共查询到20条相似文献,搜索用时 15 毫秒
1.
J C Chien 《Journal of molecular biology》1979,133(3):385-398
Various hemoglobin derivatives have been labeled at the Cys-β93 residue with a bulky and “strongly immobilized” nitroxide maleimide (I) and a smaller, more flexible and “weakly immobilized” nitroxide iodoacetamide (II) and crystallized. The angular dependence of the paramagnetic resonance of the spin-label was measured for the ab, and planes at 298 K and 77 K for spin-labeled crystals of Oxyhemoglobin, methemoglobin fluoride, and methemoglobin azide. In the case of the methemoglobin crystals, the angular variation of the heme resonance was also monitored at 77 K. From the hyperfine splitting data, the spin-label I was found to assume specific orientations at both temperatures with some motional narrowing at 298 K. Spin-label II is specifically oriented only at room temperature but is frozen at 77 K in random orientations. Oxyhemoglobin labeled with I (I-HbO22) has the most prominent spin-label orientation (z∥b, x∥a) and the less abundant spin-labels with (z∥b ± 15 °) (Ohnishi et al., 1966). The corresponding spin-label orientations for I-Hb+ F? are () and (). Crystals of I-Hb+ N?3 have spin-labels oriented along angular directions similar, but not identical to those of I-Hb+F?. Therefore, there are probably significant peptide segmental displacements when HbO2 is oxidized to methemoglobins. At 25 °C II-Hb+ N?3 has spin-label orientations not too different from those in I-Hb+ N?3, whereas in HbO2 the two spin-labels show significant differences in their orientations. 相似文献
2.
Yuhuan Li Qingyang Zhang Guanshen Cui Fang Zhao Xin Tian Bao-Fa Sun Ying Yang Wei Li 《基因组蛋白质组与生物信息学报(英文版)》2020,18(4):371-383
N6-methyladenosine (m6A) is one of the most abundant modifications on mRNAs and plays important roles in various biological processes. The formation of m6A is catalyzed by a methyltransferase complex (MTC) containing a key factor methyltransferase-like 3 (Mettl3). However, the functions of Mettl3 and m6A modification in hepatic lipid and glucose metabolism remain unclear. Here, we showed that both Mettl3 expression and m6A level increased in the livers of mice with high fat diet (HFD)-induced metabolic disorders. Overexpression of Mettl3 aggravated HFD-induced liver metabolic disorders and insulin resistance. In contrast, hepatocyte-specific knockout of Mettl3 significantly alleviated HFD-induced metabolic disorders by slowing weight gain, reducing lipid accumulation, and improving insulin sensitivity. Mechanistically, Mettl3 depletion-mediated m6A loss caused extended RNA half-lives of metabolism-related genes, which consequently protected mice against HFD-induced metabolic syndrome. Our findings reveal a critical role of Mettl3-mediated m6A in HFD-induced metabolic disorders and hepatogenous diabetes. 相似文献
3.
Photometric titration measurements indicated in the reaction of diazacrown ether N,N′-dibenzyl-1,4,10,13-tetraoxo-7,16-diazacyclooctadecane (DD18C6, 2) with iodine in chloroform that a complex was formed in the molar ratio DD18C6:I2=1:4. This complex was also prepared on a preparative scale as dark brown compound and characterized by microanalysis, UV-Vis, IR, and Raman spectroscopy. By X-ray diffraction analysis the solid-state structure of the complex was shown to be [(DD18C6)H2]I8 ([3]I8) consisting of a doubly protonated macrocycle and an octaiodide dianion (I8 2−) in the typical (nearly planar) Z-shaped geometry. The macrocycle is Ci symmetric and the protonated nitrogen atoms adopt an endo-endo orientation that is stabilized by the three-center hydrogen bonds N-H(?O)2, where the oxygen atoms of the macrocycle act as hydrogen acceptors. The orientation of the phenyl groups of the benzyl sidearms are turned above and below the macrocycle. Quantum chemical calculations on the DFT level of theory of the non-protonated and the doubly protonated macrocycle (DD18C6, 2c) and [(DD18C6)H2]2+ (3c), respectively, were performed and discussed for 3c in terms of conformational strain of the macrocycle, the strength of the intramolecular N-H?O hydrogen bonds and cation-π interactions. 相似文献
4.
