Raman Spectroscopic Studies on the Complexation and Adsorbed Behaviour of Thiourea

Raman spectroscopic studies on thiourea (TU) in highly acidic media (e. g. >3 mol/L HC1O4) show that TU as a solution species is protonated through its sulphur atom and forms complex with anions. However, as an adsorbed species, TU is protonated via the nitrogen atom and adsorbed at the silver electrode surface through the sulphur atom. The distinct effects of pH and anions of the solution on the surface enhanced Raman (SER) spectra of TU were investigated. In acidic and neutral solutions, TU is coadsorbed with anions through its NH3 and - NH2 groups respectively.     

In Situ Confocal Microprobe Raman Spectroscopy Study of the Oxygen Species over Cerium Oxide

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Spectroscopic Studies on the Molecular Complex of the Drug Atenolol with Iodine

Spectroscopic and spectrofluorimetric studies were made of the interaction between the drug atenolol and iodine. The interaction was found to proceed through the initial formation of a charge transfer (CT) complex as an intermediate species. The product of this interaction has been isolated and characterized using UV-Vis, FT-IR and Raman spectroscopic techniques. Formation of the triodide I₃^-\mathrm{I}_{3}^{-} species was confirmed by its electronic and Raman spectra. Peaks appeared in Raman spectrum of the isolated product at 153, 102 and 85 cm⁻¹ that are assigned to ν _as(I-I), ν _s(I-I) and d(I₃^-)\delta(\mathrm{I}_{3}^{-}) respectively, which confirmed the presence of the I₃^-\mathrm{I}_{3}^{-} ion. The stoichiometry of the complex was found to be 1:2. The rate of their reaction has been measured as a function of time and solvent. Pseudo-first-order rate constants for the reaction were measured at various temperatures and the thermodynamic activation parameters (ΔG ^#,ΔS ^# and ΔH ^#) were computed. Preliminary fluorescence quenching studies indicated that the interaction between atenolol and iodine is spontaneous and proceeds through a CT complex, and the quenching of fluorescence of atenolol by iodine increases as the extent of such complexation increases     

Studies on Oxidative Coupling of Methane Catalysed by Li-Ce-Sr Oxides

The conditions for catalyst preparation and coupling reaction of methane were investigated. The experimental results showed that under the catalysts the selectivity for C2 formation may reach 98.5% and the yield 28.2% (the average within the first 30 minutes). A stale selectivity and yield for C2 formation obtained after reaction for 2h were 48.4% and 20.6%, respectively. Some kinetic parameters were also determined, including activation energy and the partial pressure dependence of the catalytic reaction rates. Finally a preliminary explanation of the reaction mechanism is suggested.     

Studies on Cyclodextrin Inclusion Complex by Fluorescence Anisotropy

An equation for determining the equilibrium association constant (KA) of cyclodextrin inclusion complex with fluorescence anisotropy is derived and used to determine KA of pyrene-B-cyclodextrin inclusion complex. The existing forms of cyclodextrin inclusion complex in solution, the interaction type of host with guest, and the possibility of application of B-cyclodextrin in the analysis of metal ions using naphthalene derivative as a ligand are discussed based on the equation derived along with the curve of fluorescence anisotropy versus cyclodextrin concentration of guest/cyclodextrin system.     

Confocal Raman Spectroscopy – Applications on Wood,Pulp, and Cellulose Fibres

The manifold possibilities using dispersive Raman spectroscopy along the production chain from wood to cellulose fibre are presented here: The distribution of the lignin, cellulose, and added resins in the wood cell; additives inside regenerated cellulose fibres; their accessibility and reactivity. On-line measurements during the phase transition of magnesium sulphite -hexahydrate into -trihydrate are performed in a stirring vessel.     

Studies on the Phenylfluorone-Mo(Ⅵ) Complex as Interacting Mode Spectroscopic Probe of Protein in OP Microemulsion Medium

The application of phenylfluorone (PF)-Mo(VI) complex as a spectroscopic probe is studied. In the presence of OP microemulsion at pH 3.04, PF-Mo(Ⅵ) complex combines protein rapidly to form a stable compound and the absorbance at 527 nm is in proportion to the concentration of protein in the range 0-16 μg mL-1 for bovine serum albumin (BSA). OP microemuslion media is introduced into protein determination, it has increased markedly the sensitivity of the system. The molar absorption coefficient was 5.98×l06 L mol-1 cm-1 for BSA. The assay, with sensitivity, simplicity and tolerance to many foreign substances, is applied to the determination of protein in samples with satisfactory results. Moreover, the binding number of BSA with the complex, which is determined by molar ratio and slope ratio methods, is in good agreement.     

