Synthesis and NMR studies of (13)C-labeled vitamin D metabolites

Isotope-labeled drug molecules may be useful for probing by NMR spectroscopy the conformation of ligand associated with biological hosts such as membranes and proteins. Triple-labeled [7,9,19-(13)C(3)]-vitamin D(3) (56), its 25-hydroxylated and 1 alpha,25-dihydroxylated metabolites (58 and 68, respectively), and other labeled materials have been synthesized via coupling of [9-(13)C]-Grundmann's ketone 39 or its protected 25-hydroxy derivative 43 with labeled A ring enyne fragments 25 or 26. The labeled CD-ring fragment 39 was prepared by a sequence involving Grignard addition of [(13)C]-methylmagnesium iodide to Grundmann's enone 28, oxidative cleavage, functional group modifications leading to seco-iodide 38, and finally a kinetic enolate S(N)2 cycloalkylation. The C-7,19 double labeling of the A-ring enyne was achieved by the Corey-Fuchs/Wittig processes on keto aldehyde 11. By employing these labeled fragments in the Wilson-Mazur route, the C-7,9,19 triple-(13)C-labeled metabolites 56, 58, and 68 as well as other (13)C-labeled metabolites have been prepared. In an initial NMR investigation of one of the labeled metabolites prepared in this study, namely [7,9,19-(13)C(3)]-25-hydroxyvitamin D(3) (58), the three (13)C-labeled carbons of the otherwise water insoluble steroid could be clearly detected by (13)C NMR analysis at 0.1 mM in a mixture of CD(3)OD/D(2)O (60/40) or in aqueous dimethylcyclodextrin solution and at 2 mM in 20 mM sodium dodecyl sulfate (SDS) aqueous micellar solution. In the SDS micellar solution, a double half-filter NOESY experiment revealed that the distance between the H(19Z) and H(7) protons is significantly shorter than that of the corresponding distance calculated from the solid state (X-ray) structure of the free ligand. The NMR data in micelles reveals that 58 exists essentially completely in the alpha-conformer with the 3 beta-hydroxyl equatorially oriented, just as in the solid state. The shortened distance (H(19Z))-H(7)) in micellar solutions as compared to that in the solid state is most easily rationalized on the basis that the 5(10)-torsion angle in 58 is decreased in micellar solutions as compared to that in the solid state.     

Characterization and electrochemical investigation of boron-doped mesocarbon microbead anode materials for lithium ion batteries

The structure and anodic performance of boron-doped and undoped mesocarbon microbeads (MCMBs) have been comparatively studied and the results obtained by XPS, XRD, SEM, Raman spectroscopy and electrochemical measurements are discussed. It is found that boron doping introduces a depressed d ₀₀₂ spacing and the larger amount of "unorganized carbon", which induces vacancy formation in the graphite planes and leads to a quite different morphology from that of the undoped material. Electrochemical charge/discharge cycle tests indicated that after boron doping the lithium intercalation was carried through at a somewhat higher potential, being attended by greater irreversible capacity loss. Electronic Publication     

Inorganic electrides

Inorganic electrides are a novel kind of ionic compounds in which the anions are electrons confined in a complex array of cavities or channels and the cations are nanoscale arrays of alkali metal ions that provide charge balance. In electrides the donated electron behaves like a low-density correlated electron gas, whereby the dimensionality of the electron gas and its electronic and magnetic properties are determined by the topology of the cavities in the host matrix. Unlike traditional electrides, in which alkali cations are encapsulated within an organic cage, inorganic electrides are thermally stable. The current inorganic electrides based on alkali metal loaded zeolites can be designed as useful reduced-dimensionality materials. Inorganic electrides are powerful reducing agents, and they are able to reduce small aromatic molecules to the radical anions within the channels of the zeolite.     

Pt/HL和Pt/KL沸石在异丙醇分解反应中的不同催化行为

Ｐｔ／ＫＬ沸石在异丙醇分解反应中具有很高的脱氢活性,而Ｐｔ／ＨＬ沸石具有明显的缺电子性,在此反应中难以显示出脱氢活性,通过加氢作用,可使沸石的酸位免受积炭覆盖,从而可增强Ｐｔ／ＨＬ沸石的酸性催化作用。     

Elucidating dominant factors of PO43-, Cd2+ and nitrobenzene removal by biochar: A comparative investigation based on distinguishable biochars

Four distinct biochars were employed to remove three typical pollutants, meanwhile, path analysis, a multi-statistical regression method, was performed to elucidate the dominant factors of biochar adsorption. This work can provide a new insight to prepare a targeted biochar as adsorbents.     