Rui Zhu Raymond P. Baumann Eric Patridge Philip G. Penketh Krishnamurthy Shyam Kimiko Ishiguro Alan C. Sartorelli 《Bioorganic & medicinal chemistry letters》2013,23(6):1853-1859
Two new agents based upon the structure of the clinically active prodrug laromustine were synthesized. These agents, 2-(2-chloroethyl)-N-methyl-1,2-bis(methylsulfonyl)-N-nitrosohydrazinecarboxamide (1) and N-(2-chloroethyl)-2-methyl-1,2-bis(methylsulfonyl)-N-nitrosohydrazinecarboxamide (2), were designed to retain the potent chloroethylating and DNA cross-linking functions of laromustine, and gain the ability to methylate DNA at the O-6 position of guanine, while lacking the carbamoylating activity of laromustine. The methylating arm was introduced with the intent of depleting the DNA repair protein O6-alkylguanine-DNA alkyltransferase (AGT). Compound 1 is markedly more cytotoxic than laromustine in both AGT minus EMT6 mouse mammary carcinoma cells and high AGT expressing DU145 human prostate carcinoma cells. DNA cross-linking studies indicated that its cross-linking efficiency is nearly identical to its predicted active decomposition product, 1,2-bis(methylsulfonyl)-1-(2-chloroethyl)hydrazine (90CE), which is also produced by laromustine. AGT ablation studies in DU145 cells demonstrated that 1 can efficiently deplete AGT. Studies assaying methanol and 2-chloroethanol production as a consequence of the methylation and chloroethylation of water by 1 and 2 confirmed their ability to function as methylating and chloroethylating agents and provided insights into the superior activity of 1. 相似文献
5.
Six new bromothallate(III)-containing salts with different alkyl diammonium cations have been prepared from bromide containing solutions and studied by single-crystal X-ray crystallographic analyses. The N,N′-diethyl-N,N,N′,N′-tetramethyl-1,2-ethylenediammonium, N-methyl-1,3-propanediammonium, N,N,N′,N′-tetramethyl-1,3-propanediammonium and N,N,N′,N′-tetraethyl-1,2-ethylenediammonium cations yield complexes (I, II, III and IV, respectively) with the [TlBr5]2− anionic stoichiometry. For I and II, both complexes contain the [TlBr5]2− anion. In complex II, this appears as a distorted octahedron with one long Tl?Br2′ contact of 3.632(4) Å from an adjacent anion, thus completing the hexacoordination about an otherwise distorted square pyramid. On the other hand, for III and IV, both complexes contain a tetrahedral [TlBr4]− anion together with an isolated, but hydrogen-bonded, Br− anion. The 1,5-hexanediammonium complex (V) contains tetrahedral [TlBr4]−, slightly distorted octahedral [TlBr6]3− and Br− anions. The asymmetric unit of the N,N-diethyl-1,3-propanediammonium salt (VI) contains one cation and half of each of a [TlBr4]− and an axially compressed octahedral [TlBr6]3− anion. Extensive hydrogen-bonded networks exist in complexes II-VI. NH?Br hydrogen bonds generally have a significant influence on the nature of the anions present in species with the formal [TlBr5] stoichiometry. 相似文献
6.
