In memory of V. M. Zhulin

Chronicle

In memory of V. M. Zhulin     

V Blue Danube Symposium on Heterocyclic Chemistry

Information Congresses, Conferences, Symposia, Workshops, and Seminars in the Field of Chemical Sciences Held with Participation of the Russian Academy of Sciences

V Blue Danube Symposium on Heterocyclic Chemistry     

Kataliz reaktsii organicheskikh soedinenii sery (Catalysis in Reactions of Organosulfur Compounds) by A.V. Mashkina, Novosibirsk: Sib. Otd. Ross. Akad. Nauk, 2005

Book Abstracts

Kataliz reaktsii organicheskikh soedinenii sery (Catalysis in Reactions of Organosulfur Compounds) by A.V. Mashkina, Novosibirsk: Sib. Otd. Ross. Akad. Nauk, 2005     

Computational studies of human class V alcohol dehydrogenase - the odd sibling

Background

All known attempts to isolate and characterize mammalian class V alcohol dehydrogenase (class V ADH), a member of the large ADH protein family, at the protein level have failed. This indicates that the class V ADH protein is not stable in a non-cellular environment, which is in contrast to all other human ADH enzymes. In this report we present evidence, supported with results from computational analyses performed in combination with earlier in vitro studies, why this ADH behaves in an atypical way.

Results

Using a combination of structural calculations and sequence analyses, we were able to identify local structural differences between human class V ADH and other human ADHs, including an elongated β-strands and a labile α-helix at the subunit interface region of each chain that probably disturb it. Several amino acid residues are strictly conserved in class I–IV, but altered in class V ADH. This includes a for class V ADH unique and conserved Lys51, a position directly involved in the catalytic mechanism in other ADHs, and nine other class V ADH-specific residues.

Conclusions

In this study we show that there are pronounced structural changes in class V ADH as compared to other ADH enzymes. Furthermore, there is an evolutionary pressure among the mammalian class V ADHs, which for most proteins indicate that they fulfill a physiological function. We assume that class V ADH is expressed, but unable to form active dimers in a non-cellular environment, and is an atypical mammalian ADH. This is compatible with previous experimental characterization and present structural modelling. It can be considered the odd sibling of the ADH protein family and so far seems to be a pseudoenzyme with another hitherto unknown physiological function.

     

III–V colloidal nanocrystals: control of covalent surfaces

Colloidal quantum dots (QDs) are nanosized semiconductors whose electronic features are dictated by the quantum confinement effect. The optical, electrical, and chemical properties of QDs are influenced by their dimensions and surface landscape. The surface of II–VI and IV–VI QDs has been extensively explored; however, in-depth investigations on the surface of III–V QDs are still lagging behind. This Perspective discusses the current understanding of the surface of III–V QDs, outlines deep trap states presented by surface defects, and suggests strategies to overcome challenges associated with deep traps. Lastly, we discuss a route to create well-defined facets in III–V QDs by providing a platform for surface studies and a recently reported approach in atomistic understanding of covalent III–V QD surfaces using the electron counting model with fractional dangling bonds.

Unveiling the atomistic surface structure of colloidal quantum dots may provide the route to rational design of highly performing III–V nanocrystals with control over energy levels position, surface energy, trap passivation, and heterojunction interface.     

Sectrophotometric determination of vanadium(V) with 7-amino-1-naphthol-3,6-disulphonic acid

Summary Vanadium(V) reacts with 7-amino-1-naphthol-3,6-disulphonic acid (2 R-acid) in the ratio 21, forming a red coloured chelate having maximum absorbance at 470 nm. The composition of the chelate has been found by the continuous variations and the mole ratio methods. The system obeys Beer's law between a range of 1.72 to 30.9 p. p. m. of vanadium and the sensitivity is 0.17g/cm² at pH 2.0, The reagent is found to be fairly selective for vanadium.

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Zusammenfassung Vanadin(V) reagiert mit 7-Amino-l-naphthol-3,6-disulfonsäure im Ver-hältnis 21 und bildet ein rotes Chelat mit dem Absorptionsmaximum bei 470 nm, dessen Zusammensetzung nachJob bestimmt wurde. Zwischen 1,72 und 30,9 ppm V ist das Beersche Gesetz erfüllt. Die Empfindlichkeit beträgt 0,17g/cm² (Sandell) bei pH 2,0. Das Reagens ist für Vanadin ziemlich selektiv.

