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1.
Synthesis and single crystal X-ray structures of the first paramagnetic transition metal complexes containing chiral ethylenedithio-tetrathiafulvalene-oxazoline (EDT-TTF-OX) 1a-c and ethylenedithio-tetrathiafulvalene-thiomethyloxazoline 2 (EDT-TTF-(SMe)OX) ligands based on copper (II) and cobalt (II) are described. The racemic [EDT-TTF-OX][Cu(hfac)2] complex 3a crystallizes in the triclinic centrosymmetric space group , whereas the enantiopure counterparts 3b-c crystallize in the triclinic non-centrosymmetric space group P1. Cu(II) adopts a distorted square pyramidal coordination geometry, a much weaker Cu?STTF interaction also being identified. The same coordination pattern around Cu(II) is observed in the complex [(rac)-EDT-TTF-(SMe)OX][Cu(hfac)2] (4) in spite of the bidentate nature of the redox active ligand. DFT theoretical calculations afforded two equilibrium configurations for a corresponding model complex, in which the metal centre establishes secondary coordination either with one STTF or with the SMe group. The same ligand coordinates the cobalt (II) to afford the octahedral complex [(rac)-EDT-TTF-(SMe)OX][Co(hfac)2] (5). In all these novel complexes, the paramagnetic centres are structurally and magnetically isolated. Cyclic voltammetry measurements show the stability of the radical cation species.  相似文献   

2.
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.  相似文献   

3.
Interactions of cationic porphyrins bearing five-membered rings at the meso position, meso-tetrakis(1,2-dimethylpyrazolium-4-yl)porphyrin (MPzP; M is H2, CuII or ZnII), with synthetic polynucleotides poly(dG-dC)2 and poly(dA-dT)2 have been characterized by viscometric, visible absorption, circular dichroisim and magnetic circular dichroism spectroscopic and melting temperature measurements. Both H2PzP and CuPzP are intercalated into poly(dG-dC)2 and are outside-bound to the major groove of poly(dA-dT)2, while ZnPzP is outside-bound to the minor groove of poly(dA-dT)2 and surprisingly is intercalated into poly(dG-dC)2. The binding constants of the porphyrin and poly(dG-dC)2 and poly(dA-dT)2 are on the order of 106 M−1 and are comparable to those of other cationic porphyrins so far reported. The process of the binding of the porphyrin to poly(dG-dC)2 and poly(dA-dT)2 is exothermic and enthalpically driven for H2PzP, whereas it is endothermic and entropically driven for CuPzP and ZnPzP. These results have revealed that the kind of the central metal ion of metalloporphyrins influences the characteristics of the binding of the porphyrins to DNA.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.  相似文献   

4.
The 5-HT(3) and GABA(A) receptors are members of the Cys-loop family of neurotransmitter-gated ion channels that also include receptors for glycine and acetylcholine. The 5-HT(3) and acetylcholine receptors (cationic ion channels) and the GABA(A) and glycine receptors (anionic ion channels) generally depolarize or hyperpolarize, respectively, the neuronal membrane. Within the amino-terminal extracellular region, all members of this family exhibit a similar architecture of ligand binding domains and a number of key residues are completely conserved. The molecular characterization of their ligand binding and gating characteristics has benefited from the existence of a large repertoire of individual subunits that contribute to the pentameric ion channel. Although differences do exist, advances in our knowledge of one member offers valuable insight into the family as a whole. Each member of the Cys-loop receptors (and all other multimeric ion channels) must face the same challenges: How to assemble individual subunits into an ion channel and which subunits to use? How are assembled receptors distinguished from those that are unassembled or misassembled, then exported from the endoplasmic reticulum and delivered to the cell surface? How are they targeted to, and anchored at synaptic and extrasynaptic sites? How and when are they to be removed from these sites to provide long-term regulation of neuronal activity? In this review, we summarize our current knowledge for the 5-HT(3) and GABA(A) receptors that have provided complementary information and helped us build an overall picture of how receptor biogenesis and trafficking occurs.  相似文献   

