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1.
The title salt, methyl (1R,2R,3S,5S,8S)‐3‐benzoyl­oxy‐8‐methyl‐8‐aza­bicyclo­[3.2.1]octane‐2‐carboxyl­ate tetra­chloro­aurate(III), (C17H22NO4)[AuCl4], has its protonated N atom intra­molecularly hydrogen bonded to the O atom of the methoxy­carbonyl group [N⋯O = 2.755 (6) Å and N—H⋯O = 136°]. Two close inter­molecular C—H⋯O contacts exist, as well as five C—H⋯Cl close contacts. The [AuCl4] anion was found to be distorted square planar.  相似文献   

2.
The cationic pseudo‐square‐planar complex tetrakis(1‐methyl‐2,3‐dihydro‐1H‐imidazole‐2‐thione‐κS)gold(III) trichloride sesquihydrate, [Au(C4H6N2S)4]Cl3·1.5H2O, was isolated as dark‐red crystals from the reaction of chloroauric acid trihydrate (HAuCl4·3H2O) with four equivalents of methimazole in methanol. The AuIII atoms reside at the corners of the unit cell on an inversion center and are bound by the S atoms of four methimazole ligands in a planar arrangement, with S—Au—S bond angles of approximately 90°.  相似文献   

3.
Crystal structure analyses are reported for anhydrous copper(II) hexafluoroacetylacetonate (Cu(hfac)(2)) and for two of its hydrates. The anhydrous compound (Cu(hfac)(2), 1: P1; at 100 K, a = 5.428(1), b = 5.849(1), c = 11.516(3) A; alpha = 81.47(2), beta = 74.57(2), gamma = 86.96(2) degrees; Z = 1) contains centrosymmetric square-planar complexes with close intermolecular Cu.F contacts. The geometry of the complex is similar to that previously reported for Cu(hfac)(2).toluene. The monoaquo compound (Cu(hfac)(2)(H(2)O), 2: P2(1)/c; at 100 K, a = 10.8300(8), b = 6.5400(6), c = 21.551(3) A; beta = 90.282(8) degrees; Z = 4) consists of square-pyramidal molecules with apical H(2)O ligands, and close-lying F atoms in the sixth coordination sites. The major difference between this structure and the two other polymorphs previously reported is the nature and direction of hydrogen bonds. The yellow-green solid formed from Cu(hfac)(2) with excess H(2)O is identified as the trihydrate. In crystalline form it is the previously unreported [trans-Cu(hfac)(2)(H(2)O)(2)].H(2)O (3: P1; at 150 K, a = 8.3899(3), b = 9.6011(3), c = 11.4852(4) A; alpha = 72.397(2), beta = 79.161(2), gamma = 87.843(2) degrees; Z = 2). There is no conclusive evidence in favor of any solid with the composition Cu(hfac)(2).2H(2)O.  相似文献   

4.
The crystal structures of the four dipeptides l ‐seryl‐l ‐asparagine monohydrate, C7H13N3O5·H2O, l ‐seryl‐l ‐tyrosine monohydrate, C12H16N2O5·H2O, l ‐tryptophanyl‐l ‐serine monohydrate, C14H17N3O4·H2O, and l ‐tyrosyl‐l ‐tryptophan monohydrate, C20H21N3O4·H2O, are dominated by extensive hydrogen‐bonding networks that include cocrystallized solvent water molecules. Side‐chain conformations are discussed on the basis of previous observations in dipeptides. These four dipeptide structures greatly expand our knowledge on dipeptides incorporating polar residues such as serine, asparagine, threonine, tyrosine and tryptophan.  相似文献   

