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1.
Three chromium(III) complexes with asparagine (Asn) and histidine (His) of the [Cr(ox)2(Aa)]2− type, where Aa = N,O–Asn, N,O–His or N,N′–His, were obtained and characterized in solution. The complexes with N,O–Aa undergo acid-catalysed aquation to give a free amino acid and cis-[Cr(ox)2(H2O)2], whereas the complex with N,N′–His undergoes parallel reaction paths: (1) isomerization to the N,O–His complex and (2) liberation of an oxalate ligand. Kinetics of the N,O–Aa complexes in HClO4 media were studied spectrophotometrically under pseudo-first-order conditions. The absorbance changes were attributed to the chelate ring opening at the Cr–N bond. The linear dependence of rate constants on [H+] was established, and a mechanism for the chelate ring cleavage was postulated. The existence of a metastable intermediate with O-monodentate Aa ligand was proved experimentally. Effect of [Cr(ox)2(Aa)]2− on 3T3 fibroblasts proliferation was studied. The tests revealed low cytotoxicity of the complexes. Complexes with Ala, His and Cys are good candidates for biochromium sources.  相似文献   

2.
Two hexacoordinated mononuclear Co(III) compounds of the type cis-[Co(L)(N3)2] X [1, X = ClO4; 2, X = PF6; L = N,N′-(bis(pyridine-2-yl)benzylidine)-1,4-butanediamine] have been synthesized and characterized by physicochemical and spectroscopic methods. The crystal structures of complexes 1 and 2 both have distorted octahedral geometry with two terminal azides in mutual cis orientations. In the crystalline state, two mononuclear units of 1 are associated by weak C–H…π interactions to produce a dimeric unit, which packs through C–H…O hydrogen bonds and π…π interactions leading to a 2-D continuum. The mononuclear units in 2 are engaged in weak cooperative intermolecular C–H…π interactions and multiple C–H…F hydrogen bonds giving rise to a 3-D network structure. These diamagnetic compounds are redox active and show luminescence in DMF solutions.  相似文献   

3.
Using the experimental values ΔH Hexc and ΔS HexcH Nexc and ΔS Nexc) for solid solutions of hydrogen and nitrogen in molybdenum, we calculate the parameters ɛHMand ɛNM of interaction between hydrogen (nitrogen) and molybdenum lattice doped with small additives of transition metals M; the values of the activity coefficients on hydrogen and nitrogen γHM and γNM, ΔH H, ΔH N, ΔS H, ΔS N; enthalpy (ηHM and ηNM) and entropy (σHM and σNM) parameters of interaction over the 1100–1300 K range for alloys of Mo1 − y M y H x and Mo1 − y M y N x types (y = 0.01 and 0.02; x = 0.01 and 0.02).  相似文献   

4.
A series of hybrid mesoporous SBA-15 materials containing four iron(III) Schiff base complexes of the type [FeL x (NO3)] (x = 4–7, L = N,N′-bis(salicylidene)ethylenediamine, N,N′-bis(salicylidene)diethylenetriamine, N,N′-bis(salicylidene)o-phenylenediamine, N,N′-bis(3-nitro-salicylidene)ethylenediamine) was synthesized by a post-grafting route. The XRD, N2 adsorption/desorption and TEM measurements confirmed the structural integrity of the mesoporous hosts, and the spectroscopic characterization techniques (FT-IR, UV–vis spectroscopy, 1H NMR) confirmed the ligands and the successful anchoring of iron(III) Schiff base complexes over the modified mesoporous support. Quantification of the supported ligand and metal was carried out by TG/DSC and ICP-AES techniques. The catalyst FeL7-SBA resulting from N,N′-bis(3-nitro-salicylidene)ethylenediamine) ligand was considerably active for the aerobic epoxidation of styrene, in which the highest conversion of styrene reached 83.6%, and the selectivity to styrene oxide was 83.0%. Moreover, it was also found that the catalytic activity increases with the decrease in the electron-donating ability of the Schiff bases, and the selectivity varies according to the types of substituents in the ligands.  相似文献   

