一代树状碳硅烷液晶研究──端基含12个丁氧基偶氮苯介晶基元

用发散法合成周边含 12个丁氧基偶氮苯介晶基元(M5 )端基新的一代树状碳硅烷(D1).并用元素分析、核磁共振、激光解吸电离飞行时间质谱、红外、紫外、偏光显微镜、差示扫描量热(DSC)和广角X射线衍射(WAXD)表征.D1为向列相与M5相同,树状物相态由介晶基元相态决定,D1相行为:K82N13 3I13 2N67K,D1熔点比M5降低 3 0～ 43℃,D1清亮点比M5增加 9～ 11℃,D1介晶相区比M5加宽 3 9～ 5 4℃,观察到 8条黑刷的树状物的高强向错(S =+ 2),D1清亮焓值略低于通常液晶n i相变清亮焓值,原因是枝化的树状物核心不易完全变形为液晶态的各向异性结构

VUV excitation properties of LnAl(3)B(4)O(12): Re (Ln = Y, Gd; Re=Eu, Tb)

Vacuum ultraviolet excitation spectra of LnAl(3)B(4)O(12):Re (Ln = Y, Gd; Re = Eu, To), along with X-ray photoelectron spectra, were measured. The spectra are tentatively interpreted in terms of the optical properties of the rare earth ions and the band structure. It was found that there is an energy transfer from the hosts to the rare earth ions. It was also found that the top of the valence band in the Gd compound is mainly formed by the 2p levels of O2- and the 4f levels of Gd3+, and in the Y compound mainly by the 2p levels of O2-. (C) 2000 Elsevier Science Ltd. All rights reserved.

Sol-gel-derived, polishable, 1 : 12-phosphomolybdic acid-modified ceramic-carbon electrode and its electrocatalytic oxidation of ascorbic acid

Novel ceramic-carbon electrodes (CCEs) containing 1:12-phosphomolybdic acid (PMo12) were constructed by homogeneously dispersing PMo12 and graphite powder into methyltrimethoxysilane-derived gel. Peak currents for the PMo12-doped CCE were surface-controlled at lower scan rates but diffusion-controlled at higher scan rates and peak potentials shifted to the negative potential direction with increasing pH. In addition, the electrode exhibited electrocatalytic activity toward the oxidation of ascorbic acid. The PMo12-modified CCE presented good chemical and mechanical stability and good surface renewability (ten successive polishing resulted in less than 5% relative standard deviation). (C) 2000 Elsevier Science B.V. All rights reserved.

Sol-gel-derived carbon ceramic composite electrodes bulk-modified with 1 : 12-silicomolybdic acid

1:12-Silicomolybdic acid (SiMo12) doped carbon ceramic composite electrodes were fabricated by incorporating SiMo12 and graphite powder in a methyltrimethoxysilane-based gel and characterized by cyclic and square-wave voltammetry, It was demonstrated that the chemically modified electrodes were suitable for electrocatalytic reduction of bromate, The electrodes had the remarkable advantage of surface renewal owing to bulk modification, as web as simple preparation, good mechanical and chemical stability and reproducibility.

环戊二烯—12-钼硅杂多四丁基铵电荷转移盐的合成、表征与晶体结构

以环戊二烯与 1 2 钼硅杂多四丁基铵为原料 ,采用光化学法合成了一种新型电荷转移盐 (Bu4N) 4(C5 H6 ) [HSiMoVI11MoVO40 ]。用元素分析、IR、CV、固体漫反射电子光谱、ESR进行了表征。X 射线晶体结构测定其晶体属三斜晶系 ,空间群P1 ,晶胞参数a =1 4.347(3) ,b =1 4.42 3(3) ,c =2 7.1 5 8(5 ) ,α =96 .90 (3) ,β =1 0 4.1 8(3) ,γ =98.2 0 (3)° ,V =5 32 2 (2 ) 3,Z =2 ,Mr=2 85 5 .30 ,Dc=1 .782 g·cm-3,F(0 0 0 ) =2 86 0 ,R =0 .0 71 9,wR =0 .1 983。标题化合物由 1个环戊二烯、4个Bu4N+阳离子和 1个 [SiMoVI11MoVO40 ]4 -阴离子构成。