     

Synthesis,spectral and structural studies of oxovanadium(IV/V) complexes derived from 2-hydroxyacetophenone-3-hydroxy-2-naphthoylhydrazone: polymorphs of oxovanadium(V) complex [VOL(OCH<Subscript>3</Subscript>)]

Abstract  

Oxovanadium(IV/V) complexes of 2-hydroxyacetophenone-3-hydroxy-2-naphthoylhydrazone (H₂L) have been synthesized and characterized. The complexes were characterized by elemental analyses, IR, electronic and EPR spectra. The oxovanadium(V) complex [VOL(OCH₃)] is crystallized in two polymorphic forms, denoted by 1a and 1b, with space groups Pn2₁a and P_[`1] P_{{\bar{1}}} , respectively. Both have distorted square pyramidal structures.     

Synthesis, characterization, reactivity and catalytic activity of oxidovanadium(IV), oxidovanadium(V) and dioxidovanadium(V) complexes of benzimidazole modified ligands

The reaction between [V(IV)O(acac)(2)] and the ONN donor Schiff base obtained by the condensation of pyridoxal and 2-aminoethylbenzimidazole (Hpydx-aebmz, I) or 2-aminomethylbenzimidazole (Hpydx-ambmz, II) in equimolar amounts results in the formation of [V(IV)O(acac)(pydx-aebmz)] 1 and [V(IV)O(acac)(pydx-ambmz)] 2, respectively. The aerobic oxidation of the methanolic solution of 1 yielded [V(V)O(2)(pydx-aebmz)] 3 and its reaction with aqueous H(2)O(2) gave the oxidoperoxidovanadium(v) complex, [V(V)O(O(2))(pydx-aebmz)] 4. The formation of 4 in solution is also established by titrations of methanolic solutions of 1 with H(2)O(2). By titrating solutions of 3 and of 4 with aqueous H(2)O(2) several distinct V(V)-pydx-aebmz species also containing the peroxido ligand are detected. The full geometry optimization of all species envisaged was done using DFT methods for suitable model complexes. The (51)V NMR chemical shifts (δ(V)) have also been calculated, the theoretical data being used to support assignments of the experimental chemical shifts. The (51)V hyperfine coupling constants are calculated for 1, the obtained values being in good agreement with the experimental EPR data. Reaction between the V(IV)O(2+) exchanged zeolite-Y and Hpydx-aebmz and Hpydx-ambmz in refluxing methanol, followed by aerial oxidation results in the formation of the encapsulated V(V)O(2)-complexes, abbreviated herein as [V(V)O(2)(pydx-aebmz)]-Y 5 and [V(V)O(2)(pydx-ambmz)]-Y 6. The molecular structure of 1, determined by single crystal X-ray diffraction, confirms its distorted octahedral geometry with the ONN binding mode of the tridentate ligand, with one acetylacetonato group remaining bound to the V(IV)O-centre. Oxidation of styrene is investigated using some of these complexes as catalyst precursors with H(2)O(2) as oxidant. Under optimised reaction conditions for the conversion of styrene in acetonitrile, a maximum of 68% conversion of styrene (with [V(V)O(2)(pydx-aebmz)]-Y) and 65% (with [V(V)O(2)(pydx-ambmz)]-Y) is achieved in 6 h of reaction time. The selectivity of the various products is similar for both catalysts and follows the order: benzaldehyde (ca. 55%) > 1-phenylethane-1,2-diol > benzoic acid > styrene oxide > phenyl acetaldehyde. Speciation of the systems and plausible intermediates involved in the catalytic oxidation processes are established by UV-Vis, EPR, (51)V NMR and DFT studies. Both non-radical (Sharpless) and radical mechanisms of the olefin oxidations were theoretically studied, and the radical pathway was found to be even more favorable than the Sharpless mechanism.     

Infrared laser enhanced reactions: V→V and V→T energy transfer in the O3SiF4O2 system

Rapid V→V energy transfer between SiF₄ and O₃ has been observed following laser excitation of either O₃ or SiF₄. A CO₂ laser tuned to either the 9.6 μ P(30) or P(32) transitions was used to promote vibrational excitation in O₃ and SiF₄, respectively. In experiments employing the P(32) transition, the V→V transfer to O₃ and subsequent reaction of O₃² with NO were used to obtain the rate constant of V→T deactivation of SiF₄² by O₂.

Fractional modulation measurements of the chemiluminescence generated by the O₃ + NO reaction were used in experiments employing the P(30) transition to obtain a rate constant for the V→V energy transfer between O₃² and SiF₄.

     

Preparation of no-carrier-added48V(IV) and48V(V) for biological tracer use

The preparation of no-carrier-added⁴⁸V(IV) and⁴⁸V(V) from a natural titanium target irradiated by a proton beam has been developed. The⁴⁸V recovered from the target by solvent extraction was purified as⁴⁸V(V) with a cation exchange column and then converted to⁴⁸V(IV) by reduction with ethanol. One hour irradiations at 10 A of 18 MeV protons gave approximately 2mCi (a radiochemical yield of 41%) of radiochemically pure and almost salt-free⁴⁸V(IV) and⁴⁸V(V) with high specific activities. They were shown to be suitable for biological tracer use.     

