希土(Ⅲ)噻吩甲酰三氟丙酮和BipyO2/PhenNO三元配合物的合成和表征

The new ternary complexes of RE(TTA)₃(BipyO₂)·H₂O and RE(TTA)₃ (PhenNO)(where RE=Sm, Eu, Gd; TTA=thenoyltrifluoroacetonate; BipyO₂=2,2′-bipyridine-N,N′-dioxide; PhenNO=1,10-phenanthroline-N-oxide)have been synthesized. The composition and properties of complexes were studied by elemental analysis, UV spectrum, IR spectrum, DTA-TG and fluorescence spectrum. The effect of solvent on fluorescent intensity is discussed.     

卡尔曼滤波法用于混合氨基酸体系分析

本文将卡尔曼波波（ＫＦ）法用于色氨酸、酪氨酸和苯丙氨酸混合体系分析，得到了满意的结果，讨论了波长范围等条件的选取对实验结果的影响，并对三个实际榈进行了分析。     

电子制冷预浓缩-双柱气相色谱-质谱/氢火焰检测器法测定空气中104种挥发性有机物

基于吸附剂辅助电子制冷预浓缩技术，建立了多维切割双柱气相色谱-质谱/氢火焰离子化检测器（GC-MS/FID）同时测定环境空气中104种挥发性有机物（VOCs）的方法。将采集于苏玛罐中的环境空气样品在配有吸附剂的电子制冷预浓缩系统中富集、脱附、除水、除CO₂和浓缩，然后通过GC-MS/FID的多维切割单元将C₂~C₃组分和C₄~C₁₂组分分别引入PLOT柱和InterCap-624柱进行分离。C₂~C₃组分用FID检测，以保留时间定性、外标法定量；C₄~C₁₂组分采用电子轰击离子源质谱检测，以保留时间和特征离子定性、内标法定量。考察了冷阱吸附剂种类、辅助压力控制单元压力设置、双柱切换时间切割点等参数对分析结果的影响，优化了GC-MS/FID条件，并评估了在此优化条件下的方法性能。104种VOCs在0.0446~0.892 μmol/m³范围内线性关系良好，相关系数（r）为0.9984~0.9999，对0.0446 μmol/m³和0.223 μmol/m³水平的混合标准气体重复6次进样，平均回收率为86.4%~116.1%，相对标准偏差为0.9%~11.3%；方法的检出限为0.145~1.90 μg/m³，定量限为0.435~5.70 μg/m³。该法稳定性好，灵敏度高，操作简便，可用于环境空气中104种VOCs的测定。     

Molecular (hyper)polarizabilities computed by pseudospectral methods

We have developed algorithms based on pseudospectral (PS) ab initio electronic structure methods for solving the first- and second-order Hartree-Fock/Kohn-Sham equations and evaluating molecular polarizabilities and first- and second-order hyperpolarizabilities in the spin-restricted and spin-unrestricted formalisms at the Hartree-Fock (HF) and density functional theory (DFT) levels. We carry out calculations on 50 small molecules to test the accuracy of the PS approach. Our results demonstrate that the molecular polarizability alpha computed by the PS method is essentially identical to the value obtained from conventional methods for both HF and DFT calculations, while the first-order hyperpolarizability beta and second-order hyperpolarizability gamma have mean unsigned percentage differences of 1.26% and 0.62% (HF) and 0.78% and 0.65% (DFT), respectively. We also present CPU timing comparisons between the PS and conventional methods at the 6-31 G(**) level for 14 molecules having 185 to 1185 basis functions. The timing results show that the PS method is 25 (PS-HF) and 13 (PS-DFT) times faster than the conventional method for a system with 500 basis functions. The PS methods are found scale as N(2.70) (PS-HF) and N(2.40) (PS-DFT), while the conventional methods scale as N(2.93) (PRISM-HF) and N(2.87) (PRISM-DFT), where N is the number of basis functions.     

