Components of natural gas resulting from thermal degradation of the blue-green alga (cyanobacterium)Oscillatoria tenuis

Cultures of the blue-green alga (cyanobacterium)Oscillatoria tenuis were used to simulate thermal degradation and gas formation by heating without oxygen at 250° and 350 °C for 100 h. Analysis through gas chromatography showed that the gases were mainly CH₄, C₂H₆, C₃H₈, iC₄ (isobutane), nC₄ (normal butane), iC₅ (isopentane), nC₅ (normal pentane), H₂, C0₂ and N₂. The volume of gases per g dry weight of alga was 44 ml at 250 °C and 100 ml at 350 °C. Alkane gas comprised only 2.04% of the total at 250 °C and rising to 40.0% at 350 °C. The fraction of C0₂ decreased from 83.3% at 250 °C to 40.0% at 350 °C. The quantity of alkane in the soluble organic matter doubled with rising temperature but the H/C atomic ratio in the ‘kerogen’, insoluble organic matter, decreased sharply. Infrared spectra of the ‘kerogen’ showed that the peak of adipose radical at 2900 cm⁻¹ disappeared gradually with rising temperature, which reflects the gradual break of CH₄ or C₂H₆ from ‘kerogen’. This demonstrates that insoluble organic matter rather than soluble organic matter in blue-green algae are the main sources of the gas alkanes in the process of simulated thermal degradation.     

Evaluation of preferred binding regions on ubiquitin and IgG1 FC for interacting with multimodal cation exchange resins using DEPC labeling/mass spectrometry

There is significant interest in identifying the preferred binding domains of biological products to various chromatographic materials. In this work, we develop a biophysical technique that uses diethyl pyrocarbonate (DEPC) based covalent labeling in concert with enzymatic digestion and mass spectrometry to identify the binding patches for proteins bound to commercially available multimodal (MM) cation exchange chromatography resins. The technique compares the changes in covalent labeling of the protein in solution and in the bound state and uses the differences in this labeling to identify residues that are sterically shielded upon resin binding and, therefore, potentially involved in the resin binding process. Importantly, this approach enables the labeling of many amino acids and can be carried out over a pH range of 5.5–7.5, thus enabling the protein surface mapping at conditions of interest in MM cation exchange systems. The protocol is first developed using the model protein ubiquitin and the results indicate that lysine residues located on the front face of the protein show dramatic changes in DEPC labeling while residues present on other regions have minimal or no reductions. This indicates that the front face of ubiquitin is likely involved in resin binding. In addition, surface property maps indicate that the hypothesized front face binding region consists of overlapping positively charged and hydrophobic patches. The technique is then employed with an IgG1 F_C and the results indicate that residues on the C_H2–C_H3 interface and the hinge are significantly sterically shielded upon binding to the resin. Further, these regions are again associated with significant overlap of positively charged and hydrophobic patches. On the other hand, while, residues on the C_H2 and the front face of the IgG1 F_C also exhibited some changes in DEPC labeling upon binding, these regions have less distinct charged and hydrophobic patches. Importantly, the hypothesized binding patches identified for both ubiquitin and F_C using this approach are shown to be consistent with previously reported NMR studies. In contrast to NMR, this new approach enables the identification of preferred binding regions without the need for isotopically labeled proteins or chemical shift assignments. The technique developed in this work sets the stage for the evaluation of the binding domains of a wide range of biological products to chromatographic surfaces, with important implications for designing biomolecules with improved biomanufacturability properties.     

Further crystallographic evidence of NH· · ·π (system) and CO· · ·π (system) interactions: The structures of bis(diarylhydrazonecarbonyl)methylene derivatives [{ArPhCNNH—C(O)}2CH2] (Ar = Ph, 2‐C5H4N, 2‐C4H3S)

In this study are reported the syntheses of three bis(diarylhydrazonecarbonyl)methylene derivatives [{ArPhCNNH C(O)}₂CH₂] [Ar = 2 C₅H₄N (5), C₆H₅ (6), and 2‐C₄H₃S (7)], obtained by condensation of corresponding hydrazones with carbon suboxide, C₃O₂. The solid‐state self‐assembly of these carbonyl derivatives, giving rise to polymeric and dimeric networks, is described. In the formation of these structural features, in addition to N—H· · ·OC intermolecular hydrogen bonds, stabilizing intramolecular NH· · · π (systems) and intermolecular CO· · ·π (systems) interactions also seem to play an important role. Solution ¹H‐nmr data of compounds 5–7 indicate that the polymeric and dimeric structures are not maintained in solution and show the occurrence of keto‐enolic equilibria. © 1999 John Wiley & Sons, Inc. Biopoly 49: 541–549, 1999     

