Sulfide oxidation with H2O2 catalyzed by manganese complex of N,N′,N″-tris(2-hydroxypropyl)-1,4,7-triazacyclononane

[MnL](ClO₄)₂ (L = N,N′,N″-tris(2-hydroxypropyl)-1,4,7-triazacyclononane) has been tested for catalyzing sulfide oxidation. In the presence of this complex, ethyl phenyl sulfide, butyl sulfide and phenyl sulfide are completely oxidized to the corresponding sulfoxides and sulfones with H₂O₂ as the oxidant. 2-Chloroethyl phenyl sulfide oxidation yield 2-chloroethyl phenyl sulfone and phenyl vinyl sulfone. In ethyl phenyl sulfide oxidation, effects of complex and H₂O₂ concentration and temperature on the reaction rate have been discussed. Through controlling reaction conditions, ethyl phenyl sulfoxide and ethyl phenyl sulfone may be produced selectively. The UV–Vis and electron paramagnetic resonance (EPR) studies on catalyst solution indicate that metal centre of the complex is transformed from Mn(II) to Mn(IV) after the addition of H₂O₂. At 25 °C, rate constant for ethyl phenyl sulfide oxidation is 4.38 × 10⁻³ min⁻¹.     

The Diazosafranin Method; Control of Nitrite Concentration and Refinements in Specificity

Safranin is diazotized by using the customary molar ratio—dye, 1:HCl, 3:NaNO₂l. Partly oxidized NaNO₂ can be used, if necessary, by increasing the concentration of its solution enough to cause the normal color change from red to deep blue to occur within 2 min after adding the NaNO₂. To avoid carrying over excess HNO₂ into the alkaline coupling solution, 1 ml of 3% alcoholic urea solution (30 mg) is added for each milliliter excess of 1 N NaNO₂ used. Any free HNO₂ remaining at the end of the diazotization period produces a deep blue violet on starch-KI paper. Prolonged acid washing may be applied after coupling to decolorize cationic dye staining or triazenes. Na₂S₂O₄, TiCl₃ or SnCl₂ may be used to bleach true azo colorations. This decolorization is not limited to newly formed azo compounds with tissue.     

Comparative characterization of a recombinant Volvariella volvacea endoglucanase I (EG1) with its truncated catalytic core (EG1-CM), and their impact on the bio-treatment of cellulose-based fabrics

Recombinant Volvariella volvacea endoglucanase 1 (EG1) and its catalytic module (EG1-CM) were obtained by expression in Pichia pastoris, purified by two-step chromatography, and the catalytic activities and binding capacities were compared. EG1 and EG1-CM exhibited very similar specific activities towards the soluble substrates carboxymethyl cellulose, lichenan and mannan, and insoluble H₃PO₄ acid-swollen cellulose, whereas the specific activities of EG1-CM towards the insoluble substrates -cellulose, Avicel and filter paper were approximately 58, 43 and 38%, respectively compared to EG1. No increase in reducing sugar release was detected in the reaction mixture supernatants after 50 h exposure of filter paper, Avicel or -cellulose to EG1-CM, whereas increases in the total reducing sugar equivalents (i.e. reducing sugar released into solution together with new reducing ends generated in the cellulosic substrates) in reaction mixtures were observed after 1 h. In reaction mixtures containing EG1, soluble reducing sugar equivalents were detected in supernatants after 3 h incubation with the insoluble cellulosic substrates. EG1-CM did not adsorb to Avicel, and the binding capacities of EG1-CM towards filter paper and H₃PO₄ acid-swollen cellulose were 27.9–33.3% and 29.6–60.6%, respectively of values obtained with EG1 within the range of total added protein. In enzymatic deinking experiments, the ink removal rate in EG1-CM-treated samples was only slightly higher (8%), than that of untreated controls, whereas that of the EG1-treated samples was 100% higher. Bio-stoning of denim with EG1-CM resulted in increases of 48% and 40% in weight loss and indigo dye removal, respectively compared with untreated controls. These increases were considerably lower than the corresponding values of 219% and 133% obtained when samples were treated with EG1.     

