d9配合物MOSE曲面和几何构型的研究

d~9电子构型的金属离子所形成的配合物几何构型一般为拉长八面体或平面正方形,晶体场理论和角重叠模型都对此作出了较满意的描述,但就该电子构型的中心离子与指定配体配位时易形成配合物的配位数、配体所处的位置等问题,至今尚无满意解释.本文通过分子轨道稳定化能(MOSE)的计算及其曲面的绘制,形象地解释了上述问题.     

Investigations on Preparation,Crystal Structure and Thermal Stability of Bis(O-ethylcarbonodithiolato-S,S′)(1,10-phenanthroline-N~1,N~(10))cobalt(II) Complex:[Co(Et-XA)_2·phen]·H_2O (XA=xanthate)

IntroductionTheincreasingcommercialvalueoftransitionmetalcomplexesofxanthateshasarousedconsiderableinterestintheirchemistry .Whiletheiranalyticalapplicationsarewellknown ,1theyarenowfindingextensiveuseinvulcan izationofrubber ,frothfloatationprocessforconcentrationofsulphideores ,asantioxidants ,lubricants ,2 ,3andhavebeenfoundtopossessfungicidalandinsecticidalactivi ties .4 Recently ,molecularrecognitionbetweenhostandguestmolecules ,inclusionphenomenaandnoncovalentmolecularinteractionarefunda…     

Further Daphniphyllum Alkaloids from the Leaves of Daphniphyllum macropodum Miq.

Five new polycyclic Daphniphyllum alkaloids, macropodumines F ( 1 ) and G ( 2 ), 17‐oxoyuzurimine ( 3 ), and macropodumines H ( 4 ) and I ( 5 ), were isolated from the leaves of D. macropodum Miq ., collected in Sichuan Province, China. The structures and relative configurations of the new compounds – as well as of four known, related alkaloids – were elucidated on the basis of in‐depth spectroscopic and mass‐spectrometric analyses, by chemical derivatization, and by comparison of spectroscopic data with those of known compounds.     

Proton transfer dynamics of the reaction H3O(+)(NH3,H2O)NH4+ studied using the crossed molecular beam technique

The proton transfer reaction of H3O+ and NH3 was studied using the crossed molecular beam technique at relative energies of 0.41, 0.81, and 1.27 eV. At all three energies, the center-of-mass flux distribution of the product ion NH4+ exhibits sharply asymmetry, and the maximum is close to the velocity and direction of the precursor ammonia beam. The reaction transforms almost all of the 1.69 eV exothermicity into internal excitation of the products at all three collision energies. At the lowest collision energy of 0.41 eV, nearly 77% of the total energy appears in NH4+ internal excitation. However, almost 100% of the incremental translational energy in the two higher-energy experiments appears in the product translational energy. Such an observation provides a classic example of the "induced repulsive energy release" mechanism that is expected to be operative on the highly skewed potential energy surfaces characteristic of the heavy+light-heavy mass combination. These results indicate that the proton transfer proceeds through a direct reaction mechanism; a Rice-Ramsperger-Kassel-Marcus theory calculation shows that the lifetime of the intermediate complex [NH3-H-H2O]+ is about 100 fs. Proton transfer occurs early on the reaction coordinate, when the incipient N-H bond is extended, and results in highly vibrationally excited NH4+ products, with excitation primarily in N-H stretching modes.     

New Nitrogenous Bisabolene‐Type Sesquiterpenes from a Hainan Sponge Axinyssa aff. variabilis

Two new uncommon nitrogenous sesquiterpenes, 11‐ethoxy‐3‐formamidotheonellin ( 1 ) and 7‐ethoxy‐3‐formamidobisabolane‐8,10‐diene ( 2 ), together with two known related sesquiterpenes, 3‐formamidotheonellin (=theonellin formamide; 3 ) and theonellin isothiocyanate ( 4 ), were isolated from the Hainan sponge Axinyssa aff. variabilis. Their structures were determined on the basis of extensive spectroscopic analysis and by comparison of their NMR data with those of known compounds.     