Studies on Polyoxins,Antifungal Antibiotics

Seven additional components, polyoxins C, D, E, F, G, H and I were isolated from polyoxin complex. They have molecular formulae corresponding to C₁₁H₁₅N₃O₈, C₁₇H₂₃N₅O₁₄, C₁₇H₂₃N₅O₁₃, C₂₃H₃₀N₆O₁₅, C₁₇H₂₅N₅O₁₂, C₂₃H₃₂N₆O₁₃ and C₁₉H₂₄N₄O₁₂, respectively. These polyoxins except inactive polyoxins C and I were highly active against various kinds of phytopathogenic fungi. The close structural similarity among them including polyoxins A and B is also discussed.     

Studies on Mitomycins,Carcinostatic Antibiotics

Mitomycin A (C₁₆H₁₉O₆N₃) and mitomycin C (C₁₅H₁₈O₅N₄) are pigments which have the quinoid structure. When treated with aqueous ammonia, mitomycin A is converted to mitomycin C. Acid hydrolysis of mitomycin C gave three degradation products, namely, C₁₄H₁₅O₅N₄, C₁₄H₁₅O₆N₃ and C₁₃H₁₄O₅N₂. Acetylation with acetic anhydride and pyridine and methylation with methyl iodide gave monoacetyl and monomethyl derivatives of mitomycin C respectively, though diacetate of demethyl derivatives were obtained when boiled with acetic anhydride.     

Five- and six-coordinate hydridorhodium(III) complexes containing metalated Schiff-bases as ligands

The reactions of either [RhCl(C₈H₁₄)₂]₂ (2) or [RhCl(C₂H₄)₂]₂ (3) with Schiff-bases 1a-d derived from 2-aminopyridine afford, in the presence of four equivalents of PiPr₃, the octahedral chloro(hydrido)rhodium(III) complexes [{(C₅H₄N)NC(C₆H₄R)}RhHCl(PiPr₃)₂] (4a-d) in which the metalated Schiff-base behaves as a chelating ligand. Treatment of 4a (RH) with NaI and CF₃SO₃Tl produce the corresponding derivatives [{(C₅H₄N)NC(C₆H₅)}RhHX(PiPr₃)₂] (5, 6) by salt metathesis. The triflato compound 6 reacts with nBu₄NF · xH₂O to give [{(C₅H₄N)NC(C₆H₅)}RhHF(PiPr₃)₂] (7). While attempts to eliminate HCl from 4a failed, the reaction of 4a with AgPF₆ generates the five-coordinate cationic complex [{(C₅H₄N)NC(C₆H₅)}RhH(PiPr₃)₂]PF₆ (8) which adds one equivalent of acetonitrile to give [{(C₅H₄N)NC(C₆H₅)}RhH(NCCH₃)(PiPr₃)₂]PF₆ (9). Treatment of 4a with either nBu₂Mg or LiAlH₄ affords the dihydridorhodium(III) compound [{(C₅H₄N)NC(C₆H₅)}RhH₂(PiPr₃)₂] (10) being also accessible from 8 and nBu₂Mg.     

Studies on reactions of metallic iron with mixtures of aryl carboxylic acids (ArCOOH) and organic halides relevant to corrosion of steel. Preparation of [FeX(OCOAr)]n (X = Cl,Br, I) and its characterization

Crystalline, multinuclear [FeX(OCOAr)]_n (X = Cl, Br, I; Ar = C₆H₅, C₆H₅CHCH, C₆H₅CH₂) is produced by reactions acids (ArCOOH) and alkyl halides (RX). The reactions proceed smoothly above 180 °C, and the formation of [FeX(OCOAr)]_n is accompanished by formation of ester (ArCOOR), and H₂; the stoichiometry of the reaction is expressed by an equation, Fe + 2 ArCOOH + RX → (1/n)[FeX(OCOAr)]_n + ArCOOR + H₂. [FeX(OCOAr)]_n has been characterized by elemental analysis, its chemical reactivities with basic ligands, IR spectroscopy, powder X-ray diffraction pattern, thermogravimetric analysis, and magnetic susceptibility. A reaction mechanism involving a successive reaction of ArCOOH and RX with iron is proposed to elucidate the formation of [FeX(OCOAr)]_n. A reaction of metallic iron with a mixture of C₆H₅COOH and CCl₄ gives C₆H₅COCl in a good yield.     

