Theoretical Study of Synthesis Mechanism and Electronic Structure for 3-Octylthien-2,5-ylenediethynylenecobenzo[c]- 1 ＇ 2＇ 5＇ -thiadiazo-3,6-ylenedi（2,5-thienylene）

采用密度泛函理论中的广义梯度近似（DFT／GGA）方法,在PW91／DNP水平上研究了4,7-（2-噻吩基）苯并噻二唑-3-辛基噻吩二炔在PdCl2（PPh3）2催化下的合成机理．优化了反应过程中的反应物、中间体、过渡态和产物,通过能量分析结果证实了中间体和过渡态的真实．在同样的方法和精度研究了4,7．二（2．噻吩基）苯并噻二唑．3．辛基噻吩二炔在没有催化剂下的合成机理．通过计算结果得到此反应在有PdCl2（PPh3）2催化情况下的活化能小于没有催化剂情况下的活化能,从而证明了PdCl2（PPh3）2催化剂的催化活性．采用密度泛函理论与周期性平板模型相结合的方法,研究了产物P在Ti02（100）表面的吸附,通过Mulliken charge和前线轨道分析表明：当P吸附在Ti02（100）表面时,P向Ti02（100）表面转移0．692e电荷,前线轨道能隙变窄．理论预测的结果与实验值吻合．     

一种新型低带隙共轭聚合物的合成及其光学性质

在钯催化剂作用下, 通过4,7-二(5-溴-2-噻吩基)[2,1,3]苯并噻二唑与2,5-二乙炔基-3-辛基噻吩的偶联反应, 合成了一种新的共轭高分子聚4,7-二(2-噻吩基)苯并噻二唑-3-辛基噻吩二炔(PTE-DTBT). 通过紫外可见吸收光谱及荧光光谱对其光学性质进行了研究. 紫外-可见吸收谱结果表明, PTE-DTBT的固体膜光学带隙为1.71 eV; 电化学测试其带隙为1.88 eV. TiO₂/PTE-DTBT共混固体膜的荧光发射谱结果表明电子供体PTE-DTBT分子与电子受体TiO₂分子间存在有效的电子转移.     

2-甲基噻吩光异构化成3-甲基噻吩的理论研究

用CASSCF方法以6-31G基组研究了2-甲基噻吩光异构化为3-甲基噻吩的光化学反应和基态(S₀)及三重激发态(T₁)的相关势能面.反应主要发生在三重态(T₁)上,其间经历了两个双自由基,1个三元环中间体及4个过渡态.沿着反应路径找到了2个T₁/S₀势能面交叉点,其结构都类似于双自由基.在第二个T₁/S₀势能面交叉点附近由T₁向S₀的系间窜越(ISC)最为有利.     

苯-噻吩低聚物电子结构及载流子传输性质的理论研究

采用密度泛函理论(DFT)的B3LYP/6-31G(d)方法对以低聚噻吩为端基、 苯并二噻吩(TPT)和并三噻吩(TTT)为共轭桥、 炔键为连接臂的20个模型化合物进行了计算研究. 在优化中性与离子态几何构型基础上, 获得了前线轨道能级、 电离能(IPs)、 电子亲和势(EAs)、 空穴/电子重组能(λ_h/λ_e)、 载流子迁移率(μ_h/μ_e)及吸收光谱等信息. 结果表明, 炔键的引入及端基低聚噻吩的增加对LUMO能级的调控作用较为显著, 而共轭桥的类型对HOMO能级影响较大; 合理选择端基、 共轭桥和连接臂等结构单元可对该类材料吸光波段及强度进行有效调节. 一维电荷传输模型结果表明, 所设计的化合物均是潜在的双极性有机半导体材料, 其中2,7-二([2,2':5',2'-三噻吩]-5-基)苯并[1,2-b:6,5-b']二噻吩(A3)和2,7-二(二噻吩并噻吩-2-基乙炔基)苯并[1,2-b:6,5-b']二噻吩(a-3)具有较高的电子迁移率, 值得进一步的实验探索研究.     

2-己硫醇生成2,5-二甲基噻吩机理的理论研究

采用密度泛函理论的B3LYP方法,在6-311+G(d,p)基组水平上研究了2-亿硫醇生成2,5-二甲基噻吩的微观反应机理,全参数优化了反应势能面上各驻点的几何构型,内禀反应坐标反应机理解析证实了过渡态的真实性,找到了具体的反应途径.结果发现,在2-己硫醇环化生成2,5-二甲基四氢噻吩的反应过程中,中间体Ⅰ异构化生成中...     