I. Ravikumar 《Inorganica chimica acta》2010,363(12):2886-520
Syntheses and crystal structures of tren-based amide, L1, N,N′,N″-tris[(2-amino-ethyl)-4-nitro-benzamide] and L2, N,N′,N″-tris[(2-amino-ethyl)-2-nitro-benzamide] are reported and compared with previously published tripodal amide receptor L3, N,N′,N″-tris[(2-amino-ethyl)-3-nitro-benzamide]. The crystallographic results show intramolecular and intermolecular hydrogen-bonding interactions between two arms of the tripodal receptor and two other adjacent molecules in cases of L1 and L2 whereas in addition to the above interactions an aromatic π···π stacking among tripodal arms is also observed in L3. Receptors L1, L2 and L3 having electron withdrawing -NO2 substituted (para, ortho and meta, respectively) phenyl moieties are explored toward their solution state anion binding properties and selectivity studies. The substantial changes in chemical shifts are observed for the amide protons (-NH) and aromatic protons (-CH) with F− and Cl− in cases of L1 and L3, and only with F− for L2, indicating the participation of -NH and -CH protons in the solution state binding events. Binding constants for the above cases are calculated by 1H NMR titration upon monitoring the -NH signal. Receptor L2 shows exclusive selectivity toward F− in dimethyl sulfoxide (DMSO). The structural aspects of binding I−, ClO4− and SiF62− with the monoprotonated L1, L1H+·I−·DMF (1), L1H+·ClO4−·DMF (2) and L1H+·0.5SiF62−·H2O (3), respectively are examined crystallographically. Anion binding with multiple receptor units is observed via amide N-H···anion as well as aryl C-H···anion hydrogen-bonding interactions in all the complexes as observed in cases of previously reported crystal structures of anionic complexes of protonated L3. The aryl group having nitro functionality that contributes to solution state anion binding with the neutral receptor and solid state coordination in complexes 1-3 through CH···anion interactions is noteworthy. 相似文献
7.
《Cell calcium》2019
AimsThe effects of acute (100 s) hypoxia and/or acidosis on Ca2+ signaling parameters of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) are explored here for the first time.Methods and results1) hiPSC-CMs express two cell populations: rapidly-inactivating ICa myocytes (τi<40 ms, in 4–5 day cultures) and slowly-inactivating ICa (τi ≥ 40 ms, in 6–8 day cultures). 2) Hypoxia suppressed ICa by 10–20% in rapidly- and 40–55% in slowly-inactivating ICa cells. 3) Isoproterenol enhanced ICa in hiPSC-CMs, but either enhanced or did not alter the hypoxic suppression. 4) Hypoxia had no differential suppressive effects in the two cell-types when Ba2+ was the charge carrier through the calcium channels, implicating Ca2+-dependent inactivation in O2 sensing. 5) Acidosis suppressed ICa by ∼35% and ∼25% in rapidly and slowly inactivating ICa cells, respectively. 6) Hypoxia and acidosis suppressive effects on Ca-transients depended on whether global or RyR2-microdomain were measured: with acidosis suppression was ∼25% in global and ∼37% in RyR2 Ca2+-microdomains in either cell type, whereas with hypoxia suppression was ∼20% and ∼25% respectively in global and RyR2-microdomaine in rapidly and ∼35% and ∼45% respectively in global and RyR2-microdomaine in slowly-inactivating cells.ConclusionsVariability in ICa inactivation kinetics rather than cellular ancestry seems to underlie the action potential morphology differences generally attributed to mixed atrial and ventricular cell populations in hiPSC-CMs cultures. The differential hypoxic regulation of Ca2+-signaling in the two-cell types arises from differential Ca2+-dependent inactivation of the Ca2+-channel caused by proximity of Ca2+-release stores to the Ca2+ channels. 相似文献
8.
