苯部分加氢制环己烯的非晶态Ru-M-B/ZrO2催化剂的表征

采用化学还原法，制备了高活性，高选择性非晶态RU-M-B/ZRO2催化剂，并将其用于催化苯部分加氢制环己烯，在140℃、5.0Mpa氢压下，苯转化40%时，环己烯选择性达到85%左右。环己烯最高收率达到52.1%，用XRD、SEM、BET比表面积测定等手段对摧化剂进行表征，XRD和SEM测试表明，RU-U-B/ZRO2属于非晶态，活性组分高度分散，XRD结果证实，在加氢过程中，非晶分解，RU晶化；温度愈高，RU晶化愈快，催化剂的活性、选择性与RU微晶的粒径有关，RU微晶粒径应控制在5nm左右，BET比表面积测定表明，ZRO2的负载提高了催化剂的比表面积，从而有利于活性组分的高度分散，并可阻止RU微晶的长大，讨论了B和ZRO2对提高选择性的作用。     

微波常压法合成水杨酸酯

在浓硫酸催化下，采用微波常压法由水杨酸分别与正丁醇、异丁醇、正戊醇和异戊醇反应合成相应的水杨酸酯。结果表明：当水杨酸：醇：Ｈ２ＳＯ４＝１：５．５：０．３（摩尔比）时，采用５６０Ｗ微波辐射２２ｍｉｎ，水杨酸酯的产率可达８８．７％￣９６．４％，反应速度至少是常规反应的１４倍。     

1β—Methyl Carbapenem中间体的合成

综述了１β－Ｍｅｔｈｙｌ Ｃａｒｂａｐｅｎｅｍ中间体的合成方法，重点强调了如何构筑１位β构型的甲基。参考文献３７篇。     

Synthesis and Characterization of Novel Orange-emitting Iridium（Ⅲ） Complexes with Diphenylquinoline Ligands Containing Fluorinated Substituent

Three new cyclometalated iridium（m） complexes based on ligands of diphenylquinoline with fluorinated subsfituents were prepared, and characterized by elemental analysis （EA）, ^1H NMR, and mass spectroscopy （MS）. The photophysical and electrophosphorescent properties of the complexes were briefly discussed.     

ROOM-TEMPERATURE FLUORESCENCE PROPERTIES OF THE POLYNUCLEOTIDE POLYdA POLYdT

The room-temperature fluorescence spectrum of the non-alternating polynucleotide polydA.polydT is found to have its maximum at about 325 nm and, when exciting in the spectral region where both adenine (A) and thymine (T) absorb, to coincide with that obtained for excitation at 293 nm where thymine is selectively excited. The fluorescence anisotropy is found to be equal to 0.18 and independent of the excitation and emission wavelengths. These observations are consistent with: (i) emission stemming from T; and (ii) transfer of electronic energy from A to T being not efficient. These inferences are also supported by the observed dependence of the fluorescence quantum yield on the excitation wavelength.     

High-frequency (140-GHz) time domain EPR and ENDOR spectroscopy: the tyrosyl radical-diiron cofactor in ribonucleotide reductase from yeast

High-frequency pulsed EPR and ENDOR have been employed to characterize the tyrosyl radical (Y*)-diiron cofactor in the Y2-containing R2 subunit of ribonucleotide reductase (RNR) from yeast. The present work represents the first use of 140-GHz time domain EPR and ENDOR to examine this system and demonstrates the capabilities of the method to elucidate the electronic structure and the chemical environment of protein radicals. Low-temperature spin-echo-detected EPR spectra of yeast Y* reveal an EPR line shape typical of a tyrosyl radical; however, when compared with the EPR spectra of Y* from E. coli RNR, a substantial upfield shift of the g(1)-value is observed. The origin of the shift in g(1) was investigated by 140-GHz (1)H and (2)H pulsed ENDOR experiments of the Y2-containing subunit in protonated and D(2)O-exchanged buffer. (2)H ENDOR spectra and simulations provide unambiguous evidence for one strongly coupled (2)H arising from a bond between the radical and an exchangeable proton of an adjacent residue or a water molecule. Orientation-selective 140-GHz ENDOR spectra indicate the direction of the hydrogen bond with respect to the molecular symmetry axes and the bond length (1.81 A). Finally, we have performed saturation recovery experiments and observed enhanced spin lattice relaxation rates of the Y* above 10 K. At temperatures higher than 20 K, the relaxation rates are isotropic across the EPR line, a phenomenon that we attribute to isotropic exchange interaction between Y* and the first excited paramagnetic state of the diiron cluster adjacent to it. From the activation energy of the rates, we determine the exchange interaction between the two irons of the cluster, J(exc) = -85 cm(-)(1). The relaxation mechanism and the presence of the hydrogen bond are discussed in terms of the differences in the structure of the Y*-diiron cofactor in yeast Y2 and other class I R2s.     

Orthogonal PbS nanowire arrays and networks and their Raman scattering behavior

Three-dimensional, orthogonal lead sulfide (PbS) nanowire arrays and networks have been prepared by using a simple, atmospheric pressure chemical vapor deposition (APCVD) method. These uniform nanowires (average diameter 30 nm) grow epitaxially from the surface of the initial PbS crystal seeds and form orthogonal arrays and networks in space. The growth mechanism has been explored, and the process was classified as homogeneous, epitaxial growth in the 200 directions. Furthermore, Raman spectra of PbS nanowires are reported here, and their characteristic Raman peak (190 cm(-1), no shoulder) could be used as a unique probe for the study of PbS nanomaterials.     

A Novel Oxidative N-Demethylation of 12-Membered Macrolide with Lead Tetraacetate

Erythromycin has been extensively used in the treatment of bacterial infections for over 50 years1. In addition to the antimicrobial effect, the quite unique antiinflammatory activity of the erythromycin derivatives has attracted much attention as new the…     

Separation of Sulfonylurea Herbicides and Determination of Bensulfuron-methyl Residues in Tapwater by HPTLC

JPC – Journal of Planar Chromatography – Modern TLC - In this work we have studied the separation of a mixture of the sulfonylurea herbicides (metsulfuron-methyl, chlorsulfuron,...