Crystal Structures and Magnetic Studies of Naphthalene Derivatives Containing Nitronly Nitroxides

Crystal structures of new nitronyl nitroxide derivatives 1, 2 and 3 were determined with X‐ray diffraction analysis: 1, monoclinic, C₂/c, a = 1.2404(5) nm, b = 0.9730(5) um, c = 2.7049(10) ran, β = 98.189(15)°, V = 3.2315(24) nm³, Z = 8; 2, or‐thorhombic, Pbca, a = 0.61262(2) nm, b = 1.11426(6) nm, c = 2.30543(13) nm, V = 1.57373(13) nm³, Z = 4; 3, monoclinic, P2(1)/n, a=0.64253(4) nm, b=2.55003(17) nm, c = 1.15497(6) nm, β = 95.000(3)°, V = 1.8852(2) nm³, Z = 4. Their magnetic properties were measured with SQUID and analyzed based on their crystal structures with simple singlet‐triplet, modified one dimensional antiferromagnetic chain and modified singlet‐triplet models respectively: 1, J/k_b= ?2.5 K; 2, J/k_b = 7.8 K, θ = 2.8 K; 3, J/k_b = ?0.96 K, θ = 0.21 K.     

应用普通扫描仪作薄层色谱定量分析的初步研究

尝试应用普通扫描仪作薄层色谱定量分析。样品通过硅胶板层析展开后，用碘蒸汽显色，再用普通扫描仪记录其图像，通过图像分析技术计算出斑点中样品的量。结果表明，对油醇、油酸、月桂胺和焦谷氨酸油酯等长碳链有机化合物，样点在nmol级的范围内时计算量与实际量有良好的线性相关性。     

Direct electrochemistry and electrocatalysis of hemoglobin in gelatine film modified glassy carbon electrode

Direct electrochemical and electrocatalytic behavior of hemoglobin (Hb) immobilized on glass carbon electrode (GCE) containing gelatine (Gel) films was investigated. The characteristics of Hb/Gel film modified GC electrode were performed by using SEM microscopy, UV-vis spectroscopy and electrochemical methods. The immobilized Hb showed a couple of quasi-reversible redox peak with a formal potential of −0.38 V (versus SCE) in 0.1 M pH 7.0 PBS. The formal potential changed linearly from pH 4.03 to 8.41 with a slope value of −52.0 mV pH⁻¹, which suggested that a proton transfer was accompanied with each electron transfer (ET) in the electrochemical reaction. The Hb/gelatine/GCE displayed a rapid amperometric response to the reduction of H₂O₂ and nitrite.     

A new Fluorimetric Reagent for Highly Selective and Sensitive Determination of Terbium Ion

 In this work, a new ligand, 2,9-bis[N,N-bis(carboxymethyl)-aminomethyl]-1,10-phenanthroline (BBCAP), was synthesized and used to establish a novel fluorimetric method for the determination of trace amounts of terbium in a binary system. Its luminescence mechanism was studied. The excitation and emission wavelengths are 284 nm and 547 nm, respectively. Other rare-earth metal ions in 100-fold excess caused no interference. The fluorescence intensity was a linear function of the concentration of terbium in the range of 5.0 × 10⁻¹⁰–1.0 × 10⁻⁶ mol/L. The detection limit was 2.0 × 10⁻¹¹ mol/L (n = 12). The standard addition method was used to determine the terbium in a synthetic rare-earth sample with satisfactory results. This method represents a direct, rapid, selective and sensitive analytical procedure with a widely linear range. Received November 29, 2001 Revision February 9, 2002     

固液相变的分子动力学研究Ⅰ─—(KI)_(108)离子簇的熔化和凝固(英)

通过分子动力学模拟，考查并分析了（KI）108离子簇的结构、能量和相变的动力学行为．在加热和冷却过程中，离子簇再现了熔化和凝固现象，而且熔化起始于立方体的其一顶点，熔化的离子簇不是球形的，说明了离子簇的非湿特征．根据结晶的成核速率，讨论了电子衍射实验中观察KI凝固的可能性