Stefan Wirth Andreas U. Wallek Anna Zernickel Florian Feil M. Sztiller-Sikorska K. Lesiak-Mieczkowska Christoph Bräuchle Ingo-Peter Lorenz M. Czyz 《Journal of inorganic biochemistry》2010,104(7):774-789
The synthesis, structural characterization and biological activity of eight ortho-quinone(N-aryl)-oximine rhenium(i) complexes are described. The reaction of the halogenido complexes (CO)5ReX (X=Cl (4), Br (5)) with 2-nitroso-N-arylanilines {(C6H3ClNO)NH(C6H4R)} (R = p-Cl, p-Me, o-Cl, H) (3a–d) in tetrahydrofurane (THF) yields the complexes fac-(CO)3XRe{(C6H3ClNO)NH(C6H4R)} (6a–d, 7a–d) with the tautomerized ligand acting as a N,N′-chelate. The substitution of two carbonyl ligands leads to the formation of a nearly planar 5-membered metallacycle. During coordination the amino-proton is shifted to the oxygen of the nitroso group which can be observed in solution for 6 and 7 by 1H NMR spectroscopy and in solid state by crystal structure analysis. After purification, all compounds have been fully characterized by their 1H and 13C NMR, IR, UV/visible (UV/Vis) and mass spectra. The X-ray structure analyses revealed a distorted octahedral coordination of the CO, X and N,N′-chelating ligands for all Re(i) complexes. Biological activity of four oximine rhenium(i) complexes was assessed in vitro in two highly aggressive cancer cell lines: human metastatic melanoma A375 and human chronic myelogenous leukemia K562. Chlorido complexes (6a and 6c) were more efficient than bromido compounds (7d and 7b) in inducing apoptotic cell death of both types of cancer cells. Melanoma cells were more susceptible to tested rhenium(i) complexes than leukemia cells. None of the ligands (3a–d) showed any significant anticancer activity. 相似文献
9.
The lilac pyralid, Palpita nigropunctalis Bremer (Lepidoptera: Crambidae), is a common pest of Oleaceae plants. A crude extract of the female sex pheromone glands was examined by gas chromatography-electroantennogram detection (GC-EAD) and GC coupled to a mass spectrometer (GC/MS). The GC-EAD analysis revealed three EAG-active components (I–III) in a ratio of 1:0.2:0.01 (I: II: III). GC/MS analysis successfully recorded the mass spectra of I and II. For I, ions at m/z 238 (M+) and 220 ([M-18]+) indicated the structure of a monoenyl aldehyde with a 16-carbon chain. For II, M+ was not detected, but ions at m/z 222 ([M-60]+) and 61 ([AcOH+1]+) suggested that II was a monoenyl acetate with a 16-carbon chain. Further GC/MS analysis of the extract treated with dimethyl disulfide revealed that the double bonds in both I and II are located at the same position of 11th-carbon. In addition, the pheromone extract was examined by GC/Fourier transform-infrared spectrophotometer (GC/FT-IR). An IR spectrum of I showed characteristic absorption at 1716 and 966?cm?1, indicating a formyl group and E configuration of the double bond, respectively. In the case of II, absorption at 1745 and 968?cm?1 indicated an ester carbonyl and E configuration, respectively. Taken together and by comparison with authentic standards, I and II were confirmed as (E)-11-hexadecenal and (E)-11-hexadecenyl acetate, respectively; while III was speculated as (E)-11-hexadecen-1-ol. The synthetic I, II and III all coincided well with those of the natural components in chemical data, and elicited strong electroantennographic activity in male P. nigropunctalis. 相似文献
10.
《Cell calcium》2015,58(5-6):321-336
The quintessential property of developing cardiomyocytes is their ability to beat spontaneously. The mechanisms underlying spontaneous beating in developing cardiomyocytes are thought to resemble those of adult heart, but have not been directly tested. Contributions of sarcoplasmic and mitochondrial Ca2+-signaling vs. If-channel in initiating spontaneous beating were tested in human induced Pluripotent Stem cell-derived cardiomyocytes (hiPS-CM) and rat Neonatal cardiomyocytes (rN-CM). Whole-cell and perforated-patch voltage-clamping and 2-D confocal imaging showed: (1) both cell types beat spontaneously (60–140/min, at 24 °C); (2) holding potentials between −70 and 0 mV had no significant effects on spontaneous pacing, but suppressed action potential formation; (3) spontaneous pacing at −50 mV activated cytosolic Ca2+-transients, accompanied by in-phase inward current oscillations that were suppressed by Na+-Ca2+-exchanger (NCX)- and ryanodine receptor (RyR2)-blockers, but not by Ca2+- and If-channels blockers; (4) spreading fluorescence images of cytosolic Ca2+-transients emanated repeatedly from preferred central cellular locations during spontaneous beating; (5) mitochondrial un-coupler, FCCP at non-depolarizing concentrations (∼50 nM), reversibly suppressed spontaneous pacing; (6) genetically encoded mitochondrial Ca2+-biosensor (mitycam-E31Q) detected regionally diverse, and FCCP-sensitive mitochondrial Ca2+-uptake and release signals activating during INCX oscillations; (7) If-channel was absent in rN-CM, but activated only negative to −80 mV in hiPS-CM; nevertheless blockers of If-channel failed to alter spontaneous pacing. 相似文献
11.
