CM⁃Phos配体在钯催化交叉偶联反应中的应用

本文综合评述了近年来2-[2-(二环己膦基)苯基]-1-甲基-1H-吲哚(CM-Phos)膦配体及其衍生物在钯催化的交叉偶联反应中的应用, 主要根据不同种类的交叉偶联反应进行系统性分述, 并对该领域的发展前景进行了展望.     

一种蓝光发射星型有机分子的合成及光电性质

采用分子设计的思想,通过多步反应合成了一种新型的以N原子为中心的蓝光发射星型有机小分子。用1H NMR,MS和元素分析进行了表征,研究了化合物的热稳定性和真空镀膜膜层的光致发光性质,用循环伏安法测定了其电化学性能。结果表明,这种合成的有机化合物光致发光性能优良(量子效率达到87%),热稳定性好,可作为制作有机电致发光器件的候选材料。     

“绿色”液体激光介质的非线性光学特性研究

 利用氧化钕和盐酸为原料制得Nd(phen)2Cl3(三氯二邻菲罗啉合钕),测得其光谱特性并以稀土氧化钕、苯甲酸和邻菲罗啉为原料制得绿色液体激光介质钕离子的配合物——NdB3phen（三苯甲酸—邻菲罗啉合钕）.利用飞秒激光器,采用单光束Z-扫描法研究了NdB3phen的三阶非线性光学特性.结果表明:当入射飞秒激光脉冲波长为400 nm,峰值功率密度为2.94×1014 W/m2,脉宽为117 fs时,测得样品NdB3phen的非线性折射率为－2.84×10－18 cm2/W|NdB3phen在开孔条件下呈现反饱和吸收现象,测出双光子吸收系数的值为9.11×10－12 m/W.实验结果表明,NdB3phen的双光子吸收系数和非线性折射率随着光强的增强而增大.     

Generalised twists, , and the p-energy over a space of measure preserving maps

Let be a bounded Lipschitz domain and consider the energy functional

with p]1,∞[ over the space of measure preserving maps

In this paper we introduce a class of maps referred to as generalised twists and examine them in connection with the Euler–Lagrange equations associated with over . The main result is a surprising discrepancy between even and odd dimensions. Here we show that in even dimensions the latter system of equations admit infinitely many smooth solutions, modulo isometries, amongst such maps. In odd dimensions this number reduces to one. The result relies on a careful analysis of the full versus the restricted Euler–Lagrange equations where a key ingredient is a necessary and sufficient condition for an associated vector field to be a gradient.     

Using FTIR spectroscopy to detect sericin on historic silk

Silks represent some of the most precious ancient and historic textile artefacts in collections worldwide.Their optimum preservation demands an appreciation of their characteristics.One important concern,especially with regard to ancient Chinese silks,is whether the fabrics have been degummed.Silks with remnant sericin gum coating the fibroin fibres would require different conservation protocol.In previous research on aged silks,the presence of sericin has been inferred from amino acid analysis of hydrolysa...     

The invariants of the non-degenerate representations of the group of the pseudo-orthogonal matrices SO (p, 1)

The invariants of the non-degenerate representations of the group of pseudo-orthogonal matrices SO(p, 1) are constructed.     

一种新型高速电影经纬仪

112高速电影经纬仪是一种新型的高速光电跟踪测量设备,可用于快速飞行目标的轨迹测量和姿态记录,单台完成定位,并有实时输出的功能。该设备与传统的电影经纬仪相比,具有明显的特点,它采用双反射镜跟踪的结构方式,减少了运动部分的惯量,并提高同步数据采集处理速率到200次/秒和高速同步摄影频率到200f/s,有利于高速跟踪测量。该设备采用电视跟踪、计算机程序控制、单杆操纵等多种跟踪方式,可根据不同的目标特性方便地选用或组合使用,可靠地完成对目标的自动捕获和跟踪测量,最大跟踪速度为90°/秒,最大跟踪加速度为90°/秒²。本文还介绍了该设备在靶场使用情况。     

QM and QM/MM studies of uranyl fluorides in the gas and aqueous phases and in the hydrophobic cavities of tetrabrachion