5.
Different salts of the 2‐phenyl‐1,10‐phenanthrolin‐1‐ium cation, (pnpH)+, are obtained by reacting 2‐phenyl‐1,10‐phenanthroline (pnp), C18H12N2, (I), with a variety of anions, such as hexafluoridophosphate, C18H13N2+·PF6, (II), trifluoromethanesulfonate, C18H13N2+·CF3SO3, (III), tetrachloridoaurate, (C18H13N2)[AuCl4], (IV), and bromide (as the dihydrate), C18H13N2+·Br·2H2O, (V). Compound (I) crystallizes with Z′ = 2, with both independent molecules adopting a coplanar conformation. In (II)–(IV), a hydrogen bond exists between the cation and anion, while one of the lattice water molecules serves as a hydrogen‐bonded bridge between the cation and anion in (V). Reaction of (I) with HAuCl4 gives the salt complex (IV); however, reaction with KAuCl4 produces the monodentate complex trichlorido(2‐phenyl‐1,10‐phenanthroline‐κN10)gold(III), [AuCl3(C18H12N2)], (VI). Dichlorido(2‐phenyl‐1,10‐phenanthroline‐κ2N,N′)copper(II), [CuCl2(C18H12N2)], (VII), results from the reaction of CuCl2·2H2O and (I), in which the CuII center adopts a tetrahedrally distorted square‐planar geometry. The pendent phenyl ring twists to a bisecting position relative to the phenanthroline plane. The square‐planar PdII complex, bromido[2‐(phenanthrolin‐2‐yl)phenyl‐κ3C1,N,N′]palladium(II), [PdBr(C18H11N2)], (VIII), is obtained from the reaction of (I) with [PdCl2(cycloocta‐1,5‐diene)], followed by addition of bromine. A coplanar geometry for the pendent ring is adopted as a result of the tridentate bonding motif.  相似文献   

6.
The title bimetallic compound, [Yb43‐OH)4(C6H13NO2)7(H2O)7][ZnCl4][ZnCl3(OH)]Cl4·8H2O, was synthesized at near physiological pH (6.0). The compound exhibits some novel structural features, including an asymmetric [Yb43‐OH)4(l ‐leucine)7(H2O)7]8+ complex cation in which four OH groups act as bridging ligands, linking four Yb3+ cations into a Yb4O4 structural unit. Each pair of adjacent Yb3+ ions is further bridged by one carboxy group from a leucine ligand. Water mol­ecules and a monodentate leucine ligand also coordinate to Yb3+ ions, completing their eight‐coordinate square‐antiprismatic coordination. The Yb43‐OH)4(l ‐leu­cine)7(H2O)7]8+ cation, the [ZnCl4]2−, [ZnCl3OH]2− and Cl anions, and the lattice water mol­ecules are linked via hydrogen bonds.  相似文献   

7.
The effect of nonionic micelles of Triton X‐100 on the oxidative decarboxylation of l ‐glutamic acid by chloroaurate(III) complexes has been investigated in acetate buffer medium. The reaction is first order with respect to Au(III), but a complex order with respect to glutamate. H+ ion has both accelerating and retarding effects in the pH range 3.72–4.80, whereas a Cl? ion has an inhibiting effect in the range 0.02–0.56 mol dm?3. Under the experimental conditions, AuCl?4 and AuCl3(OH)? are the predominant and effective oxidizing species, whereas the zwitterion (H2A) and mononegative anion (HA?) are the predominant reducing species of the amino acid. The reaction involves a one‐step two‐electron transfer process and passes through the intermediate formation of iminic cation. In the presence of surfactant, the reaction passes through a maximum and it appears to follow Berezin's model, where both the oxidant and the substrate are partitioned between the aqueous and the micellar phase and then react. The binding constants between the reactants and the surfactant have been evaluated at different temperatures. Compensation between substrate–water interaction and substrate–micelle interaction plays an important role in such redox reactions in the presence of a surfactant. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 482–493, 2012  相似文献   