A novel series of benzoic acid N′-[2-(4-benzothiazol-2-yl-piperazin-1-yl)-acetyl]-hydrazides 6a–j were synthesized and characterized by IR, 1H, 13C NMR, elemental and mass spectral analyses. The in-vitro cytotoxicity and cell viability assay of the synthesized compounds 6a–j were evaluated against Dalton’s lymphoma ascites (DLA) cells. Our results showed that compound 6c with a bromo group on phenyl ring has showed promising antiproliferative efficacy. Further investigation of compound 6c on in-vivo treatment model depicts the increased tumor suppression through inhibition of angiogenesis. 相似文献
12.
《Inorganica chimica acta》1988,149(2):259-264
The bis(N-alkylsalicylaldiminato)nickel(II) complexes Ni(R-sal)2 with R = CH(CH2OH)CH(OH)Ph (I), R = CH(CH3)CH(OH)Ph (II) and R = CH2CH2Ph (III; Ph = phenyl) were prepared and characterized. In the solid state I and II are paramagnetic (μ = 3.2 and 3.3 BM at 20 °C, respectively), whereas III is diamagnetic. It follows from the UV-Vis spectra that in acetone solution I is six-coordinate octahedral and III is four-coordinate planar, the spectrum of II showing characteristics of both modes of coordination. Vis spectrophotometry and stopped-flow spectrophotometry were applied to study the kinetics of ligand substitution in I–III by H2salen (= N,N′-disalicylidene-ethylenediamine) in the solvent acetone at different temperatures. The kinetics follow a second-order rate law, rate = k[H2-salen] [complex]. At 20 °C the sequence of rate constants is k(III):k(II):k(I) = 11 850:40.6:1. The activation parameters are ΔH≠(I) = 112, ΔH≠(II) = 40.7, ΔH≠(III) = 35.7 kJ mol−1 and ΔS≠(I) = 92, ΔS≠(II) = −103, ΔS≠(III) = −89 J K−1 mol−1. The enormous difference in rate between complexes I, II and III, which is less pronounced in methanol, is attributed to the existence of a fast equilibrium planar ⇌ octahedral, which is established in the case of I and II by intramolecular octahedral coordination through the hydroxyl groups present in the organic group R. An A-mechanism is suggested to control the substitution in the sense that the entering ligand attacks the four-coordinate planar complex, the octahedral complex being kinetically inert. 相似文献
13.
《Inorganica chimica acta》1987,132(2):217-222
XPd(μ-dppm)2Pt(C6F5) (X = Cl (I), Br (II)) have been prepared by reacting Pd2(dba)3·CHCl3 and PtX- (C6F5)(η1-dppm)2. Reaction of complex I with SnCl2 gives the SnCl3− derivative, whilst ligands L (PPh3, P(OPh)3, SbPh3) render the cationic complexes. The species R2N+, SO2 or MeOOC)CCCOOMe insert into the PdPt bond of I to give A-frame Pd(II)- Pt(II) complexes. The reactions of CIPd(μ-dppm)2- Pt(C6F5) with isonitriles CNR (R = p-Tol, Cy) lead to products containing either terminal or inserted isocyanide or both. 相似文献
14.
