双通道毛细管离子色谱法同时测定降水中阴、阳离子

采用离子色谱法测定降水中的阴阳离子。F–,Cl–,NO2–,NO3–,SO42–,PO43–6种阴离子的检出限在0.002~0.015 mg/L之间,Na+,NH4+,K+,Mg2+,Ca2+5种阳离子的检出限在0.010~0.025 mg/L之间。阴离子加标回收率在88.4%~109%之间,相对标准偏差小于5%;阳离子加标回收率在85.0%~112%之间,相对标准偏差小于7%。用离子色谱法测定降水中的阴阳离子,操作简单、快捷,灵敏度高。     

钼氧簇(MoO_3)_n~+(n=1～4)的结构及其与CO反应机理的理论研究

采用密度泛函理论对化学计量比钼氧簇阳离子(MoO_3)_n~+(n=1~4)的结构和反应性进行理论研究.计算结果表明,化学计量比钼氧簇阳离子(MoO_3)_n~+(n=1~4)的基态结构均为二重态,且含有一个拉长的Mo–O键连接的端氧自由基(Mo–Ot·).这类氧自由基具有很高的反应活性,可作为催化反应的活性中心.在杂化泛函B3LYP水平下,通过计算反应势能面研究钼氧簇阳离子(MoO_3)_n~+(n=1~4)与CO的反应机理:CO先以C端吸附在与氧自由基(Ot·)相连的金属Mo原子上;随后,Mo–Ot·键断裂,氧自由基转移到CO上,形成CO_2基团;最后CO_2分子脱去.上述反应均是无能垒的放热反应,单核钼氧簇MoO_3~+的高反应活性与其中心钼原子的低配位环境有关.     

K改性的Pt/Al2O3催化剂上CO氧化反应：反应动力学和红外光谱研究

CO氧化不仅具有重要的实用价值,而且在基础研究中被用于考察反应机理及催化剂结构敏感性等一些重要问题,因此,该反应在催化领域中具有重要意义. Pt基催化剂被广泛应用于CO氧化反应.其催化活性取决于催化剂的制备方法.其中,碱金属如Na、K等助剂的添加可有效促进催化活性,红外光谱证据表明,其促进作用在于碱金属的添加可降低CO与表面Pt原子的相互作用.尽管如此,催化剂上反应动力学证据却十分缺乏.反应动力学的研究可以提供一些本证反应信息如反应基元步骤、反应速率表达式以及反应机理等.通过对比不同催化剂之间的反应动力学行为,可以进一步解释碱金属对催化剂结构以及反应行为的影响.因此在本工作中,我们制备了一系列以K为助剂的Pt/Al2O3催化剂,并进行了CO氧化的反应动力学研究,考察了助剂对CO反应级数和反应活化能的影响.结合原位红外光谱表征,进一步揭示了助剂在反应中的作用.通过对比不同Pt和K含量的催化剂上CO氧化反应活性,我们发现, K的添加能促进反应活性,且随着催化剂中K含量的增加,促进程度越明显.例如,0.42K-2Pt/Al2O3上T50温度比对应的2Pt/Al2O3降低了30oC.不同催化剂上CO氧化的反应动力学实验表明,反应速率随着CO的分压的增加而降低;但随着O2分压的增加而增大.幂函数反应速率表达式推导得到的反应级数发现,对于含K的催化剂其CO的反应级数(约为–0.2)明显比不含K的催化剂(约为–0.5)中高,说明K的添加减弱了CO与表面Pt原子之间的吸附能力.但对O2的反应级数影响较小.例如：在0.42K-2.0Pt/Al2O3上反应速率表达式为r =6.55′10–7pco–0.22po20.63;而在2.0Pt/Al2O3上为r =2.56′10–7pco–0.53po20.70.表观反应活化能的计算表明,含K的催化剂上表观反应活化能较低,进一步说明K的添加有利于反应进行.根据反应速率表达式,我们进行了基元步骤的推导,并计算了反应动力学参数.结果发现,与不含K的催化剂相比,含K的催化剂中本征反应速率常数明显增加,而CO吸附平衡常数降低了一半,表明K的存在使CO在Pt表面上的覆盖度降低.我们还通过原位红外光谱对比了催化剂上CO吸附行为的差异.数据表明,与不含K的催化剂相比, K的添加一方面降低了CO在催化剂表面的吸附量(峰面积变小);另一方面显著降低了CO在Pt表面上的脱附温度,说明两者之间的相互作用力减弱.综上所述,通过反应动力学和红外光谱实验,我们认为K助剂与表面Pt原子相互作用后生成了较为稳定的Pt–O–K物种.尽管该物种的具体结构目前还不明确,但我们的实验证据表明,该物种的存在可以有效减弱CO与表面Pt原子之间的相互作用,降低CO的表面覆盖度并有利于O2在Pt表面的竞争吸附,从而降低了表面吸附的CO与O2之间反应的能垒,促进了反应性能.     