Electrochemical and Spectroscopic Studies on Interaction between Complex of Copper（Ⅱ） with Schiff Base Ligand and DNA

Introduction Deoxyribonucleicacid(DNA)isthemostim- portantgermplasmofmostorganisms.Thebind- ingofsmallmolecules,especiallytransitionmetal complexestoDNAandmolecularidentificationare importantresearchsubjectsinlifescience.There- searchontheinteractionbetweensmallmolecules andDNAhasbecomeafieldofgeneralinterest[1], becausethisisveryimportanttoexpoundtheac- tionmechanismofanticancerdrugs,theexternal selectionofdrugsandcarcinogenesisofcarcino- geniccompounds.Ithasbeenreportedthatmany metalcomp…     

Electrochemical and Spectroscopic Studies on Interaction between Complex of Copper(Ⅱ) with Schiff Base Ligand and DNA

The crystal structure of ( [CuL (H2O) 2 ] (ClO4) 2 · 2H2O, CuL) (L ＝ N- (5-sulfosalicylidene)-4' -bromoaniline) was determined by means of X-ray crystallography. The interaction between CuL and salmon sperm DNA in a 0. 1 mol/L HOAc-NaOAc buffer solution (pH 5.10) was investigated by cyclic voltammetry and UV-Vis spectroscopy. A couple of redox peaks of CuL in the cyclic voltammograms(CV) can be seen at the glassy carbon electrode. It was found that the peak current of CuL decreased significantly with a negative shift of the peak potential in the presence of DNA compared with that in the absence of DNA. In addition,the decreased absorbance of CuL was observed with increasing the concentration of DNA; the absorption spectrum of an ethidium bromide(EB)-DNA system inthe presence of CuL confirms that the binding mode of CuL to DNA is different from the intercalation of EB with DNA. All the experimental results indicate that CuL can bind to DNA by electrostatic binding and form a 1:1 association complex with a binding constant of 2.72×104 L/mol.     

The Active Oxygen Species for Oxidative Coupling of Methane over CeO_2/BaF_2 Catalyst by in Situ Confocal Microprobe Raman Spectroscopy

ＴｈｅＡｃｔｉｖｅＯｘｙｇｅｎＳｐｅｃｉｅｓｆｏｒＯｘｉｄａｔｉｖｅＣｏｕｐｌｉｎｇｏｆＭｅｔｈａｎｅｏｖｅｒＣｅＯ２／ＢａＦ２ＣａｔａｌｙｓｔｂｙｉｎＳｉｔｕＣｏｎｆｏｃａｌＭｉｃｒｏｐｒｏｂｅＲａｍａｎＳｐｅｃｔｒｏｓｃｏｐｙ＊＊Ｓｕｐｐｏｒｔｅ...     

甲烷氧化偶联催化剂La2O3／SrCO3—BaCO3的催化活性与表征

在甲烷氧化偶联制Ｃ２烃的研究中，人们发现碱土金属与稀土金属组成的复合氧化物催化剂具有高的催化活性［１，２］．稀土化合物作为有希望的工业催化剂之一，已受到广泛的关注．一般认为，它们含有的氧空位对活化甲烷的有效氧物种有利．Ｄｅｂｅｙ等在１％Ｓｒ／Ｌａ２Ｏ...     

氟化锶／氧化钕催化剂的甲烷氧化偶联性能及其吸附氧物种的原位FTIR光谱研究

氟化锶／氧化钕催化剂的甲烷氧化偶联性能及其吸附氧物种的原位ＦＴＩＲ光谱研究龙瑞强，万惠霖，赖华龙，蔡启瑞（厦门大学化学系固体表面物理化学国家重点实验室，厦门，３６１００５）关键词甲烷氧化偶联，氟化锶／氧化钕，吸附氧物种近年来，甲烷氧化偶联（ＯＣＭ）的...     

稀土氧化物在高炉喷吹煤粉助燃催化剂中的应用及机制分析

在模拟高炉喷吹条件下,对添加CeO2和La2O3的混合煤粉进行了燃烧反应试验,考察了稀土氧化物对高炉喷吹煤粉燃烧过程的影响,为探讨其助燃作用机制,采用等离子体热解试验模拟煤粉在高炉风口回旋区的快速热分解过程,考察了稀土氧化物助燃催化剂对煤粉挥发分挥发过程的影响;采用固定碳在空气气氛条件下的差热和热重试验(TG&DTA)模拟稀土氧化物助燃催化剂对煤粉中固定碳在高炉风口条件下燃烧过程的影响,提出了稀土氧化物对煤粉挥发分挥发过程和固定碳燃烧过程的助燃催化作用机制.     