M. Dolores Santana Gabriel García Joaquín García Luis García 《Inorganica chimica acta》2011,378(1):49-55
Direct reaction between the hydroxo-complexes [{Pd(μ-OH)(C^N)}2] (C^N = 2-(2-pyridyl)phenyl (Phpy) I; C^N = 7,8-benzoquinolyl (Bzq) II) and N-naphtylsalycilaldimine (N-naphsal) 1 yields new mononuclear cyclometallated palladium(II) complexes [Pd(N-naphsal)(C^N)] (I1, II1). Photophysical properties were investigated together with those of complexes with related ligands N-phenylsalycilaldiminate (N-Phsal) 2, N-p-chlorophenylsalycilaldiminate (N-pClPhsal) 3. All the compounds absorb intensely below 300 nm via1LC transitions located in Bzq or Phpy ligands, and display additional low energy absorptions of mixed 1MLCT-1LC character. The complexes under study are quite unusual in terms of luminescence behavior, since some of them are emissive in solution at room temperature and all display intense emissions in frozen CHCl3 solution, but also in solid state at 298 and 77 K. Structural characterization by X-ray diffraction of complexes I2, I3 and II2 confirmed the proposed formulae. 相似文献
15.
Aleem Gangjee Nilesh Zaware Ravi Kumar Vyas Devambatla Sudhir Raghavan Cara D. Westbrook Nicholas F. Dybdal-Hargreaves Ernest Hamel Susan L. Mooberry 《Bioorganic & medicinal chemistry》2013,21(4):891-902
A series of fourteen N4-(substituted phenyl)-N4-alkyl/desalkyl-9H-pyrimido[4,5-b]indole-2,4-diamines was synthesized as potential microtubule targeting agents. The synthesis involved a Fisher indole cyclization of 2-amino-6-hydrazinylpyrimidin-4(3H)-one with cyclohexanone, followed by oxidation, chlorination and displacement with appropriate anilines. Compounds 6, 14 and 15 had low nanomolar potency against MDA-MB-435 tumor cells and depolymerized microtubules. Compound 6 additionally had nanomolar GI50 values against 57 of the NCI 60-tumor panel cell lines. Mechanistic studies showed that 6 inhibited tubulin polymerization and [3H]colchicine binding to tubulin. The most potent compounds were all effective in cells expressing P-glycoprotein or the βIII isotype of tubulin, which have been associated with clinical drug resistance. Modeling studies provided the potential interactions of 6, 14 and 15 within the colchicine site. 相似文献
16.
《Inorganica chimica acta》1986,123(4):193-196
The stoichiometry of the reaction between Cu(II) and MoS42− in neutral aqueous solution was observed to proceed with a 1.5:1 Cu:Mo ratio. The reaction results in the reduction of Cu(II) and the quantitative formation of an insoluble solid. The results contrast with an earlier report of a 1:1 stoichiometric ratio, this latter ratio was, however, observed with CuII(albumin) as reactant, in this case no precipitate was observed. The insoluble products were examined by a number of spectroscopic techniques and by X-ray power diffraction and elemental analysis. Two products were identified. Solid A is isostructural with the known (NH4)CuIMoVVIS4, i.e. has the composition MICuMoS4, MI= NH4+, Na+ or Et4N+. Solid B has the approximate composition CuMoS4Ox, x=2−3 and contains Cu(I) and Mo(V) centres. Formation of compound B therefore involves an unusual internal two-electron redox process. The reaction and products are of particular biological significance. 相似文献
17.
Zheng Li Mengyang Luo Bin Cai Lichuan Wu Mengtian Huang Jun Jiang Lisheng Wang 《Bioorganic & medicinal chemistry letters》2018,28(4):677-683
Using matrine (1) as the lead compound, a series of new 14-(N-substituted-2-pyrrolemethylene) matrine and 14-(N-substituted-indolemethylene) matrine derivatives was designed and synthesized for their potential application as anticancer agents. The structure of these compounds was characterized by 1H NMR, 13C NMR and ESI-MS spectral analyses. The target compounds were evaluated for their in vitro cytotoxicity against three human cancer cell lines (SMMC-7721, A549 and CNE2). The results revealed that compound A6 and B21 displayed the most significant anticancer activity against three cancer cell lines with IC50 values in range of 3.42–8.05?μM, which showed better activity than the parent compound (Matrine) and positive control Cisplatin. Furthermore, the Annexin V-FITC/PI dual staining assay revealed that compound A6 and B21 could significantly induce the apoptosis of SMMC-7721 and CNE2 cells in a dose-dependent manner. The cell cycle analysis also revealed that compound A6 could cause cell cycle arrest of SMMC-7721 and CNE2 cells at G2/M phase. 相似文献
18.