5.
Exechia and Bibio have retained several plesiomorphic groundplan features of Diptera and Bibionomorpha, including a fully exposed and sclerotized head capsule, the transverse undivided labrum, the absence of movable premandibles, and undivided mandibles without combs. The fusion of the hypostomal bridge with the head capsule and largely reduced antennae are derived features shared by both taxa. The absence of teeth at the anterior hypostomal margin is a potential autapomorphy of Bibionomorpha. A basal position of Anisopodidae is suggested by a number of plesiomorphies retained in this family. Apomorphies of Bibionomorpha excluding Anisopodidae are the reduction of tentorial elements, the partial fusion of the labrum and clypeus, one-segmented antennae, the absence of a separate submental sclerite, the loss of the labial palpus, and the reduction of the pharyngeal filter apparatus. Head structures of Bibio are largely unmodified. The subprognathous orientation is one of few autapomorphic features. In contrast, the mouthparts of Exechia are highly modified in correlation with the specialized food uptake. The rasping counterrotating movements of maxillae and mandibles with teeth oriented in opposite directions are carried out by strongly developed extensors and flexors of the paired mouthparts. The modified labium mechanically supports the “drill head” formed by the mandibles und maxillae. The necessary stability of the head capsule is provided by the hypostomal bridge which also compensates the far-reaching reduction of the tentorium.  相似文献   

6.
R M Wartell 《Biopolymers》1972,11(4):745-759
Helix–coil transition curves are calculated for poly (dA) poly(dT) and poly (dA-dT) poly (dA-dT) using the integral equation approach of Goel and Montroll.5 The transitions are described by the loop entropy model with the exponent of the loop entropy factor, k, remaining an arbitrary constant. The theoretical calculations are compared with experimental transition curves of the two polymers. Results indicate that the stacking energies for these two polymers differ by about 1 kcal/mole of base pairs. Also, a fit between theory and experiment was not possible for k > 1.70.  相似文献   

7.
N-(3,5-Dichlorophenylsulfonyl)-(R)-thioprolyl biarylalanine 10a has been identified as a potent and specific antagonist of the alpha(4)beta(1) integrin. Altering the configuration of thioproline from R to S led to a series of dual antagonists of alpha(4)beta(1) and alpha(4)beta(7), and the N-acetyl analogue 8b was found to be the most potent dual antagonist. A binding site model for alpha(4)beta(1) and alpha(4)beta(7) is proposed to explain the structure-activity relationship.  相似文献   

8.
The trinuclear [{RuII(bpy)2(bpy-terpy)}2CoII]6+ complex (16+) in which a Co(II)-bis-terpyridine-like centre is covalently linked to two Ru(II)-tris-bipyridine-like moieties by a bridging bipyridine-terpyridine ligand has been synthesised and characterised. Its electrochemical, photophysical and photochemical properties have been investigated in CH3CN. The cyclic voltammetry exhibits two successive reversible oxidation processes, corresponding to the CoIII/CoII and RuIII/RuII redox couples at E1/2 = −0.06 and 0.91 V vs Ag/Ag+ 10 mM, respectively. The one-electron oxidized form of the complex, [{RuII(bpy)2(bpy-terpy)}2CoIII]7+ (17+) obtained after exhaustive electrolysis carried out at 0.2 V is fully stable. 16+ and 17+ are only poorly luminescent, indicating that the covalent linkage of the Ru(II)-tris-bipyridine centre to the cobalt subunit leads to a strong quenching of the RuII excited state by an intramolecular process. Luminescence lifetime experiments carried out at different temperatures indicate that the transfer is more efficient for 17+ compare to 16+ due to lower activation energy. Continuous irradiation of 17+ performed at 405 nm in the presence of P(Ph)3 acting as sacrificial electron donor leads to its quantitative reduction into 16+, whereas similar experiment starting from 16+ with a sulfonium salt as sacrificial electron acceptor converts 16+ into 17+ with a slower rate and a maximum yield of 80%. These photoinduced electron transfers were followed by UV-Visible spectroscopy and compared with those obtained with a simple mixture of both mononuclear parent complexes i.e. [RuII(bpy)3]2+ and [CoII(tolyl-terpy)2]2+ or [CoIII(tolyl-terpy)2]3+ (tolyl-terpy = 4′-(4-methylphenyl)-2,2′:6′,2′′-terpyridine).  相似文献   

