非化学化工专业“大学化学”课程考核方法改革实践与探索

对"大学化学"课程的考核方法进行了改革。引入过程考核，降低期末考试在总成绩中的权重，在教学过程中增加理论联系实际的课外作业，以巩固基础理论知识的学习，并锻炼学生分析问题、解决问题的能力，作为考核指标记入总成绩。鼓励学生全程学习，避免突击应试。问卷调查结果表明大部分学生认同该考核方法。     

Highly efficient phosphine-catalyzed aza-Michael reactions of α,β-unsaturated compounds with carbamates in the presence of TMSCl

Aza-Michael reactions of enones with carbamates took place efficiently in the presence of a catalytic amount of phosphine and TMSCl to afford the total products in high yields. The new catalytic system was also efficient in the aza-Michael reaction of chalcone, which was difficult to react with carbamates by transition metal salts catalysts.     

Orthogonal array optimization of microwave-assisted derivatization for determination of trace amphetamine and methamphetamine using negative chemical ionization gas chromatography–mass spectrometry

An orthogonal array design (OAD) was applied to optimize microwave-assisted derivatization (MAD) for analysis of trace amphetamine (AM) and methamphetamine (MA) by negative chemical ionization gas chromatography–mass spectrometry (NCI GC–MS). The 2,3,4,5,6-pentafluorobenzoyl chloride (PFBC) was used as a derivatization reagent. Experimental factors including solvent, microwave power, and irradiation time at four-levels were studied in 16 trials by OAD₁₆ (4⁴). The significance of these factors was investigated using analysis of variance (ANOVA) and percent contribution (PC). Solvent is statistically demonstrated a chief factor; microwave power and irradiation time are secondary factors. Under the optimum condition, calibration curve of AM is linear over a range from 0.01 to 100 ng mL⁻¹ with correlation coefficient 0.9988, and MA from 0.1 to 1000 ng mL⁻¹ with correlation coefficient 0.9951. The limit of detection (LOD) is 1.20 pg mL⁻¹ for AM and 13.04 pg mL⁻¹ for MA. An applicability of the method was tested by analyzing urine samples from amphetamine-type stimulants (ATS)-abusing suspects. Consequently, the OAD method not only optimizes the MAD condition for determination of trace AM and MA, but identifies the effects of factor solvent, microwave power and irradiation time on the MAD performance.     

金属离子导向合成两个金属配位聚合物:晶体结构和荧光性质

以2,5-呋喃二羧酸和六水硝酸锌/四水硝酸镉为原料,在溶剂热条件下,合成出2个金属有机配位聚合物,[Zn (FDC)(DMF)₂]_n(1)和{(Me₂NH₂)₂[Cd₂(FDC)₃(H₂O)₂]·4H₂O}_n(2)(H₂FDC=2,5-呋喃二甲酸,DMF=N,N-二甲基甲酰胺)。通过元素分析、红外光谱、差热分析、X射线粉末衍射和X射线单晶衍射等手段对配合物进行了结构表征。结果显示,化合物1为一维链结构,通过分子间氢键作用构筑成二维结构;而2为二维(4,4)网络结构。热稳定性表明化合物1脱去DMF配体后稳定到300℃;而2脱去配体水、阴离子和溶剂分子后结构立即发生坍塌。常温固态下,激发波长分别为303和350 nm时考察了配合物1和2的荧光性质,结果显示2个化合物均发射蓝色荧光(λ_max=406,470 nm),荧光寿命分别为76.2和138.1 ns。     

Optimal configuration of capillary electrophoresis microchip with expansion chamber in separation channel

This study develops a novel capillary electrophoresis (CE) microfluidic device featuring a conventional cross-form injection system and an expansion chamber located at the inlet of the separation channel. The combined injection system/expansion chamber arrangement is designed to deliver a high-quality sample band into the separation channel such that the detection performance of the device is enhanced. Numerical simulations are performed to investigate the electrokinetic transport processes in the microfluidic device and to establish the optimal configuration of the expansion chamber. The results indicate that an expansion chamber with an expansion ratio of 2.5 and an expansion length of 500 microm delivers a sample plug with the correct shape and orientation. With this particular configuration, the peak intensities of the sample are sharp and clearly distinguishable in the detection region of the separation channel. Therefore, this configuration is well suited for capillary electrophoresis applications which require a highly sensitive resolution of the sample plug. The novel CE microfluidic device developed in this study has an exciting potential for use in high-performance, high-throughput chemical analysis applications and in many other applications throughout the field of micro-total-analysis-systems.     

