Langduin C, a novel dimeric diterpenoid from the roots of Euphorbia fischeriana

Langduin C, a novel dimeric diterpenoid, was isolated from the roots of Euphorbia fischeriana and its structure was established by spectral data and single-crystal X-ray diffraction analysis.     

Self-assembly in palladium(II) and platinum(II) chemistry: the biomimetic approach

The self-assembly of complex cationic structures by combination of cis-blocked square planar palladium(II) or platinum(II) units with bis(pyridyl) ligands having bridging amide units has been investigated. The reactions have yielded dimers, molecular triangles, and polymers depending primarily on the geometry of the bis(pyridyl) ligand. In many cases, the molecular units are further organized in the solid state through hydrogen bonding between amide units or between amide units and anions. The molecular triangle [Pt(3)(bu(2)bipy)(3)(mu-1)(3)](6+), M = Pd or Pt, bu(2)bipy = 4,4'-di-tert-butyl-2,2'-bipyridine, and 1 = N-(4-pyridinyl)isonicotinamide, stacks to give dimers by intertriangle NH.OC hydrogen bonding. The binuclear ring complexes [[Pd(LL)(mu-2)](2)](CF(3)SO(3))(4), LL = dppm = Ph(2)PCH(2)PPh(2) or dppp = Ph(2)P(CH(2))(3)PPh(2) and 2 = NC(5)H(4)-3-CH(2)NHCOCONHCH(2)-3-C(5)H(4)N, form transannular hydrogen bonds between the bridging ligands. The complexes [[Pd(LL)(mu-3)](2)](CF(3)SO(3))(4), LL = dppm or dppp, L = PPh(3), and 3 = N,N'-bis(pyridin-3-yl)-pyridine-2,6-dicarboxamide, and [[Pd(LL)(mu-4)](2)](CF(3)SO(3))(4), LL = dppm, dppp, or bu(2)bipy, L = PPh(3), and 4 = N,N'-bis(pyridin-4-yl)-pyridine-2,6-dicarboxamide, are suggested to exist as U-shaped or square dimers, respectively. The ligands N,N'-bis(pyridin-3-yl)isophthalamide, 5, or N,N'-bis(pyridin-4-yl)isophthalamide, 6, give the complexes [[Pd(LL)(mu-5)](2)](CF(3)SO(3))(4) or [[Pd(LL)(mu-6)](2)](CF(3)SO(3))(4), but when LL = dppm or dppp, the zigzag polymers [[Pd(LL)(mu-6)](x)](CF(3)SO(3))(2)(x) are formed. When LL = dppp, a structure determination shows formation of a laminated sheet structure by hydrogen bonding between amide NH groups and triflate anions of the type NH-OSO-HN.     

硅钨酸与盐酸巴马汀相互作用光谱研究及其分析应用

在pH 为0.91 的HCl-NaOAc 缓冲介质中, 盐酸巴马汀与硅钨酸通过静电相互作用导致共振光散射信号显著增强,最大散射波长为297 nm, 增强的散射信号强度与盐酸巴马汀浓度在0.09～3.2 μg/mL 范围内呈线性关系, 据此建立了盐酸巴马汀的共振光散射分析方法, 检测限为9.1 ng/mL. 实验考察了pH、离子强度对体系的影响, 研究了体系紫外吸收光谱及荧光光谱, 讨论了共振光散射增强机理. 该方法用于黄藤素片、黄藤素胶囊及血清样品中盐酸巴马汀含量测定,RSD≤4.2%.     