9.
The preparation is reported of [(NH3)3Pt(9- MeA)] X2 (9-MeA = 9-methyladenine) with XCl (1a) and XClO4 (1b) and of trans-[(OH)2Pt(NH3)3- (9-MeA)]X2 with XCl (2a) and XClO4 (2b), and the crystal structure of 1b. [(NH3)3Pt(C6H7N5)](ClO4)2 crystallizes in space group P21/n with a = 20.810(7) Å, b = 7.697(3) Å, c = 10.567(4) Å, β = 91.57(6)°, Z = 4. The structure was refined to R = 0.054, Rw = 0.063. In all four compounds Pt coordination is through N7 of 9-MeA, as is evident from 3J coupling between H8 of the adenine ring and 195Pt. Pt(II) and Pt(IV) complexes can be differentiated on the basis of different 3J values, larger for Pt(II) than for Pt(IV) by a factor of 1.57 (av). In Me2SO-d6, hydrogen bonding occurs between Cl? and C(8)H of 9-MeA as weil as between Cl? and the NH3 groups in the case of the Pt(II) complex 1a. Protonation of the 9-MeA ligands was followed using 1H NMR spectroscopy and pKa values for the N1 protonated 9-MeA ligands were determined in D2O. They are 1.9 for 1a and 1.8 for 2a, which compares with 4.5 for the non-platinated 9-MeA. Possible consequences for hydrogen bonding with the complementary bases thymine or uracil are discussed briefly. Protonation of the OH groups in the Pt(IV) complexes has been shown not to occur above pH 1.  相似文献   

10.
Xia Z  Zhuang J 《Luminescence》2012,27(5):379-381
A novel blue‐emitting Sr3.5Y6.5O2(PO4)1.5(SiO4)4.5:Eu2+ phosphor was synthesized via a solid‐state reaction. Powder X‐ray diffraction (XRD) analysis demonstrated that the Sr3.5Y6.5O2(PO4)1.5(SiO4)4.5 host had a hexagonal crystal structure in the space group P63/m and unit cell parameters a = 9.418 Å, c = 6.900 Å. The as‐prepared phosphor showed a blue emission and all the main emission peaks were located at around 466 nm for different excitation wavelengths of 297, 333 and 391 nm. The temperature dependence of the photoluminescence property was investigated in the range 20–250 °C, and the emission intensity decreased to 71% of the initial value at room temperature on increasing the temperature to 150 °C. According to the classical theory of fluorescent thermal quenching, the activation energy (ΔE) for the thermal quenching luminescence of the as‐prepared Sr3.45Y6.5O2(PO4)1.5(SiO4)4.5:0.05Eu2+ phosphor was determined to be 0.20 eV. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

11.
Four allelic forms of serum plasminogen (PLG) were detected in baboons (Papio hamadryas Linneaus 1758) by isoelectric focusing and were determined to be inherited as autosomal codominant traits. Linkage analysis of data from 179 progeny and their parents revealed that PLG is tightly linked (lod score = 30.20) to the gene encoding apolipoprotein(a) (LPA), as in humans. No recombinant individuals were identified. This is the first linkage detected between PLG and LPA in any species other than humans and is the first genetic linkage identified in a nonhuman primate species by family studies.  相似文献   

12.
A cladistic analysis of Simulium ( Trichodagmia ) sensu Crosskey and Howard, using 34 morphological characters of larvae (6 characters), pupa (5) and adults (23), yields nine most parsimonious trees under equal weights (length 101 steps CI 0.49 RI 0.73). Successive weighting based on the maximal rescaled consistency index preferred one of the nine (31.37 steps CI 0.62 RI 0.87 total fitcon3= 235.8), which was also one of two trees found under implicit weights with concavity values of 3–6. The cladogram justifies the recognition of two subgenera. Simulium ( Trichodagmia ) sensu stricto (containing S. muiscorum, sumapazense, S. wygodzinskyorum, S. nigrimanum, S. chalcocoma, S. huairayacu and S. lahillei ) is supported by the branchial tip sclerotization and the presence of cibarial teeth, larval body tegument covered with lanceolate hairs, female with simple claw, and gonapophysis size. Simulium ( Thyrsopelma ) (containing S. scutistriatum, S. hirtipupa, S. orbitale, S. guianense, S. perplexum and S. itaunense ) is supported by the hypostomial teeth.  相似文献   