The structural properties and electronic structures of pentacoordinated uranyl complexes belonging to the [UO(2)F(n)(H(2)O)(5-n)](2-n) series have been studied in the gas and aqueous phases using density functionals with relativistic pseudopotentials and all-electron basis sets in the gas-phase calculations in combination with COSMO in the aqueous phase. In addition, the conformational orientation and structural and electronic properties of [UO(2)F(5)](3-) in the hydrophobic cavities of the right-handed coiled-coil (RHCC) protein of tetrabrachion have been determined using the hybrid QM/MM method. Although there is good agreement between the available experimental geometrical parameters and the values obtained in the aqueous phase using pseudopotentials or all-electron basis sets, variation of the uranyl U═O bond with the number of fluoride ligands is only truly captured after the inclusion of five water molecules in the second coordination sphere around the molecules. The docking procedure used in this work shows that there are only two possible orientations of the uranyl group of [UO(2)F(5)](3-) embedded in the hydrophobic cavities of the RHCC protein. The two orientations are exclusively along the axes perpendicular to the protein axial channel with no possible orientation of the uranyl group along the axial channel because of both steric effects and interaction with the alkyl chain of the isoleucine residues pointing into the axial channel. In addition, the embedded complex is always positioned nearer to the isoleucine residues at the N-terminal ends of the hydrophobic cavities. Energy analysis, however, reveals that both conformations can only be observed in cavity 2, the largest hydrophobic cavity. The structural and electronic properties of the ligand embedded in this cavity are very similar to those of the gas-phase structure. A comparable study of [Pt(CN)(6)](2-) and the anticancer drug cisplatin, [PtCl(2)(NH(3))(2)], in cavity 2, revealed the existence of just two orientations for the former, similar to the uranyl complex, and multiple orientations for the latter.     

Theoretical study of the structural properties of plutonium(IV) and (VI) complexes

The structural properties of several plutonium(IV) and (VI) complexes have been examined in the gaseous and aqueous phases using Kohn-Sham density functional theory calculations with scalar relativistic effective core potentials and the polarizable continuum solvation model. The aquo and nitrate complexes of PuO(2)(2+) and Pu(4+) were considered in addition to the aquo-chloro complexes of PuO(2)(2+). The nitrate and chloro- complexes formed with triphenylphosphine oxide (TPPO) and tributylphosphate (TBP) respectively were also studied. The structural parameters of the plutonyl complexes were compared to their uranyl and neptunyl analogues. The bond lengths and vibrational frequencies of the plutonyl complexes can generally be computed with sufficient accuracy with the pure PBE density functional with shorter bond lengths being predicted by the B3LYP functional. The structural parameters of the [PuO(2)Cl(2)L(2)] systems formed with TPPO and TBP as well as the aqueous [PuO(2)Cl(2)(H(2)O)(3)] complex are matched to previous experimental results. Overall, the inclusion of ligands in the equatorial region results in significant changes in the stretching frequency of the plutonyl group. The structural features of the plutonyl (VI) systems are rather similar to those of their 5f(0) uranyl and 5f(1) neptunyl counterparts. For the Pu(IV) aquo and nitrate complexes, the average of the calculated Pu-OH(2) and Pu-O(nitrate) bond lengths are generally within 0.04 ? of the reported experimental values. Overall Kohn-Sham DFT can be used successfully in predicting the structures of this diverse set of Pu(VI) and Pu(IV) complexes.     

Theoretical exploration of uranyl complexes of a designed polypyrrolic macrocycle: structure/property effects of hinge size on Pacman-shaped complexes

A polypyrrolic macrocycle with naphthalenyl linkers between the N(4)-donor compartments (L(2)) was designed theoretically according to its experimentally-known analogues with phenylenyl (L(1)) and anthracenyl (L(3)) linkers. The uranyl and bis(uranyl) complexes formed by this L(2) ligand have been examined using scalar-relativistic density functional theory. The calculated structural properties of the mononuclear uranyl-L(2) complexes are similar to those of their L(1) counterparts. The binuclear L(2) complexes exhibit a butterfly-like bis(uranyl) core in which a linear uranyl is coordinated in a side-by-side fashion to a cis-uranyl unit. The calculated U[double bond, length as m-dash]O bond orders in the uranyl-L(2) complexes indicate partial triple bonding character with the only exceptions being the U-O(endo) bonds in the U(2)O(4) core of the butterfly-shaped binuclear complexes. Overall, the bond orders agree with the trends in the calculated U[double bond, length as m-dash]O stretching vibrational frequencies. Regarding the bis(uranyl) L(1), L(2) and L(3) complexes, the phenylenyl-hinge L(1) complexes adopt a butterfly-like and a T-shaped isomer in the oxidation state of U(vi), but only a butterfly-like one in the U(v), which differs from that of the naphthalenyl-hinge L(2) complexes as well as the lateral twisted structure of the anthracenyl-hinge L(3) complexes. The intramolecular cation-cation interactions are found in the L(1) and L(2) complexes, but are absent in the L(3) complexes. Finally, using model uranyl transfer reactions from the L(1) complexes, the formation of the mononuclear L(2) complexes is calculated to be a slightly endothermic process. This suggests that it should be possible to synthesize the L(2) complexes using similar protocols as employed for the L(1) complexes.