第二周期AO_2(A=C,N,O)分子的理论研究

在MP2/6-311 G**水平上对第二周期AO2(A=C,N,O)分子进行了量子化学计算,根据计算结果讨论了分子的电子结构、成键特征,得出了AO2分子的稳定性及其化学性质的变化规律,较好地解释了实验事实.     

Syntheses and characterization of alkylzirconium complexes containing two silanolato ligands with a bowl-shaped framework

The reaction of a bowl-type silanol with tetrabenzylzirconium yielded a dibenzylbis(silanolato)zirconium complex selectively, which is an intriguing species in connection to the chemistry of silica-supported ZrR₄ olefin polymerization catalysts. Treatment of this neutral complex with B(C₆F₅)₃ afforded the corresponding cationic monobenzyl complex, presenting the first example of a cationic zirconium complex containing a silanolato ligand. The structures of both complexes have been characterized by X-ray crystallography.     

Simple wavefunctions for dipositronium and the relationship between this species and the hydrogen molecule

Dipositronium (two electrons and two positrons) has a closer relationship to the hydrogen molecule than has often been assumed in past treatments. This article shows that appropriately modified mixtures of simple molecular orbital and Heitler–London wavefunctions are a good basis for the ground state of this species. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

High-throughput single molecule screening of DNA and proteins

We report a novel imaging technology for real time comprehensive analysis of molecular alterations in cells and tissues appropriate for automation and adaptation to high-throughput applications. With these techniques it should eventually be possible to perform simultaneous analysis of the entire contents of individual biological cells with a sensitivity and selectivity sufficient to determine the presence or absence of a single copy of a targeted analyte (e.g., DNA region, RNA region, protein), and to do so at a relatively low cost. The technology is suitable for DNA and RNA through sizing or through fluorescent hybridization probes, and for proteins and small molecules through fluorescence immunoassays. This combination of the lowest possible detection limit and the broadest applicability to biomolecules represents the final frontier in bioanalysis. The general scheme is based on novel concepts for single molecule detection (SMD) and characterization recently demonstrated in our laboratory. Since minimal manipulation is involved, it should be possible to screen large numbers of cells in a short time to facilitate practical applications. This opens up the possibility of finding single copies of DNA or proteins within single biological cells for disease markers without performing polymerase chain reaction or other biological amplification.     

Scattering Factor of C_(60) Molecule

ThisprojectwassupportedbytheYouthScienceFoundationoftheUniveristyofScienceandTechnologyofChinainspiredconsiderableinterestinthephysicalandchemicalpropertiesofthisnewformofcarbon.TheC6omoleculeisproposedtohaveatomsdistributedonthesurfaceofaspherewithalternatingfiveandsixmemberringsasinthepatternofseamsonasoc-cerballt3'4i.Atroomtemperature,single-crystalX-raydiffractionshowsthatthemoleculesarecenteredonsitesofaface-centered-cubic(fcc)Bravaislattice,a=1.4l7nm,withahighdegreeofrotationaldisord…     

Mapping protein pockets through their potential small-molecule binding volumes: QSCD applied to biological protein structures

Previously we demonstrated a method, Quantized Surface Complementarity Diversity (QSCD), of defining molecular diversity by measuring shape and functional complementarity of molecules to a basis set of theoretical target surfaces [Wintner E.A. and Moallemi C.C., J. Med. Chem., 43 (2000) 1993]. In this paper we demonstrate a method of mapping actual protein pockets to the same basis set of theoretical target surfaces, thereby allowing categorization of protein pockets by their properties of shape and functionality. The key step in the mapping is a `dissection' algorithm that breaks any protein pocket into a set of potential small molecule binding volumes. It is these binding volumes that are mapped to the basis set of theoretical target surfaces, thus measuring a protein pocket not as a single surface but as a collection of molecular recognition environments.     

分子图导图在求本征多项式系数中的应用

本文以分子图的导图为基本图来讨论分子的拓扑性质。找到了应用分子图导图求共轭分子a_k一般表示式的实用方法。应用这种方法求出了常见同系列共轭分子a_k的一般表示式。     

Electronic states of the NiCu molecule determined byab initio Hartree-Fock and configuration interaction methods

The interaction between a Ni atom and a Cu atom in the configurations (3d)⁹(4s)¹ and (3d)¹⁰(4s)¹, respectively, has been calculated usingab initio Hartree-Fock and configuration interaction methods. The chemical bond between the two atoms is due to a bonding 4sσ molecular orbital. Equilibrium distances, dissociation energies and vibrational frequencies are predicted for the low-lying states. Finally the influence of spin-orbit coupling on the low-lying states is considered.     

Electrophilic attack on sulfur-sulfur bonds: coordination of lithium cations to sulfur-rich molecules studied by ab initio MO methods

Complex formation between gaseous Li+ ions and sulfur-containing neutral ligands, such as H2S, Me2Sn (n = 1-5; Me = CH3) and various isomers of hexasulfur (S6), has been studied by ab initio MO calculations at the G3X(MP2) level of theory. Generally, the formation of LiS(n) heterocycles and clusters is preferred in these reactions. The binding energies of the cation in the 29 complexes investigated range from -88 kJ mol(-1) for [H2SLi]+ to -189 kJ mol(-1) for the most stable isomer of [Me2S5Li]+ which contains three-coordinate Li+. Of the various S6 ligands (chair, boat, prism, branched ring, and triplet chain structures), two isomeric complexes containing the S5==S ligand have the highest binding energies (-163+/-1 kJ mol(-1)). However, the global minimum structure of [LiS6]+ is of C(3v) symmetry with the six-membered S(6) homocycle in the well-known chair conformation and three Li--S bonds with a length of 256 pm (binding energy: -134 kJ mol(-1)). Relatively unstable isomers of S6 are stabilized by complex formation with Li+. The interaction between the cation and the S6 ligands is mainly attributed to ion-dipole attraction with a little charge transfer, except in cations containing the six sulfur atoms in the form of separated neutral S2, S3, or S4 units, as in [Li(S3)2]+ and [Li(S2)(S4)]+. In the two most stable isomers of the [LiS6]+ complexes, the number of S--S bonds is at maximum and the coordination number of Li+ is either 3 or 4. A topological analysis of all investigated complexes revealed that the Li--S bonds of lengths below 280 pm are characterized by a maximum electron-density path and closed-shell interaction.