双帽Keggin型杂多阴离子[PM12O40(VO)2]n-(M=Mo,n=5; M=V, n=9)的离散变分方法研究

使用密度泛函理论的离散变分方法(DFT-DVM)研究了双帽Keggin型杂多阴离子[PM12O40(VO)2]n-(M=Mo, n=5; M=V, n=9),即[PMo12O40(VO)2]5- (a)和[PV12O40(VO)2]9- (b)的电子结构,讨论了双帽的形成对Keggin型杂多阴离子的电子结构和催化性质的影响,并与其Keggin型杂多阴离子(PM12O40)n-(M=Mo, n=3; M=V, n=15)的计算结果进行了对比分析,计算结果表明,双帽的形成对Keggin型杂多阴离子的电子结构产生了很大的影响,因而它们在催化活性上可能会表现出较大的差异.     

双帽Keggin型杂多阴离子[H4As3Mo12O40]^-和Keggin型杂多酸HaPM12O40（M=Mo，W）质子化的DFT研究

选用B3LYP方法在LanL2MB水平下，对双帽α—Keggin型杂多阴离子[H4As3Mo12O40]^-的电子结构和质子的定位进行了密度泛函理论（DFT）研究．结果表明，双帽的形成大大影响了杂多阴离子[As3Mo12O40]^5-的电子结构和性质，NBO分析显示参与成帽的三桥氧上的电子密度比双桥氧上的要大，简单地从电荷密度来看，质子将首先在三桥氧上定域成键，但通过比较质子定域在几种桥氧上质子化稳定化能的大小，发现[H4As3Mo12O40]^-中的四个质子将在八个双桥氧中的其中四个氧原子上定位，而不是如文献中报道的在四个三桥氧上定域成键．对杂多酸H3PM12O40（M=Mo，W）中质子的定位也进行了理论计算并与文献进行了比较，结果显示，H3PMo12O40中质子是定位在双桥氧上；而H3PW12O40中质子将优先在双桥氧上定位，但也可在端氧上定位；这一结果与文献报道的相一致。     

双帽Keggin型杂多阴离子[H4As3Mo12O40]-和Keggin型杂多酸H3PM12O40(M=Mo,W)质子化的DFT研究

选用B3LYP方法在LanL2MB水平下,对双帽α-Keggin型杂多阴离子[H4As3Mo12O40]-的电子结构和质子的定位进行了密度泛函理论(DFT)研究.结果表明,双帽的形成大大影响了杂多阴离子[As3Mo12O40]5-的电子结构和性质,NBO分析显示参与成帽的三桥氧上的电子密度比双桥氧上的要大,简单地从电荷密度来看,质子将首先在三桥氧上定域成键,但通过比较质子定域在几种桥氧上质子化稳定化能的大小,发现[H4As3Mo12O40]-中的四个质子将在八个双桥氧中的其中四个氧原子上定位,而不是如文献中报道的在四个三桥氧上定域成键.对杂多酸H3PM12O40(M=Mo,W)中质子的定位也进行了理论计算并与文献进行了比较,结果显示,H3PMo12O40中质子是定位在双桥氧上;而H3PW12O40中质子将优先在双桥氧上定位,但也可在端氧上定位;这一结果与文献报道的相一致.     

Dawson结构杂多阴离子(P2M18O62)6-(M=Mo,W)的电子结构和催化性质的理论研究

用第一原理密度泛函理论的离散变分方法(DFT-DVM)计算典型的Dawson结构杂多阴离子(P₂M₁₈O₆₂)^6-(M=Mo,W)的电子结构,比较两者之间的差异。结果表明,Dawson结构中极位和赤道位的原子有不同的化学行为,还原电子将主要进入赤道位的金属原子。(P₂Mo₈O₆₂)^6-的反应活性中心主要是配位金属原子Mo、极位桥氧O_pb、赤道位端氧O_et和赤道位中心氧O_ei;(P₂W₁₈O₆₂)^6-的反应活性中心主要是配位金属原子W、极位桥氧O_pb、赤道位端氧O_et.(P₂Mo₈O₆₂)^6-的氧化性强于(P₂W₁₈O₆₂)^6-,而酸性则与此相反。这与Keggin结构(PM₁₂O₄₀)^3-杂多阴离子的情况相同。     

区分α-,β-[Siw9M3(H2O)3O39]7-(M=Al3+,Ga3+)Keggin结构三取代杂多阴离子几何异构体新方法

Keggin结构三取代的杂多化合物,α-和β-[Siw9M3(H2O)3Ｏ39]7-是两种重要的几何异构体[1],它们在催化、高质子导体和抗病毒等方面有重要应用[2,3].本文实验采用相转移方法[4～9],首次研究了三取代Keggin系列杂多化合物在有机溶剂苯中不同的微观结晶形态.提出了以杂多阴离子在有机溶剂中的微观结晶形态差异,作为区分Keggin结构三取代杂多阴离子几何异构体的新方法,该项工作填补了多酸在有机溶剂中微观晶态学研究方面的空白.     