M(CO)4~(2+)(M=Ni,Pd,Pt)的几何结构与自旋态的理论研究

对标题化合物的几何结构和可能的自旋态在密度泛函DFT-BP86和从头算的水平上进行了研究.计算结果表明:作为16电子配合物阳离子,Pd(CO)_4~(2+)和Pt(CO)~(2+)都以低自旋态平面四边形构型存在,这与实验事实相符,计算得到的键长Pd-C和Pt-C相对趋势也与实验数据一致.而对于Ni(CO)_4~(2+)阳离子计算,在低自旋态平面四边形构型和高自旋态的(扭曲)四面体之间无法给出明确的答案,因为CCSD(T)//BP86和CCSD(T)//MP2水平下得到的两种结构之间的能量差几乎可以忽略.     

三七水煎液中还原型谷胱甘肽及腺嘌呤的分离与鉴定

三七经水煎提取,阴、阳离子交换树脂分离以及RP-HPLC分离获得多种含肽类化合物组分,采用游离及酸水解后氨基酸组成及含量对照分析的方法预示了提取液中肽类化合物的存在,经氨基酸组成分析、聚丙烯酰胺薄膜双向层析、羧肽酶C-末端序列分析、质谱测定等方法分析,将YN-3H12组分鉴定为还原型谷胱甘肽,YN-3H11组分鉴定为腺嘌呤,本研究方法可为植物中水溶性肽类化合物等活性成分的研究提供参考。     

离子色谱法测定纯净水中6种阴离子

建立离子色谱法测定纯净水中F–,Br O3–,Cl–,NO2–,Br–,NO3–等6种阴离子的方法。淋洗液为1.2mmol/L Na HCO3–1.0 mmol/L Na2CO3混合溶液,流量为1.5 m L/min,柱箱温度为35℃。在底液中加入与淋洗液同浓度的Na2CO3–Na HCO3碱化底液可有效消除水负峰。6种阴离子的检出限为1.0~21.0μg/L,加标回收率在90.0%~106.0%之间,相对标准偏差为1.43%~4.49%(n=5)。该方法测定结果准确、可靠,操作简便快速,适用于纯净水中F–,Br O3–,Cl–,NO2–,Br–,NO3–的测定。     

阳离子掺杂水滑石的制备及其性质研究

研究了掺杂阳离子水滑石的制备及阳离子对水滑石性质的影响. 分别制备了掺杂Zn2+、Ni2+、Fe3+型的水滑石, 考察了掺杂阳离子对水滑石晶相结构、层间距、层间阴离子含量、水滑石表面形态、水滑石碱性的影响, 结果表明, 由于阳离子的引入, 导致水滑石层间距减小及层间阴离子结合量降低, 且使水滑石培烧产物电负性提高, 并最终降低其碱性. 以上述水滑石培烧产物作为固体碱催化剂促进苯甲醛和丙醛缩合, 合成α-甲基肉桂醛, 关联了水滑石培烧产物碱性与反应活性的关系.     

