苯并三氮唑及其羧酸酯衍生物对铜缓蚀机理的分子动力学模拟研究

用分子动力学(MD)方法, 模拟计算了5种铜缓蚀剂[苯并三氮唑(BTA)、苯并三氮唑-5-羧酸甲酯(MBTC)、苯并三氮唑-5-羧酸丁酯(BBTC)、苯并三氮唑-5-羧酸己酯(HBTC)、苯并三氮唑-5-羧酸辛酯(OBTC)]与Cu₂O晶体的相互作用. 结果发现, 中性条件下缓蚀剂分子与Cu₂O晶体的结合能均大于酸性条件下的数值, 但两种条件下结合能的大小排序均为OBTC＞HBTC＞BBTC＞MBTC＞BTA. 对体系各种相互作用以及对关联函数g(r)的分析表明, 体系结合能主要由库仑作用提供, Cu₂O晶体中的Cu原子与缓蚀剂分子中的N原子之间形成了配位键. 在与Cu₂O(001)晶面结合过程中, BTA及其衍生物分子发生了扭曲变形, 但形变能远小于体系的非键相互作用能.     

金属四重键化合物M2X4（PMe3）4（M=Cr，Mo，W;X=F，CI，Br，I）结构和电子光谱的密度泛函理论研究

采用密度泛函理论方法，在TZ2P-STO基组水平下，对金属四重键化合物M2Cl4（PMe3）4（M=Cr，Mo，W）和Mo2X4（PMe3）4（X=F，Cl，Br，I）的几何结构进行优化，分析了电子结构，并运用TDDFT方法对其低占据激发态进行了计算．考虑相对论效应的ZORA方法能够较好地重现M2X4（PMe3）4的几何结构．M2X4（PMe3）4的电子结构分析表明其d电子的组态为σ^2π^4δ^2，前线轨道能级顺序为πlig〈πd／σd〈δd〈δd^＊．金属原子和卤素配体的改变虽然使轨道能量发生变化，但没有影响轨道的排布顺序．TDDFT方法对M2Xa（PMe3）4δd→δd^＊和π→δd^＊跃迁能量的计算较为准确，对πlig→δd^＊（LMCT）跃迁能量的计算误差较大．金属原子、卤素配体以及相对论效应对激发能的影响可以根据分子轨道能级的变化给予解释．     

单核锌双卟啉配合物构象平衡的理论研究及光谱分析

合成了一系列以不同长度柔韧链相连的p/p型单核锌双卟啉配合物。选用Tripos力场,利用分子动力学模拟退火和分子力学构象搜索相结合的方法对该系列双卟啉进行了能量优化和构象分析。理论计算结果表明:该类双卟啉稳定存在的最低能量构象为叠合式,最高能量构象为伸展式,并存在一系列的中间能量构象;双卟啉分子内π-π作用和能量转移与双卟啉存在的两种主要构象密切相关;分析了分子内π-π作用的本质。运用不同光谱测试手段验证了理论计算结果: 利用可见和相应二阶导数吸收光谱研究了双卟啉主要存在的叠合式和伸展式构象,通过红外光谱观察了对双卟啉构象和卟啉环间π-π作用较为敏感的吸收谱带;利用荧光光谱计算了双卟啉的分子内能量转移效率。     

Au(II)化合物[Au(CH2)2PH2]2X2 (X＝F, Cl, Br, I)的量子化学理论研究

采用从头计算HF, MP2方法和密度泛函理论, 对Au(II)系列化合物[Au(CH₂)₂PH₂]₂X₂ (X＝F, Cl, Br, I)的几何结构、电子结构和振动频率进行了研究. 研究表明Au的5d和6s电子参与Au—Au以及Au—X之间的成键. Au—Au, Au—X键强烈的电子相关作用使HF方法不适于该体系的研究, BP86和B3LYP两种泛函给出较大的Au—Au和Au—X键长, 而MP2方法和局域的密度泛函方法则给出了合理的结构参数. 局域密度泛函方法计算得到的Au—Au键和 Au—X键振动频率也与实验数据符合较好. 还运用含时密度泛函理论计算了[Au(CH₂)₂PH₂]₂X₂的电子激发能, 对分子在紫外-可见光谱范围内的电子跃迁进行了分析, 考察了卤素配体对激发能的影响, 并结合分子轨道能级的变化对此给予了解释.     

