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1.
[MnL](ClO 4) 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 H 2O 2 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 H 2O 2 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 H 2O 2. At 25 °C, rate constant for ethyl phenyl sulfide oxidation is 4.38 × 10 −3 min −1. 相似文献
2.
The chlorocadmate(II) systems of (H 2me 2pipz)[Cd 2Cl 6(H 2O) 2] (1) and (H 2mepipz) 2[Cd 3Cl 10(H 2O)] (2) (L = me 2pipz = N, N′-dimethylpiperazine; L′ = mepipz = N-methylpiperazine) were prepared and their structural and thermal properties investigated. Compound 1 is monoclinic, space group P2 1/ c, A = 7.664(1), B = 7.472(4), C = 15.347(1) Å, β = 99.468(7)°, Z = 2, R = 0.024. The crystal structure consists of organic cations and infinite one-dimensional chains of [CdCl 3(H 2O)] n3− anions. Each Cd atom is octahedrally surrounded by bridged and terminal chlorine atoms and by a water molecule, which is in trans position with respect to the terminal chlorine atom. Inter- and intrachain hydrogen bond interactions between the terminal chlorine atoms and the water molecules contribute to the crystal packing. Compound 2 is orthorhombic, space group Cmc2 1, A = 15.286(3), B = 13.354(3), C = 13.154(3) Å, R = 0.023. The crystal structure consists of organic dications and infinite chains of [Cd 2Cl 6(CdCl 4H 2O] n4− units running along the [001] axis. Each unit is formed of regularly alternate six-coordinated Cd atoms, one of them linking one pentacoordinated Cd atom which completes its coordination througha water molecule. A strong hydrogen bond interaction involving the organic dication and the inorganic chain contributes to the crystal packing. Differential hydrogen bond interaction involving the organic dication and the inorganic chain contributes to the crystal packing. Differential scanning calorimetry measurements did not show the presence of any structural phase transitions. The structures are compared with those of (H 2pipz)[Cd 2Cl 6(H 2O) 2] (3), (H 2mepipz)[Cd 2Cl 6(H 2O) 2]·H 2O (4) and (H 2mepipz)[Cd 2Cl 6] (5) (L = pipz = piperazine, L′ = mepipz = N-ethylpiperazine). 相似文献
3.
The X-ray structure is reported for the complex Cu 2(medpco-2H)Cl 2, (medpco = N, N′-bis- N, N-dimethylaminoethyl)pyridine-2,6-dicarboxamide 1-oxide. The complex is triclinic,
, a=8.313(4), B=11.403(5), C=11.611(3) Å, =91.66(3), β=108.99(4), γ=109.60(3)° and Z=2. The deprotonated ligand (medpco-2H) 2− acts as a binulceating ligand, producing an N-oxide-bridged complex. Each copper in Cu 2(medpco-2H)Cl 2 is five-coordinate, being coordinated by a bridging N-oxide oxygen, a deprotonated amide nitrogen, a tertiary amine nitrogen and two bridging chlorides. The complex does not exhibit significant magnetic interaction, and this may be the result of distortion of the bridging geometry from planarity. A range of other, apparently N-oxide-bridged, complexes of the type Cu 2(medpco-2H)X 2 is reported. The complex Cu 2(medpco-2H)Br 2·H 2O is strongly antiferromagnetic, with magnetic data closely fitting the expected binuclear structure. 相似文献
4.
The ligand N, N′-bis[2,2-dimethyl-4-(2-hydroxyphenyl)-3-aza-3-buten] oxamide with two identical coordination sites reacts with copper ions in its tetradeprotonated form to yield the dinuclear complex [Cu 2(C 24H 26N 4O 4)]·H 2O. The structure of this compound has been determined by the X-ray diffraction method. The crystals are orthorhombic with a = 11.744(1), B = 16.369(2), C = 26.340(3) Å, V = 5064(1) Å 3, Z = 8, space group Pbca. The oxamide is in a trans conformation with two different environments for the copper centres, a (4 + 1) coordination mode for the first one and a square planar environment for the other one. The water molecule is not directly bound to a copper centre, but involved in hydrogen bonding with the two oxygen atoms of an N 2O 2 coordination site. Indeed, extra coordination comes from a phenolic oxygen atom belonging to an adjacent dinuclear unit. Static susceptibility measurements point to a strong intrapair antiferromagnetic exchange interaction of 2 J = −520(±4) cm −1 and possibly an interpair ferromagnetic exchange interaction of 10(±5) cm −1. 相似文献
5.
