Elsevier B.V. All rights reserved

Two isomeric fourteen-membered bis-dithioacetals derived from (Z)- and (E)-but-2-ene-1,4-dithiols

(Z)-But-2-ene-1,4-dithiol was found to undergo isomerization into the E isomer. Condensation of (Z)- and (E)-but-2-ene-1,4-dithiols with acetaldehyde gave isomeric fourteen-membered bis-dithioacetals whose structure was determined by X-ray analysis. © 2009 Pleiades Publishing, Ltd

Stereochemistry of seven-membered heterocycles: XLVII. Synthesis, NMR, XRD, and theoretical investigation of monosulfoxides of (Z)-4,7-dihydro- 1λ4,3-dithiepine series

By oxidation of (Z)-4,7-dihydro-1,3-dithiepines with meta-chloroperbenzoic acid the corresponding 4,7-dihydro-1λ4,3-dithiepine 1-oxides were synthesized in ∼85% yield. A complete assignment of signals in the 1H and 13C NMR spectra of the compounds obtained was established. According to XRD analysis the seven-membered heterocycles crystallized in conformations chair or boat. The calculations by DFT method in the B3LYP/6-31G(d,p) version showed the possibility of conformational equilibrium of these forms in the gas phase. © 2010 Pleiades Publishing, Ltd

ШЕСТИЛЕТНИЙ ОПЫТ ТРАНСПЛАНТАЦИИ СЕРДЦА В ФГБУ «СЕВЕРО-ЗАПАДНЫЙ ФЕДЕРАЛЬНЫЙ МЕДИЦИНСКИЙ ИССЛЕДОВАТЕЛЬСКИЙ ЦЕНТР ИМЕНИ В.А. АЛМАЗОВА»

Aim. To estimate the results of 6-year experience of heart transplantation (HT) in Federal Almazov North-West Medical Research Centre. Methods. From 2010 to 2015 we have performed 65 HT. Mean age was 44.3 ± 14 years old (from 10 to 64 years old). We used biventricular assist device (BIVAD, Berlin Heart Excor) support in 7 heart transplant candidates before HT. 19 patients (29%) received thymoglobulin, whereas 46 patients (71%) had basiliximab to induce immunosuppression.Results. Extracorporeal membrane oxygenation machines were implanted in 5 patients (7.7%) after HT due to acute right ventricular failure. Suture annuloplasty (the Batista procedure) for tricuspid valve repair was carried out in 3 cases (4.6%). Venovenous hemodiafi ltration was used in 11 patients (16.9%). A total of 598 endomyocardial biopsies (EMB) were performed after HT. Evidence of cellular rejection (R1 and R2) was presented in 286 biopsies (48%). The 30-day in-hospital mortality rate was 3.1%. The 6-month survival rate after HT was 92%, 1-year – 91% and overall survival for the 6-year period of observation – 89.2%. Maximum observation period was 71 months.Conclusions. The 6-year experience of HT in our Center has shown a high level of survival. BIVAD Excor support can be effectively used as a «bridge» to HT. Prevention of graft loss due to acute rejection in heart transplant recipients can be achieved only through regular EMB monitoring. The rate of viral infection increased in 2 months after HT.Цель исследования. Оценить результаты трансплантаций сердца (ТС), выполненных в ФГБУ «Северо-Западный федеральный медицинский исследовательский центр имени В.А. Алмазова» за шесть лет.Материалы и методы. В период с 2010-го по 2015 год в Центре было выполнено 65 ТС. Средний возраст реципиентов составил 44,3 ± 14 лет (от 10 до 64 лет). В качестве «моста» к ТС у 7 пациентов перед пересадкой были имплантированы устройства вспомогательного кровообращения (УВК) Excor. Для индукции иммуносупрессивной терапии у 19 пациентов (29%) применялся антитимоцитарный иммуноглобулин, у 46 пациентов (71%) – базиликсимаб.Результаты. У 5 (7,7%) пациентов, в связи с тяжелой правожелудочковой недостаточностью, в раннем периоде после ТС была установлена система ЭКМО. У 3 (4,6%) больных ввиду развития трикуспидальной недостаточности была выполнена пластика трикуспидального клапана по Батиста. Проведение сеансов заместительной почечной терапии после ТС потребовалось у 11 (16,9%) реципиентов. Всего за шестилетний период наблюдения у всех пациентов было выполнено 598 эндомиокардиальных биопсий (ЭМБ). В 286 (48%) случаях диагностировано клеточное отторжение трансплантата стадии R1 или R2. 30-дневная госпитальная летальность составила 3,1% (2 пациента). Выживаемость в отдаленном периоде составила: через 6 месяцев – 92%, через 1 год – 91%, общая выживаемость за 6 лет наблюдения – 89%. Максимальный срок наблюдения – 71 месяц.Заключение. Шестилетний опыт ТС в нашем Центре показал высокий уровень выживаемости после операции. Имплантация УВК является «мостом» к ТС у больных с терминальной стадией ХСН. ЭМБ остается единственным эффективным методом диагностики острого отторжения трансплантата сердца. Через два месяца после ТС в структуре инфекционных осложнений увеличивается частота вирусной инфекции