层流恒界面池中CA-12萃取钇的质量传递动力学

用层流恒界面池研究了CA-12萃取钇的动力学。测定了搅拌速度、酸度、萃取剂浓度、温度对萃取速率的影响。测得CA-12萃取钇的活化能为48.96kJ/mol,此过程属于化学反应控制。当CA-12中加入少量的P507时,其活化能降至23.19kJ/mol。萃取过程由化学反应控制转变为扩散和化学反应混合控制。

Electrochemical and in situ spectroelectrochemical behavior of 2,3,7,8,12,13,17,18-octakis(hexyl-thio) tetraazaporphyrin (H(2)OHTTAP) and (Zn(II)OHTTAP)

The characterization of free base porphyrin 2,3,7,8,12,13,17,18-octakis(hexyl-thio) tetraazaporphyrin (H(2)OHTTAP) and its zinc(II) complexes [Zn(II)OHTTAP] containing eight thioether groups at the beta -pyrrole positions of the macrocycle was reported. Results obtained by cyclic voltammetry and differential pulse voltammetry indicated a five-electron reduction in five steps for each complex. They were oxidized in two single-electron-transfer steps to yield pi -cation radicals and dications and reduced in three single-electron-transfer steps to yield pi -anion radicals, dianions and trianions, respectively. The redox property of H(2)OHTTAP was unusual as compared to porphyrins (PPs) and phthalocyanines (Pcs). Each process was monitored by in situ thin-layer spectroelectrochemistry, which indicated that only the Ligand was electroactive. The existence of the eight hexylthio groups was responsible for the intrastack interactions and enhanced intracolumnar and intercolumnar electron motions, resulting in improved conductivity. Copyright (C) 2001 John Wiley & Sons, Ltd.

~(57)Fe,~(119)Sn掺杂Bi_2Sr_2Ca_(n-1)Cu_nO_(2n+4)的化学键性质和Mssbauer谱位移研究

利用电介质的平均能带模型计算了Bi2 Sr2 Can- 1CunO2n +4 (n =1,2 ,3)的化学键参数 .应用由共价性和极化率定义的化学环境因子计算了57Fe和119Sn在Bi2 Sr2 Can - 1CunO2n +4 中的M ssbauer同质异能位移 ,确定了57Fe和119Sn在Bi2 Sr2 Can- 1CunO2n +4 中的价态和占位情况 .

己二胺-12-钼磷酸电荷转移盐的光化学合成与晶体结构

采用光化学法合成一种有机-无机电荷转移盐，（HMDH2）[H2PMo12O40]·AA·3H2O·DMF（HMD = 1,6-己二胺，AA = 乙醛，DMF = N,N-二甲基甲酰胺）超分子化合物。用元素分析，IR，固体漫反射电子光谱，ESR进行了表征。X-射线四圆衍射测定其晶体结构属三斜晶系，空间群 Pī，Mr=2081.68，晶胞参数a = 14.092(3)，b =14.347(3)，c =14.358(3)?，α=75.10(3)，β=80.70(3)，γ=80.73(3)°,V=2746.6(10)?3，Z=2，Dc=2.517g/cm3，F(000)=1970，μ(MoKα)=2.766mm- 1，全矩阵最小二乘法修正至R=0.0832，wR=0.2638。标题化合物是由1个质子化的1,6-己二胺、12-钼磷混合价杂多阴离子 [PMo12O40]4ˉ、3个水分子、2个乙醛分子和1个二甲基甲酰胺分子构成。

用3种方法合成Y_3Al_5O_(12)∶RE~(3+)(RE=Eu,Dy)发光粉的对比研究

以金属硝酸盐为反应原料 ,分别采用柠檬酸 凝胶法、共沉淀法和固相法制备了YAG和YAG∶RE3+ (RE =Eu ,Dy) (1% ,摩尔分数 )发光粉 ,并通过XRD ,TG DTA和发光光谱对样品进行了表征。柠檬酸 凝胶法、共沉淀法和固相法制备的YAG和YAG∶Eu的晶相形成温度分别是 80 0和 90 0℃。Eu3+ 在非晶态和晶态YAG中其激发和发射光谱有明显差异 ,在一定温度范围内 ,发光强度随烧结温度的升高而增强。由于碳杂质的存在 ,90 0和 10 0 0℃下柠檬酸 凝胶法制备样品的发射强度较其他两种方法低。