5.
To date, no reference method for the extraction of labile Mn species from biological tissues is published which provides sufficient extraction efficiency combined with monitoring speciation. Here, an extraction method is reported using cryogenic conditions (+N) under inert gas atmosphere. Fresh brain and liver tissues were used, then stored either 1 day (+N) or 1 month in N2liq (+N 1 m) to evaluate degradation effects during long-term storage. Both attempts were compared to a previous extraction method (−N) using neither N2liq nor storage ability. Mn and Fe concentrations in extracts and pellets were determined with inductively coupled plasma (ICP)-atomic emission spectroscopy (AES) and compared to acid digests of the same sample. Element ratios of extracts/digest indicated the extraction efficiency, which was increased from 17% (−N) to 26% (+N) for Mn in brain or from 28% (−N) to 44% (+N) in liver extracts. For Fe species, the increase was only from 40% (−N) to 44% (+N) in brain but from 64% (−N) to 74% (+N) in liver. Size exclusion chromatography (SEC)-ICP-mass spectrometry (MS) was employed to screen for Mn and Fe species pattern in extracts. In brain, surplus extracted Mn (+N, +N 1 m) was assigned to organic Mn species, mainly from the 0.7–4 kDa fraction, while in the liver, it was seen in the 70–80 kDa fraction. Fe speciation was similar for −N and +N methods in brain extracts. In liver, higher amounts of Fe species were extracted from the 140–160 kDa fraction. Storage at −196 °C for 1 month did neither affect Mn speciation in brain nor in liver extracts. Fe species pattern showed a negligible shift (≤5%) from 140–160 to 70–80 kDa fraction in liver extracts stored 1 month in N2liq.  相似文献   

6.
Peroxydisulfate (PDS) oxidizes N,N′-ethylenebis(isonitrosoacetyleacetoneimine)copper(II) complex, CuIIL, to the corresponding copper(III) complex, [CuIIIL]+. The kinetic runs were performed in the presence of EDTA to scavenge any trace metal impurities. The kinetics of the reaction at constant pH, ionic strength, and temperature obeys the rate law d[CuIIIL]/dt = 2k 2[CuIIL][S2O8 2−] with k 2 having a value of (8.85 ± 0.32) × 10−2 M−1 s−1 at μ = 0.30 M and T = 25.0 °C. The rate constant k 2 is not affected by variation of pH over the range 3.60–5.20. The second order rate constant is also unaffected by changing ionic strength. The values of k obs were determined over the temperature 25.0–40.0 °C range. The enthalpy of activation, ∆H*, and entropy of activation, ∆S*, have been calculated as 34.9 ± 0.5 kJ mol−1 and −173.3 ± 11.4 J K−1 mol−1, respectively. The kinetics of this reaction, as far as we know, is the first evidence that copper(III) is the likely reactive species in copper catalyzed PDS oxidation reactions.  相似文献   

7.
The [InCl3(L) n ] (where L is 2,2′-bipyridine (bipy), 2,2′-bipyridine N,N′-dioxide (bipyNO), N,N-dimethylacetamide (dma), urea (u), thiourea (tu) or 1,1,3,3-tetramethylthiourea (tmtu); n = 1.5, 3 or 4) were synthesized and characterized by melting points, elemental analysis, thermal analysis and IR spectroscopy. The enthalpies of dissolution of the adducts, Indium(III) chloride and ligands in 1.2 M aqueous HCl were measured and by using thermochemical cycles, the following thermochemical parameters for the adducts have been determined: the standard enthalpies for the Lewis acid/base reactions (Δr H θ), the standard enthalpies of formation (Δf H θ), the lattice standard enthalpies (ΔM H θ), and the standard enthalpies of decomposition (ΔD H θ).  相似文献   

8.
In this study, an efficient procedure was developed for callus induction and regeneration of kiwifruit (Actinidia deliciosa) using different organs of shoots developed under in vitro conditions. Effects of explants source and media (M1, 1.0 mg l−1 BA + 2.0 mg l−1 2,4-D–M2, 1.0 mg l−1 NAA + 2.0 mg l−1 2,4-D) on initiation of callus were examined in order to obtain callus for organogenesis. The best callus for plant regeneration was obtained from leaf explants on Murashige and Skoog’s medium (MS) supplemented with M2. Formation of callus from leaf of kiwifruit (A. deliciosa) was cultured in MS medium containing different concentration of N6-benzylaminopurin (BA; 0.0, 1.0, 2.0, 4.0, 6.0, 8.0 mg l−1) for callus proliferation and plant regeneration. Although the first shoot formation was appeared in medium containing 6.0 and 8.0 mg l−1 BA, the best shoots formation was obtained in medium with 4.0 mg l−1 BA.  相似文献   

