Complexation of trivalent lanthanide cations by inositol in solid state. The crystal structure and Raman spectra study of NdCl3·inositol·9H2O

The crystal structure of NdCl₃·C₆H₁₂O₆·9H₂O has been determined. It crystallizes in the monoclinic system, p2(1)/n space group with cell dimensions: a=15.824(3) Å, b=8.633(2) Å, c=16.219(3) Å, β=107.24°, V=2116.1(7) ų and Z=4. Each Nd ion is coordinated to nine oxygen atoms, two from inositol and seven from water molecules, with an Nd–O distance of 2.449–2.683 Å, the other two water molecules are hydrogen bonded. No direct contacts exist between Nd and Cl. There is an extensive network of hydrogen bonds in hydroxyl groups, water molecules and chloride ions in the crystal structure of the lanthanide complex. The Raman spectra of Pr–, Nd– and Sm–inositol are similar, which show that the three metal ions have the same coordination mode. The Raman spectra are consistent with their structures.     

Isoindole Cycloadditions. Part III: The Synthesis of "Windscreen Wiper" and Other N-Bridged Cavity Systems

The thermal addition of N-carbobenzyloxyisoindole (N-Z isoindole) 11a, generated by the reaction of 3,6-di(2-pyridyl)-s-tetrazine 9 with N-Z 7-azabenzonorbornadiene 8a, onto dimethyl tricyclo[4.2.1.0^2.5]nona-3,7-diene-3,4-dicarboxylate 17 occurred site selectively at the cyclobutene -bond to form a stereoisomeric mixture of 1 : 1-adducts 18 and 19, in which the bent-frame isomer 19 was dominant (ratio 5 : 1). In contrast, N-benzyl tetrafluoroisoindole 11c reacted with 17 only under high-pressure conditions (14 kbar, RT, 4 days) to afford 1 : 1-adducts at the cyclobutene site, in which the extended-frame isomer 18c was dominant and the accompanying bent-frame product 19c reverted to starting materials soon after isolation. These same stereoselectivities were used to prepare "windscreen wiper" compound 28c having two mobile N-benzyl substituents attached to a rigid scaffold by the reaction of N-benzyl tetrafluoroisoindole 11c with tetramethyl tetracyclo[4.4.1.0.^2,5.0^7.10]undeca-3,8-diene-3,4,7,8-tetracarboxylate 23. Cavity bis-(cyclobutene-1,2-diester) 6 reacted with N-benzyl tetrafluoroisoindole 11c twice over to produce cavity structure 36 with two O- and two N-benzyl bridges on the inner face, whereas the narrower cavity bis-alkene 32 stopped at the 1 : 1-addition stage. The dynamics of the Z-group in the dual adducts 26a–28a are discussed briefly and key adducts and cavity systems have been structurally evaluated by X-ray crystallography, VT NMR, and molecular modeling.     

β-环糊精和部分有机物分子识别作用的焓熵判断

应用气相色谱实验技术,测定了一些有机溶剂（或溶质）在β-环糊精（β-CD）固体表面上的吸附热力学函数.实验结果表明,气相中的有机物质在β-CD表面上的吸附过程之焓、熵互补现象与它们之间的分子识别作用密切相关,它们的绝对值之和可以作为分子识别作用强弱的判据.     

Theoretical study of silicon–sulfur clusters (SiS2)n (n = 1–6)

 The possible geometrical structures and relative stability of (SiS₂) _n (n=1–6) silicon–sulfur clusters are explored by means of density functional theory quantum chemical calculations. The effects of polarization functions and electron correlation are included in these calculations. The electronic structures and vibrational spectra of the most stable geometrical structures of (SiS₂) _n are analyzed by the same method. As a result, the regularity of the (SiS₂) _n cluster growth is obtained, and the calculation may used for predicting the formation mechanism of the (SiS₂) _n cluster. Received: 17 November 1999 / Accepted: 3 November 2000 / Published online: 3 May 2001     

Preparation and mass spectrometric study of egg yolk antibody (IgY) against rabies virus

Rabies virus was used as the antigen to immunize laying chickens. Anti-rabies virus immunoglobulin Y(IgY) was isolated from yolks of the eggs laid by these chickens using a two-step salt precipitation and one-step gel filtration protocol. The purified IgY was reduced with dithiothreitol, and heavy chains (HC) and light chains (LC) were obtained. In addition, the purified IgY was digested with pepsin and the fragment with specific antigen binding properties (Fab) was produced. Using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS), the average molecular weights of IgY, HC, LC, and Fab were determined as 167 250, 65 105, 18 660, and 45,359 Da, respectively. IgY has two structural differences compared with mammalian IgGs. First, the molecular weight of the heavy chain of IgY is larger than that of its mammalian counterpart, while the molecular weight of the light chain of IgY is smaller. Second, upon pepsin digestion, anti-rabies virus IgY is degraded into Fab, in contrast to mammalian IgG, which has been reported to be degraded into F(ab')(2) under the same conditions.     