16-and 18-electron Cp*Rh complexes with 1,2-dicarba-closo-dodecabofane(12)-1,2-dichalcogenolato ligands, as studied by multinuclear magnetic resonance

The reaction of [Cp*RhCl2](2) 1 with dilithium 1,2-dicarba-closo-dodecaborane(12)-1,2-dithiolate (a) and -diselenolate (b) afforded the 16-electron rhodium(III) half-sandwich complexes Cp*Rh[E2C2(B10H10)] [E=S (3a), Se (3b)]. The 18-electron trimethylphosphane rhodium(III) half-sandwiches Cp*Rh(PMe3)[E2C2(B10H10)] 4a-c were prepared from the reaction of Cp*RhCl2(PMe3) 2 with the same dichalcogenolates, including the ditelluride (c). The complexes 4a,b could also be obtained from the reaction of 3a,b with trimethylphosphane. The molecular geometry of 4b was determined by X-ray structural analysis. The 16-electron complexes 3 an monomeric in solution as shown by multinuclear magnetic resonance (H-1-, B-11-, C-13-, P-31- Se-77-, Rh-103-, Te-125-NMR). also in comparison with the data for the trimethylphosphane analogues 4a-c and for 6a in which the rhodium bears the eta(5)-1,3-C5H3 Bu-t(2) ligand. The Rh-103 nuclear shielding is reduced by 831 ppm (3a) and 1114 ppm (3b) with respect to the 18-electron complexes 4a,b. Similarly, the Se-77 nuclear shielding in 3b is reduced by 676.4 ppm with respect to that in 4b. (C) 1999 Elsevier Science S.A. All rights reserved.

助熔剂对发光体BaAl_(12)O_(19):Mn结构及发光的影响

在几种不同的助熔剂的作用下合成了BaAl12O19：Mn发光体，XRD谱显示助熔剂不仅有利于基质的结晶成核，而且对基质的不同晶面的生长也有影响.其UV光谱表明不同的助熔剂对其发光的影响不一样，H3Bo3不利于其发光，AIF3对其发光的提高不大，BaF2则可以较大地增加其发光强度．其VUV光谱显示在150nm附近有较强的激发证实了其可成为用于PDP的荧光粉之一．

Preparation of a composite film electrode containing 12-tungstosilicic acid and its electrocatalytic reduction for nitrite

A novel organic-inorganic composite film was formed by attaching Keegin-type heteropolyanion, SiW12O404- (devoted briefly as SiW12), on a glassy carbon electrode derivatized by 4-aminophenyl group. The composite film has an ionic bonding character between SiW12 and the surface amino group, which greatly improves the Blm stability and exhibits a more reversible electrochemical behavior. The modified electrode offers an excellent and stable electrocatalytic response for the reduction of nitrite. Possible mechanism was provided for the reaction of nitrite with SiW12O404-/aminophenyl composite film.

The structure and properties of 12-heteropolyacid of molybdenum and tungsten (H3PMo6W6O40) solvated by dimethyl ether

The crystal structure of H3PMo6W6O40 3C2H6O was determined by X-ray crystallography and refined to R = 0.0698 based on 2279 observed reflections to give unit cell parameters a = 16.48(2)Angstrom, c = 25.205(5)Angstrom , gamma = 120 degrees, hexagonal, space group R (3) over bar. The organic solvent molecules were characterized also by IR, H NMR spectra. Weak interaction existed between the organic solvent and the heteropoly acid in the secondary structure. The novel compound showed different behaviours in solubility, oxidizability and photosensitivity in comparison with classical dodeca heteropolyacid of molybdenum and tungsten. (C) 1998 Elsevier Science B.V.