Spectroscopic Studies on Charge Transfer from Ce^3＋ to Yb^3＋ in KMgF3 ： Ce, Yb Nanocrystals

Nanocrystals of KMgF3 single-doped and codoped with Ce^3＋ or/and Yb^3＋ were synthesized separately by the mi-croemulsion method. The X-ray diffraction（XRD） patterns were indexed to show that the KMgF3 crystal system was unchanged. The fluorescent spectra of KMgF3： Ce, Yb polycrystal powders were studied and compared with those of the Ce,Yb doped KMgF3 crystals produced using the high-temperature solid phase method. The diffuse reflection spectra and infrared emission of KMgF3： Ce, Yb were investigated. From the results, the authors could confirm that there were charge transfer processes from Ce^3＋ to Yb^3＋ in both KMgF3： Ce,Yb nanocrystals and polycrystal powders.     

双核镍(Ⅱ)配合物的合成、晶体结构和磁性质

合成了通过N-N键桥联的不对称的N₂O₃席夫碱配体(H₃L)的镍(Ⅱ)配合物[Ni₂(HL)₂]₂(DMF)₈(H₂O)₂ (1)。配合物晶体属于三斜晶系，空间群为P1，a=1.273 5(2) nm，b=1.360 4(3) nm，c=1.427 6(3) nm，α=85.358(4)°，β=63.513(3)°，γ=79.545(4)°，V=2.176 8(7) nm³，Z=1，F(000)=980，R₁=0.073 6。配合物1的不对称单元中含有两个双核结构Ni₂(HL)₂(DMF)₂(H₂O)₂ (Ⅰ)和Ni₂(HL)₂(DMF)₄ (Ⅱ)以及两个DMF溶剂分子。通过酚基氧原子桥联的镍-镍距离分别为：Ni(1)-Ni(1A)，0.308 4 nm；Ni(2)-Ni(2B)，0.310 3 nm(对称操作：A：1-x，2-y，-z；B：1-x，1-y，1-z)。金属镍(Ⅱ)离子采取扭曲的八面体配位构型，一个配体的NO₂三齿配位单元和另一个配体的酚基氧原子位于赤道面位置，两个溶剂分子占据轴向位置。晶体中存在着分子内以及分子与溶剂分子间的两种氢键作用。配合物1的变温磁化率测定表明，Ni(Ⅱ)离子之间的反铁磁耦合作用在它的磁性质中起主导作用。     

N2,O2水溶液光谱的分子动力学模拟

用分子动力学模拟方法研究了N2和O2水溶液的光谱性质．给出了能描述分子内部运动的溶质－溶剂相互作用势．对溶质和溶剂原子的速度自相关函数（VACF）作了计算．讨论了所得VACF的性质并计算了其谱密度．溶质分子振动谱出现的红移，与液态N2，O2的Raman实验结果相吻合．模拟得出的转动谱表明了溶剂分子对溶质转动运动的阻滞，模拟结果也表明VACF计算对溶液和液体光谱的研究十分有效．     

New syntheses and chemistry of hexafluorotropone

Two new routes to hexafluorotropone have been developed, one from hexachlorotropone and a superior synthesis from hexafluorobenzene. Hexafluorotropone was found to be a very weak base, with a conjugate acid pK(a) of -6.2 +/- 0.5. The tropone adds in [6 + 4] fashion to cyclopentadiene and photocyclizes to hexafluorobicyclo[3.2.0]hepta-3,6-dien-2-one. Lithium hydroxide in benzene transforms the tropone into pentafluorotropolone, which functions as a bidentate ligand.     

草酸电还原制取乙醛酸的研究

研究了由草酸电解还原制备乙醛酸时，温度、草酸纯度、电解时间、电极状态和电解产物对电流效率和产率的影响。实验发现，除温度和原料纯度是重要的影响因素外，电极表面的有机物吸附和电解产物－乙醛酸的浓度具有更大的影响。     

表面修饰纳米CdS制备中两个重要影响因素及结构表征

利用溶胶-凝胶法制备了PVP表面修饰的CdS纳米晶粒。考察了影响纳米CdS制备的两个重要因素Cd²⁺/S^2-和PVP,及其作用机理。确证表面过剩S^2-和PVP在反应体系中的作用是在较高浓度下制备纳米CdS的两个重要因素,进一步确定了PVP的最佳用量。通过TEM、ED、XRD、FT-IR等手段对合成的纳米粒子进行了结构表征,最小粒径为7～10nm,闪锌矿构型,粒子大小及形貌可通过改变Cd²⁺/S^2-及反应物浓度来控制。最后给出了CdS/PVP纳米晶粒的结构模型。     

Novel statistical approach for primary high-throughput screening hit selection

The standard activity threshold-based method (the "top X" approach), currently widely used in the high-throughput screening (HTS) data analysis, is ineffective at identifying good-quality hits. We have proposed a novel knowledge-based statistical approach, driven by the hidden structure-activity relationship (SAR) within a screening library, for primary hit selection. Application to an in-house ultrahigh-throughput screening (uHTS) campaign has demonstrated it can directly identify active scaffolds containing valuable SAR information with a greatly improved confirmation rate compared to the standard "top X" method (from 55% to 85%). This approach may help produce high-quality leads and expedite the hit-to-lead process in drug discovery.     

Ramberg-B(a)cklund反应在功能有机分子合成中的应用

碳碳双键广泛地存在于功能有机分子中,其构筑在合成化学中具有极其重要的意义.Ramberg-B(a)cklund反应是构筑碳碳双键的重要方法之一,其关键步骤是砜在碱性条件下进行1,3-消除,得到环状砜,然后重排除去SO2形成双键.该方法具有良好的立体选择性,底物在不同的反应条件下得到不同构型的产物,因而可以应用于合成许多功能有机分子,具有很好的应用前景.结合自己的研究工作对Ramberg-B(a)cklund反应在功能有机分子合成中的应用进行了较为系统的总结,也对Ramberg-B(a)cklund反应的拓展进行了简要介绍.     

Progression of Organic Reactions on Resin Supports Monitored by Single Bead FTIR Microspectroscopy

We report the time courses of five solid-phase reactions obtained using single bead FTIR microspectroscopy. This time-resolved information aided in the determination of the required reaction time, the nature of the solid-phase reaction, and resin property, effectively assisting in the initial phase of our combinatorial chemistry efforts. Our results showed that solid-phase organic reactions proceed faster than generally speculated. In addition, we have shown that reactions on the surface and in the interior of the bead occur at the same rate for reactions studied. The reaction on the TentaGel resin was shown to be not faster than reactions on Wang resin, suggesting that the diffusion of the substrate into polystyrene bead copolymerized with 1% divinylbenzene is not rate-limiting. Finally, the capability of obtaining IR spectra from the partial surface of a single bead demonstrated the femtomolar detection limit of single bead FTIR microspectroscopy.     

DABCO-catalyzed reaction of alpha-halo carbonyl compounds with dimethyl acetylenedicarboxylate: a novel method for the preparation of polysubstituted furans and highly functionalized 2H-pyrans

[Chemical reaction: see text] Polysubstituted furans and highly functionalized 2H-pyrans were prepared in good yields by DABCO-catalyzed reactions of alpha-halo carbonyl compounds with dimethyl acetylenedicarboxylate (DMAD) at room temperature.