The heteroditopic ligand 4′-(4,7,10-trioxadec-1-yn-10-yl)-2,2′:6′,2″-terpyridine, 2, contains an N, N′, N″-donor metal-binding domain that recognizes iron(II), and a terminal alkyne site that selectively couples to platinum(II). This selectivity has been used to investigate routes to the formation of heterometallic systems. The single crystal structures of ligand 2 and the complex [Fe(2) 2][PF 6] 2 are reported. 相似文献
6.
Single muscle fibers continue to twitch for up to 20 min when immersed in ethylene glycol bis(β-aminoethyl ether)- N, N′-tetraacetic acid (EGTA) solutions containing less than 10 −8 M free calcium. Failure of the twitch results from reversible depolarization, which occurs after 15–20 min in EGTA. The results make it clear that external calcium or calcium in the transverse tubules play no essential part in action potential propagation or excitation-contraction coupling. 相似文献
7.
Dithiothreitol in the presence of menadione or N, N, N′, N′-tetramethyl- p-phenylenediamine provides the reducing equivalents for oxidative phosphorylation and the ATP-dependent reduction of NAD + in submitochondrial particles. With menadione the reaction is nearly as fast as with succinate and it is insensitive to antimycin, indicating electron entry between the first and second sites of oxidative phosphorylation. The phenylenediamine-mediated reduction of NAD + is nearly as fast as succinate-linked reduction and is antimycin sensitive. 相似文献
8.
A new approach to ligand design for the sequestration of metal-oxo cations has been called stereognostic coordination chemistry, in that the ligand incorporates a traditional Lewis base coordination to the metal center and a hydrogen bond donor to interact with the oxo group. This paper reports the synthesis of ligands that are more rigid and sterically predisposed to bind the targeted UO 22+ cation. These are the tripod ligands tris- N, N′, N′′-[2-(2-carboxy-phenoxy)ethyl]-1,4,7-triazacyclononane bis-hydrochloride (ETAC · 2HCl) and tris- N, N′, N′′-[2-(2-carboxy-4-decyl-phenoxy)ethyl]-1,4,7-triazacyclononane tris-hydrochloride (DETAC · 3HCl), which chelate uranyl with a tris-carboxylate coordination sphere and provide a hydrogen bond donor through a protonated amine on the triazacyclononane macrocycle to interact with one uranyl oxo atom. Structural models predict that upon uranyl binding the hydrogen bond donor must point directly towards the oxo atom, enforcing a stereognostic interaction. Both ETAC and DETAC chelate the uranyl ion; DETAC is a powerful extractant and will quantitatively extract uranyl into an organic phase at pH 1.9 and above. The extraction coefficient is estimated to be 10 14 in neutral aqueous conditions. Vibrational spectra of 18O labeled UO 22+ have been used to probe the stereognostic coordination to uranyl utilizing hydrogen bonding. 相似文献
9.
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 H 2L and Ln(NO 3) 3 · 6H 2O give rise to three mononuclear lanthanide complexes Ln(H 2L)(NO 3) 3 [H 2L = 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 O 2O 2 set of donor atoms capable of effective coordination. These species are fairly stable and have been isolated. Then, addition of Cu(Ac) 2 · H 2O to the mononuclear lanthanide complex yields expected heterodinuclear (3d–4f) complexes Cu(L)Ln(NO 3) 3 · H 2O [Ln = Nd (4) and Eu (5)] where the Cu(II) ion is inserted to the inner N 2O 2 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. 相似文献
10.