双帽Keggin型杂多阴离子[H4As3Mo12O40]-和Keggin型杂多酸H3PM12O40 (M＝Mo, W)质子化的DFT研究

选用B3LYP方法在LanL2MB水平下, 对双帽α-Keggin型杂多阴离子[H₄As₃Mo₁₂O₄₀]^-的电子结构和质子的定位进行了密度泛函理论(DFT)研究. 结果表明, 双帽的形成大大影响了杂多阴离子[As₃Mo₁₂O₄₀]^5－的电子结构和性质, NBO分析显示参与成帽的三桥氧上的电子密度比双桥氧上的要大, 简单地从电荷密度来看, 质子将首先在三桥氧上定域成键, 但通过比较质子定域在几种桥氧上质子化稳定化能的大小, 发现[H₄As₃Mo₁₂O₄₀]^-中的四个质子将在八个双桥氧中的其中四个氧原子上定位, 而不是如文献中报道的在四个三桥氧上定域成键. 对杂多酸H₃PM₁₂O₄₀ (M＝Mo, W)中质子的定位也进行了理论计算并与文献进行了比较, 结果显示, H₃PMo₁₂O₄₀中质子是定位在双桥氧上; 而H₃PW₁₂O₄₀中质子将优先在双桥氧上定位, 但也可在端氧上定位; 这一结果与文献报道的相一致.     

荧光探针5-羰基咪唑苯并吖啶酮的合成及其LC-APCI-MS法测定胺

在不加任何催化剂条件下, 2-(12-苯并吖啶酮)-乙酸(BAAA)与N,N′-羰基双咪唑(CDI)缩合生成新型荧光探针5-羰基咪唑苯并吖啶酮(IEBA). IEBA在DMF溶剂中与胺类化合物形成的酰胺类衍生物不仅可发出强烈的荧光, 还具有较高的质谱离子化能力. 该衍生物在乙腈和甲醇-水溶液中的百分离子化δ值分别在0~57.32% 和0~62.14%范围内. 最大激发和发射波长λex/λem=272 nm/505 nm. 12种胺类衍生物的荧光检出限范围为0.15~0.50 ng/mL, 在线APCI-MS检出限范围为1.43~8.51 ng/mL.     

乙醇-水分子团簇C2H5OH(H2O)n (n=1-9)稳定结构的量子化学研究

采用密度泛函理论B3LYP方法, 在B3LYP/6-311++G(2d,2p)//B3LYP/6-311++G(d,p)基组水平上对乙醇-水分子团簇(C₂H₅OH(H₂O)_n (n=1-9))的各种性质进行研究, 如: 优化的几何构型、结构参数、氢键、结合能、平均氢键强度、自然键轨道(NBO)电荷分布、团簇的生长规律等. 结果表明, 从二维(2-D)环状结构到三维(3-D)笼状结构的过渡出现在n=5的乙醇-水分子团簇中. 此外, 利用团簇结合能的二阶差分、形成能、能隙等性质, 发现在n=6时乙醇-水分子团簇的最低能量结构稳定性较好, 可能为幻数结构. 最后, 为了进一步探讨氢键本质, 将C₂H₅OH(H₂O)_n (n=2-9)最低能量结构的各种性质与纯水分子团簇(H₂O)_n (n=3-10)比较, 结果表明前者与后者中的水分子之间氢键相似.     

[M6Om(C25N4H18)n]2-(M=W, Mo; n=1, 2; m=17,18)的二阶非线性光学性质的理论研究

运用密度泛函理论(DFT)的BP86方法, 对[M6Om(C25N4H18)n]2-(M=W, Mo; n=1, 2; m=17,18)进行了几何结构优化, 其中Mo系列结构化合物优化的几何结构与实验值吻合较好. 在净电场为零的条件下, 运用DFT/LB94方法计算了体系的二阶非线性光学系数β值: 体系1和2的βvec值分别为154.4×10-30和124.8×10-30 esu. 表明它们具有较大的二阶非线性光学系数, 且Mo系列比W系列的β值大. 而体系3和4的βvec值分别为218.0×10-30和191.8×10-30 esu. 体系3和4的βvec值分别比体系1和2的大, 表明增加给体的数目有利于提高NLO响应, 但都小于它们的2倍.     

A Convenient Method for Synthesis of Novel Cyclic Ethers (1R,2R,3R,5S,7S,9R,12R)-3-(t-Butyldimethylsilyl)oxy-7-methoxymethyl-oxy-2,10-dimethyl-12-oxatricyclo [7.2.1.0~(5,12)] dodecane

Coloradocin, a novel macrolide antibiotic from cultures of Actinoplanes coloradoensis1exhibits activity against pathogenic anaerobic and microaerophilic species2. Because itslow toxicity and substantial oral activity3, , as well as its unusual structure5, several 4research groups initiated approaches towards the synthesis of coloradocin6, whichculminated in the synthesis of 18-deoxynargenicin A1 by Kallmerten et al.7. …     