Studies on Carbohydrates ⅩⅩⅧ. Synthesis of Key Intermediates of Oligosaccharides Related to Serratia marcescens O10 Antigen

TheO-antigenofbacteriacanbeusedasahaptenandvaccine.Preparationofanantigeninv0lvesthesynthesisofacorrespondinghaPtenbearingeithernarrow0rwiderspeci-ficity.Generally,fragmentsofcarbohydratechainsbearingthes0-calledcompleterepeatingunitareemployedashaPtens.Synthesis0foligosaccharides,whichareveryspecificfragments,isatpresentoneoftheimP0rtantaspectsofcarb0hydratechemistry.TheS.marcescensOlOantigenhasbeenisolatedfromtheLPSofthereferencesKain(C.D.C.l287-54)ofS.marcescens.Itsbiol0gicalrepeatun…     

Chiral Separation of Esmolol and Terazosin by Cyclodextrinmodified Capillary Zone Electrophoresis

IntroductionTheincreasingnecessity0fpharmacologicalresearchforchiraldrugshasrenderedchiralseparationanactiveareaincaPillaryelectroph0resis(CE)today.Variousmodes0fCE,includingcaPillaryzoneelectroph0resis(CZE),micellarelectrokineticchromatography(MEKC),caPillarygelelectrophoresis(CGE)andcapillaryisotachophoresis(CITP),havebeenappliedforthispurp0se',amongwhichCZEisthemostpopularoneforitshighefficiency,lowexpenseandeaseofoperation.Forsuccessfulchiralseparati0ninCZE,theselectortypeisofcr…     

An Ab Initio Study of N_2O Decomposition on MgO Catalyst

Nl0isalwaysusedasoxidantinalotofoxidativecatalyticprocesses,suchastheoxidativecouplingofmethane(0CM),oxidativedehydr0genationofalkanesands0on,becauseitdecomPosestoprovideOadspeciesonmetal0xidecatalystsandleadstothespecificoxidativeselectivity.Forexample,itwasf0undthatf0rOCMreacti0nonMgOandLougOcatalystS,thereactiontemPeraturerequiredislowerwhenoneusesN20asoxidantthanusing0,'.TheunderstandingofN20dec0mposihon0nmetal0xidecatalystsandthepropertiesofthereIevant0adspeciesshouldbeagoodstarting…     

CH(A^2Δ)自由基被醇类分子猝灭动力学的温度效应研究

用266nm激光光解CHBr3产生CH自由基, 利用精密控温仪控制反应温度, 测定CH(A→X)荧光的时间分辨信号, 测量了290K至653K范围内CH(A)被乙醇、丙醇、丁醇猝灭的速率常数, 利用修正的碰撞配合物模型, 定性解释了在多极吸引势与活化势垒的双重影响下, 猝灭截面与温度间的关系。     

氮化铁催化剂的制备及其苯胺催化加氢性能

用α－Ｆｅ２Ｏ３与氨气程序升温还原方法制备出不同温度氮气的氮化铁系列催化剂。通过ＸＲＤ测试对氮化过程中的晶相转变进行了分析。在中压反应装置上考察了氮化铁系列催化剂上苯胺加氢活性以及反应条件对苯胺加氢反应活性的影响。结果表明，在７００℃氮化制香的氮化铁催化剂显示有较高的苯胺加氢活性，在氢压为３．０ＭＰａ，温度为２５０℃，ｎ（Ｈ２）／ｎ（ｏｉｌ）＝１８，液体空速（ＷＨＳＶ）为０．３ｈ＾－１时，该催化剂     

二维色谱/光谱重叠峰的定性定量方法研究(I)——水中多种酚二维色谱/光谱重叠峰的分辨与定性定量

探讨了HELP法在水中酚类色谱重叠峰的分辨与定性定量分析中的应用.实验结果表明,各组分浓度比为1:50的范围内分辨光谱与真实光谱十分吻合.在10^-4～10^-6g/mL的浓度范围内分辨色谱的定量结果线性关系良好.分辨下限3.0×10^-7g/mL,相对标准偏差为5.0%.     

Studies on synthesis and infrared and fluorescence spectra of new europium and terbium complexes with an amide-based open-chain crown ether

An amide-based open-chain crown ether ligand and its complexes with europium and terbium were synthesized. The complexes were characterized by elemental analysis, infrared spectra and conductivity. The europium and terbium ions were found to coordinate to the C=O oxygen atoms and pyridine nitrogen atoms. The fluorescence properties of these complexes in DMF and CH3OH/CHCl3 were studied. Under the excitation of UV light, these complexes exhibit characteristic fluorescence of europium and terbium ions. The solvent factors influencing the fluorescent intensity are discussed.