Steric effects on the substitution of pentaamine-chromium(III) and -rhodium(III) complexes. Anation reaction rate constants as an indicative of the dissociative shift of the mechanism on crowding the [M(RNH2)5H2O] (M = Rh, R = H, Me, Et, Pr; M = Cr, R = H, Me, Pr) complexes

The kinetics of the anation reactions of [M(RNH₂)₅H₂O]³⁺ (M = Rh, R = H, Me, Et, Pr; M = Cr, R = H, Me, Pr) with several ligands (H₃PO₄/H₂PO₄⁻, H₃PO₃/H₂PO₃⁻, CF₃COO⁻, Br⁻, Cl⁻, SCN⁻) have been studied at different temperatures and acidities at I = 1.0 M (LiClO₄. Results obtained for the anation rate constants and thermal activation parameters are compared with the previously published data for R = H, in order to establish the effects of the amine substituents in the reaction mechanism proposed for the substitution reactions of these complexes. The results obtained are interpreted on the basis of a mechanism where the bond formation process is more important in the substitution on M = Cr complexes than in that of the M = Rh complexes, as already pointed out for the published ΔΛ^≠ values for the water exchange on these systems. A simple Langford-Gray classification becomes inadequate to describe these situations where the increase of the steric demand of the amine substituents shifta the I_a-I_d classification to the I_d side, although no dramatic changes in the reaction mechanism are found. It is concluded that a More O'Ferall ‘continuous’ type of approach to the mechanism classification of the substitution reactions is much more useful in this case.     

Serendipitous syntheses of Rh(H)2Cl(PRPh2)3 complexes, and their crystal structures, where R = Me, Cy (cyclohexyl)

Reactions of RhCl(cod)(THP) (cod = 1,5-cyclooctadiene; THP = P(CH₂OH)₃) with PMePh₂ or PCyPh₂ (Cy = cyclohexyl) in acetone/MeOH solution under H₂ surprisingly form the complexes cis, mer-Rh(H)₂Cl(PRPh₂)₃ (R = Me or Cy); both complexes are characterized by crystallography (the first structures in which the hydride ligands of such dihydrido-chloro-trisphosphine complexes have been located), and by detailed ¹H and ³¹P NMR spectroscopy. The key role of the THP in the observed chemistry is discussed.     

Dinuclear sulfide–thiolate complexes [Pt2(μ-S)(μ-SR)(PPh3)4] as cationic metalloligands

The cationic monoalkylated derivatives of the well-known metalloligand [Pt₂(μ-S)₂(PPh₃)₄], viz. [Pt₂(μ-S)(μ-SR)(PPh₃)₄]⁺ (R = n-Bu, CH₂Ph) are themselves able to act as metalloligands towards the Ph₃PAu⁺ and R′Hg⁺ (R′ = Ph or ferrocenyl) fragments, by reaction with Ph₃PAuCl or R′HgCl, respectively. The resulting dicationic products [Pt₂(μ-SR)(μ-SAuPPh₃)(PPh₃)₄]²⁺ and [Pt₂(μ-SR)(μ-SHgR′)(PPh₃)₄]²⁺ are readily isolated as their hexafluorophosphate salts, and have been fully characterised by spectroscopic techniques and an X-ray structure determination on [Pt₂(μ-SR)(μ-SHgFc)(PPh₃)₄](PF₆)₂.     

Histamine controls food intake in sheep via H1 receptors

Histamine is a well known amine which controls many physiological functions of the CNS, including fluid balance, appetite, thermoregulation, cardiovascular control, learning and the stress response. All these functions are mediated via three well known membrane receptors (H₁, H₂ and H₃) and, in laboratory animals, feeding behavior is under the control of H₁ type. In order to investigate the central effect of histamine on feeding behavior in sheep and the characterization of the receptor involved, two Latin square design experiments were undertaken using four Iranian Nainee rams implanted with intracerebroventricular cannulae. In the first experiment, 12 h fasted (7:00 p.m.–7:00 a.m.) rams in individual pens were infused with 0 (control), 100, 400 and 800 nM of histamine such that each ram received each dose four times on different days. Ten minutes after injection (7:00 a.m.) water and a food container were put in the pens and the consumption of water and food were recorded at 0.5, 1, 3 and 12 h. Results from this experiment revealed that histamine significantly (P < 0.01) suppressed food intake with no effect on water consumption. In the second experiment the use of three specific histamine antagonists: chloropheniramine, ranitidine and thioperamide, showed that the anorexic effect of histamine was significantly (P < 0.01) blocked by chloropheniramine. It is concluded that feeding behavior in sheep is inhibited by histamine acting via H₁ receptors.     