(enH_2)_4Na_4H_3[(VO)_(12)O_6B_(18)O_(42)]·8H_2O的水热合成和晶体结构

在水热的条件下合成了多钒硼酸盐(enH2)4Na4H3[(VO)12O6B18O42]8H2O, 化学式为C8H59B18N8Na4O68V12 (Mr=2253.45), 用单晶X射线衍射方法测定了它的结构, 该晶体属单斜晶系, P21/n空间群, 晶胞参数为a = 13.8989(4), b = 16.1954(5), c = 14.4520(4) ?β = 94.7490(5), V= 3241.95(16) ?, Z = 2, Dc = 2.308 g/cm3, ?= 1.819mm-1, F(000) = 2234, 4798个可观察衍射点(I > 2s(I)), 最终结构精修到偏离因子R = 0.0449, wR = 0.1163, S = 0.996。在该化合物的结构中, V12B18簇是由环状的B18O42通过18个B(μ3-O)V键被2个V6O18环夹在中间组成的, V12B18簇通过4个Na+与相邻的簇相连, 形成二维网状结构, 孔道尺寸为6.109×10.562 拧?     

胆汁酸的双敏感探针苯并[b]吖啶酮-5-乙基对甲苯磺酸酯:荧光检测和APCI-MS鉴定

在HypersilC18色谱柱上,利用新型荧光试剂苯并[b]吖啶酮-5-乙基对甲苯磺酸酯(BAETS)作柱前衍生化试剂,采用梯度洗脱对10种胆汁酸衍生物进行了优化分离.在二甲亚砜溶剂中,以碳酸钾作催化剂,95℃,45min后获得稳定的荧光产物.衍生物在稳态荧光条件下,在乙腈和甲醇水溶液中的百分离子化δ值在0%～88.83%和0%～89.15%范围内.最大激发和发射波长为λex/λem=272/505nm.采用大气压化学电离源(APCI)正离子模式实现了胆汁中胆汁酸的定性定量测定.线性回归系数均在0.9995以上,线性范围宽,检出限为0.76～1.62ng/mL.     

Synthesis of (2-hydroxy-5-nitrophenyl)di[1-(2-hydroxynaphthyl)]methane and 12-[1-(2-hydroxynaphthyl)]-10-nitro-12H-benzo[α]xanthene from of 5-nitrosalicylaldehyde derivatives and β-naphthol

The reaction of the morpholinal or anil of 5-nitrosalicylaldehyde with β-naphthol yielded (2-hydroxy-5-nitrophenyl)di[1-(2-hydroxynaphthyl)]methane. Condensation of the latter compound in boiling nitromethane gave 12-[1-(2-hydroxynaphthyl)]-10-nitro-12H-benzo[α]xanthene. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1336–1339, July, 1997.     

A thermal and structural study on Lanthanum Hexacyanocobaltate(III) pentahydrate,La[Co(CN)6]·5H2O. Part III

On dehydration of La[Co(CN)₆]·5H₂O, the color of the complex, changes from white to pale blue at around 230°C. Heating the pale blue specimen, the color changes to deep blue at around 290°C. This deep blue specimen is easily rehydrated to a pink one. As reported previously, in the pale blue specimen, Co³⁺ ions are situated in the center of the D_4h crystal field formed by six CN^- ions. The deep blue specimen is due to the presence of [Co(CN)₄]^2- ions in which Co²⁺ was situated in a T_d coordination field formed by four CN^- ions and the Co-C bond length is 1.67 Ĺ. The pink species corresponded to trans-[Co(CN)₄(H₂O)₂]^2- and the bond lengths of Co-C and Co-O are 1.89 and 1.85 Ĺ, respectively. The Raman spectra of the complex observed at 25°C displays two bands at 2157 and 2176 cm^-1 associated with the vibration of C-N bond, and the band of 2157 cm^-1 was split into two bands, 2150 and 2156 cm^-1, at around 100°C. When the complex was heated to around 230°C, three new bands were observed at 2103, 2116 and 2141 cm-1. The bands of 2103 and 2116 cm^-1 were assigned to the stretching vibration of C=N bonding to Co²⁺. The band of 2141 cm^-1 was assigned to the stretching vibration of the inverted CN^- as follows: Co-C=N-La→Co-N=C-La. The activation energy for the inversion of CN^- was estimated as 67 kJ mol^-1. This revised version was published online in August 2006 with corrections to the Cover Date.     

Application of Electrochemical Detection for the Quantitation of 1, 4-Dihydroxy-5, 8-Bis-[2-(2-Hydroxyethyl) Aminoethylamino]-9,10-Anthracenedione Following Liquid Chromatography

Abstract

Electrochemical monitoring of 1, 4-dihydroxy-5, 8-bis-[2-(2-hydroxyethy1) aminoethy amino]-9, 10-anthracenedione was employed for the quantitation of this cancer chemotherapy drug following high performance liquid chromatography. Detection was performed by oxidation of the compound at a glassy carbon electrode at +0.80 V vs. SCE. A rapid and convenient sample treatment procedure was developed which is suitable for determination involving physiological samples. A detection limit of 2 ng injected was obtained for urine samples.