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91.
以钛氧有机物为前驱物制备具有高光催化活性的纳米二氧化钛晶体 总被引:9,自引:0,他引:9
纳米二氧化钛的制备方法及前驱物的差别影响其光催化活性.将20ml钛酸丁酯及30ml乙酐在密闭容器中与50ml环己烷混合,在70~85℃反应30min,生成微细的非晶钛氧有机物;经FT-IR和TGA分析,该物质被确认为计量式是TiOOOCCH3)2和TiO(OC4H9)(OOCCH3)的混合体.该钛氧有机物前驱物经焙烧后得到具有高光催化活性的纳米二氧化钛晶体.表征结果表明,钛氧有机物在焙烧过程中,其表面的吸附物及键合有机基团在400℃以前发生脱附和氧化分解;在389~405℃间形成锐钛矿型晶体,在600℃出现金红石晶型;600℃焙烧3h所得样品的比表面积为86m2/g,其二次粒子呈200~300nm条形体,孔隙大于20nm;单分散粒子为球形单晶,粒径为22nm;表面物理吸附水量为1.21%,加热至800℃时失重1.48%,粉体稳定纯净.光催化实验结果表明,以钛氧有机物为前驱物制备的纳米二氧化钛晶体具有高的光催化活性,光降解丁基罗丹明溶液的反应速率常数约为溶胶-凝胶法制备的催化剂样品的4倍.表面氧空缺和一定量的表面羟基可能是粉体具有高光催化活性的重要因素. 相似文献
92.
Li-Ya Wang Xiao-Qiang Wang Kai Jiang Jiu-Li Chang Yu-Fang Wang 《Journal of Molecular Structure》2007,840(1-3):14-21
A new nitronyl nitroxide NIT2-bithph (1) and its manganese(II) compound [Mn(hfac)2(IMHBithph)]2·(NIT2-bithph)(C6H14) (2) (hfac = hexafluoroacetylacetonate; NIT2-bithph = 4,4,5,5-tetramethyl-2-(bithiophenal-2-yl)imidazoline-1-oxyl-3-oxide; IMHBithph = 1-hydroxy-2-bithiophenal-4,4,5,5-tetramethyl-4,5-dihydro- 1H-imidazole) have been synthesized and structurally characterized by X-ray diffraction methods. The units of compound 1 were connected as one-dimensional chain by the intermolecular hydrogen bonds which afford an intermolecular antiferromagnetic interaction between nitronyl nitroxide radicals within the chain (J = −1.89 cm−1). Compound 2 resulting from the reaction of Mn(hfac)2·2H2O and NIT2-bithph is dinuclear and includes the reduced amidino-oxide form of NIT2-bithph, it is made up of three parts: a [Mn(hfac)2(IMHBithph)]2 dimer unit, an uncoordinated NIT2-bithph radical and a noncoordinated solvent molecule of hexane, the molecule of radical is hydrogen bonded to its reduced form. Two reduced IMHBithph ligands bridge the two manganese(II) ions through their amidino-oxide oxygen atoms resulting in a small intramolecular antiferromagnetic interaction between the manganese ions (J = −1.55 cm−1). 相似文献
93.
1-苯基-3-甲基-4-(6-氢-4-甲基氨基-5-硫杂-2,3-吡嗪)-吡唑啉酮的合成与晶体结构 总被引:1,自引:0,他引:1
通过1-苯基-3-甲基-4-氯乙酰基-吡唑啉酮-5 (PMCP) 和4-甲基氨基硫脲 (MTSC) 缩合, 形成了一种新的双杂环化合物 (PMCP-MTSC)。利用元素分析与单晶X-射线衍射进行了表征。 该化合物(C14H15N5OS)属单斜晶系, P21 空间群, 晶体学参数为 a = 7.634(1), b = 11.639(2), c = 8.150(2) ? ?= 98.13(1), V = 716.9(2) ?, Z = 2, Dc = 1.396 g/cm3, (MoKa) = 0.232 mm-1, F(000) = 316, Mr = 301.37。结构由直接法解出,共收集3114个衍射点,其中I > 2(I)的独立衍射点有2453个,用全矩阵最小二乘法修正,最终偏离因子:R = 0.0294, wR = 0.0738。结构分析表明: 该化合物以酮式存在,分子间通过氢键作用(N(5)H…O)连接起来并形成一维链状结构。 相似文献
94.
95.