A number of N, N′-bis(4-substituted phenyl)-1,7-diaza-12-crown-4 and N, N′-bis(4-substituted phenyl)-1, 10-diaza-18-crown-6 (where the substituents are OCH 3, CH 3, H, Cl, respectively) have been prepared by cyclization reaction of a ditosylate with the appropriately substituted diol. These new macrocyclic ligands have been characterized by means of elemental analysis, IR, 1H NMR and MS spectra. The crystal structures of N, N′-bis(4-chlorophenyl)-1,10-diaza-18-crown-6 (21) and its complex with barium thiocyanate Ba(SCN) 2 (22) have been determined by single crystal X-ray diffraction. The crystallographic data are as follows: 21: C 24H 32Cl 2N 2O 4, orthorhombic, P2 12 12 1, A=4.852(1), B=11.989(2), C=41.231(8) Å, V=2398.7(8) Å 3, Z=4; 22: C 26H 32Cl 2N 4O 4S 2Ba, monoclinic, P2 1/ c, A=8.801(2), B=11.653(9), C=15.756(6) Å, ß=105.96(3)°, V=1553.7(14) Å 3, Z=2. In the complex, the Ba atom is eight-coordinate (O(1), O(2), O(1)′, O(2)′, N(1), N(1)′, N(21), N(21)′) to form a distorted D6h geometry with the Ba atom at the center of crystallographic symmetry. 相似文献
11.
Under 12/12 h light/dark cycles, 1 mM ethyleneglycol-bis-(β-aminoethyl ether)- N, N, N′, N′-tetraacetic acid (EGTA, pH 8.0) added at the start of the dark period, inhibited the increase of dark respiration which was associated with nitrogen fixation in Synechococcus RF-1. Twenty-five millimolar NaNO 3 added 30 min before the start of dark period suppressed this respiratory increase. If 1.25 mM CaCl 2 was added to the EGTA-treated sample from 3 to at least 10 h later in the dark period, a quick rise in respiratory rate was observed. This rise was also reduced by 25 mM NaNO 3. Extracellular Ca 2+ appears to be required for the increase in dark respiration associated with the rhythmic appearance of nitrogenase activity in the dark cycle. 相似文献
12.
In 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) poisoned chloroplasts, the restoration of the fluorescence induction is presumed to be due to a back reaction of the reduced primary acceptor (Q −) and the oxidized primary donor (Z +) of Photosystem II. Carbonylcyanide m-chlorophenylhydrazone (CCCP) is known to inhibit this back reaction. The influence of reduced N-methylphenazonium methosulfate (PMS) in the absence of CCCP and of oxidized PMS in the presence of CCCP on the back reaction was investigated and the following results were obtained: 1. (1) Reduced PMS at the concentration of 1 μM inhibits the back reaction as effectively as hydroxylamine, suggesting an electron donating function of reduced PMS for System II. 2. (2) The inhibition of the back reaction by CCCP is regenerated to a high degree by oxidized PMS which led to assume a cyclic System II electron flow catalysed by PMS. 3. (3) At concentrations of reduced PMS higher than 1 μM it is shown that both the fast initial emission and more significantly the variable emission are quenched.
Abbreviations: PMS, N-methylphenazonium methosulfate; CCCP, carbonylcyanide m-chlorophenylhydrazone; FCCP, carbonylcyanide p-trifluoromethoxyphenylhydrazone; TMPD, N,N,N′,N′-tetramethyl-p-phenylendiamine; DCMU, 3-(3,4-dichlorophenyl)-1,1-dimethylurea 相似文献
13.
Primary structure and crystallographic data of several legume lectins were used to predict the involvement in carbohydrate binding of six amino acid residues (Asp 88, Glu 108, Tyr 134, Asn 136, Leu 226 and Gln 227) in Griffonia simplicifolia lectin II (GS-II). The functional involvement of these residues was evaluated by assessing GlcNAc binding of modified forms of GS-II in which these residues were eliminated in truncated peptides or systematically substituted with other amino acids by site-specific mutations. Mutations at (Asp 88, Tyr 134 or Asn 136 eliminated GlcNAc binding activity by GS-II, while those at Glut 108, Leu 226 or Gln 227 did not alter the activity. The former three amino acids were functionally essential for carbohydrate binding by GS-II presumably through hydrogen bonding to and hydrophobic interactions with GlcNAc. Although an Asp or Gly substitution for Tyr 134 eliminated GlcNAc affinity, substitution with Phe did not appreciably affect binding. Despite the fact that mutations to Leu 226 and Gln 227 did not alter carbohydrate binding, a truncated form of GS-II lacking these residues no longer exhibited carbohydrate binding affinity. 相似文献
14.
