新型铕双β-二酮红光材料的合成与发光性质

通过分子设计,合成了一种新颖的双β-二酮有机配体9-乙基-3,6-二（乙酰基-3-苯甲酰基）咔唑（H2L）及其铕配合物,红外光谱和电子光谱表明Eu^3＋与H2L发生配位。配合物的溶液荧光光谱不仅有613 nm处的中心离子Eu^3＋的特征红光,属^5D0→^7F2跃迁带,还有445nm处配体的宽带蓝色发光,属H2L^＊→H2L跃迁带,而配合物的光致发光光谱只有611 nm处为中心离子Eu^3＋的特征红光,属^5D0→^7F2跃迁带,峰形尖锐,半峰宽仅7 nm,单色性好,表明该固体铕双β-二酮配合物是一种潜在的红色发光材料。     

Density functional study of the l-proline-catalyzed α-aminoxylation of aldehydes reaction: The reaction mechanism and selectivity

The reaction mechanism of the l-proline-catalyzed α-aminoxylation reaction between aldehyde and nitrosobenzene has been investigated using density functional theory (DFT) calculation. Our calculation results reveal following conclusions [1]. The first step that corresponds to the formation of C–O bond, is the stereocontrolling and rate-determining step [2]. Among four reaction channels, the syn-attack reaction channel is more favorable than that of the anti one, and the TS-ss channel dominates among the four channels for this reaction in the step of C–O bond formation [3]. The intermolecular hydrogen bond between the acidic hydrogen of l-proline and the N atom of the nitrosobenzene in an early stage of the process catalyzes very effectively the C–O bond formation by a large stabilization of the negative charge that is developing at the O atom along the electrophilic attack [4]. The effect of solvent decreases the activation energy, and also, the calculated energy barriers are decrease with the enhancement of dielectric constants for C–O bond formation step. These results are in good agreement with experiment, and allow us to explain the origin of the catalysis and stereoselectivity for l-proline-catalyzed α-aminoxylation of aldehyde reaction. The addition of H₂O to substituted imine proline, intermolecular proton-transfer steps, and the l-proline elimination process were also studied in this paper.     

Aerobic oxidation assisted by ligand-free palladium catalysts

Aerobic oxidation of electron-rich benzylic and phenyl allylic alcohols was achieved with high yields with only 0.1 mol.% of Pd(OAc)2 catalyst in the absence of any ligand. This procedure was expected to be valuable for realistic industrial-scale applications from both economic as well as environmental points of view.     

Study of urinary nucleosides as biological marker in cancer patients analyzed by micellar electrokinetic capillary chromatography

Thirteen normal and modified nucleosides, primarily degradation products of transfer ribonucleic acid (tRNA), were evaluated as potential tumor markers for cancer patients. Their urinary concentrations were determined by means of micellar electrokinetic capillary chromatography (MEKC) in the urine from 54 healthy adults and 70 cancer patients, then quantitatively expressed as a function of creatinine excretion. It was found that urinary nucleosides for cancer patients were on the average significantly higher than those for healthy controls, however, no significant differences were found between male and female or between different ages. Based on 13 urinary nucleoside concentrations, principal component analysis (PCA) could be used to classify 72% of cancer patients from the healthy controls. The present study shows that the precise measurement of urinary nucleosides by MEKC in combining with PCA technique may provide a clinically useful approach for diagnosis of cancer.     

Stereoselective Synthesis of Piperamide Alkaloids by Modified Ramberg-Bcklund Reaction

A convenient and rapid approach for the synthesis of piperamide alkaloids la ~ h by the recently developed one-flask Ramberg-Backlund reaction was described. The synthesis of 1e was reported for the first time.     

Determination of the Enantiomeric Purity of l-Carnitine and Acetyl-l-Carnitine by Chiral Liquid Chromatography

A chiral liquid chromatographic method for determination of the enantiomeric purity of both l-carnitine and acetyl-l-carnitine is described. Separation of the enantiomers of dl-carnitine and acetyl-dl-carnitine was achieved on a commercial chiral column (Chiralcel OD-R) after derivatization with (alpha-bromo)methyl phenyl ketone. Introduction of this lipophilic UV chromophoric group to the carnitine and acetylcarnitine molecules improved their retention, resolution, and UV detection. The mobile phase was 74:26 (v/v) 0.5 mol L^-1 sodium perchlorate–acetonitrile, pH 3.8, and the flow rate was 0.4 mL min^-1. Detection was performed at 235 nm. The method is selective and reliable for determination of the enantiomeric purity of bulk drug substances l-carnitine and acetyl-l-carnitine.     

Fluorimetric determination of ascorbic acid with o-phenylenediamine

A simple and sensitive fluorimetric method for the determination of ascorbic acid (AA) is described. The method is based on the condensation reaction between AA and o-phenylenediamine (OPDA) in the absence of the oxidant. The fluorescence intensity is measured at excitation and emission wavelengths of 360 and 430 nm, respectively. Under optimum condition, a linear relationship is obtained between the fluorescence intensity and the concentration of AA in the range of 0.05-40 μg ml⁻¹. The detection limit is 0.006 μg ml⁻¹, which is obviously lower than that of other fluorimetric methods reported.     

Silicalite-1膜反应器中的丙烷芳构化

在丙烷芳构化反应中，氢气起着相当重要的作用；根据理论分析，消除氢气将会有利于芳构化反应的进行。在Ｓｉｌｉｃａｌｉｔｅ－１沸石分子筛膜反应器，丙烷芳构化反应中的芳烃选择性提高了１０％－２０％。针Ｓｉｌｉｃａｌｉｔｅ－ｌ膜反应器与氧化铝膜反应器中的反应结果相比较，表明膜反应器效果不仅取决于膜的渗透选择性，而且还取决于膜的渗透率。     

掺杂电活性离子聚吡咯膜内的电荷传输

用循环伏安法和计时库仑法研究了掺杂亚铁氰化钾离子的聚哟咯膜内的电荷传输问题。实验结果表明，聚吡咯膜内的电荷传递可以处理成电子在膜内的扩散模型，电荷传递速度可以 用电子表观扩散系数（Ｄａｐｐ）来表征。Ｄａｐｐ的大小由聚合物膜的结构、电活怀离子之间的过及对离了在膜中的运动决定。