9.
New divalent transition metal 3,5-pyrazoledicarboxylate hydrates of empirical formula Mpz(COO)2(H2O)2, where M=Mn, Co, Ni, Cu, Zn and Cd (pz(COO)2=3,5-pyrazoledicarboxylate), metal hydrazine complexes of the type Mpz(COO)2N2H4 where M=Co, Zn or Cd and Mpz(COO)2nN2H4·H2O, where n=1 for M=Ni and n=0.5 for M=Cu have been prepared and characterized by physico-chemical methods. Electronic spectroscopic data suggest that Co and Ni complexes adopt an octahedral geometry. The IR spectra confirm the presence of unidentate carboxylate anion (Δν=νasy(COO)–νsym(COO)>215 cm–1) in all the complexes and bidentate bridging hydrazine (νN–N=985–950 cm–1) in the metal hydrazine complexes. Both metal carboxylate and metal hydrazine carboxylate complexes undergo endothermic dehydration and/or dehydrazination followed by exothermic decomposition of organic moiety to give the respective metal oxides as the end products except manganese pyrazoledicarboxylate hydrate, which leaves manganese carbonate. X-ray powder diffraction patterns reveal that the metal carboxylate hydrates are isomorphous as are those of metal hydrazine complexes of cobalt, zinc and cadmium.  相似文献   

10.
Kinetics of oxidation of dl-pipecolinate by bis(hydrogenperiodato)argentate(III) complex anion, [Ag(HIO6)2]5−, has been studied in aqueous alkaline medium in the temperature range of 25–40 °C. The oxidation kinetics is first order in the silver(III) and pipecolinate concentrations. The observed second-order rate constant, decreasing with increasing [periodate] is virtually independent of [OH]. α-Aminoadipate as the major oxidation product of pipecolinate has been identified by chromatographic analysis. A reaction mechanism is proposed that involves a pre-equilibrium between [Ag(HIO6)2]5− and [Ag(HIO6)(H2O)(OH)]2−, a mono-periodate coordinated silver(III) complex. Both Ag(III) complexes are reduced in parallel by pipecolinate in rate-determining steps (described by k 1 for the former Ag(III) species and k 2 for the latter). The determined rate constants and their associated activation parameters are k 1 (25 °C) = 0.40 ± 0.02 M−1 s−1, ∆H 1 = 53 ± 2 kJ mol−1, ∆S 1 = −74 ± 5 J K−1 mol−1 and k 2 (25 °C) = 0.64 ± 0.02 M−1 s−1, ∆H 2 = 41 ± 2 kJ mol−1, ∆S 2 = −110 ± 5 J K−1 mol−1. The time-resolved spectra, a positive dependence of the rate constants on ionic strength of the reaction medium, and the consistency of pre-equilibrium constants derived from different reaction systems support the proposed reaction mechanism.  相似文献   

11.
Reaction of [Au(PPh3)2(tht)2](OSO2CF3)3 with RaaiR′ in CH2Cl2 medium following ligand addition leads to [Au(PPh3)2(RaaiR′)](OTf)3 [RaaiR′ = p-R–C6H4–N=N–C3H2–NN–1–R′, (1–3), abbreviated as N,N′-chelator, where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), Me (b), Cl (c) and R′ = Me (1), CH2CH3 (2), CH2Ph (3), PPh3 is triphenylphosphine, OSO2CF3 is the triflate anion, tht is tetrahydrothiophen]. The maximum molecular peak of the corresponding molecule is observed in the ESI mass spectrum. The 1H-nmr spectral measurements suggest methylene, –CH2–, in RaaiEt gives a complex AB type multiplet while in RaaiCH2Ph it shows AB type quartets. 13C-nmr spectrum suggests the molecular skeleton. In the 1H–1H COSY spectrum as well as contour peaks in the 1H–13C heteronuclear multiple-quantum coherence (HMQC) spectrum assign the solution structure. Electrochemistry assign ligand reduction part rather than metal oxidation.  相似文献   

12.
An indigenously isolated fungal strain identified as Aspergillus terricola with assigned fungal strain number MTCC 7588 has been used as source for pectin lyase production. The extracellular pectin lyase was purified to homogeneity from the culture filtrate of A. terricola by ion exchange and gel filtration chromatography. The determined molecular weight was 35 ± 01 kDa. The K m and k cat (turnover) values of the purified enzyme at 37 °C using citrus pectin as the substrate were found to be 1.0 mg/ml and 110.0 s−1, respectively. The pH and temperature optima of the enzyme were 8.0 and 50 °C, respectively. The retting ability of the purified pectin lyase for natural fibers viz. Cannabis sativa and Linum usitatissimum has been demonstrated for the first time.  相似文献   