Thermal and photochemical substitution reactions of CpRe(PPh3)2H2 and CpRe(PPh3)H4. Catalytic insertion of ethylene into the C-H bond of benzene

The thermal and photochemical reactions of CpRe(PPh₃)₂H₄ and CpRe(PPh₃)H₄ (Cp = η⁵-C₅H₅) with PMe₃, P(p-tolyl)₃, PMe₂Ph, DMPE, DPPE, DPPM, CO, 2,6-xylylisocyanide and ethylene have been examined. While CpRe(PPh₃)₂H₂ is thermally inert, it will undergo photochemical substitution of one or two PPh₃ ligands. With ethylene, substitution is followed by insertion of the olefin into the C-H bond of benzene, giving ethylbenzene. CpRe(PPh₃)H₄ undergoes thermal loss of PPh₃, which leads to substituted products of the type CpRe(L) H₄. Photochemically, reductive elimination of dihydrogen occurs preferentially. The complex trans-CpRe(DMPE)H₂ was structurally characterized, crystallizing in the monoclinic space group P2₁/n (No. 14) with a = 6.249(6), b = 16.671(8), c = 13.867(7) Å, β = 92.11(6)°, V = 1443.7(2.9) Å and Z = 4. The complex trans-CpRe(PMe₂Ph)₂H₂ was structurally characterized, crystallizing in the monoclinic space group P2₁/n (No. 14) with a = 7.467(3), b = 23.874(14), c = 11.798(6) Å, β = 100.16(4)°, V = 2070.2(3.4) ų and Z = 4.     

Synthesis and characterization of trisodium salt of bis(thiosalicylato)aurate(I): Na3[Au(TSA)2]·5H2O

Sodium salt of a water-soluble, anionic, and monomeric 1:2 complex of Au(I) with a dianion of thiosalicylic acid TSA²⁻(Hin2TSA) = o-HS(C₆H₄)COOH) was first prepared and isolated as colorless needle crystals through a stoichiometric reaction of NaAuCl₄:H₂TSA:NaOH = 1:4:8 molar ratio in aqueous/EtOH solution. In this reaction, TSA²⁻ ligand has played a role of a reducing agent for the starting Au(III) ion and also of donor ligands coordinating to the reduced Au(I). This compound was characterized by complete elemental analyses, TG/DTA, FT-IR, 2D-NMR (¹H-¹H COSY, ¹H-¹³C HMBC, and ¹H-¹³C HMQC) spectroscopy, and the molmass measurement based on the cryoscopic method. It was shown that this complex was a monomeric species of Au(I) with a formula of Na₃[Au(TSA)₂]·5H₂O in the solid state, but not a polymeric species even in aqueous solution. A full assignment of seven carbon and four proton resonances in the coordinated TSA²⁻ ligand was achieved by the 2D ¹H-¹³C HMBC NMR technique.     

Does histamine stimulate cyclic amp formation in the avian pineal gland via a novel (non-H1, non-H2, non-H3) histamine receptor subtype