Amidino-complexes of iron(II) and (III)

Lithioamidines {R′N(Li)C(R)NR′, I; R = CH₃, R′ = C₆H₅, p-CH₃,C₆H₄} react with iron(III) chloride

in monoglyme to produce navy-blue, high spin Fe{R′NC(R)NR′}₃ complexes which are extremely air and moisture sensitive. The corresponding reaction when R = R′ = C₆H₅ produces a soluble red complex and an air-stable green complex, whereas when R = H, R′ = C₆H₅ and R = R′ = C₆H₅ and the reaction is started at ca. ?20°, red and green complexes respectively are formed. Though all the complexes are formulated Fe{R′NC(R)NR′}₃, their properties reflect association through bridging amidino-groups. Iron(II) chloride reacts with I(R = CH₃, R′ = p-CH₃C₆H₄) to form two complexes, one crimson and soluble in organic solvents, and one brown and insoluble, which are fomulated [Fe{R′NC(R)NR′}₂]_n. The iron(III) complexes failed to react with, or were decomposed by, a variety of reducing, electrophilic and nucleophilic reagents, though blue Fe{p-CH₃C₆H₄NC(CH₃)N-p-CH₃C₆H₄}₃ reacts readily with nitric oxide to form a purple addition complex from which the N-nitroso-compound p-CH₃C₆H₄NC(CH₃)N(NO)-p-CH₃C₆H₄ was obtained in high yield. Treatment of the corresponding brown iron(II) complex with nitric oxide gave no reaction.     

Screening for potential energetic C–N cages with high energy and good stability: a theoretical comparative study

This paper presents a theoretical study on carbon-nitrogen cages as potentially high energy density materials (HEDMs) using density functional theory. The energetic properties, detonation performance, and stability of two C₆N₆H₁₂ cages were researched comparison with two similar common cage compounds hexaazaisowurtzitane and cubane. Results indicate that both of two C₆N₆H₁₂ cages have high positive heat of formation and good stability. Their densities and detonation characteristics are equivalent or slightly superior to those of hexaazaisowurtzitane and cubane, indicating that they have good detonation performance.     

Synthesis, characterization and structure of some arylantimony ferrocenylacrylates

A series of arylantimony ferrocenylacrylates with the formula (C₅H₅FeC₅H₄CHCHCO₂)_nSbAr_(5−n) (n=1, 2; Ar C₆H₅, 4-CH₃C₆H₄, 3-CH₃C₆H₄, 2-CH₃C₆H₄, 4-FC₆H₄) have been synthesized and characterized by elemental analysis, IR, ¹H NMR and mass spectra. The crystal structures of C₅H₅FeC₅H₄CHCHCO₂Sb(C₆H₅)₄ (I₁) and (C₅H₅FeC₅H₄CHCHCO₂)₂Sb(C₆H₅)₃ (II₁) have been determined by X-ray diffraction.     

An aluminoborate cluster [AlB12O14(OH)12]: Synthesis and structure of [C5H6N][AlB12O14(OH)12]

A new aluminoborate, [C₅H₆N][AlB₁₂O₁₄(OH)₁₂], has been hydrothermally synthesized at 200 °C. The single-crystal diffraction study reveals that it crystallizes in space group C2/c. It consists of aluminoborate clusters [AlB₁₂O₁₄(OH)₁₂]⁻ and counterions [C₅H₆N]⁺. The aluminoborate cluster contains an Al(OH)₆ octahedron as a core that is capped by two raft-like polyborate units [B₆O₇(OH)₆]. These clusters are further interlinked by extensive hydrogen bonding to form a three-dimensional (3D) network, containing large channels along the b-axis, in which the [C₅H₆N]⁺ cations are located.     

Gas phase assembly and X-ray crystal structure of copper(I) 3,5-bis(trifluoromethyl)benzoate network with corannulene

Gas-phase co-deposition of [Cu(O₂C(3,5-CF₃)₂C₆H₃)] (1) with C₂₀H₁₀ at 170 °C affords crystals of the first copper(I)-corannulene adduct [Cu₆(O₂C(3,5-CF₃)₂C₆H₃)₆](C₂₀H₁₀)₂ (2). The X-ray crystallographic characterization of 2 reveals its main structural building blocks: a planar hexanuclear metal core supported by bridging 3,5-bis(trifluoromethyl)benzoate groups and two corannulene molecules. The Cu?Cu distances within the core of 2.6826(8)-2.7607(8) Å fall within the range of cuprophilic interactions. Several intermolecular Cu?C contacts between the cyclic Cu₆-unit and corannulene ranging from 2.799(5) to 3.266(5) Å can be identified. The shortest ones lying within the sum of the van der Waals radii for Cu and C (Σr_vdW (Cu, C) = 3.10 Å) are to the rim sites of corannulene. A noticeable flattening of the C₂₀H₁₀-bowl in 2 is also observed.     