13.
A heterobimetallic cyano-bridged 1D coordination polymer of the composition [Ni(baepn)(μ-NC)Fe(CN)3(NO)(μ-CN)]n·3H2O has been synthesized by the reaction of nickel(II) nitrate hexahydrate, baepn (baepn = N, N′-bis(2-aminoethyl)-1,3-propanediamine), and sodium nitroprusside dihydrate in a methanol–water mixture. The complex was characterized by physicochemical and spectroscopic methods. The crystal structure was established by single-crystal X-ray diffraction analysis. It reveals cyano-bridged heterometallic chains consisting of alternating arrays of Ni(II) and Fe(II) atoms, both being embedded in distorted octahedral environments. Low-temperature susceptibility measurements show the presence of weak antiferromagnetic exchange interactions between paramagnetic Ni(II) centers (J = −0.46 cm−1) through long diamagnetic [Fe(CN)5(NO)]2− bridges. Spin state of the iron atom was established by 57Fe M?ssbauer spectroscopy.  相似文献   

14.
Organic solvent- and detergent-resistant proteases are important from an industrial viewpoint. However, they have been less frequently reported and only few of them are from actinomycetes. A metalloprotease from Streptomyces olivochromogenes (SOMP) was purified by ion exchange with Poros HQ and gel filtration with Sepharose CL-6B. Apparent molecular mass of the enzyme was estimated to be 51 kDa by sodium dodecyl sulfate–polyacrylamide gel electrophoresis and gelatin zymography. The activity was optimum at pH 7.5 and 50 °C and stable between pH 7.0 and 10.0. SOMP was stable below 45 °C and Ca2+ increased its thermostability. Ca2+ enhanced while Co2+, Cu2+, Zn2+, Mn2+, and Fe2+ inhibited the activity. Ethylenediaminetetraacetic acid and ethylene glycol-bis (β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid, but not phenylmethylsulfonyl fluoride, aprotinin, and pefabloc SC, significantly suppressed the activity, suggesting that it might be a metalloprotease. Importantly, it is highly resistant against various detergents, organic solvents, and oxidizing agents, and the activity is enhanced by H2O2. The enzyme could be a novel protease based on its origin and peculiar biochemical properties. It may be useful in biotechnological applications especially for organic solvent-based enzymatic synthesis.  相似文献   

15.
The thiosemicarbazide and hydrazide Cu(II) complexes, [Cu3L21(py)4Cl2] (1), [Cu(HL2)py] (2) and [Cu(HL3)py] (3), (H2L1 = 1-picolinoylthiosemicarbazide, H3L2 = N′-(2-hydroxybenzylidene)-3-hydroxy-2-naphthohydrazide, H3L3 = 2-hydroxy-N′-((2-hydroxy-naphthalen-1-yl)methylene)benzohydrazide) have been prepared and characterized through physicochemical and spectroscopic methods as well as X-ray crystallography. Complex 1 has a centrosymmetric structure with –N–N– bridged Cu3 skeleton. Neighboring molecules are linked into a 3D supermolecular framework by π–π stacking interactions, N–H···Cl and C–H···Cl hydrogen bonds. Complexes 2 and 3 have similar planar structures but different dimers formed by concomitant Cu···N and Cu···O interactions, respectively. Solvent accessible voids with a volume of 391 ?3 are included in the structure of complex 2, indicating that this complex is a potential host candidate. Thermogravimetric analysis shows that the three complexes are stable up to 100 °C.  相似文献   

16.
Two new neodymium complexes, [Nd2(abglyH)6(2,2′-bipy)2(H2O)2] · 4H2O 1 and {[Nd(abglyH)3(H2O)2] · (4,4′-bipy) · 7H2O}n 2 (abglyH2 = N-P-acetamidobenzenesulfonyl-glycine acid, 2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridine), have been synthesized and their structures have been measured by X-ray crystallography. In 1, nine-coordinated Nd(III) ions are bridged by two synsyn bidentate and two tridentate bridging carboxylate groups from four different abglyH anions to form dinuclear motifs, which are further connected into a 3-D supramolecular framework via hydrogen bonds between the binuclear motifs and the uncoordinated water molecules. In 2, eight-coordinated Nd(III) ions are linked by six carboxylate groups adopting a synsyn bidentate bridging fashion to form a 1-D inorganic–organic alternating linear chain. These polymeric chains generate microchannels extending along the a direction, and these cavities are occupied by discrete tetradecameric water clusters, which interact with their surroundings and finally furnish the 3-D supramolecular network via hydrogen bonds. At the same time, π–π stacking interactions between benzene rings from abglyH anions also play an important role in stabilizing the network.  相似文献   