1,10-Phenanthroline-5,6-dione (C 12H 6N 2O 2 (1)) reacts with V(η 6-mesitylene) 2 and Ti(η 6-toluene) 2 affording coordination compounds of general formula M( O, O′---C 12H 6N 2O 2) 3 (M=Ti (2); M=V (3)) which further react with TiCl 4 or TiCp 2(CO) 2 yielding the tetrametallic species M( O, O′---C 12H 6N 2O 2--- N, N′) 3(M′L n) 3 (M=V, M′L n=TiCl 4 (4); M=Ti, M′L n=TiCp 2 (5); M=V, M′L n=TiCp 2 (6)). The complex salt [Fe( N, N′---C 12H 6N 2O 2) 3][PF 6] 2 (7) has been obtained from iron(II) chloride tetrahydrate and 1 in the presence of NH 4PF 6. The reaction of 7 with TiCp 2(CO) 2 affords the tetrametallic derivative [Fe( N, N′---C 12H 6N 2O 2--- O, O′) 3(TiCp 2) 3][PF 6] 2 (8). TiCl 2(THF) 2 reacts with MCp 2( O, O′---C 12H 6N 2O 2) to give MCp 2( O, O′---C 12H 6N 2O 2--- N, N′)TiCl 2 (M=Ti (9); M=V (10)). By reaction of TiCp 2( O, O′---C 12H 6N 2O 2--- N, N′)TiCl 2 (9) with C 12H 6N 2O 2, the bimetallic derivative TiCp 2( O, O′---C 12H 6N 2O 2--- N, N′)TiCl 2( O, O′---C 12H 6N 2O 2) (11) has been prepared, which readily adds to TiCl 4, to give the trimetallic titanium derivative TiCp 2( O, O′---C 12H 6N 2O 2--- N, N′)TiCl 2( O, O′---C 12H 6N 2O 2--- N, N′)TiCl 4 (12). VCp 2( O, O′---C 12H 6N 2O 2--- N, N′)TiCl 2 (10) reacts with the tris-chelate iron(II) cation 7 affording the heptametallic cationic complex [Fe( N, N′---C 12H 6N 2O 2--- O, O′)TiCl 2( N, N′---C 12H 6N 2O 2--- O, O′)VCp 2] 3 +2 isolated as the hexafluorophosphate 13. 相似文献
15.
Celiac disease (CD) is characterized by a permanent intolerance to wheat gliadin and related proteins in genetically susceptible individuals. It is generally considered that CD is an immuno-mediated multifactorial disease, but a direct cytotoxic activity of gliadin-derived peptides (GL-PT) on intestinal mucosa cannot be excluded. Many efforts have been done to identify possible antagonists of this direct toxicity and several studies indicated that mannan and oligomers of N-acetylglucosamine, [ N, N′-diacetylchitobiose (GLcNAc)2 and N, N′, N″;-triacetylchitotriose (GLcNAc)3], could be very promising candidates. In the present study we investigated the ability of mannan, (GLcNAc)2 and (GLcNAc)3 to interfere with some toxic effects exerted by GL-PT, as cell growth and viability impairment, increased intestinal permeability and cellular inflammation, on a clone of the human intestinal Caco-2 cell line, Caco-2/TC7, expressing a more homogeneous population than the parental one. Our present results demonstrate that mannan, among the three molecules investigated, is the most suitable to counteract the adverse effects induced by GL-PT on Caco-2/TC7 cells, for all the parameters considered in this study. 相似文献
16.
The low-spin ferric cyanide complex of beef heart cytochrome aa3 can be partially reduced by stoichiometric additions of ferrous cytochrome c or by similar additions of N, N, N′, N′-tetramethyl- p-phenylene diamine. In both cases the initial ratio of cytochrome c oxidized: cytochrome a reduced or Wurster's Blue: cytochrome a reduced approximates the value 2. It is concluded that the binding of a single HCN prevents the reduction of both cytochrome a3 and its associated EPR-invisible Cu atom. 相似文献
17.
