红外光谱法观察二茂镧系氯化物与氧及水蒸气的反应

用实时红外光谱法在特制的收池中分别观察了一些二茂镧系氯化物Ｃｐ２ＬｎＣｌ（Ｃｐ＝Ｃ５Ｈ５，Ｌｎ＝Ｈｏ，Ｇｄ，Ｌｕ）和Ｃｐ＇Ｌｕ（Ｃｐ＝Ｃ５Ｈ４ＣＨ２ＯＣＨ３）与干燥氧气及水蒸气的反应，结果证实这些二茂镧系配合物在室温干燥氧气氛中很稳定，但在水蒸气中很快水蒸气的反应，结果证实这些二茂镧系配合物在室温干燥氧气氛中很稳定，但在水蒸气中很快水解。从水解反应的最初始阶段和较后期采得的红外光谱提示可能存在...     

丙酮在XeCl准分子激光辐射下的多光子电离和碎裂研究

我们用扩散分子束多光子电离光谱技术研究了丙酮在XeCl准分子激光辐射下的多光子电离和碎裂行为。实验表明丙酮没有产生母体离子峰(m/e=58), 只给出m/e=43和15两个峰, 分别对应于丙酮光解所产生的两个碎片CH_3 CO和CH_3。其离子信号(1)分别与激光强度(Ⅰ)的3和3.6次方成正比。分析表明离子是由中性碎片电离产生的。     

The Photochemistry of Diazomethane the Reactions of Methylene with Toluene and P-Xylene in Liquid Phase (I)

The photochemistry of diazomethane in toluene and p-xylene solutions was investigated. The reactions of methylene with toluene gave eight products. In the diazomethane p-xylene solution, p-ethyltoluene, 1,2,4-trimethylbenzene, 1,4-dimethylcyclohepatriene-1,3,5 and three unidentified compounds were found as products of the reaction of methylene with p-xylene. The relative rates of addition and insertion reaction of methylene with toluene and p-xylene have been calculated.     

贫水电解质体系制备多孔阳极氧化铝模板的研究

在有机溶剂为主的含草酸电解质中,研究了大孔径有序度高的阳极氧化铝(AAO)的一步法电化学制备.实验证实,电解质中水含量的降低能够有效抑制铝的电氧化速率和溶解速率,使得其氧化膜孔道的生长能够稳定进行,所得到的六方孔道排列有序度明显高于纯水溶剂制备的电解质体系下的产物.考察了水含量、有机溶剂种类以及电解质浓度对AAO模板孔道形貌的影响.结果表明,有机溶剂贫水电解质体系使得电氧化电压的选取范围比水溶液电解质体系更宽,孔径连续可调,反应条件温和.该方法适合于制备均匀大孔径的AAO模板.     

Surface hydration and its effect on fluorinated SAM formation on SiO2 surfaces

Substrate hydration is demonstrated to be crucial to film quality during self-assembled (SA) film deposition of tridecafluoro-1,1,2,2,-tetrahydrooctyltrichlorosilane (FOTS) from the vapor phase. The surface hydration was studied by thermogravimetric analysis, and a model was developed to predict the conditions necessary to desorb all of the water adsorbed on a fused silica surface without significantly altering the concentration of the surface hydroxyl groups. The nature of the SA film was investigated as a function of the degree of rehydration of the dehydrated silica surface. The wettability and microstructure of the SA films were examined by water contact angle, ellipsometry, X-ray photoelectron spectroscopy, and atomic force microscopy. There is an optimum degree of substrate hydration, on the order of 1-1.2 monolayers of adsorbed water, required to produce a dense, durable and uniform FOTS film with high water repellency and a smooth surface.     

