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201.
The thermal behaviour of [Ba(C2H6O2)4][Sn(C2H4O2)3] used as a BaSnO3 precursor, and its phase evolution during thermal decomposition are described. The initially formed transient barium tin oxycarbonate phase disintegrates into BaCO3 and SnO2, reacting subsequently to BaSnO3. The existence of the intermediate oxycarbonate phase is evidenced by Fourier transformed infrared (FT-IR), X-ray powder diffraction (XRD) and electron energy loss spectroscopy (EELS (ELNES)) investigations. 相似文献
202.
RING-OPENING POLYMERIZATION OF TRIMETHYLENE CARBONATE CATALYZED BY NOVEL SINGLE COMPONENT RARE EARTH CALIXARENE COMPLEXES 总被引:2,自引:0,他引:2
Wei-puZhu JunLing HongXu Zhi-quanShen 《高分子科学》2005,(4):407-410
In this paper, ring-opening polymerization of trimethylene carbonate (TMC) with rare earth (Nd, Y, La) p-tert-butylcalix[n]arene (n=4, 6, and 8) complexes as catalysts has been studied. Poly(trimethylene carbonate) (PTMC) with Mv of 21,400 was produced by bulk polymerization under the conditions as follows: [TMC]0/[Nd] (molar ratio)=1000,80℃,8h. Mechanism study reveals that the polymerization proceeds via a coordination mechanism. 相似文献
203.
CompoundsformedfromCu ,AgandAuwithdithio lateligands ,suchasthedialkyldithiocarbamate (DTC) ,mercaptothiazoline (HMT)anddialkyldithiophosphates(DDP) ,haveplayedanimportantroleintechnology .1Cu(I) Sclustersalsohavebeenimplicatedinbiologyasan ti oxidants .2Thecuban… 相似文献
204.
205.
用TEA CO_2激光将C_2H_4分子激发到高振动激发态,高振动激发态的C_2H_4分子与基态的K原子碰撞发生振动态→电子态(V→E)传能过程,根据提出的能级组模型,对测得的时间分辨原子荧光信号进行处理,获得温度在453-663 K范围内,C_2H_4-K体系中V→E传能速率的数量级为10~(-10)/cm~3·molecule~(-1)·s~(-1),对应的碰撞传能截面约为0.30~0.80 nm.随着反应温度升高,V→E传能截面减小.上述实验结果表明碰撞体间吸引相互作用在这种非共振的V→E传能过程中起主要作用.利用多极相互作用势下的碰撞络合物模型对实验结果进行了讨论. 相似文献
206.
Green Bis-(2-iminoisopropyl-thiophenolato)nickel(II) and other Similar NiII Complexes The compounds [NiII(iitp)2] 1 (iitp = 2-iminoisopropyl-thiophenolate), [Ni(imptp)2] · 2 CH3OH 2 , a dinuclear compound with an Ni? Ni distance of 276 pm, and [PPh4] · [NiII(imptp)(SCN)] 3 (imptp = 2-(2-iminopentane-4-on)-thiophenolate) have been prepared by the reaction of nickel(II)-acetate-tetrahydrate with 2-iminoisopropyl-thiophenole and 2-(2-iminopentane-4-on)-thiophenole in methanol, respectively. They have been characterized by single-crystal X-ray structure analysis and other physical methods. The redox behaviour of 1–3 has been studied in detail (chemically as well as by cyclovoltammetry and ESR spectroscopy). Particularly interesting are the electronic properties of 1 and its reduction with NaBH4 and the following reaction of the product with O2. The complexes are model compounds for some Ni-containing enzymes. For details of the crystal structure determination see “Inhaltsübersicht”. 相似文献
207.
络合物晶体的电子吸收光谱作为研究晶体的电子结构的基础内容,很早以前就得到人们注意,虽然对Cu~(2+)、Ni~(2+)等络合物电子光谱的能级的经验指认已是一项较为成熟的工作,但对吸收光谱的系统的理论计算和定量解释在以前的文献中尚不多见.近年来,我们对多种晶体的电子吸收光谱进行了定量的解释,结果表明理论计算值总是能很好地符合于实验测定值。一般说来,吸收峰位的波数误差在8%以内. 早在本世纪四十年代就奠定了乙二胺四乙酸(EDTA)在分析化学中的应用基础。 相似文献
208.
Mino R. Caira Devric R. Dodds 《Journal of inclusion phenomena and macrocyclic chemistry》1999,34(1):19-29
The preparation and X-ray crystal structure of a 1 : 1 complex between -cyclodextrin (-CD) and the analgesic p-bromoacetanilide are reported. Thermogravimetric and UV spectrophotometric analyses of single crystals grown from an aqueous solution containing host and guest in 1 : 1 molar ratio yielded the composition -CD p-bromoacetanilide $ 13.5H2O. Crystals of the complex are triclinic, space group P1, with a = 15.197(3), b = 15.613(2), c = 15.743(4) Å, = 87.16(2), = 98.29(2), = 103.39(1)° and Z = 2 crystallographically independent complex units per unit cell. The -CD molecules form head-to-head dimers which pack in the channel-mode. Each dimer contains two guest molecules whose acetylamino substituents are located at the dimer interface while the bromine atoms protrude from the -CD primary faces. The acetyl residues of both guest molecules were found to be disordered but the X-ray data permitted 相似文献
209.
Ning Zhang Qing-Cheng Kong Zhen-Zhen Chen Ke-Hua Xu Bo Tang 《Mikrochimica acta》2007,158(1-2):165-171
A sensitive catalytic kinetic spectrofluorimetric approach for determining ng mL−1 levels of rhodium is presented, and the possible mechanism of the catalytic reaction was investigated. The determination
is based on the catalytic property of rhodium to enhance the reaction of o-vanillin salicylhydrazone (OVSH) with potassium
bromate in a water-ethanol medium at pH 4.80 and 45 °C. The presence of β-cyclodextrin (β-CD) obviously sensitized the assay
due to its high inclusion ability towards OVSH. Under optimized experimental conditions, fluorescence measurements of the
β-CD-rhodium-KBrO3-OVSH catalytic kinetic reaction system were carried out in its fluorescent band centered at λex = 333 nm and λem = 476 nm, respectively. The calibration graph was linear over the concentration range of 0.47–100 ng mL−1 with a detection limit of 0.14 ng mL−1. The effect of interferences was discussed, and the results show that the extraction method can be used to separate rhodium
from interference species such as iridium. The proposed method, applied to several synthetic mixtures containing rhodium mixed
with varying amounts of metal salts, produced satisfactory results. 相似文献
210.
Summary. GABA-receptor-ligands are still very interesting in drug-development. Usually benzodiazepines are used in the treatment but they
have serious side-effects. Thus, a recently synthesized quioxaline derivative which showed reduced side-effects in an animal
model was used as a model-substance. The cyclus was modified to optimize the pharmacological profile. Accordingly, a series
of imidazo-thieno-thiazines was synthesized starting from 5-acetyl-2-chloro-3-nitrothiophene to yield 6-ethyl-2,3-dihydro-1H-thieno[2,3-b][1,4]thiazine-2-one. Reaction with potassium tert-butoxide and diethylchlorophosphate gave an intermediate, which resulted in the desired ring system after adding the corresponding
isocyanides and potassium tert-butoxide.
Corresponding author. E-mail: thomas.erker@univie.ac.at
Received August 6, 2002; accepted August 13, 2002 相似文献