文物附着物水浸取液中阴、阳离子的离子色谱法测定

采用电导检测离子色谱法,对海底打捞文物附着物水浸取液中阴阳离子进行分析,测定了其中的常见阴离子(F^-、Cl^-、NO2^-、Br^-等)和阳离子(Na^ 、NH^ 、K^ 、Mg^2 、Ca^2 等),其中阴离子的检出限(S／N=3)在4．4～25．1μg／L之间,阳离子的检出限在5．8～14．3μg/L之间,阴阳离子的线性范围均在2个数量级以上,回收率在96％～107％之间,RSD(n=7)在2．5％以下,该方法简便、可靠。     

Study of Mechanisms of CO and NO2O xidation on Zn–CNT(6,0) and Zn–BNNT(6,0),Mn–B38N38 and Mn–C76

The abilities and performances of Mn–C76,Mn–B38N38,Zn–CNT(6,0)and Zn–BNNT(6,0)to the oxidation of NO2 and CO are investigated.The oxidation reactions of NO2 and CO through the Langmuir-Hinshelwood(LH)and Eley-Rideal(ER)mechanisms by theoretical methods are examined.The most stable intermediates of oxidation reactions of NO2 and CO on Mn–C76,Mn–B38N38,Zn–CNT(6,0)and Zn–BNNT(6,0)are obtained from thermodynamics view point.In the LH pathway,Mn–C76,Mn–B38N38,Zn–CNT(6,0)and Zn–BNNT(6,0)catalysts are deactivated via the second NO2 and CO molecules.In the ER pathway,the second NO3 and CO2 molecules are separated.Finally,the Mn–C76,Mn–B38N38,Zn–CNT(6,0)and Zn–BNNT(6,0)are proposed to oxidize NO2 and CO molecules with high performances at room temperature.     

通过“双离子键”固载于季鏻盐聚合物的[Rh(CO)I_3]~(2–)物种在多相乙醇羰基化中的应用（英文）

贵金属物种(Rh或Ir络合物)在均相羰基化和氢甲酰化催化过程得到了广泛的应用,但始终存在分离繁琐等问题,其均相多相化可很大程度上简化分离操作,故一直广受重视.单位点催化剂因其具有可与均相相比拟的较高金属利用率和选择性而成为均相多相化的重要研究方向之一.研究发现,在碘物种存在的情况下用于固载金属物种的配位键容易断裂,进而导致金属物种的流失,而通过离子键固载的[Rh(CO)2I2]–物种更加稳定,比如著名的甲醇羰基化“Acetica TM”工艺中,[Rh(CO)2I2]–负一价阴离子物种是以离子键的方式固定在带有阳离子骨架的甲基化聚乙烯吡啶树脂上.与甲醇羰基化过程类似的乙醇羰基化过程是生产重要化工中间体丙酸的主要途径之一,但该过程的均相多相化始终存在着稳定性差这一关键问题.为了解决这一问题,基于之前将固载于季鏻盐聚合物的[Rh(CO)I3]2–应用于甲醇羰基化的工作,我们将类似的季鏻盐聚合物固载Rh基催化剂Rh-TPISP用于多相乙醇羰基化过程,通过多种表征进一步证明了Rh物种和P物种结构,并提出了“双离子键”模型.P的K边XANES证明了聚合物TPISP的季鏻化阳离子骨架特征.HAADF-STEM测试表明Rh-TPISP中的Rh呈现单位点分散的状态.Rh的XPS和XANES结果证明了Rh-TPISP中Rh物种的价态介于0～+1.通过EXAFS的拟合解析给出了[Rh(CO)I3]2–活性中心结构.由于[Rh(CO)2I2]–为经典的羰基化活性中心,为了进一步证明该结构的正确性,我们将Rh-TPISP的EXAFS和IR谱图与标样[PPh3Et]+[Rh(CO)2I2]–对比发现:在EXAFS谱图中, Rh-TPISP中的Rh-C峰高低于[PPh3Et]+[Rh(CO)2I2]–的Rh-C峰高,而Rh-TPISP中的Rh-I峰高高于[PPh3Et]+[Rh(CO)2I2]–的Rh-I峰高,这就说明Rh-TPISP中Rh物种的Rh-C配位数小于2,而Rh-I配位数大于2;在IR谱图中,标样[PPh3Et]+[Rh(CO)2I2]–中有两个羰基振动峰,与该物种的两个Rh-C配位键相符,而Rh-TPISP中的只有一个羰基振动峰,说明Rh-C配位数为1.因此, Rh-TPISP催化剂的季鏻盐骨架中的每个P物种带有一个正电荷,每个带有两个负电荷的[Rh(CO)I3]2–通过与两个[P]+的静电作用进行固载,形成“双离子键”结构.该催化剂在固定床乙醇羰基化过程中表现出优异的羰基化活性、选择性和稳定性.在3.5 MPa、195 oC反应近1000 h后,Rh-TPISP催化剂TOF保持在约350 h–1,丙酰基选择性为95%以上,高出所有文献报道的均相和多相乙醇羰基化活性.其较高的活性主要是因为[Rh(CO)I3]2–比传统Rh活性相[Rh(CO)2I2]–具有更强的富电子性,而较高的稳定性主要是由于“双离子键”这种强静电作用比“AceticaT M”工艺中“单离子键”更有利于Rh物种的固载.故Rh-TPISP催化剂中的“双离子键”对其优异的催化性能具有极其重要的作用,对后续多相乙醇羰基化的发展具有重要意义.     