WATER STATES IN SBR BASED WATER SWELLING RUBBER

Water swelling rubber (WSR) was prepared by reaction blending SBR andsodium polyacrylate (PAANa). The existing states of water in the WSR was studied bymeans of DSC and TG. It was found that water exists in three states: nonfreezing water,bound freezable water and free water. The relationships between water states and structureof PAANa were investigated. The results showed that the amount of non-freezing waterwas related to total water content, and the ratio of non-freezing water versus -COONagroups on PAANa (mol/mol) was about 4. However, total water content slightly affectedthe content of bound freezable water and remarkably affected the amount of free waer.     

Streamlined construction of peptide macrocycles via palladium-catalyzed intramolecular S-arylation in solution and on DNA

A highly efficient and versatile method for construction of peptide macrocycles via palladium-catalyzed intramolecular S-arylation of alkyl and aryl thiols with aryl iodides under mild conditions is developed. The method exhibits a broad substrate scope for thiols, aryl iodides and amino acid units. Peptide macrocycles of a wide range of size and composition can be readily assembled in high yield from various easily accessible building blocks. This method has been successfully employed to prepare an 8-million-membered tetrameric cyclic peptide DNA-encoded library (DEL). Preliminary screening of the DEL library against protein p300 identified compounds with single digit micromolar inhibition activity.

A highly efficient and versatile method for construction of peptide macrocycles via palladium-catalyzed intramolecular S-arylation of alkyl and aryl thiols with aryl iodides under mild conditions is developed.     

二氧化碳—环氧丙烷—甲苯二异氰酸酯的三元共聚

二氧化碳和环氧丙烷(PO)在阴离子配位催化剂,如二乙基锌和等摩尔的水作用下,可接式(1)发生共聚。但产物聚丙撑碳酸酯(PPC)的热稳定性较差。改进途径之一是在反应中引入甲苯二异氰酸酯(TDI)进行三元共聚。本文报导在双金属阴离子配位催化剂PBM存在下合成一种热稳定性优于PPC的聚碳酸酯聚氨酯(PCPU)的研究结果(式2)。     

有机锆交联剂的制备及其性能

随着油田深部调剖应用的不断推广，以及环保要求的提高，适用于深部调剖调驱体系的低污染有机锆交联剂逐渐受到关注。以ZrOCl₂·8H₂O、乳酸、乙二胺、硫脲为原料，制备了有机锆交联剂和HPAM-锆交联凝胶，其结构和性能经SEM和岩心驱替装置表征。并利用正交实验法优化了制备条件。结果表明：制备有机锆交联剂的最佳条件为：氧氯化锆、乳酸、乙二胺及硫脲的质量比为7.8/1/6.7/5，反应温度为70 ℃，反应时间为3 h。交联温度为60 ℃，HPAM浓度为2 g·L^-1、聚锆比为30/1时，聚合物凝胶成胶强度达到24968 mPa·s，成胶时间约8 h，凝胶体系可维持90 d不破胶。在级差为3.9的双管驱替岩心实验中，两管的岩心分流率均接近50%，剖面改善率达到66.77%。     

STM study on quinacridone derivative assemblies: modulation of the two-dimensional structure by coadsorption with dicarboxylic acids

We describe the two-dimensional (2D) assemblies of N,N'-dialkyl-substituted quinacridone derivatives on highly orientated pyrolytic graphite observed by scanning tunneling microscopy, and focus our discussion on whether the supramolecular organization can be modulated by the coadsorption of dicarboxylic acids. Our experiments have demonstrated that the quinacridone derivatives can form different 2D nanostructures when coadsorbed with dicarboxylic acids of different length at the liquid/graphite interface. Interestingly, N,N'-dihexadecyl-substituted quinacridone derivative alternately takes two different conformations in two columns for its coadsorption with pentadecanedioic acid and form a gridlike structure. It is shown that a cooperative effect of different interactions can be modulated by introducing guest molecule, leading to formation of different self-assembled nanostructures.