17.
Galactomannans with galactose:mannose ratios 1:1.48 and 1:1.33, [α]D +67.9 and +76.4°, [η] 870.3 and 1337.1 mL/g, and molecular weights 999 and 1549 kDa, respectively, were isolated in 0.59 and 4.65% yields (of seed mass) from seeds of Astragalus alpinus and A. tibetanus (Fabaceae). Physicochemical methods (CrO3 oxidation; methylation–GC/MS; IR, NMR, and 13C spectroscopy) found that the main polysaccharide chain consisted of 1,4-β-D-mannopyranose units substituted 67.5% (A. alpinus) and 75.2% (A. tibetanus) at the C-6 position by single α -D-galactopyranose units. The contents of mannobiose blocks Man–Man, (Gal)Man–Man/Man–Man(Gal), and (Gal)Man–Man(Gal) variously substituted with galactose were according to 13C NMR spectroscopy 15.9, 55.5, and 28.6% in A. alpinus galactomannan and 9.9, 42.3, and 47.8% in A. tibetanus galactomannan.  相似文献   

18.
Photooxidation of water by the uranyl ion was studied. Solutions of uranyl in 0.01–4.0M H2SO4, HClO4, or 0.1–1.0M Na2SO4 and NaClO4 containing “lacunary” heteropolytungstate (HPT) K10P2W17O61 or K8SiW11O39 were irradiated with a nitrogen laser, a mercury or xenon lamp, or visible light. Spectrophotometric analysis showed that the irradiation results in the accumulation of UIV. Simultaneously the formation of H2O2 proceeds. The quantum yield Φ of the reaction increases as the concentration of the acid or salt increases. For aerated solutions of 1M H2SO4 or 1M HClO4, irradiation by light with λ=337.1 Φ is close to (1.5–2)·10−3. The irradiation of solutions with pH −4 for many days leads to an almost quantitative transformation of UO2 2+ into UIV. When the irradiation was carried out in the absence of HPA, UIV was not detected, although hydrogen peroxide was observed in the solution. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 2, pp. 282–287, February, 2000.  相似文献   

19.
Arene ruthenium complexes containing long-chain N-ligands L1 = NC5H4–4-COO–C6H4–4-O–(CH2)9–CH3 or L2 = NC5H4–4-COO–(CH2)10–O–C6H4–4-COO–C6H4–4-C6H4–4-CN derived from isonicotinic acid, of the type [(arene)Ru(L)Cl2] (arene = C6H6, L = L1: 1; arene = p-MeC6H4Pr i , L = L1: 2; arene = C6Me6, L = L1: 3; arene = C6H6, L = L2: 4; arene = p-MeC6H4Pr i , L = L2: 5; arene = C6Me6, L = L2: 6) have been synthesized from the corresponding [(arene)RuCl2]2 precursor with the long-chain N-ligand L in dichloromethane. Ruthenium nanoparticles stabilized by L1 have been prepared by the solvent-free reduction of 1 with hydrogen or by reducing [(arene)Ru(H2O)3]SO4 in ethanol in the presence of L1 with hydrogen. These complexes and nanoparticles show a high anticancer activity towards human ovarian cell lines, the highest cytotoxicity being obtained for complex 2 (IC50 = 2 μM for A2780 and 7 μM for A2780cisR).  相似文献   

20.

Abstract  

A new 2-D organic–inorganic hybrid Wells–Dawson-Type polyoxotungstate K[Cu(Im)2]6P2W18O62·2H2O·(OH) (Im = Imidazole) (1) has been synthesized under hydrothermal conditions and characterized by IR spectroscopy, TG, and single crystal X-ray structural analysis. Crystal data for 1: triclinic, P-1, a = 15.3676(12) ?, b = 15.5059(14) ?, c = 24.6437(19) ?, α = 98.088(2)°, β = 96.930(2)°, γ = 119.312(2)°, Z = 2. Single crystal X-ray structural analysis reveals that the [P2W18O62]6− polyoxoanion is linked by [Cu(Im)2]+ cation to form a 1-D chain along the a axis which is connected by K+ cation down the c axis to form a 2-D layer.  相似文献   

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