离子色谱法同时测定茶叶中多种阴离子

研究了离子色谱法同时测定茶叶中F<'->、Cl<'->、NO<,2><'->、NO<'-><,3>、H<,2>PO<'-><,4>和SO<'2-><,4>6种无机阴离子含量的方法.茶叶样品中6种阴离子经95℃超声浸提20 min后,以浓度为1.92 mmol/L Na<,2>CO<,3>和1.80 mmol/L NaH...     

金催化CO氧化湿度增强效应的理论研究

实验发现纳米金催化的CO氧化有良好的湿度增强效应,但有关机制仍不清楚.我们应用密度泛函理论研究了湿度增强效应的微观机制,以Au4团簇为例,研究了金催化CO氧化的微观机理,考察了H2O在反应中的角色和作用.计算结果表明,H2O与Au4团簇一样,在反应中扮演催化剂的角色,参与反应的进行、改变反应历程、降低反应能垒.催化循环包含4个基元步骤：O2＋H2O→OOH＋OH,CO＋OOH→CO2＋OH,CO＋OH→COOH,和COOH＋OH→CO2＋H2O,其中自由基OOH和OH的形成是催化循环的速控步骤,其能垒为100.31kJ/mol,明显低于非水参与反应的能垒（161.41kJ/mol）.目前的结果合理地解释了实验观测的CO催化氧化的湿度增强效应,给出了其微观反应机制.     

应用离子色谱分析地层水研究

应用离子色谱仪测定了电缆地层测试取样获得的海上某井两个深度的水样品中的阴离子F-、Cl-、NO2-、Br-、NO3-、PO43-、SO24-和阳离子Li+、Na+、NH4+、K+、Ca2+、Mg2+、Sr2+的离子含量。对离子色谱在分析地层水离子含量的应用进行了简单的探讨,认为该技术在判断油田水类型和指导钻井液调配方面具有很好的应用前景及价值。     

Catalytic involvement of CO2 in the mutagenesis caused by reactions of ONOO(-) with guanine