激光诱导钡的原子与离子荧光光谱研究

许多作者报导了在 ICP 和火焰等原子化系统中钡的原子和离子荧光检测,并将其应用于光谱分析.但有关钡的荧光光谱特性研究报道较少.本工作以空心阴极灯作为原子化器,利用连续波染料激光器研究了钡的原子与离子荧光,观察了各种因素对钡荧光信号强度的影响,测量了不同类型的原子和离子荧光,研究了所观察到的反常信号产生的机理.实验中用全谱线的氩离子激光器(南京电子管厂,362型,约5W)泵浦 R6G 染料激光器。在570—815nm 范围产生可调谐激光.典型的光谱带宽约0.1GHz.激光束经调制后用透镜聚     

Development of a polarizable force field for proteins via ab initio quantum chemistry: first generation model and gas phase tests

We present results of developing a methodology suitable for producing molecular mechanics force fields with explicit treatment of electrostatic polarization for proteins and other molecular system of biological interest. The technique allows simulation of realistic-size systems. Employing high-level ab initio data as a target for fitting allows us to avoid the problem of the lack of detailed experimental data. Using the fast and reliable quantum mechanical methods supplies robust fitting data for the resulting parameter sets. As a result, gas-phase many-body effects for dipeptides are captured within the average RMSD of 0.22 kcal/mol from their ab initio values, and conformational energies for the di- and tetrapeptides are reproduced within the average RMSD of 0.43 kcal/mol from their quantum mechanical counterparts. The latter is achieved in part because of application of a novel torsional fitting technique recently developed in our group, which has already been used to greatly improve accuracy of the peptide conformational equilibrium prediction with the OPLS-AA force field.1 Finally, we have employed the newly developed first-generation model in computing gas-phase conformations of real proteins, as well as in molecular dynamics studies of the systems. The results show that, although the overall accuracy is no better than what can be achieved with a fixed-charges model, the methodology produces robust results, permits reasonably low computational cost, and avoids other computational problems typical for polarizable force fields. It can be considered as a solid basis for building a more accurate and complete second-generation model.     

[La(CCl3COO)3(bipy)·H2O]2和Tb(CCl3CO)3(bipy)2·H2O混配 配合物的合成及其结构测定

利用不同溶剂合成并测定了希土三氯醋酸盐与α,α'-联吡啶(bipy)不同比例的配合物(Ⅰ)La:bipy=1:1,[La(CCl₃COO)₃(bipy)·H₂O]₂和(Ⅱ)Tb:bipy=1:2,Tb(CCl₃COO)₃(bipy)₂·H₂O,结构测定表明配合物(Ⅰ)与(Ⅱ)均为三斜晶系,中心离子La(或Tb)具有配位数为8的畸变四方反棱柱多面体;但是配合物(Ⅰ)形成具有对称中心的二聚体。     

Visible‐Light Photoredox‐Catalyzed C−H Difluoroalkylation of Hydrazones through an Aminyl Radical/Polar Mechanism

An unprecedented visible‐light‐induced direct C?H bond difluoroalkylation of aldehyde‐derived hydrazones was developed. This reaction represents a new way to synthesize substituted hydrazones. The salient features of this reaction include difluorinated hydrazone synthesis rather than classical amine synthesis, extremely mild reaction conditions, high efficiency, wide substrate scope, ease in further transformations of the products, and one‐pot syntheses. Mechanistic analyses and theoretical calculations indicate that this reaction is enabled by a novel aminyl radical/polar crossover mechanism, with the aminyl radical being oxidized into the corresponding aminyl cation through a single electron transfer (SET) process.     

Enantioselective arylation of aldehydes catalyzed by a soluble optically active polybinaphthols ligand

A soluble chiral polymer ligand was synthesized by the polymerization of (R)-6,6′-dibutyl-3,3′-diformyl-2,2′-binaphthol (R-M-1) with 2,5-diaminopyridine (M-2) via a nucleophilic addition-elimination reaction. While arylboronic acids were used as the source of the transferable aryl group, the chiral polybinaphthols ligand in combination with Et₂Zn without Ti(OⁱPr)₄ exhibited higher enantioselectivity in asymmetric addition to aromatic aldehydes than alphatic aldehydes. When aromatic aldehydes with electron-withdrawing groups were chosen as substrates, the resulting diarylmethanols were produced in higher ee values than those with electron-donating groups as substrates. 2-Naphthaldehyde used as a substrate afforded product in 95% ee, which could be ascribed to the steric effect influence on this asymmetric arylation reaction. Moreover, the chiral polymer was easily recovered and reused, but exhibited a decrease of enantioselectivity in the third recycle.