甲烷氧化偶联催化剂ThO_2－La_2O_3／BaCO_3上活性氧物种研究

本文运用电子顺磁共振（ＥＰＲ）技术研究了Ｏ２在甲烷氧化偶联催化剂ＴｈＯ２，Ｌａ２Ｏ３／ＢａＣＯ３及ＴｈＯ２－Ｌａ２Ｏ３／ＢａＣＯ３上的吸附．通过对这三种催化剂上生成的Ｏ２超氧离子性质的比较，并与其催化活性相关联，发现ＴｈＯ２的掺杂使Ｏ２离子的ｇｚｚ值向低场方向移动，这可能有利于Ｏ２离子在升温过程中向Ｏ２离子的转化，从而使ＴｈＯ２－Ｌａ２Ｏ３／ＢａＣＯ３的催化活性和选择性有明显的提高．本文还考察了ＣＯ２对Ｏ２离子的影响．     

STUDIES OF THE OXIDATIVE COUPLING OF METHANE OVER A La_2O_3-CaO CATALYST

ｎｔｒｏｄｕｃｔｉｏｎＯｘｉｄａｔｉｖｅｃｏｕｐｌｉｎｇｏｆｍｅｔｈａｎｅ（ＯＣＭ）ｉｓｏｎｅｏｆｔｈｅｍｏｓｔｉｍｐｏｒｔａｎｔｒｅａｃｔｉｏｎｓｉｎｒｅｌａｔｉｏｎｔｏｔｈｅｕｔｉｌｉｚａｔｉｏｎｏｆｎａｔｕｒａｌｇａｓ．Ｍａｎｙｓｔｕｄｉｅｓｈ...     

稀土氧化钐上甲烷氧化偶联反应的FT—IR研究

用傅里哀变换红外(FT-IR)光谱原位考察了稀土氧化钐上甲烷氧化偶联反应及乙烯,乙烷的氧化反应。在700℃以下,甲烷,乙烯和乙烷分别与氧化钐表面反应时,除检测到表面碳酸基外,未观察到其它表面物种。这些表面碳酸基物种只有在700℃以上才大部分脱附,在氧存在下,高于700℃时这些低碳烃的完全氧化很显著,但在内循环反应体系中发现过量的气相CO_2可抑制烃类的深度氧化。甲烷的偶联反应在700℃以上才可明显观察到。而大部分表面碳酸基也在700℃以上才脱附,但经脱碳酸基或高温氧化处理后的氧化钐上均未明显观察到O~-物种的ESR峰。本文认为经高温脱碳酸基后形成的表面配位不饱和氧物种O~(δ-)(1<δ<2)在甲烷氧化偶联反应中起主要作用。     

模板法制备La2O3/ZrO2复合氧化物及其催化小桐子油合成生物柴油

以桦木为模板制备了一系列La2O3/Zr O2固体碱催化剂。采用BET、XRD、XPS和SEM等技术手段对其进行了表征。结果表明,与浸渍法和共沉淀法制备的样品相比,所制得的复合氧化物具备桦木的生物形态,具有更高的比表面积、更小的晶粒尺寸、更大的孔径和孔容等特点。当La/Zr质量比为10%时,样品的碱性最高,催化性能最好。以所制复合氧化物为催化剂,考察小桐子油和甲醇的催化酯交换反应。结果表明,在醇油摩尔比72∶1,固体碱催化剂质量分数8%,反应温度200℃,反应时间6 h的条件下,酯交换反应的甲酯转化率达93.6%。该样品具有一定的抗酸和抗水性。相同反应条件下,样品循环使用3次生物柴油收率仍为83%左右。     

甲烷氧化偶联CaF2／Sm2O3催化剂的研究

甲烷氧化偶联ＣａＦ_２／Ｓｍ_２Ｏ_３催化剂的研究周水琴，龙瑞强，黄亚萍，万惠霖，蔡启瑞（厦门大学化学系，固体表面物理化学国家重点实验室，厦门，３６１００５）关键词甲烷氧化偶联，氟化钙，三氧化二钐，离子交换，氧物种甲烷氧化偶联制乙烯是催化领域中最活跃的?..     

Effect of Steam on the Oxidative Coupling of Methane over La-Ba System Catalysts

ＥｆｅｃｔｏｆＳｔｅａｍｏｎｔｈｅＯｘｉｄａｔｉｖｅＣｏｕｐｌｉｎｇｏｆＭｅｔｈａｎｅｏｖｅｒＬａ┐ＢａＳｙｓｔｅｍＣａｔａｌｙｓｔｓ＊＊ＳｕｐｐｏｒｔｅｄｂｙｔｈｅＮａｔｉｏｎａｌＮａｔｕｒａｌＳｃｉｅｎｃｅＦｏｕｎｄａｔｉｏｎｏｆＣｈｉｎａ．＊＊...