The catalytic role of CO2 in reactions of ONOO- with guanine, leading to the formation of the mutagenic species 8-oxoguanine (8-oxoG) and 8-nitroguanine anion (8-nitroG-), was investigated by considering the reactions of nitrosoperoxycarbonate anion (ONOOCO2-), an adduct of ONOO- and CO2, with guanine at the B3LYP/6-31G** and B3LYP/AUG-cc-pVDZ levels of density functional theory in gas phase. In order to study bulk solvent effect, single-point energy calculations in aqueous media were carried out for all the species occurring in the reactions at the B3LYP/AUG-cc-pVDZ level of theory, by use of the polarizable continuum model (PCM). Vibrational frequency analysis was performed, and zero-point-energy (ZPE)-corrected total energies and Gibbs free energy changes at 298.15 K were obtained. The genuineness of the calculated transition states was confirmed by visually examining the vibrational modes and also by intrinsic reaction coordinate (IRC) calculations. The reaction between ONOOCO2- and guanine occurring through four different mechanisms leads to the formation of 8-oxoG or its anion, while the reaction between the same two species occurring through a different scheme leads to the formation of 8-nitroG-. It has been shown that the presence of a water molecule along with ONOOCO2- would not affect the reaction mechanisms significantly. Structures of the reactant complexes, product complexes and barrier energies involved in the reactions reveal that CO2 acts as a catalyst for the reaction between ONOO- and guanine. The cause of the catalytic action of CO2 is mainly due to intermediacy of the CO3 radical anion and NO2 radical into which ONOOCO2- is fragmented while reacting with guanine. The relative stabilities of the different product complexes suggest that the mutation caused by ONOO- in the presence of CO2 would mainly involve 8-oxoG.     

Vibrational predissociation spectrum of the carbamate radical anion, C(5)H(5)N-CO(2)(-), generated by reaction of pyridine with (CO(2))(m)(-)

We report the vibrational predissociation spectrum of C(5)H(5)N-CO(2)(-), a radical anion which is closely related to the key intermediates postulated to control activation of CO(2) in photoelectrocatalysis with pyridine (Py). The anion is prepared by the reaction of Py vapor with (CO(2))(m)(-) clusters carried out in an ionized, supersonic entrainment ion source. Comparison with the results of harmonic frequency calculations establishes that this species is a covalently bound molecular anion derived from the corresponding carbamate, C(5)H(5)N-CO(2)(-) (H(+)). These results confirm the structural assignment inferred in an earlier analysis of the cluster distributions and photoelectron spectra of the mixed Py(m)(CO(2))(n)(-) complexes [J. Chem. Phys. 2000, 113 (2), 596-601]. The spectra of the (CO(2))(m)(-) (m = 5 and 7) clusters are presented for the first time in the lower energy range (1000-2400 cm(-1)), which reveal several of the fundamental modes that had only been characterized previously by their overtones and combination bands. Comparison of these new spectra with those displayed by Py(CO(2))(n)(-) suggests that a small fraction of the Py(CO(2))(n)(-) ions are trapped entrance channel reaction intermediates in which the charge remains localized on the (CO(2))(m)(-) part of the cluster.     

Infrared photodissociation spectroscopy of mononuclear iron carbonyl anions

The infrared photodissociation spectroscopy of mass-selected mononuclear iron carbonyl anions Fe(CO)(n)(-) (n = 2-8) were studied in the carbonyl stretching frequency region. The FeCO(-) anion does not fragment when excited with infrared light. Only a single IR active band was observed for the Fe(CO)(2)(-) and Fe(CO)(3)(-) anions, consistent with theoretical predictions that these complexes have linear D(∞h) and planar D(3h) symmetry, respectively. The Fe(CO)(4)(-) anion is the most intense peak in the mass spectra and was characterized to have a completed coordination sphere with high stability. Anion clusters larger than n = 4 were determined to involve a Fe(CO)(4)(-) core anion that is progressively solvated by external CO molecules. Three CO stretching vibrational fundamentals were observed for the Fe(CO)(4)(-) core anion, indicating that the Fe(CO)(4)(-) anion has a C(3v) structure. All the carbonyl stretching frequencies of the Fe(CO)(n)(-) anion complexes are red-shifted with respect to those of the corresponding neutrals.     

1CH2＋N2O反应的势能面

利用密度泛函理论（B3LYP）计算了1CH2＋N2O反应的反应物、中间体、过渡态及产物 的几何构型.进而用从头算方法（QCISD（T））计算了单点能量.由此描绘了反应的势能面, 确定了反应的最终产物通道为N2＋H2CO和NO＋HCN＋H.后者比前者有更大的分支比.N2、H2CO 、NO、HCN的存在有待于实验检测.作者认为,反应在室温下是加成-消除机理,而在高温下 可以通过直接取代的机理获得N2＋H2CO.     