Aluminum Lon Removal from Monoaluminum Ovotransferrin by Pyrophosphate

The rates at which aluminum was removed from the N- and C-terminal monoaluminum ovotransferrins by pyrophosphate were evaluated by UV difference spectra in 0.01 mol/L Hepes, pH=7.4 and at 37℃. Pesudo first-order rate constants as a function of pyrophosphate concentration were measured. The results indicate that the pathways of aluminum removal are different. For the N-terminal binding site, aluminum removal follows simple saturation kinetics, while the removal of aluminum from the C-terminal binding site reverts to the combination of saturation and first-order kinetics. The saturation component is consistent with a rate-limiting conformational change in the protein as has been reported. We propose that the first-order kinetics mechanism is attributed to a pre-equilibrium process. The rate constants of saturation kinetics are accelerated from both terminals with the addition of 0.1 mol/L chloride to the monoaluminum ovotransferrin solutions, whereas the rates of the first-order kinetics are decreased for the C-terminal binding site. The effect of chloride ionic strength causes a continuing increase on kobs for the N- and C-terminal binding sites. Moreover, the kinetics behavior of the N-terminal is more easily affected by chloride than that of the C-terminal. In the experiment presumably the N-terminal site is apparently kinetically more labile than the C-terminal site.     

Specific heat and Lindemann-like parameter of metallic clusters: mono- and polyvalent metals

The Brownian-type molecular dynamics simulation is revisited and applied to study the thermal and geometric properties of four mono- and two polyvalent metallic clusters. For the thermal property, we report the specific heat at constant volume CV and study the solid-liquid-like transition by scrutinizing its characteristic. For the geometric property, we calculate the root mean square relative bond-length fluctuation delta as a function of increasing temperature. The thermal change in delta reflects the movement of atoms and hence is a relevant parameter in understanding the phase transition in clusters. The simulated results for the CV of alkali and aluminum clusters whose ground state structures exhibit icosahedral symmetry generally show one phase transition. In contrast, the tetravalent lead is quite often seen to exhibit two phase transitions, a premelting process followed by a progressive melting. In connection with the premelting scenario, it is found here that those (magic number) clusters identified to be of lesser stability (among other stable ones) according to the second energy difference are clusters showing a greater possibility of undergoing premelting process. This energy criterion applies to aluminum clusters nAl=28 and 38. To delve further into the thermal behavior of clusters, we have analyzed also the thermal variation of deltaT and attempted to correlate it with CV(T). It turns out that the premelting (if exist) and melting temperatures of the smaller size clusters (n less, similar 50) extracted from CV do not always agree quantitatively with that deduced from delta.     

Surface composition and property of film prepared with aqueous dispersion of polyurethaneurea-acrylate including fluorinated block copolymer

The aqueous dispersion of polyurethaneurea-acrylate (PUA) including small amount of fluorinated block copolymers containing carboxyl groups (PATF), which can be dissolved in water, was used to make films and the surface properties of these films were examined. The experimental data show that the modified PUA film exhibits a hydrophobic surface property, although the original surface of PUA film is hydrophilic. The surface composition of the modified PUA film was measured by ATR and XPS. The results indicate that there is a concentration gradient of the fluorine groups along the lines of thickness of the modified film and towards the outmost surface layer, resulting from the migration of fluorinated blocks to the air side surface of the modified PUA film during the film formation process. However, the PUA film can not be modified effectively by adding the sodium salt of PATF, since the urethane groups in the system are easy to occupy on the surface of the film.     

Studies on the Total Synthesis of Hainanolide (VII) - Analysis of the Relative Stereochemistry of key Intermediate 2

The natural product, hainanolide 1, also under the name harringtonolide2 demonstrated antitumor and antiviral activities in preliminary test. Its structure was determined by X-ray diffraction. The total synthesis of 1 was reported recently by Mander3. A different scheme of its synthesis has been studied in our laboratory4. Here the determination of the stereochemical structure of the key intermediate 2 in the synthesis was reported. HMBC and HMQC spectra identified the skeleton and H,…     

5,15-二(对-取代苯基)八烷基卟啉及其金属配合物的合成

本文报道了五种5,15-二(对-取代苯基)-2,8,12,18-四乙基-3,7,13,17-四甲基卟啉(Ⅱa—Ⅱe)和五种5,15-二(对-取代苯基)-2,3,7,8,12,13,17,18-八甲基卟啉(Ⅰa—Ⅰe)以及它们的铜、铁、镍金属配合物的合成。这些化合物的结构均经元素分析、UV、~1HNMR和MS鉴定。芳环上不同取代基对卟啉成环反应有一定影响,拉电子基团有利于反应。其顺序如下:NO_2>H>CH_3>OCH_3>N(CH_3)_2。