13.
[Alpha 1(III)]3 collagen was solubilized by pepsin digestion of normal human placental membranes and was purified by differential salt precipitation and carboxymethylcellulose chromatography. This collagen was digested with CNBr, and the resultant nine peptides were isolated and characterized. The chains are cross-linked by cysteinyl residues in the COOH-terminal peptide. Isolation of peptides derived from CNBr digestion of insoluble tissues was used as an assay for the presence of [alpha 1(I)]2alpha 2 and [alpha 1(III)]3 collagens. Both types are present in human skin, intestine, liver, spleen, kidney, lung, aorta, umbilical cord, placental membranes, and myocardium. Bone and tendon contain [alpha 1(I)]2alpha 2 collagen but, unlike the other tissues, lack [alpha 1(III)]3 collagen. Both [alpha 1(I)]2alpha 2 and[alpha 1(III)]3 collagens are present in scars of human skin, myocardium, tendon, and liver and of rabbit skin. The degree of hydroxylation of proline was 4 to 5% lower in the same peptides in skin, bone, and tendon than in the other tissues. The degree of hydroxylation of lysine in the same peptides derived from different tissues varied more widely.  相似文献   

14.
The enzymes chlorocatechol-1,2-dioxygenase, chloromuconate cycloisomerase, dienelactone hydrolase, and maleylacetate reductase allow Ralstonia eutropha JMP134(pJP4) to degrade chlorocatechols formed during growth in 2,4-dichlorophenoxyacetate or 3-chlorobenzoate (3-CB). There are two gene modules located in plasmid pJP4, tfdC(I)D(I)E(I)F(I) (module I) and tfdD(II)C(II)E(II)F(II) (module II), putatively encoding these enzymes. To assess the role of both tfd modules in the degradation of chloroaromatics, each module was cloned into the medium-copy-number plasmid vector pBBR1MCS-2 under the control of the tfdR regulatory gene. These constructs were introduced into R. eutropha JMP222 (a JMP134 derivative lacking pJP4) and Pseudomonas putida KT2442, two strains able to transform 3-CB into chlorocatechols. Specific activities in cell extracts of chlorocatechol-1,2-dioxygenase (tfdC), chloromuconate cycloisomerase (tfdD), and dienelactone hydrolase (tfdE) were 2 to 50 times higher for microorganisms containing module I compared to those containing module II. In contrast, a significantly (50-fold) higher activity of maleylacetate reductase (tfdF) was observed in cell extracts of microorganisms containing module II compared to module I. The R. eutropha JMP222 derivative containing tfdR-tfdC(I)D(I)E(I)F(I) grew four times faster in liquid cultures with 3-CB as a sole carbon and energy source than in cultures containing tfdR-tfdD(II)C(II)E(II)F(II). In the case of P. putida KT2442, only the derivative containing module I was able to grow in liquid cultures of 3-CB. These results indicate that efficient degradation of 3-CB by R. eutropha JMP134(pJP4) requires the two tfd modules such that TfdCDE is likely supplied primarily by module I, while TfdF is likely supplied by module II.  相似文献   

15.
16.
天然型与非天然型脱落酸的生物活性比较   总被引:2,自引:0,他引:2  
采用新方法精制脱落酸(ABA)异构体试样,提高了(S)-(+)-ABA与(R)-(-)-ABA两对映体纯度。抑制生长试验和残留量分析以及气孔闭合试验表明:天然型(S)-(+)-ABA活性显著高于非天然型(R)-(-)-ABA或(SR)-(±)-ABA。抑制莴苣种子发芽50%的活性强度,(S)-(+)-ABA约是(R)-(-)-ABA的5倍,(SR)-(±)-ABA介于两者之间。抑制萝卜下胚轴生长试验,最显著有效期为2~6d,生理作用期约为一周,(S)-(+)-ABA活性是(R)-(一)-ABA的3.5倍。鸭跖革气孔闭合试验,(S)-(+)-ABA活性比(R)-(-)-ABA高1倍。  相似文献   

17.
Copper(II) and nickel(II) complexes are prepared of potentially quadridentate ligands (LH3), N-{2-(2- hydroxyethylamino)ethyl}- (seeH3), N-{3-(2-hydroxy- ethylamino)propyl}- (steH3), and N-{2-(3-hydroxypropylamino)ethyl}-salicylamide (setH3). The nickel complexes Na[Ni(see)] and Na[Ni(set)]·1/2H2O are diamagnetic and square-planar, in which the ligands act as a quadridentate one coordinated through secondary amino-N, and deprotonated phenolic-O, alcoholic-O, and amido-N atoms. The three copper complexes Na [CuL]·H2O (L = see, ste, set) with a normal magnetic moment have a similar square-planar structure. In another type complexes Cu(LH)·H2O (LH = seeH, setH) an alcohol group is not deprotonated. Two isomers are present in Cu(seeH)·H2O: one has a normal and the other a subnormal magnetic moment. The difficulty of complex formation of steH3 may be attributed to an unfavourably fused 6-6-5 membered chelate ring with strain.  相似文献   

