Maximum overlap symmetry molecular orbital model

This paper provides a brief and systematic presentation of the basic principle and method of the maximum overlap symmetry molecular orbital (MOSMO ) model and its application to simplification of molecular orbital calculation and to calculation of molecular structures and properties, together with some new results about the MOSMO calculation and new insights concerning the further extension of the principle and method. It has been shown that the theoretical method of the MOSMO model is very simple, reliable, and useful and can be employed to study the structure–property relation in even very large molecular systems. The numerical results obtained from the MOSMO calculation on various semiempirical molecular orbital approximation levels show that when the same parametrization, such as one of those employed in EHMO , CNDO /2, and HMO methods, is adopted, the MOSMOS are very close to the canonical molecular orbitals obtained from the customary LCAO method and the MOSMO calculation requires less computing time than does the LCAO method. The MOSMO calculation can be used for rapidly obtaining reasonably good molecular geometries, vibrational frequencies, and other properties of molecules by employing a simple improved semiempirical parametrization. Equilibrium geometries, vibrational frequencies, and other results are in good agreement with the experimental data and the results obtained from ab initio molecular orbital calculation. The basic calculational procedure of the MOSMO model can be extended further and has been employed to give some new results, to propose some new theoretical schemes and principles, and to introduce some new interesting theoretical problems that deserve to be studied further.     

Tetra­aqua(2,2′‐bi­pyridine)­nickel(II) terephthalate

The reaction of nickel(II) nitrate with terephthalic acid and 2,2′‐bi­pyridine in di­methyl­form­amide solution gives the title complex, [Ni(C₁₀H₈N₂)(H₂O)₄](C₈H₄O₄). The Ni^II ion is octahedrally coordinated to one 2,2′‐bi­pyridine and four water mol­ecules and does not coordinate to the terephthalate anion. Hydro­gen bonds between the terephthalate anions and the [Ni(2,2′‐bipy)(H₂O)₄]²⁺ cations produce a two‐dimensional hydrogen‐bonding architecture with double sheets.     

微米及纳米丝光沸石分子筛上二甲醚羰基化反应的积碳分析

对比研究了在传统微米尺寸和新结构纳米丝光沸石催化剂上二甲醚羰基化合成乙酸甲酯的反应行为.结果表明,通过减小分子筛的尺寸到纳米水平,可以有效提高反应物和产物到达或者脱离反应活性位的效率,从而提高了二甲醚的转化率;更重要的是,抑制了硬积碳的生成,使催化剂保持了更高的稳定性.     

Bioactive metabolites from <Emphasis Type="Italic">Penicillium</Emphasis> sp. P-1, a fungal endophyte in <Emphasis Type="Italic">Huperzia serrata</Emphasis>

A chemical study of metabolites of the strain Penicillium sp. P-1, an endophyte from the stems of Huperzia serrata, furnished a new chromone derivative, (2S)-2,3-dihydro-7-hydroxy-6,8-dimethyl-2-[(E)-prop-1-enyl]- chroman-4-one (1), an enantiomer of a known compound, and seven known compounds 2–8. The structure and absolute configuration of 1 were established using spectroscopic methods, including extensive 2D NMR and CD analyses. Cytotoxic activity of compounds 1–3 against HeLa and HepG2 cell lines were evaluated, in which compounds 2 and 3 exhibited marked cytotoxic activity against HeLa cells.     

Time-dependent density functional theory calculations of the photoabsorption of fluorinated alkanes

Time-dependent density functional theory (TD-DFT) calculations of the transition energies and oscillator strengths of fluorinated alkanes have been performed. The TD-DFT method with the non-local B3LYP potential yields transition energies for the methanes, which are smaller by about 10% as compared to the experimental values. An empirical linear correlation was found between the calculated and experimental transition energies both at the B3LYP/DZ+Ryd(C, F) and B3LYP/cc-pVTZ+Ryd(C, F, H) levels for a total of 19 transitions of the fluorinated methanes with linear correlation coefficients of 0.987 for the former and 0.988 for the latter. This empirical correlation for fluorinated methane molecules is found to agree well with the previously obtained empirical correlations between calculated and experimental values for non-fluorinated molecules. The results show that a single empirical-correlation relationship can be used for both non-fluorinated and fluorinated molecules to predict transition energies. This linear relationship is then used to predict the photoabsorption spectra of ethane, propane, butane, and partially and fully fluorinated derivatives. A key result of these calculations is the dominance of Rydberg transitions in the spectral region of interest.     

A vanadium(IV) phosphite with a pillared layered structure: hydrothermal synthesis and characterization of (VO)4(4,4'-bpy)2(HPO3)4

A novel vanadium(IV) phosphite, (VO)(4)(4,4'-bpy)(2)(HPO(3))(4), was hydrothermally synthesized and characterized by single-crystal X-ray diffraction. This compound crystallizes in the monoclinic system with the space group C2/c and cell parameters a = 35.970(3) A, b = 15.9400(13) A, c = 10.7681(7) A, beta = 101.073(4) degrees, and Z = 8 with R(1) = 0.0482. The structure of the compound consists of trigonal bipyramidal [VO(4)N] and pseudopyramidal [HPO(3)] blocks, which are connected by corner-sharing, to form vanadium phosphite layers in the bc plane. These layers are further linked through 4,4'-bpy pillars, generating a 3D framework. Thermogravimetric analysis and magnetic susceptibility data for this compound are given.     

聚电解质型正渗透汲取液

聚电解质作为正渗透汲取液具有渗透压高、溶质反向渗透、易于回收等特点,符合理想正渗透汲取液的要求。此外,多种分离方法诸如纳滤、超滤和热处理可用于其回收,使得聚电解质型汲取液成为诸如氯化钠等的传统无机汲取液的理想代替物。近年来关于聚电解质型汲取液的研究日益增加,而聚电解质型汲取液较无机型汲取液有许多独特的性质,应对相关研究进展予以总结。本文以聚电解质的化学结构分类对其研究进展进行了概述。重点总结了不同种类聚电解质的分子量、渗透压、黏度等性质,以及正渗透过程的水通量及溶质反向渗透情况,同时还介绍了相应的正渗透机理。最后,探讨和总结了各类汲取液的特点,并展望了未来的研究方向。     

Tuning Chemical and Physical Properties of Phosphorus Corroles for Advanced Applications

Although the affinity of metallocorroles to axial ligands is quite low, this is not the case when the chelated element is phosphorus. This work is hence focused on the mechanism of ligand exchange of six-coordinate phosphorus corroles as a tool for affecting their chemical and physical properties. These fundamental investigations allowed for the development of facile methodologies for the synthesis of a large series of complexes and the establishment of several new structure/activity profiles that may be used to understand and predict spectroscopic features and for tailor-made modification of photophysical and electrochemical properties. This is exemplified by the facile access to complexes with terminal groups that are of large potential for practical applications based on click chemistry, optical imaging, and surface science.