The effects of histamine (HA), and selective HA, H₁-, H₂ and H₃-receptor agonists on cyclic AMP formation were investigated in intact thick and duck pineal glands. HA potently stimulated the pineal cyclic AMP formation. The effect of HA was mimicked fully by N-methylated histamines, and partially by several histaminergic drugs: 2-thiazolylethylamine (H₁), amthamine (H₂) and R-methylhistamine (H₃). Dimaprit, another selective H₂-agonist showed marginal activity. Forskolin highly potentiated the action of HA, and only weakly affected the effects of 2-thiazolyethylamine and amthamine. In the chick pineal, the stimulatory effects of HA and the tested histaminergic drugs were not blocked by mepyramine and thioperamide (H₁- and H₃-blockers, respectively), but they were antagonized by H₂-receptor selective compounds ranitidine and aminopotentidine, which, however, acted in a noncompetitive manner. Another H₂-selective blocker zolantidine antagonized the HA effect only when used at very high (30–100 μM) concentrations. In the duck pineal, the stimulatory effect of HA on cyclic AMP production was unaffected by mepyramine (H₁), thioperamide (H₃), and ranitidine (H₂), and only partially inhibited by the H₂-blocker aminopotentidine. Electrophysiological experiments revealed that HA is capable of evoking inward currents in most of the tested cells acutely isolated from chick pineal gland. The present findings further indicate that the pharmacological profile of the avian pineal HA receptor, whose stimulation leads to activation of cyclic AMP production, is different from any known HA receptor type (H₁, H₂, H₃), and suggest the existence of either an avian-specific HA receptor, or a novel HA receptor subtype. Electrophysiological data suggest that the pineal HA receptor may be somehow linked to activation of an ionic channel.     

Isolation of four major subunits from Clostridium thermocellum cellulosome and their synergism in the hydrolysis of crystalline cellulose

The cellulosome of Clostridium thermocellum, purified by affinity chromatography, was dissociated under mild conditions and separated by SDS-PAGE. Two major p-nitrophenylcellobiosidases (PNPCases I and II) corresponding to the S₅ (103 kDa) and S₈ (78 kDa) subunits and one major carboxymethylcellulase (CMCase) coinciding with the S₁₁ (60.5 kDa) subunit were isolated and characterized using carboxymethylcellulose (CMC), H₃PO₄-swollen cellulose and cello-oligosaccharides. Both PNPCases showed little effect on the viscosity of CMC and released twice as much total sugar as reducing sugar from H₃PO₄-swollen cellulose. The CMCase released ten times more total sugar than reducing sugar from H₃PO₄-swollen cellulose and reduced the viscosity of CMC rapidly. None of these enzymes was active on cellotriose. Both PNPCases released cellobiose from cellotetraose, and cellobiose and cellotriose from cellopentaose. In contrast, CMCase was active only on cellopentaose and released mainly glucose. Use of MeUmb(Glc)_n revealed that both PNPCases cleaved preferentially either the second or fourth linkage from the non-reducing end while the CMCase was specific for the internal glycosidic bonds. Thus, the PNPCases and CMCase behaved as typical exo- and endoglucanases, respectively. When tested individually, all three enzymes degraded Avicel only to a small extent. A 1.5–2.0-fold increase in sugar release was observed when CMCase was combined with either PNPCase I, II or both. Combining S₁ with either PNPCase II or CMCase resulted in fourfold synergism in the hydrolysis of Avicel. Synergism was sevenfold when all three enzymes were combined with S₁.     

Mixed anion lanthanide(III) crown ether complexes: crystal structures of [LaCl2(NO3)(12-crown-4)]2, [La(NO3)(OH2)4-(12-crown-4)]Cl2·CH3CN and [LaCl2(NO3)(18-crown-6)]