Trajectory studies of S(N)2 nucleophilic substitution. 8. Central barrier dynamics for gas phase Cl(-) + CH(3)Cl

Quasiclassical direct dynamics trajectories, calculated at the MP2/6-31G level of theory, are used to study the central barrier dynamics for the C1(-) + CH(3)Cl S(N)2 reaction. Extensive recrossings of the central barrier are observed in the trajectories. The dynamics of the Cl(-)-CH(3)Cl complex is non-RRKM and transition state theory (TST) is predicted to be an inaccurate model for calculating the Cl(-) + CH(3)Cl S(N)2 rate constant. Direct dynamics trajectories also show that Cl(-) + CH(3)Cl trajectories, which collide backside along the S(N)2 reaction path, do not form the Cl(-)-CH(3)Cl complex. This arises from weak coupling between the Cl(-)-CH(3)Cl intermolecular and CH(3)Cl intramolecular modes. The trajectory results are very similar to those of a previous trajectory study, based on a HF/6-31G* analytic potential energy function, which gives a less accurate representation of the central barrier region of the Cl(-) + CH(3)Cl reaction than does the MP2/6-31G* level of theory used here. Experiments are suggested for investigating the non-RRKM and non-TST dynamics predicted by the trajectories.     

萃取体系中的分子有序现象及其对萃取的影响

萃取体系中存在分子有序聚集体是一普遍现象,并对液－液传质过程有重要影响。本文从分子有序聚集体的形成条件,研究方法,对萃取机制的影响和应用前景等几方面做了简要评述,以期有助于该领域研究的进一步深入。     

非水体系中甲醇在粗糙铂电极上解离吸附的表面增强拉曼 光谱研究

利用共焦显微拉曼系统和表面增强拉曼散射(SERS)效应研究了非水体系中甲醇在粗糙铂电极上的解离吸附过程。结果表明：甲醇在粗糙铂电极上解离吸附后产生了毒性中间物CO,在较负的电位区间内,H与CO共吸附于电极表面并影响CO的吸附行为,随电位正移,ν~P~t~-~C的变化可以用电化学Stark效应进行解释,而ν~C~~O的变化则是由于电化学Stark效应和CO偶极耦合的共同作用所引起的。     

乙腈溶液中银电极的表面增强拉曼光谱研究

利用共焦显微拉曼系统研究了非水体系0.1mol·L^-1LiClO4/CH3CN溶液中,乙腈分子在粗糙银和金电极表面的吸附和解离行为。结果表明非水体系中乙腈可在银、金表面发生还原反应,产物CN^-离子与电极表面作用形成的表面配合物可以较宽的电位区间吸附于电极表面。溶液中的微量水、激光照射以及电极电位均对该反应有较大的影响。通过拉曼谱图的比较,得出乙腈分子解离出的CN^-在金电极表面比在银电极表面有更强的吸附作用。     

有机官能团对硅基MSU-X织构性能的影响

采用有机硅氧烷(RTES)与硅氧烷(TEOS)共水解缩聚合成了有机官能化的MSU-1中孔材料(R=甲基,苯基,乙烯基,脲丙基)。当前驱体中RTES与TO64EOS的摩尔比为0.1:0.9时合成R10-MSU-1分子筛,通过现化分析技术证明BA所选有机官能团均能进入分子筛骨架,而且在相同摩尔数的各数有机硅氧烷存在下,由于其反应速率、空间位阻的不同使其对骨架的缩聚程度、孔道和表面性质有不同的影响。利用SAXS实验技术对所合成R10-MSU-1材料结构表面以及由于有机官能团的存在对无机骨架产生的影响进行了研究。SAXS较强的散射强度分布对Porod定理形成负偏离,表明孔和基体之间有明显的界而层存在,并求得界面层的平均厚度。实验证明有机基团的均匀分布于孔道表面而形成有机界面层。SAXS测试还显示上述分子筛呈质量分形特征,其形成过程可能为非平衡非线性的聚集机制。