High-throughput selection system for assessing the activity of epoxide hydrolases

Crucial to the success of directed evolution of enantioselective enzymes for use as catalysts in synthetic organic chemistry is the availability of high-throughput assays for determining the enantiopurity of thousands of samples. Although several such ee-assays are available, they entail time and effort, which means that pre-tests for activity have been developed to eliminate non-active mutants prior to ee-screening. Pre-selection systems may be even more efficient and simple to perform. In the present paper an efficient pre-selection test for assessing the activity of epoxide hydrolases has been developed. The bacterial (E. coli) growth on agar plates is shown to be directly related to the presence of active epoxide hydrolases which catalyze the detoxicating hydrolysis of the epoxide substrates. Visual inspection of agar plates is all that is necessary to identify positive (active) hits in large libraries of mutant epoxide hydrolases.     

New terpenoids from Amentotaxus formosana

[structure: see text] Amentoditaxone (1), possessing an unprecedented diterpenoid skeleton, along with two new terpenoids, amentotaxin WC (2) and amentotaxone (3), were established by extensive analysis of spectroscopic data.     

Enantioselective Synthesis of N-N Atropisomers by Palladium-Catalyzed C−H Functionalization of Pyrroles

The catalytic asymmetric construction of N−N atropisomeric biaryls remains a formidable challenge. Studies of them lag far behind studies of the more classical carbon-carbon biaryl atropisomers, hampering meaningful development. Herein, the first palladium-catalyzed enantioselective C−H activation of pyrroles for the synthesis of N−N atropisomers is presented. Structurally diverse indole-pyrrole atropisomers possessing a chiral N−N axis were produced with good yields and high enantioselectivities by alkenylation, alkynylation, allylation, or arylation reactions. Furthermore, the kinetic resolution of trisubstituted N−N heterobiaryls with more sterically demanding substituents was also achieved. Importantly, this versatile C−H functionalization strategy enables iterative functionalization of pyrroles with exquisite selectivity, expediting the formation of valuable, complex, N−N atropisomers.     

Atroposelective Synthesis of C−N Vinylindole Atropisomers by Palladium-Catalyzed Asymmetric Hydroarylation of 1-Alkynylindoles

Transition-metal-catalyzed hydroarylation of unsymmetrical internal alkynes remains challenging because of the difficulty in controlling regioselectivity and stereoselectivity. Moreover, the enantioselective hydroarylation of alkynes using organoboron reagents has not been reported. Herein, we report for the first time that palladium compounds can catalyze the hydroarylation of 1-alkynylindoles with organoborons for the synthesis of chiral C−N atropisomers. A series of rarely reported vinylindole atropisomers was synthesized with excellent regio-, stereo- (Z-selectivity), and enantioselectivity under mild reaction conditions. The ready availability of organoborons and alkynes and the simplicity, high stereoselectivity, and good functional group tolerance of this catalytic system make it highly attractive.     

Efficient Pyrazolo[5,4-f]quinoxaline Functionalized Os(II) Based Emitter with an Electroluminescence Peak Maximum at 811 nm

Upon fusing the pyrazinyl pyrazole entity in giving pyrazolo[3,4-f]quinoxaline chelate, the corresponding Os(II) based NIR emitter exhibited “invisible” and efficient electroluminescence with a peak maximum at 811 nm. A maximum external quantum efficiency of 0.97 % and a suppressed efficiency roll-off till a current density of 300 mA cm⁻² was also exhibited.