The molecular structure of the title complexes [Fe(H 2O) 4][Fe(Hedta)(H 2O)] 2 · 4H 2O (I) and [Fe(H[ 2edta)(H 2O)] · 2H 2O (II) have been determined by single-crystal X-ray analyses. The crystal data are as follows: I: monoclinic, P2 1/ n, A = 11.794(2), B = 15.990(2), C = 9.206(2) Å, β = 90.33(1)°, V = 1736.1(5) Å 3, Z = 2 and R = 0.030; II: monoclinic, C2/ c, A = 11.074(2), B = 9.856(2), C = 14.399(2) Å, β = 95.86(1)°, V = 1563.3(4) Å 3, Z = 4 and R = 0.025. I is found to be isomorphous with the Mn II analog reported earlier and to contain a seven-coordinate and approximately pentagonal-bipyramidal (PB) [Fe II(Hedta)(H 2O] − unit in which Hedta acts as a hexadentate ligand. The [Fe II(H 2edta)(H 2O)] unit in II has also a seven-coordinate PB structure with the two protonated equatorial glycine arms both remaining coordinated, and thus bears a structural resemblance to the seven-coordinate [Co II(H 2edta)(H 2O)] reported previously. 相似文献
18.
The dielectric constant, ′, and the dielectric loss, ″, for gelatin films were measured in the glassy and rubbery states over a frequency range from 20 Hz to 10 MHz; ′ and ″ were transformed into M* formalism ( M*=1/( ′− i″)= M′+ iM″; i, the imaginary unit). The peak of ″ was masked probably due to dc conduction, but the peak of M″, e.g. the conductivity relaxation, for the gelatin used was observed. By fitting the M″ data to the Havriliak–Negami type equation, the relaxation time, τHN, was evaluated. The value of the activation energy, Eτ, evaluated from an Arrhenius plot of 1/ τHN, agreed well with that of Eσ evaluated from the DC conductivity σ0 both in the glassy and rubbery states, indicating that the conductivity relaxation observed for the gelatin films was ascribed to ionic conduction. The value of the activation energy in the glassy state was larger than that in the rubbery state. 相似文献
19.
As an artificial ligand, a glycoconjugate polymer carrying carbohydrate moiety of lactosyl ceramide or globotriaosyl ceramide (Gb 3) was synthesized. Gb 3 is known as the receptor of Shiga toxin-producing Escherichia coli O157: H7. The preparation of the glycoconjugate polymer initially involves the construction of the carbohydrate moiety of Gb 3 derivative which has n-pentenyl group as polymerizable group. In addition, the n-pentenyl group of the Gb 3 derivative was modified and different polymerizable groups such as acrylamide group were introduced at ω-position of the aglycon. Radical polymerization of the synthesized glycosyl monomers with or without acrylamide proceeded smoothly in water using ammonium persulfate and N, N, N′, N′-tetramethylethylenediamine as usual initiator system and gave water-soluble glycoconjugate polymers having various polymer compositions. These polymers have the potential to neutralize Shiga toxin by reason of cluster effect and multivalency. 相似文献
20.
Plastocyanin is a copper protein found in photosynethetic tissue and it exhibits the properties of a physiological redox reagent. This protein has been purified from the blue-green alga Anabaena variabilis. Plastocyanin is required for a number of partial reactions of the photosynthetic electron transfer chain. These reactions include the transfer of electrons from reduced 2,3′,6-trichlorophenolindophenol, N, N, N′, N′- tetramethyl- p-phenylenediamine and 2,3,5,6-tetramethyl- p-phenylenediamine to low potential oxidants. Reduced cytochrome c photooxidation does not appear to be dependent on plastocyanin. Cytochrome f, isolated from this alga, will partially replace plastocyanin in many of these reations. Inhibition of photosynthetic reactions by copper chelators appears to occur at some site other than the site of plastocyanin function. 相似文献
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