8.
Tetraaqua(18‐crown‐6)cerium(III) hexacyanoferrate(III) dihydrate, [Ce(C12H24O6)(H2O)4][Fe(CN)6]·2H2O, and tetraaqua(18‐crown‐6)neodymium(III) hexacyanoferrate(III) dihydrate, [Nd(C12H24O6)(H2O)4][Fe(CN)6]·2H2O, are isomorphous and isostructural in the C2/c space group, where the cations, which contain ten‐coordinate lanthanoid centres, lie across twofold rotation axes and the anions lie across inversion centres. In these compounds, an extensive series of O—H...O and O—H...N hydrogen bonds links the components into a continuous three‐dimensional framework. Triaqua(18‐crown‐6)lanthanoid(III) hexacyanoferrate(III) dihydrate, [Ln(C12H24O6)(H2O)3][Fe(CN)6]·2H2O, where Ln = Sm, Eu, Gd or Tb, are all isomorphous and isostructural in the P space group, as are triaqua(18‐crown‐6)gadolinium(III) hexacyanochromate(III) dihydrate, [Gd(C12H24O6)(H2O)3][Cr(CN)6]·2H2O, and triaqua(18‐crown‐6)gadolinium(III) hexacyanocobaltate(III) dihydrate, [Gd(C12H24O6)(H2O)3][Co(CN)6]·2H2O. In these compounds, there are two independent anions, both lying across inversion centres, and the lanthanoid centres exhibit nine‐coordination; in the crystal structures, an extensive series of hydrogen bonds links the components into a three‐dimensional framework.  相似文献   

9.
The Rose Bengal‐sensitized photooxidations of the dipeptides l ‐tryptophyl‐l ‐phenylalanine (Trp‐Phe), l ‐tryptophyl‐l ‐tyrosine (Trp‐Tyr) and l ‐tryptophyl‐l ‐tryptophan (Trp‐Trp) have been studied in pH 7 water solution using static photolysis and time‐resolved methods. Kinetic results indicate that the tryptophan (Trp) moiety interacts with singlet molecular oxygen (O2(1Δg)) both through chemical reaction and through physical quenching, and that the photooxidations can be compared with those of equimolecular mixtures of the corresponding free amino acids, with minimum, if any, influence of the peptide bond on the chemical reaction. This is not a common behavior in other di‐ and polypeptides of photooxidizable amino acids. The ratio between chemical (kr) and overall (kt) rate constants for the interaction O2(1Δg)‐dipeptide indicates that Trp‐Phe and Trp‐Trp are good candidates to suffer photodynamic action, with krlkt values of 0.72 and 0.60, respectively (0.65 for free Trp). In the case of Trp‐Tyr, a lower krlkt value (0.18) has been found, likely as a result of the high component of physical deactivation of O2(1Δg) by the tyrosine moiety. The analysis of the photooxidation products shows that the main target for O2(1Δg) attack is the Trp group and suggests a much lower accumulation of kynurenine‐type products, as compared with free Trp. This is possibly because of the occurrence of another accepted alternative pathway of oxidation that gives rise to 3a‐oxidized hydrogenated pyrrolo[2,3‐b]indoles.  相似文献   

10.
The structures of two brucinium (2,3‐dimeth­oxy‐10‐oxostrychnidinium) salts of the α‐hydr­oxy acids l ‐malic acid and l ‐tartaric acid, namely brucinium hydrogen (S)‐malate penta­hydrate, C23H27N2O4+·C4H5O5·5H2O, (I), and anhydrous brucinium hydrogen (2R,3R)‐tartrate, C23H27N2O4+·C4H5O6,(II), have been determined at 130 K. Compound (I) has two brucinium cations, two hydrogen malate anions and ten water mol­ecules of solvation in the asymmetric unit, and forms an extensively hydrogen‐bonded three‐dimensional framework structure. In compound (II), the brucinium cations form the common undulating brucine sheet substructures, which accommodate parallel chains of head‐to‐tail hydrogen‐bonded tartrate anion species in the inter­stitial cavities.  相似文献   

11.
l ‐Valine, l ‐leucine, l ‐isoleucine, l ‐phenylalanine, and l ‐tyrosine are important proposed biomarkers for the early detection and diagnosis of type 2 diabetes. A simple and selective hydrophilic interaction chromatography with tandem mass spectrometry method was developed for the simultaneous determination of these amino acids in human serum, using stable isotope‐labeled amino acids as internal standards. Chromatographic separation was carried out on a Syncronis HILIC column (150 mm × 2.1 mm, 5 μm) with the column temperature of 35°C and a mobile phase consisted of acetonitrile/120 mM ammonium acetate (89:11, v/v), and the run time was 11.0 min. The mass spectrometric analysis was performed using a QTRAP 5500 mass spectrometer coupled with an electrospray ionization source in positive ion mode. As these five amino acids are endogenous compounds in serum, we used the corresponding stable isotope‐labeled amino acids to evaluate the matrix effect and recovery in serum. The matrix effect was 98.7–107.3%, and the recovery was 92.7–102.3%. Calibration curves spiked unlabeled amino acids in water were linear over the range of 0.200–100 μg/mL. The accuracy, inter‐, and intraday precision were below 10.2%. Analytes were stable during the study. This assay method has been validated and applied to the early diagnosis research of type 2 diabetes.  相似文献   