In vitro anti-leishmanial activities of germatranyl and Silicon incorporated diorganotin derivatives: Synthesis and spectroscopic properties

A series of germanium and silicon incorporated diorganotin derivatives of general formula where R¹ = H₃C, C₆H₅, p-CH₃C₆H₄, p-FC₆H₄; R² = H₂CSi(CH₃)₂C₆H₅, H₂CC₆H₅, p-CH₃C₇H₇ were synthesized by the reaction of appropriate diorganotin dichlorides and germatranyl (substituted) propionic acid in 1:2 mole ratio, respectively. The evidence regarding their structure is mainly based on spectroscopic data obtained by multinuclear (¹H, ¹³C, ²⁹Si, ¹¹⁹Sn) NMR and ^119mSn Mössbauer, IR and mass spectral studies in combination with melting points and elemental analyses. The compounds have been screened for in vitro anti-leishmanial activity against promastigotes of Leishmania major and the results offer potent activities which are better than the standard drug, pentamidine, for one compound.     

The Abiotic Formation of Hydrocarbons from Dissolved CO2 Under Hydrothermal Conditions with Cobalt-Bearing Magnetite

Conversion of CO₂ to organic compounds in hydrothermal systems is important in understanding prebiotic chemical evolution leading to the origin of life. However, organic compounds with carbon number of more than 3 have never been produced from dissolved CO₂ in simulated hydrothermal experiments. In this paper, we report that not only CH₄, C₂H₆ and C₃H₈, but also n-C₄H₁₀ and n-C₅H₁₂ could be produced from dissolved CO₂ and H₂ in the presence of cobalt-bearing magnetite at 300°C and 30 MPa. It is shown that unbranched alkanes in Anderson–Schulz–Flory distribution were the dominant hydrocarbon products produced from dissolved CO₂ catalyzed by cobalt-bearing magnetite under certain hydrothermal conditions. It is proposed that magnetite with other transition metals may act potentially as effective mineral catalysts for abiotic formation of organic compounds from dissolved CO₂ in hydrothermal systems.     

Destabilization of CH2 domains in intact IgG2 is accompanied by reduced ability to inhibit complement system factor C1

Fc fragments (hFc) of human myeloma IgG2 proteins LOM and SIN having core hinge (Cys-Cys-Val-Glu-Cys-Pro-Pro-Cys) were first obtained by a modified proteolytic procedure. The thermostability of C_H2 domains inside of standard Fc, hFc fragments, and intact IgG2 LOM and SIN was studied by fluorescence spectroscopy. It was found that C_H2 domains of intact IgG2 are destabilized. The destabilization is accompanied by reduced ability of IgG2 to inhibit the activation of complement system by classical pathway. This could be due to the decrease in the affinity of C_H2 domains to factor C1q.     

Filiation biochimique des acides phénoliques produits parPenicillium brevi-compactum

Résumé LeP. brevi-compactum produit onze substances phénoliques différentes: l'acide mycophénolique, les acides phénoliques C₁₀H₁₀O₅, C₁₀H₁₀O₆, C₁₀H₁₀O₇ et C₈H₆O₆ et les substances phénoliques non identifiées désignées par les chiffres VI, VII, VIII, IX, X et XI. L'acide mycophénolique et les substances X et XI qui en dérivent, sont synthétisés par la moisissure suivant un processus plus complexe que les autres substances phénoliques et sans rapport direct avec lui. Ces dernières dérivent les unes des autres par une série de transformations dont certaines sont réversibles. Il semble que les substances VI et VII soient des intermédiaires entre C₁₀H₁₀O₇ et C₈H₆O₆, tandis que les substances VIII et IX seraient des produits de réduction de C₁₀H₁₀O₅.