Reaction of LaCl₃·7H₂O containing small amounts of La(NO₃)₃·7H₂O as an impurity with 12-crown-4 or 18-crown-6 in 3:1 CH₃CN:CH₃OH resulted in the isolation of the mixed anion complexes [LaCl₂(NO₃)(12-crown-4)]₂, [La(NO₃)(OH₂)₄(12-crown-4)]Cl₂·CH₃CN and [LaCl₂(NO₃)(18-crown-6)]. The nine-coordinate dimer, [LaCl₂(NO₃)(12-crown-4)]₂, has all of the anions in the inner coordination sphere and La³⁺ has a capped square antiprismatic geometry. It crystallizes in the orthorhombic space group Pbca with (at −150 °C) a = 12.938(6), B = 15.704(3), C = 13.962(2) Å, and D_calc = 2.08 g cm⁻³ for Z = 4. The second complex isolated from the same reaction, [La(NO₃)(OH₂)₄(12-crown-4)]Cl₂·CH₃CN, has the bidentate nitrate anion in the inner coordination sphere but the two chloride anions are in a hydrogen bonded outer sphere. This complex is ten-coordinate 4A,6B-expanded dodecahedral and crystallizes in the monoclinic space group P2₁ with (at 20 °C) A = 7.651(2), B = 11.704(7), C = 11.608(4) Å, β = 95.11(2)°, and D_calc = 1.80 g cm⁻³ for Z = 2. The 18-crown-6 complex, [LaCl₂(NO₃)(18-crown-6)], has all inner sphere anions and has ten-coordinate 4A,6B-expanded dodecahedral La³⁺ centers. It crystallizes in the orthorhombic space group Pbca with (at 20 °C) a = 14.122(7), B = 13.563(5), C = 19.311(9) Å, and D_calc = 1.89 g cm⁻³ for Z = 8.     

Studies of the oxovanadium(IV)—oxalate system: syntheses and crystal structures of binuclear (Ph4P)2[(VO)2(H2O)2(C2O4)3]·4H2O and of the one-dimensional chain material, (Ph4P)[VOCl(C2O4)]

The hydrothermal reactions of (Ph₄P)[VO₂Cl₂] and H₂C₂O₄ at 150 and 125°C yield (Ph₄P)₂[V₂O₂(H₂O)₂(C₂O₄)₃]·4H₂O (1) and (Ph₄P)[VOCl(C₂O₄)] (2), respectively. The structure of the molecular anion of 1 consists of a binuclear unit of oxovanadium(IV) octahedra bridged by a bisbidentate oxalate group. The VO₆ coordination geometry at each vanadium site is defined by a terminal oxo group, an aquo ligand, and four oxygen donors — two from the bisbidentate bridging oxalate and two from the terminal bidentate oxalate. The structure of 2 consists of discrete Ph₄P⁺ cations occupying regions between [VOCl(C₂O₄)]⁻_∞ spiral chains. The structure of the one-dimensional anionic chain exhibits V(IV) octahedra bridged by bisbidentate oxalate groups. Crystal data: 1·4H₂O, monoclinic P2₁/n, A = 12.694(3), B = 12.531(3), C = 17.17(3) Å, β = 106.32(2)°, V = 2621.3(13) ų, Z = 2, D_calc = 1.501 g cm⁻³, structure solution and refinement converged at a conventional residual of 0.0518; 2, tetragonal P4₃, A = 12.145(2), C = 15.991(3) Å, V = 2358.7(12) ų, Z = 4, R = 0.0452.     

Solution and crystal structure of the dihydrogen complex [Ru(H2)(H)(PMe2Ph)4]PF6, an active alkyne hydrogenation catalyst

The complex [Ru(H₂)(H)(PMe₂Ph)₄]PF₆ (1) has been prepared by reaction of [Ru(H)(PMe₂Ph)₅] FP₆ (2) in THF with 1 atm H₂ and characterised by variable temperature ³¹P and ¹H NMR. It undergoes four distinct fluxional processes listed in order of decreasing activation energy: (i) exchange of H₂ in solution with the dihydrogen ligand above 273 K; (ii) isomerisation of cis and trans isomers of 1 above 230 K; (iii) exchange of H atoms between H₂ and hydride in trans-1 above 180 K; (iv) rapid H₂/hydride exchange in cis-1 to below 180 K. A single crystal X-ray diffraction study of 1 at 173 K shows that the complex has the cis geometry in the solid state but does not clearly reveal the positions of the hydrogen ligands. Complex 1 starts out as a catalyst of high activity for the selective hydrogenation of 1-alkynes to 1-alkenes (RC≡CH; R=¹¹Bu, Ph) but it is rapidly deactivated, possibly because of formation of the enynyl complex [Ru(η³RC₃CHR)(PMe₂Ph)₄]⁺. Complex 1 efficiently catalyzes the hydrogenation of internal alkynes (3-hexyne, 2-pentyne) to internal cis-alkenes with little deactivation, although some isomerisation of the alkene produced is observed. These observations are consistent with those of Nkosi, Coville, Albers and Singleton who reported that complex 2 must dissociate one PMe₂Ph ligand to produce the species active for alkyne hydrogenation. Complex 2 catalyses these hydrogenations with slower initial rates than complex 1 but deactivates less readily. In contrast to 1, complex 2 does not appear to cause the isomerisation of internal alkenes.     