12.
El-Beck JA  Lash TD 《Organic letters》2006,8(23):5263-5266
[Structure: see text] Reaction of 4-hydroxyisophthalaldehyde with excess phenyl magnesium bromide gave a dicarbinol and this condensed with pyrrole and aromatic aldehydes in the presence of BF3.Et2O to afford, following oxidation with DDQ, novel tetraarylcarbaporphyrinoids in 10-24% yield. Further reaction with silver(I) acetate or gold(III) acetate gave stable organometallic derivatives that retained the aromatic characteristics of the parent macrocycle.  相似文献   

13.
The ortho‐metallation product of the reaction of (±)‐amphetamine with gold(III) chloride, [D,L‐2‐(2‐aminopropyl)phenyl‐κ2N,C1]dichloridogold(III), [Au(C9H12N)Cl2], and the two salts resulting from crystallization of (+)‐methamphetamine with gold(III) chloride, D‐methyl(1‐phenylpropan‐2‐yl)azanium tetrachloridoaurate(III), (C10H16N)[AuCl4], and of (±)‐ephedrine with gold(III) chloride, D,L‐(1‐hydroxy‐1‐phenylpropan‐2‐yl)(methyl)azanium tetrachloridoaurate(III), (C10H16NO)[AuCl4], have different structures. The first makes a bidentate complex directly with a dichloridogold(III) group, forming a six‐membered ring structure; the second and third each form a salt with [AuCl4] (each has two formula units in the asymmetric unit). The organic components are all members of the same class of stimulants that are prevalent in illicit drug use. These structures are important contributions to the understanding of the microcrystal tests for these drugs that have been employed for well over 100 years.  相似文献   

14.
The asymmetric unit of the title compound, [InNa(C3H5O3)4]n, consists of one InIII ion, one NaI ion and four crystallographically independent l ‐lactate monoanions. The coordination of the InIII ion is composed of five carboxylate O and two hydroxy O atoms in a distorted pentagonal–bipyramidal coordination geometry. The NaI ion is six‐coordinated by four carboxylate O atoms and two hydroxy O atoms from four l ‐lactate ligands in a distorted octahedral geometry. Each InIII ion is coordinated by four surrounding l ‐lactate ligands to form an [In(l ‐lactate)4] unit, which is further linked by NaI ions through Na—O bonds to give a two‐dimensional layered structure. Hydrogen bonds between the hydroxy groups and carboxylate O atoms are observed between neighbouring layers.  相似文献   

15.
16.
Crystallographic analysis of a solid solution of two diastereoisomers, i.e. ({(1S,R)‐1‐carboxy‐3‐[(R,S)‐methylsulfinyl]propyl}aminocarbonyl)methanaminium tetrachloridoaurate(III) and ({(1S,R)‐1‐carboxy‐3‐[(S,R)‐methylsulfinyl]propyl}aminocarbonyl)methanaminium tetrachloridoaurate(III), (C7H15N2O4S)[AuCl4], has shown that in the presence of gold(III), the methionine part of the Gly‐d ,l ‐Met dipeptide is oxidized to sulfoxide, and no coordination to the AuIII cation through the S atom of the sulfoxide is observed. In view of our observation, literature reports that methionine acts as an N,S‐bidentate donor ligand forming stable gold(III) complexes require verification. Moreover, it has been demonstrated that crystallization of the oxidation product leads to a substantial 77:23 excess of both S‐methionine/R‐sulfoxide and R‐methionine/S‐sulfoxide over S‐methionine/S‐sulfoxide and R‐methionine/R‐sulfoxide. The presence of two different diastereoisomers at the same crystallographic site is a source of static disorder at this site.  相似文献   