《Inorganica chimica acta》1986,121(1):81-87
The crystal structures of two modifications of gadoliniumdicyclopentadienidebromide, [Gd(C5H5)2Br]2 (I) and 1∞[Gd(C5H5)2Br] (II) have been determined from X-ray diffraction data. I crystallizes in the [Sc(C5H5)2Cl]2-type structure, space group P21/c, with a=14.110(3), b=16.488(3), c= 13.765(3) Å, β=93.25(2)°, V=3197(2) Å3, and Dc= 2.289 g cm−3 for Z=6 molecules. II crystallizes in space group P21/c with a=5.946(7), b=8.447(5), c=20.239(9) Å, β=90.11(4)°, V=1020(2) Å3, Dc=2.392 g cm−3 for Z=4 formula units. The structures have been refined by full matrix least-squares techniques to conventional R factors of 0.034 for 3014 (I) and 1964 (II) reflections (with I>2σ(I)). I consists of dimers with two bromine bridges (mean GdBr 2.872 Å). II has a double chain structure with alternating juxtaposition of gadolinium and bromine atoms (GdBr 2.912 Å (once) and 3.133 Å (twice)). The arrangement of the C5H5 groups with regard to the metal η5 fashion) is nearly identical in I and II (mean GdC 2.63(1) Å (I) and 2.62(1) Å (II)). Single crystals of I and II are obtained by sublimation at different temperatures. The formation of both modifications is discussed as to its dependence on the state of the gaseous phase equilibrium [Gd(C5H5)2Br]2 ⇄ 2Gd(C5H5)2Br. Obviously, I crystallizes from gaseous phase dimers while II forms from the monomers. 相似文献
19.
《Inorganica chimica acta》1988,145(2):247-252
Various palladium salts react with n-propane thiol to form a mixture of the cyclic mercaptides Pd8(S-nPr)16 (I) and the known Pd6(S-nPr)12 (II). I is described as an octagonal toroid, containing a planar ring of palladium atoms, each being bridged by four mercapto groups in approximately square planar geometry. The pendant n-propyl groups radiate outward in approximately axial and equatorial orientations with respect to the ring, which was also observed in solution by 1H and 13C NMR. Crystal data: space group C2/c, a=22.251(15), b=27.623(6), c=14.621(17) Å, β=116.35°(4), V=8053(4) Å3. Least-squares refinement based on 3103 observed reflections led to an R value of 0.078. I and II failed to complex any appropriate guest species, as evidenced by the UV-Vis spectra. I was found to have a reversible oxidation wave at E/2= 0.77 V, and a irreversible oxidation wave of 1.09 V. II displayed two irreversible peak potentials at 0.77 and 1.09 V. In each case, the waves were one electron processes, in which the reversibility was not enhanced at low temperatures. 相似文献
20.
《Bioorganic & medicinal chemistry letters》2014,24(18):4466-4471
A novel synthesis of the translocator protein (TSPO) ligand 7-chloro-N,N,5-trimethyl-4-oxo-3-phenyl-3,5-dihydro-4H-pyridazino[4,5-b]indole-1-acetamide (SSR180575, 3) was achieved in four steps from commercially available starting materials. Focused structure–activity relationship development about the pyridazinoindole ring at the N3 position led to the discovery of 7-chloro-N,N,5-trimethyl-4-oxo-3(6-fluoropyridin-2-yl)-3,5-dihydro-4H-pyridazino[4,5-b]indole-1-acetamide (14), a novel ligand of comparable affinity. Radiolabeling with fluorine-18 (18F) yielded 7-chloro-N,N,5-trimethyl-4-oxo-3(6-[18F]fluoropyridin-2-yl)-3,5-dihydro-4H-pyridazino[4,5-b]indole-1-acetamide ([18F]-14) in high radiochemical yield and specific activity. In vivo studies of [18F]-14 revealed this agent as a promising probe for molecular imaging of glioma. 相似文献