The infrared spectrum of Au-.CO2

The Au-.CO2 ion-molecule complex has been studied by gas phase infrared photodissociation spectroscopy. Several sharp transitions can be identified as combination bands involving the asymmetric stretch vibrational mode of the CO2 ligand. Their frequencies are redshifted by several hundred cm(-1) from the frequencies of free CO2. We discuss our findings in the framework of ab initio and density-functional theory calculations, using anharmonic corrections to predict vibrational transition energies. The infrared spectrum is consistent with the formation of an aurylcarboxylate anion with a strongly bent CO2 subunit.     

Synthesis and X-ray characterization of the phosphido-carbonyl cluster anions

The [Co(9)P(CO)(21)](2)(-) anion has been isolated from the products of the reaction between Na[Co(CO)(4)] and PCl(5) in tetrahydrofuran at reflux. The structure of the cluster anion [Co(9)P(CO)(21)](2)(-) in its tetraphenylphosphonium salt has been elucidated by X-ray analysis. The crystals are monoclinic, space group P2(1)/n, a = 12.528(3), b = 14.711(5), c = 19.312(6) A, beta = 93.68(2) degrees, Z = 2. Final R = 0.065 for 2300 unique reflections having I > 3sigma(I). The anion, which is disordered about an inversion center, consists of a monocapped square antiprismatic cluster containing an interstitial phosphide and surrounded by 13 terminal and 8 edge-bridging carbonyl ligands. Average values are: Co-Co 2.685 A, and Co-P 2.256 A. The [Co(10)P(CO)(22)](3)(-) anion has been obtained by condensation of the [Co(9)P(CO)(21)](2)(-) anion with [Co(CO)(4)](-) in tetrahydrofuran at reflux. While the [Co(9)P(CO)(21)](2)(-) anion is stable under CO, the [Co(10)P(CO)(22)](3)(-) anion is decomposed to [Co(9)P(CO)(21)](2)(-) and [Co(CO)(4)](-). The benzyltrimethylammonium salt of the [Co(10)P(CO)(22)](3)(-) anion has been studied by X-ray analysis. It gives triclinic crystals, space group P_1, a = 11.452(3), b = 23.510(6), c = 25.606(4) A, alpha = 112.46(1), beta = 95.79(1), gamma = 73.548(2) degrees, Z = 4. Final R = 0.041 for 8600 unique reflections having I > 3sigma(I). There are two independent trianions in the asymmetric unit, both showing similar geometries, consisting of bicapped square antiprismatic clusters with a central P atom, each bearing 10 terminal and 12 edge-bridging carbonyl ligands, 8 of which, bound to the capping metals, are markedly asymmetric. Average values are: Co-Co 2.678 A, and Co-P 2.262 A. Electrochemistry shows that [Co(9)P(CO)(21)](2)(-) and [Co(10)P(CO)(22)](3)(-) in acetonitrile solution undergo either a one-electron oxidation or a two-electron reduction. This latter process appears as a single step in the case of the dianion and as two separated one-electron steps in the case of the trianion. All the processes are accompanied by slow chemical complications, thus testifying that no stable redox congeners exist for these phosphide clusters.     

循环伏安和现场FTIR反射光谱研究甲醛在金电极上的氧化

The electro-oxidation of formaldehyde on a gold electrode in a gold electrode in a solution containing 0.1mol •L -1 Na2CO3＋0. 1mol•L - 1NaHCO3＋0. 1 mol•L - 1 HCHO was investigated by cyclic voltammetry and in -situ FTIR spetroscopy . The experimental results demonstrated that the oxidation of formaldehyde at different potential range connected with different surface species of gold. At lower potentials, the main product of formaldehyde oxidation was HCOO-, and at higher potentials, the products HCOO- and CO2 were detected simultaneously. From the results, a possible reaction mechanism was proposed.