Spin-crossover iron(II) complexes [Fe(Medpq)(py)2(NCS)2] and [Fe(Medpq)(py)2(NCSe)2]: syntheses, characterization and magnetic properties

Two new spin-crossover complexes, [Fe(Medpq)(py)₂(NCS)₂] · py · 0.5H₂O (1) and [Fe(Medpq)(py)₂(NCSe)₂] · py (2) (Medpq = 2-methyldipyrido[3,2-f:2′,3′-h]-quinoxaline, py = pyridine), have been synthesized. The crystal structures were determined at both room temperature (298 K) and low temperature (110 K). Complexes 1 and 2 crystallize in the orthorhombic space group Pbca and monoclinic space group P2₁/n, respectively. In both complexes, the distorted [FeN₆] octahedron is formed by six nitrogen atoms from Medpq, the trans pyridine molecules and the cis NCX⁻ groups. The thermal spin transition is accompanied by the shortening of the mean Fe–N distances by 0.194 Å for 2. The mononuclear [Fe(Medpq)(py)₂(NCS)₂] and [Fe(Medpq)(py)₂(NCSe)₂] neutral species interact each other via π-stacking, resulting in a one-dimensional extended structure for both 1 and 2. There exist C–HX (X = S, Se) hydrogen bonds for both complexes. Variable-temperature magnetic susceptibility measurements and Mössbauer spectroscopy reveal the occurrence of a gradual spin transition. The transitions are centered at T_1/2 = 120 K for 1 and T_1/2 = 180 K for 2, respectively.     

N,N′-Ethylene-bis(3-methoxysalicylideneimine) mononuclear (4f) and heterodinuclear (3d–4f) metal complexes: Synthesis, crystal structure and luminescent properties

The stepwise synthesis of mononuclear (4f) and heterodinuclear (3d–4f) Salen-like complexes has been investigated through structural determination of the intermediate and final products occurring in the process. In the first step, reactions of ligand H₂L and Ln(NO₃)₃ · 6H₂O give rise to three mononuclear lanthanide complexes Ln(H₂L)(NO₃)₃ [H₂L = N,N′-ethylene-bis(3-methoxysalicylideneimine), Ln = Nd (1), Eu (2) and Tb (3)], in which N,N′-ethylene-bis(3-methoxysalicylideneimine) acts as tetradentate ligands with the O₂O₂ set of donor atoms capable of effective coordination. These species are fairly stable and have been isolated. Then, addition of Cu(Ac)₂ · H₂O to the mononuclear lanthanide complex yields expected heterodinuclear (3d–4f) complexes Cu(L)Ln(NO₃)₃ · H₂O [Ln = Nd (4) and Eu (5)] where the Cu(II) ion is inserted to the inner N₂O₂ cavity. Luminescent analysis reveals that complex 3 exhibits characteristic metal-centered fluorescence of Tb(III) ion. However, the characteristic luminescence of both Sm(III) and Eu(III) ions is not observed both in solution and solid state of the complexes.     