Co-ordination complexes of niobium and tantalum. XVIII. Peroxo-EDTA Niobates(V) and Tantalates(V)

Preparation and Properties of peroxoethylenediaminetetraacetato niobates(V) and tantalates(V) are reported. These stable, crystalline complexes can be recrystallized from aqueous and hydrogen peroxide solutions. According to chemical and spectral evidence the complexes correspond to the formula M[M^V (O₂)₃EDTA] nH₂O₂, M^I = K, NH₄; M^V = Nb, Ta; n ≤ 1. Niobium and tantalum compounds are isomorphous.     

Triterpene glycosides and their genins fromThalictrum foetidum. V. Structure of cyclofoetoside B

A new glycoside (cyclofoetoside B) (I) has been isolated from the epigeal part of the plantThalictrum foetidum L. (Ranunculaceae). On the basis of chemical transformations and with the aid of physicochemical characteristics it has been established that cyclofoetoside B is 24S-cycloartane-3, 16, 24, 25, 29-pentaol 3-O--L-arabinopyranoside 16-O-[O--L-rhamnopyranoside-(1 6)--D-glucopyranoside], C₄₇-H₈₀O₁₇, mp 194–197°C (methanol); [] _D ²⁴ +15.7 ± 2° (c 0.88; pyridine). The enzymatic hydrolysis of (I) has yielded cyclofoetigenin B (III), 24S-cycloartane-3,16,24,25,29-pentaol 16-O--D-glucopyranoside, (IV), C₃₆H₆₂O₁₀, mp 223–225°C (acetone), [] _D ²⁴ +37 ± 2° (c 0.97; methanol) and 24S-cycloartane-3,16,24,25,29-pentaol 16-O-[O--L-rhamnopyranosyl-(1 6)--D-glucopyranoside, C₄₂H₇₂O₁₄, mp 229–231°C (methanol), [] _D ³⁰ +41 ± 2° (c 0.7; methanol). Details of the IR and¹H and¹³C NMR spectra of the compounds are given.Irkutsk Institute of Organic Chemistry, Academy of Sciences of the USSR. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Trashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 341–345, May–June, 1986.     

Thermoanalytical studies of organic compounds. part V

This paper deals with the thermal analysis of the new benzoyl, methoxy- and ethoxycarbonyl-3-hydroxybenzisoxazoles by means of derivatograph. In the serial stages of tautomeric, isomeric and decarboxylic transformation, the newN-acylated benzisoxazolin-3-ones, benzoxazolin-2-ones and 3-alkylbenzoxazolin-2-ones were obtained.

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Zusammenfassung Der Artikel befasst sich mit der Thermoanalyse der neuen Benzoyl-, Methoxy- und Äthoxycarbonyl-3-hydroxybenzisoxazolen unter Anwendung der derivatographischen Methode. Die neuen N-acylierten Benzisoxazolin-3-one, Benzoxazolin-2-one und 3-Alkylbenzoxazolin-2-one wurden an Hand der Stufenfolge tautomerer, isomerer und Decarboxilierungs-Umwandlungen erhalten.

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Résumé Le comportement thermique de nouveaux benzoyl, méthoxy et éthoxycarbonyl-3-hydroxybenzisoxazoles a été étudié à l'aide d'un Derivatograph. Lors des étapes successives correspondant aux transformations tautomères, isomères et de décarboxylation, il se forme de nouvelles N-acétylées benzisoxazoline-3-ones, benzoxazoline-2-ones et 3-alkylbenzoxazoline-2-ones.

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-, - -3- -3- . , , , N-a -3-, -2- 3- -2-.

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Part IV. E. Domagalina, T. Sawik, Acta Pol. Pharm. 33/1976/623.

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Work partly supported by Faculty of Medicine, Polish, Academy of Sciences.     