17.
Manganese(III) (Mn(III)) has been stabilized in weakly acidic solution by means of pyrophosphate and the nature of the complex was elucidated spectrophotometrically. Stoichiometry of Mn(III)‐oxidation of levodopa and methyl dopa in pyrophosphate medium was established in the pH range 2.5–4.0 by iodometric and spectrophotometric methods. The reaction shows a distinct variation in kinetic order with respect to [Mn(III)], a first‐order dependence in the pH range 1.9–2.6, decreasing to fractional order above pH 3. Other common features include first‐order dependence on [dopa], positive fractional order dependence on [H+], and inverse first‐order dependence on [Mn(III)] in the pH range studied. The effects of varying ionic strength and solvent composition were studied. Added ions such as SO42? and ClO4? alter the reaction rate, probably due to the change in the formal redox potential of Mn(III)–Mn(II) couple because of the changes in coordination environment of the oxidizing species. Evidence for the transient existence of the free radical intermediate is given. Cyclic voltametric sensing of levodopa and methyl dopa has ruled out the formation of dopaquinones as oxidation products in the pH range studied. Activation parameters have been evaluated using the Arrhenius and Erying plots. Mechanisms consistent with the kinetic data have been proposed and discussed. These studies are expected to throw some light on dopa metabolism. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 449–457, 2001  相似文献   

18.
Poly(ethylene glycol) (PEG) is often used to biocompatibilize surfaces of implantable biomedical devices. Here, block copolymers consisting of PEG and l ‐cysteine‐containing poly(amino acid)s (PAA's) were synthesized as polymeric multianchor systems for the covalent attachment to gold surfaces or surfaces decorated with gold nanoparticles. Amino‐terminated PEG was used as macroinitiator in the ring‐opening polymerization, (ROP), of respective amino acid N‐carboxyanhydrides (NCA's) of l ‐cysteine (l ‐Cys), l ‐glutamate (l ‐Glu), and l ‐lysine (l ‐Lys). The resulting block copolymers formed either diblock copolymers, PEG‐b‐p(l ‐Gluxcol ‐Cysy) or triblock copolymers, PEG‐b‐p(l ‐Glu)xb‐p(l ‐Cys)y. The monomer feed ratio matches the actual copolymer composition, which, together with high yields and a low polydispersity, indicates that the NCA ROP follows a living mechanism. The l ‐Cys repeat units act as anchors to the gold surface or the gold nanoparticles and the l ‐Glu repeat units act as spacers for the reactive l ‐Cys units. Surface analysis by atomic force microscopy revealed that all block copolymers formed homogenous and pin‐hole free surface coatings and the phase separation of mutually immiscible PEG and PAA blocks was observed. A different concept for the biocompatibilization of surfaces was followed when thiol‐terminated p(l ‐Lys) homopolymer was first grafted to the surface and then covalently decorated with HOOC‐CH2‐PEG‐b‐p(Bz‐l ‐Glu) polymeric micelles. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 248–257  相似文献   

19.
We have firstly demonstrated the dual facet of gold(III) in the reaction between gold(III) and porphyrins, which could be tuned through changing the counter ions, ligands and the electronic effect of the substituents of the porphyrins.  相似文献   

20.
The title racemic complex, bis[μ‐N‐(2‐oxidobenzylidene)‐d ,l ‐glutamato(2−)]bis[(isoquinoline)copper(II)] ethanol disolvate, [Cu2(C12H11NO5)2(C9H7N)2]·2C2H6O, adopts a square‐pyramidal CuII coordination mode with a tridentate N‐salicylideneglutamato Schiff base dianion and an isoquinoline ligand bound in the basal plane. The apex of the pyramid is occupied by a phenolic O atom from the adjacent chelate molecule at an apical distance of 2.487 (3) Å, building a dimer located on the crystallographic inversion center. The Cu...Cu spacing within the dimers is 3.3264 (12) Å. The ethanol solvent molecules are hydrogen bonded to the dimeric complex molecules, forming infinite chains in the a direction. The biological activity of the title complex has been studied.  相似文献   

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