Defect properties of CuCrO₂:A density functional theory calculation

Using the first-principles methods,we study the formation energetics properties of intrinsic defects,and the charge doping properties of extrinsic defects in transparent conducting oxides CuCrO2.Intrinsic defects,some typical acceptortype,and donor-type extrinsic defects in their relevant charge state are considered.By systematically calculating the formation energies and transition energy,the results of calculation show that,V Cu,O i,and O Cu are the relevant intrinsic defects in CuCrO2 ;among these intrinsic defects,V Cu is the most efficient acceptor in CuCrO2.It is found that all the donor-type extrinsic defects have difficulty in inducing n-conductivity in CuCrO2 because of their deep transition energy level.For all the acceptor-type extrinsic defects,substituting Mg for Cr is the most prominent doping acceptor with relative shallow transition energy levels in CuCrO2.Our calculation results are expected to be a guide for preparing promising n-type and p-type materials in CuCrO2.     

钼酸催化简便合成D－葡萄庚酮糖

本文首次报道了在三氧化钼水溶液体系下催化碳链重排合成D-葡萄庚酮糖的简便方法。首先以D-甘露糖为原料在碘催化下进行异丙叉保护,产率90％;接着在碱催化下与甲醛水溶液亲核加成反应,在C-2上引入羟甲基侧链,产率40％;然后在酸性条件下异丙叉脱保护,产率92％;最后在三氧化钼水溶液催化下碳链重排合成葡萄庚酮糖,产率56％（总产率18％）。另外对2-C-羟甲基-D-甘露糖和葡萄庚酮糖的乙酰化产物进行了核磁氢谱表征。该方法原料易得,缩短了反应步骤,避免了昂贵金属试剂的使用,有较好的应用前景。     

新型1′-碘代炔丙基糖苷类化合物的合成及其抗菌活性

以四种单糖(D-葡萄糖、D-半乳糖、D-甘露糖和D-核糖)为原料,先在酸催化下与炔丙醇完成糖苷化反应(产率60%～80%);然后在碱催化下碘代合成了四个新型1′-碘代炔丙基糖苷类化合物(3a～3d,产率75%～90%),其结构经1H NMR表征.初步生物活性测试结果表明,3对引起农作物疾病的几种真菌均有抑制活性.     

亚甲基的~1U和~(13)C-NMR化学位移

该文研究了由六次甲基四胺(HA)硝解生成1,3,5-三硝基-1,3,5-三氮杂环己烷(RDX)过程所形成的七种反应产物和中间体的亚甲基在硝酸中的~1H和~(13)C-NMR化学位移。     

制备2，2′，4，4′-联苯四甲酸的新方法

氨基甲基苯甲酸;联苯四甲酸;合成;偶联;重氮盐     

酵母细胞催化芳香酮的不对称还原反应

 研究了酵母细胞催化芳香酮的不对称还原反应,采用正交试验综合考察了反应温度、反应时间、底物浓度和酵母浓度等因素对底物苯乙酮转化率和产物(S)-1-苯基乙醇对映选择性的影响. 结果表明,影响苯乙酮转化率的因素依次为底物浓度、反应时间、反应温度和酵母浓度,影响(S)-1-苯基乙醇对映选择性的因素依次为反应温度、底物浓度、酵母浓度和反应时间. 同时考察了芳香酮结构对产物对映选择性的影响,发现对映选择性的变化规律符合Prelog规则,与羰基相连的两个基团体积差异越大,对映选择性越好,最高的对映体过量值达到了96.4%.     

氟代蔗糖的密度泛函理论研究

采用密度泛函B3LYP／6—31G^＊＊方法,计算研究了蔗糖和氟代蔗糖的结构和性能,重点探讨了取代基效应。计算发现,C4＇和C3位取代物能量较低,而C3＇和C2位取代物能量较高,一氟蔗糖异构体之间的最大能量差为43．09kJ,二氟蔗糖的最大能量差达到68．96kJ。氟取代对键长、键角、远离取代位的电荷分布影响较小,但对蔗糖分子的立体构型、取代位附近的电荷分布和偶极矩的影响较大,C3＇和C6’取代可使偶极矩增大,而C2、C4’、C4取代使偶极矩减小。氟取代物的C3’位有F取代时AE较低,而C6位有F取代△E较高。除八氟蔗糖外,其他氟取代物的红外光谱在500～4000cm^-1的谱形都与蔗糖很相近。     

固体酸TiO2/SO42-在葡萄糖苷化反应中的催化性能研究

在不同条件下制备了固体酸TiO2 /SO2 -4 催化剂。用TLC法研究了该催化剂在D -葡萄糖与甲醇、乙醇、正丁醇、正戊醇和正十二醇的苷化反应中的催化性能。在反应中得到较短碳链的D -葡萄糖苷 ,如甲苷、乙苷、正丁苷和正戊苷 ,而不能得到长链的正十二烷基D -葡萄糖苷。适合于生成正丁苷的催化剂制备的较佳条件为H2 SO4浸泡浓度c =0 1mol/L ,焙烧温度θ =35 0～ 5 0 0℃ ,焙烧时间t =3h。催化剂用量约为D -葡萄糖用量的 6 %。     

First-principles study of atomic and electronic structures of kaolinite in soft rock

Kaolinite is a kind of clay mineral which often causes large deformations in soft-rock tunnel engineering and thus causes safety issues.To deal with these engineering safety issues,the physical/chemical properties of the kaolinite should be studied from basic viewpoints.By using the density-functional theory,in this paper,the atomic and the electronic structures of the kaolinite are studied within the local-density approximation(LDA).It is found that the kaolinite has a large indirect band gap with the conduction band minimum(CBM) and the valence band maximum(VBM) being at the Γ and the B points,respectively.The chemical bonding between the cation and the oxygen anion in kaolinite is mainly ionic,accompanied by a minor covalent component.It is pointed that the VBM and the CBM of kaolinite consist of oxygen 2p and cation s states,respectively.The bond lengths between different cations and anions,as well as of the different OH groups,are also compared.     

一种合成脱水糖醇的新方法

以四苄基糖(或2,3:5,6-二异丙叉基-D-甘露糖)为起始原料,经过NaBH4或LiAlH4还原、单对甲苯磺酰化、分子内环醚化反应、脱保护等步骤合成了四个脱水糖醇,总产率55%～75%,其结构经1H NMR,13C NMR,HSQC和NOESY表征.