Hamiltonian graphs of given order and minimum algebraic connectivity

In this paper, we study the algebraic connectivity of a Hamiltonian graph, and determine all Hamiltonian graphs whose algebraic connectivity attain the minimum among all Hamiltonian graphs on n vertices.     

First total synthesis of isoquinolinone alkaloid marinamide and its methyl ester

The first total synthesis of isoquinolinone alkaloid marinamide 1 and its methyl ester 2 was described. The key steps involved a regioselective Frieclel-Crafts reaction of 1-benzyl-1H-pyrrole to form the intermediate 8.     

金属四重键化合物M2X4(PMe3)4(M=Cr,Mo,W;X=F,Cl,Br,I)结构和电子光谱的密度泛函理论研究

采用密度泛函理论方法,在TZ2P-STO基组水平下,对金属四重键化合物M2Cl4(PMe3)4(M=Cr,Mo,W)和Mo2X4(PMe3)4(X=F,Cl,Br,I)的几何结构进行优化,分析了电子结构,并运用TDDFT方法对其低占据激发态进行了计算.考虑相对论效应的ZORA方法能够较好地重现M2X4(PMe3)4的几何结构.M2X4(PMe3)4的电子结构分析表明其d电子的组态为σ2π4δ2,前线轨道能级顺序为πlig<πd/σd<δd<δd*.金属原子和卤素配体的改变虽然使轨道能量发生变化,但没有影响轨道的排布顺序.TDDFT方法对M2X4(PMe3)4δd→δd*和πd→δd*跃迁能量的计算较为准确,对πlig→δd*(LMCT)跃迁能量的计算误差较大.金属原子、卤素配体以及相对论效应对激发能的影响可以根据分子轨道能级的变化给予解释.     

A New Microporous Hydrogen-Bonding Framework Constructed from 1-(4-Hydroxyphenyl)-5-Thioacetatetetrazole

Abstract  

The new complex with flexible heterocyclic carboxylate ligand, [Ba(HL⁻)₂(H₂O)₃]·H₂O (H₂L = 1-(4-Hydroxyphenyl)-5-thioacetatetetrazole), were synthesized and structurally determined by X-ray diffraction analysis. The complex belongs to the monoclinic system, space group C2/c. The center Ba(II) is nine-coordinated by six carboxylate oxygen atoms from four HL-ligands and three water molecules in a distorted monocapped square trans-prism geometry. The ligand serves as a bridge to link two adjacent Ba(II) atoms into a chain structure which are further assembled into the final three-dimensional supramolecular architecture with microporous open channel via hydrogen bonds.     

Lipase Immobilized on the Hydrophobic Polytetrafluoroethene Membrane with Nonwoven Fabric and Its Application in Intensifying Synthesis of Butyl Oleate

The synthesis of butyl oleate was studied in this paper with immobilized lipase. Five types of membrane were used as support to immobilize Rhizopus arrhizus lipase by following a procedure combining filtration and protein cross-linking. Results showed that hydrophobic polytetrafluoroethene membrane with nonwoven fabric (HO-PTFE-NF) was the favorite choice in terms of higher protein loading, activity, and specific activity of immobilized lipase. The factors including solvent polarity, lipase dosage, concentration, and molar ratio of substrate and temperature were found to have significant influence on conversion. Results showed that hexane (logP = 3.53) was a favorable solvent for the biosynthesis of butyl oleate in our studies. The optimal conditions were experimentally determined of 50 U immobilized lipase, molar ratio of oleic acid to butanol of 1.0, substrate concentration of 0.12 mol/L, temperature of 37 °C, and reaction time of 2 h. The conversion was beyond 91% and decreased slightly after 18 cycles. Lipase immobilization can improve the conversion and the repeated use of immobilized lipase relative to free lipase.