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Summary P. brevi-compactum produces eleven phenolic different substances, mycophenolic acid, phenolic acids C₁₀H₁₀O₅, C₁₀H₁₀O₆, C₁₀H₁₀O₇ and C₈H₆O₆, and the non-identified substances designed by the numbers VI, VII, VIII, IX, X and XI. Mycophenolic acid and its derivates X and XI are synthesized by the mould according to a process more complex than the other phenolic substances and have no direct connection with them. The latter derive the one from the other, in a succession of transformations some of which are reversible. It seems that the substances VI and III are intermediaries between C₁₀H₁₀O₇ and C₈H₆O₆, the substances VIII and IX being produced by reduction of C₁₀H₁₀O₅.

     

A convenient synthesis of meso-substituted porphyrins

Acid-catalyzed condensations of 1,19-diunsubstituted 1,19-dideoxybiladiene-ac dihydrobromides with aldehydes, R · CHO, afford the corresponding meso-substituted porphyrins (R = C₆H₅, p-Me·C₆H₄, p-MeO·C₅H₄, p-O₂N·C₆H₄, p-HOC·C₆H₄, p-(MeO)₂CH·C₆H₄, Me, n-Pr, CO₂Et), mostly in good yield.     

N-substituted ethylcarbamate complexes of thorium(IV) and lanthanum(III) nitrates

N-substituted ethylcarbamates form with thorium nitrate the complexes Th(NO₃)₄·3RHNC(O)OC₂H₅ (where R = CH₃, C₂H₅, C₆H₅(CH₃)CH) and with lanthanum nitrate the complexes La(NO₃)₃· 2RR′NC(O)OC₂H₅·3H₂O (where R = CH₃, C₂H₅, C₆H₅(CH₃)CH; R′ = H and R = CH₃, C₆H₅; R′ = C₂H₅ or R = R′ = CH₃). In addition the anhydrous La(NO₃)₃·3(C₂H₅)₂NC(O)OC₂H₅ has been isolated. From the IR spectra it is deduced that the carbamates coordinate the metal through the carbonyl oxygen atom and that the nitrato groups act as chelated ligands. ¹H nmr spectral data of the complexes are reported and discussed.     

Heterocyclisation of ferrocenyl- and benzenetricarbonyl chromium-cyclopentadienes with o-quinone. Evidence for a SET route

A series of cyclopentadienyl ligands substituted by unsaturated systems including various transition metal groups ((C₅H₅)₂Fe, PhCr(CO)₃) were reacted with 3,5-di-tert-butyl orthoquinone producing 1,4-benzodioxines in high yields. These cycloaddition reactions were stereospecific. ¹H and ¹³C NMR studies and X-ray structural analysis are in agreement with the exclusive formation of “endo” cycloadducts. Moreover, an ESR study shows the transient formation of both the radical anion of the o-quinone and the radical cation of the dienic system indicating an alternative single electron transfer pathway.     

Part II. Chiral dirhodium (II) catalysts with ortho-metalated arylphosphane ligands in the enantioselective intramolecular cyclopropanation of a racemic α-diazo ketone

In this report, chiral dirhodium (II) with ortho-metalated phosphane ligands, namely (M)-Rh₂(O₂CR) ₂(PC)₂ [PC = ortho-metalated aryl phosphane, O₂CR = carboxylate bridging ligands) (1a-g), have been used for the intramolecular cyclopropanation of racemic1-diazo-6-methyl-3-(2-propenyl)-5-hepten-2-one (2), containing both a tri- and monosubstituted carbon-carbon double bond, in pentane. The highest level of regiocontrol has been obtained with chiral catalyst Rh₂(O₂CCH₃)₂[(p-MeC₆H₃)P(p-MeC₆H₄)₂]₂ (M)-1c, affording favorably trisubstituted cyclopropane 3 versus monosubstituted cyclopropane 4 in 74:26 ratio. An exceptional diastereoselectivity was obtained with the entire catalyst series, leading to the unique formation of the syn products. Excellent enantiocontrol values (80-90% ee) have been achieved with catalysts 1a [(PC = (C₆H₃)P(C₆H₄)₂, R = C(CH₃)₃)], 1c [PC = p-MeC₆H₃)P(p-MeC₆H₄)₂, R = CH₃], 1f [PC = m-CH₃C₆H₃)P(m-CH₃C₆H₄)₂, R = CF₃] and 1g [PC = 3,5-(CH₃)₂C₆H₃)P(3,5-(CH₃)₂C₆H₄)₂, R = CF₃] at room temperature. Pentane is found to be a convenient solvent for high enantiocontrol in the cyclopropanation of α-diazo ketone 2.