Phase relations in the system V/Nb/O. V. Investigation of mixed crystals V1-xNbxO2

Mixed crystals V_1-xNb_xO₂ exist over the whole area of the quasibinary line VO₂-NbO₂. The existence of Nb_{5+ beside V3+ and V4+ on the V-rich side and V3+ beside Nb5+ and Nb4+ on the Nb-rich side of the mixed crystals is demonstrated by XANES-measurements. The compound VNbO}4_(V0.5_Nb0.5_O2_{) is described as a double oxide with vanadium only as V3+ and niobium only as Nb5+. At this point the electric resistivity of the solid solution shows a maximum.}     

Enantioselective O-acetylcyanation/cyanoformylation of aldehydes using catalysts with built-in crown ether-like motif in chiral macrocyclic V(V) salen complexes

Chiral macrocyclic V(V) salen complexes 1a-f derived from macrocyclic ligands obtained by the reaction of 1R,2R-(−) diaminocyclohexane/(1R,2R)-(+)-1,2-diphenylethylenediamine with bis-aldehydes 2 and 3 were synthesized and used as efficient catalysts in asymmetric cyanation reactions. The V(V) catalysts demonstrated excellent performance (product yields and ees up to 99%) with potassium cyanide (KCN) and sodium cyanide (NaCN). The catalytic system also performed very well with a safer source of cyanide-ethyl cyanoformate to give cyanohydrin carbonates in excellent yield and ee (up to 97%). The V(V) macrocyclic salen complex 1b retained its performance at multi-gram level and was conveniently recycled for a number of times.     

Trennung der 8-Hydroxychinolate von V, Mo, W, Co und Cr durch HPLC

Zusammenfassung 8-Hydroxychinolin-Chelate von V, Mo, W, Co, Cr können mit der Hochdruckflüssigkeits-Chromatographie getrennt werden [polare stationäre Phase: Si 60; Eluentien: Tetrahydrofuran/Chloroform (64) bzw. Dioxan/Chloroform (64)]. Die Nachweisgrenzen sind: < 1 ng für V, Mo und Cr; 0,5 ng für Co; 1,5 ng für W.

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Separation of the 8-hydroxyquinolinates of V, Mo, W, Co and Cr by HPLC

Summary The oxinates of V, Mo, W, Co and Cr can be separated by HPLG employing Si 60 as stationary phase and either tetrahydrofuran/chloroform (64) or dioxan/chloroform (64) as eluents. Limits of detection are: < 1 ng for V, Mo and Cr; 0.5 ng for Co; 1.5 ng for W.

Ich danke der Deutschen Forschungsgemeinschaft für die Bereitstellung von Geräten und Sachbeihilfen.Mein besonderer Dank gilt Frl. Pohlmann für die Durchführung zahlreicher Meßreihen.     

Phase relations in the system V/Nb/O. V. Investigation of mixed crystals V1-xNbxO2

Mixed crystals V_1-xNb_xO₂ exist over the whole area of the quasibinary line VO₂-NbO₂. The existence of Nb_{5+ beside V3+ and V4+ on the V-rich side and V3+ beside Nb5+ and Nb4+ on the Nb-rich side of the mixed crystals is demonstrated by XANES-measurements. The compound VNbO}4_(V0.5_Nb0.5_O2_{) is described as a double oxide with vanadium only as V3+ and niobium only as Nb5+. At this point the electric resistivity of the solid solution shows a maximum.} Received: 11 May 1998 / Revised: 4 August 1998 / Accepted: 10 August 1998     

Rapid and simple chromatographic separation of V(V) and V(IV) using KH-phthalate and their determination by flame atomic absorption spectrometry

A method was developed for the chromatographic separation of V(V) and V(IV) based on the different sorption forces of these vanadium species in C18 columns in presence of KH-phthalate. The vanadium species were detected with a flame atomic absorption spectrometer with acetylene/N₂O flame. The detection limits (3σ) of V(V) and V(IV) were 0.18 μg/mL and 0.15 μg/mL, respectively. The relative standard deviations (N = 5) are 4.2% and 3.4% for 20–20 μg/mL V(V) and V(IV), respectively. The sampling frequency is 75/h. Because of the special interaction occurring between phthalate and V(IV) on the C18 column and the acetylene/N₂O flame atomic absorption detection, practically no interferences can be detected even in large inorganic matrix.     

New specific methods for the detection of chromium(VI) and vanadium(V) using primaquin

Summary New specific methods have been developed for the detection of chromium(VI) and of vanadium(V), based on the formation of a purple color with primaquin in concentrated sulfuric acid solution. The identification limits and dilution limits have been determined to be 0.05g, 11 000 000 for chromium(VI) and 0.1g, 1500 000 for vanadium(V) respectively.

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Neue spezifische Methoden zum Nachweis von Cr(VI) und V(V) mit Primachin

Zusammenfassung Die neu ausgearbeiteten Methoden sind spezifisch und beruhen auf der Bildung einer Purpur-Färbung mit Primachin in konz. Schwefelsäure. Die Nachweisgrenzen und Verdünnungsgrenzen betragen 0,05g bzw. 11 000 000 für Cr(VI) und 0,1g bzw. 1500 000 für V(V).