18.
Crystals of Pt(DMSO)4(TFMS)2 have been prepared by dissolution of platinum(II) hydroxide in a solution of CF3SO3H in DMSO and subsequent evaporation. The structure was determined by use of a CAD-4 diffractometer with monochromatic Mo Kα radiation. The space group is P with Z = 2, a = 8.630(2), b = 9.557(3), c = 16.659(3) Å, α = 73.33(2), β = 77.38(2) and γ = 79.19(3)°. The refinement converged to R = 0.056. The coordination around platinum is distorted square-planar with two S- and two O-bonded DMSO ligands in a cis-arrangement. The four donor atoms and the platinum are coplanar within 0.03 Å. There is a severe steric crowding between the two S-bonded DMSO molecules, which gives rise to a distortion of the bond angles around the platinum. The crowding is minimized as much as possible by a staggered arrangement of oxygen atoms and methyl groups of adjacent ligands. Pt---S bond lengths 2.208(3) and 2.205(4) Å are significantly shorter that those in the corresponding palladium complex, in accordance with a much stronger bond in the case of platinum. Bond length comparisons also indicate that ground state transinfluence of S-bonded DMSO probably is about the same in platinum and palladium complexes.  相似文献   

19.
trans-Bis(resorcylaldoximato)copper(II) and trans-bis-(2,3,4-trihydroxybenzaldoximato)copper(II) (CuRES2 and CuTRI2, respectively) have been tested for antiviral properties against HIV, using an in vitro assay that measures the ability of the test compounds to prevent the killing of susceptible human cells by HIV. In the case of CuTRI2, T4 lymphocytes (CEM-V and CEM-Z cell lines) were exposed to HIV at a virus to cell ratio approx. 0.05 in microtiter plates. In the case of CuRES2, a human leukemia cell line (MT-2) was used instead. The tetrazolium salt XTT was added to all wells, and the cultures were incubated and analyzed spectrophotometrically to quantitate formazan production and viewed microscopically for detection of viable cells. In spite of their antiproliferative properties, neither agent had any detectable ability to prevent the cytopathic effects of HIV in cultures of the target cells used. Because the test system employed was constructed in such a way as to detect antiviral agents acting at any stage of the virus reproductive cycle, the results obtained strongly suggest that neither studied agent has any value as the direct prevention of the cell destruction caused by HIV is concerned.  相似文献   

20.
The preparations of novel platinum and copper metallodendrimers are reported. Surface modified first generation (G0) poly(amidoamine) (PAMAM) dendritic Schiff base, prepared via a condensation reaction was coordinated with platinum chloride and copper chloride yielding [G0-Py4-[PtCl2]4] (4D) and [G0-Py4-[CuCl2]7] (7E) respectively. These functionalized hyper-branched complexes were characterized by IR spectroscopy and CHN analysis. 4D was further characterized through 1H and 13C spectroscopy, while 7E was characterized using matrix-assisted laser desorption ionization time-of-flight (MALDI/TOF) Mass Spectrometer. The cytotoxic effects of the compounds against cells of neoplastic origin (MOLT-4, MCF-7) and cells of benign origin (Chang Liver) were studied. Their cytotoxicities were then compared to their mono-nuclear analogues, [(MeCONHCH2CH2NCHPy)(PtCl2)] (1D) and [(MeCONHCH2CH2NCHPy)(CuCl2)] (1E). The multi-nuclear complexes showed increased cytotoxic activities as compared to their respective mono-nuclear compounds. Most notably, significant inhibitions were observed for 7E on all cell lines, in which its IC50 values were 11.1 ± 0.6, 10.2 ± 1.5 and 8.7 ± 0.7 μM against MOLT-4, MCF-7 and Chang Liver cells respectively. The multi-nuclear copper-based complexes (7E) are therefore most effective against a cancer cell line (MOLT-4) and a cisplatin-resistant cell line (MCF-7).  相似文献   

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