Russell G. Ross 《Journal of inclusion phenomena and macrocyclic chemistry》1990,8(1-2):227-233
The thermal conductivity and the heat capacity per unit volumec
p
have been measured for the urea-hexadecane inclusion compound using the transient hot-wire method. Measurements were made under isobaric conditions at a pressure of 0.1 GPa and in the temperature range of 100–300 K. There was evidence for a phase transition at a temperature of about 160 K, in reasonable agreement with previous work. For the high-temperature phase was independent of temperature within ±1%. The low-temperature phase showed a weak temperature dependence, with (d In/d InT)
p
= –0.13. It was inferred that interaction between acoustic phonons and low-frequency vibrational excitations of the guest molecules made a major contribution to the thermal resistivity. For the quantityc
p
a weak maximum was observed in the region of the phase transition temperature.Dedicated to Dr D. W. Davidson in honor of his great contributions to the sciences of inclusion phenomena. 相似文献
96.
相转移催化法合成糖苷化合物 总被引:1,自引:0,他引:1
糖苷化合物广泛存在于生物体内,中草药和天然药物中的许多抗病活性化合物也是糖苷化合物。根据糖苷化合物分子结构中的配糖体与糖环碳原子相连的原子类型可把糖苷化合物分为氧苷、氮苷、硫苷和碳苷等。未作特殊说明的糖苷化合物均指氧苷,且配糖体为羧酸的糖苷化合物亦称为糖酯。有关糖苷(酯)化合物和其合成方法的研究很多,其中应用相转移催化法较为常见。我们曾用相转移催化法合成过许多糖酯化合物并对其生理活性进行研究报道。本文在原合成糖酯的基础上通过相转移催化法,选用不同于文献报道催化剂及溶剂体系, 相似文献
97.
A New Diterpene Acid from the Flowers of Heteropappus altaicus 总被引:2,自引:0,他引:2
QingHuaLIU JunShanYANG YangLU QiTaiZHENG LiMAO 《中国化学快报》2005,16(7):921-924
A new compound, named heteraltaic acid was isolated from the flowers of Heteropappus altaicus (willd) Novopokr. The compound was elucidated as (5R, 6S, 8aS) -5-[2-(3-furyl) ethyl-5, 6, 8a-trimethyl-4a, 5, 6, 7, 8, 8a -hexahydro-l-naphthalenecarboxylic acid] by the combination of 1D and 2D NMR techniques (HSQC, HMBC) and X-ray analysis. 相似文献
98.
99.
Chen Xiao-Ming Wu Yu-Luan Tong Ye-Xiang Sun Ziming David N. Hendrickson 《Polyhedron》1997,16(24):1041
A novel tetranuclear terbium(III) complex [Tb4(OH)4(pybet)6(H2O)8][Tb4(OH)4(pybet)6(H2O)7 (NO3)](ClO4)14·6H2O has been synthesized and shown by X-ray crystallography to have a cubane-like Tb4(μ3-OH)4(μ2-carboxylato-O,O′)6 core. The ligand pybet is pyridinoacetate, C5H5+N-CH2CO2−. Magnetic susceptibility data were measured for this Tb4 complex in the range of 2.0–320 K and in fields of 1.0 G to 50.0 kG. It is concluded that either there is very weak antiferromagnetic exchange interaction (J = −0.015 cm−1) or there is a small crystal-field splitting of the 7F6 TbIII ground state. 相似文献
100.
Tatiana Y. Shvareva 《Journal of solid state chemistry》2005,178(2):499-504
Single crystals of the potassium uranyl iodate, K[UO2(IO3)3] (1), have been grown under mild hydrothermal conditions. The structure of 1 contains two-dimensional sheets extending in the [ab] plane that consist of approximately linear UO22+ cations bound by iodate anions to yield UO7 pentagonal bipyramids. There are three crystallographically unique iodate anions, two of which bridge between uranyl cations to create sheets, and one that is monodentate and protrudes in between the layers in cavities. K+ cations form long ionic contacts with oxygen atoms from the layers forming an eight-coordinate distorted dodecahedral geometry. These cations join the sheets together. Ion-exchange reactions have been carried out that indicate the selective uptake of Cs+ over Na+ or K+ by 1. Crystallographic data (193 K, MoKα, ): 1, orthorhombic, Pbca, a=11.495(1) Å, b=7.2293(7) Å, c=25.394(2) Å, Z=8, R(F)=1.95% for 146 parameters with 2619 reflections with I>2σ(I). 相似文献