Synthesis and characterization of SrCu2(O2CR)3(bdmap)3 and Bi2(O2CCH3)4(bdmap)2(H2O) (R = CH3, CF3; bdmap = 1,3-bis(dimethylamino)-2-propanolato)

New mixed metal complexes SrCu₂(O₂CR)₃(bdmap)₃ (R = CF₃ (1a), CH₃ (1b)) and a new dinuclear bismuth complex Bi₂(O₂CCH₃)₄(bdmap)₂(H₂O) (2) have been synthesized. Their crystal structures have been determined by single-crystal X-ray diffraction analyses. Thermal decomposition behaviors of these complexes have been examined by TGA and X-ray powder diffraction analyses. While compound 1a decomposes to SrF₂ and CuO at about 380°C, compound 1b decomposes to the corresponding oxides above 800°C. Compound 2 decomposes cleanly to Bi₂O₃ at 330°C. The magnetism of 1a was examined by the measurement of susceptibility from 5–300 K. Theoretical fitting for the susceptibility data revealed that 1a is an antiferromagnetically coupled system with g = 2.012(7), −2J = 34.0(8) cm⁻¹. Crystal data for 1a: C₂₇H₅₁N₆O₉F₉Cu₂Sr/THF, monoclinic space group P2₁/m, A = 10.708(6), B = 15.20(1), C = 15.404(7) Å, β = 107.94(4)°, V = 2386(2) ų, Z = 2; for 1b: C₂₇H₆₀N₆O₉Cu₂Sr/THF, orthorhombic space group Pbcn, A = 19.164(9), B = 26.829(8), C = 17.240(9) Å, V = 8864(5) ų, Z = 8; for 2: C₂₂H₄₈O₁₁N₄Bi₂, monoclinic space group P2₁/c, A = 17.614(9), B = 10.741(3), C = 18.910(7) Å, β = 109.99(3)°, V = 3362(2) ų, Z = 4.     

Catalytic auto-condensation of 2,4-pentanedione promoted by Sm(III) acetylacetonate: the X-ray structure of a novel complex [Sm(CH3COO)3(H2O)2](H2O)2

An efficient one-pot catalytic method to obtain 4,6-dimethyl-2-hydroxyacetophenone (A) is reported, the reaction proceeds via the intermolecular auto-condensation of 2,4-pentanedione using samarium(III) acetylacetonate (Sm(AcAc)₃) as promoter. A novel complex [Sm(CH₃COO)₃(H₂O)₂](H₂O)₂ (I) was isolated from the reaction media. The structure of I was determined by X-ray crystallography showing that the central atom is ennea-coordinated (monocapped square-antiprism geometry). This complex I also shows activity in the named autocondensation reaction.     

Preparation of ultrafine oxidized cellulose mats via electrospinning

Ultrafine oxidized cellulose (OC) mats were prepared by oxidation of ultrafine cellulose mats produced by electrospinning and subsequent deacetylation of cellulose acetate for potential applications in nonwoven adhesion barriers. When ultrafine cellulose mats were oxidized with a mixture of HNO3/H3PO4 - NaNO2 (2/1/1.4 v/v/wt %), their ultrafine mat structure remained unchanged. The yield and carboxyl content of OC mats were 86.7% and 16.8%, respectively. OC showed lower crystallinity than cellulose because the oxidation of cellulose proceeded via disruption of hydrogen bonds between cellulose chains. The swelling behaviors of ultrafine OC mats were dependent on the type of swelling solution. In a physiological salt solution, their degree of swelling was approximately 230%.     

One-dimensional copper phosphonates containing μ-halide, μ-pyridyl N-oxide and phosphonate bridging ligands

This paper reports the syntheses and characterization of four copper phosphonates with chain structures based on (2-pyridyl-N-oxide)phosphonate, namely, [Cu₂X₂(C₅H₄NOPO₃)₂][Cu(H₂O)₆] · 2H₂O [X = Cl (1), Br (2)] and CuX(C₅H₄NOPO₃H) · H₂O [X = Cl (3), Br (4)]. Compounds 1 and 2 are isostructural and show a chain structure where Cu(1) and Cu(2) are triply bridged by halide, oxygen donor of the pyridyl N-oxide and O–P–O group. The [Cu(H₂O)₆]²⁺ serves as a charge-balancing cation and locate between the chains together with the water molecules. Compounds 3 and 4 are also isostructural. In these cases, one of the three phosphonate oxygen atoms is protonated, thus leading to a neutral chain structure which is very similar to the anionic chains in compounds 1 and 2. Magnetic studies of compounds 1–4 reveal that antiferromagnetic interactions are mediated between the copper ions.