9,9-二(十六烷基)芴基二聚炔铂、金和汞配合物的合成与性质

用Hagihara脱氢卤代法合成了三种新的9,9-二(十六烷基)芴基二聚炔铂(d⁸)、金和汞(d¹⁰)化合物反式- [Pt(Ph)(PEt₃)₂C≡CRC≡CPt(Ph)(PEt₃)₂, [(PPh₃)AuC≡CRC≡CAu(PPh₃)]和[MeHgC≡CRC≡CHgMe] [R＝9,9-二(十六烷基)芴基]. 用¹H NMR, ¹³C NMR, ³¹P NMR, FT-IR, FAB-MS, UV-Vis, 荧光和磷光光谱对其进行了表征. 结果表明, 体系中的铂、金和汞产生的重原子效应可以有效地促进单线激发态S₁与三线激发态T₁的系间跃迁, 使标题化合物产生有机三线态发光.     

聚苯撑乙炔-苯并噻二唑共聚物的合成及光谱性能

利用钯催化剂[Pd(PPh₃)₂Cl₂]和相转移催化剂(PTC), 采用Heck交叉偶联缩聚反应合成了聚(苯撑乙炔撑-苯并噻二唑)系列交替共聚物(PPE-BT), 比较了聚合物的紫外吸收光谱和荧光光谱特征.     

5-取代-3,4-二卤-2(5H)-呋喃酮的Sonogashira偶联反应

以5-取代-3,4-二卤-2(5H)-呋喃酮为底物进行Sonogashira偶联反应, 考察了反应温度、反应时间、钯催化剂种类与用量、碱种类与用量、溶剂、底物结构等对偶联反应的影响, 合成了28种新的2(5H)-呋喃酮衍生物, 其结构用IR, ¹H NMR, ¹³C NMR, MS和元素分析等方法进行了表征. 在优化的反应条件下, 即反应溶剂为甲苯、催化剂为3 mol% Pd(PPh₃)₄和10 mol% CuI、碱为6 equiv. KF、反应时间72 h、反应温度30 ℃时, 反应产率42%～84%. 利用该Sonogashira偶联反应合成新型的多官能团烯二炔结构化合物, 不仅合成途径简捷、反应条件温和, 绝大部分反应产率中等以上, 而且无需额外加入配体, 适用于芳香的和脂肪的末端炔烃.     

顺-8-三甲基锡烷基-6-辛烯醛分子内环化反应立体选择性的理论研究

用密度泛函方法在B3LYP/6-31G^*水平上研究了顺-8-三甲基锡烷基-6-辛烯醛分子内环化反应的机理,通过振动分析和内禀反应坐标对过渡态进行了确认,解析了三种反应途径.结果表明,反应具有很强的立体选择性,虽然-OSn(CH₃)₃和-C₂H₃基团均处于环的平伏位,是最稳定的产物构型,但是主要产物是经过活化能最低,且具有两个六元环椅式构象的过渡态形成的,主要产物中-OSn(CH₃)₃基团处于环的直立位.该结果与实验事实一致.     

C-H键活化反应的密度泛函理论模拟对简化模型的评估

采用密度泛函理论方法, 模拟了Rh(PPh₃)₃Cl催化的C-H键活化/C-C键偶联反应. 将反应机理分为C-H键活化、 迁移插入和还原消除3个过程进行讨论. 计算结果表明, 势能面的最高点为迁移插入的过渡态, 相对于初始原料的自由能为108.3 kJ/mol. 为了探索简化计算模型对模拟反应机理的影响, 使用2种模型催化剂Rh(PMe₃)₃Cl和Rh(PH₃)₃Cl表征相同的反应过程, 结果表明配体简化模型不合理, 主要是因为PPh₃配体的空间效应和熵效应非常明显.     

PdCl2/NaI-catalyzed homodimeric coupling-cyclization reaction of 2,3-allenols: an efficient synthesis of 4-(1',3'-dien-2'-yl)-2,5-dihydrofuran derivatives

A PdCl2/NaI-catalyzed homodimeric coupling-cyclization reaction of 2,3-allenols was observed to provide an efficient route to 4-(1',3'-dien-2'-yl)-2,5-dihydrofuran derivatives. By using the easily available optically active starting materials, 2,5-dihydrofurans with high enantiopurity may be prepared. A Pd(II)-catalyzed mechanism was also discussed.     

Chiral building blocks from biomass: 2,5-diamino-2,5-dideoxy-1,4-3,6-dianhydroiditol

An efficient route towards the synthesis of 2,5-diamino-2,5-dideoxy-1,4-3,6-dianhydroiditol 4 has been developed resulting in significant improvements in both isolated yields and purity when compared to literature procedures. As a consequence, resin-grade 2,5-diamino-2,5-dideoxy-1,4-3,6-dianhydroiditol 4 has become available for laboratory scale step-growth polymer synthesis. Additionally, an interesting renewable chiral 2-amino-2-deoxy-1,4-3,6-dianhydroiditol 10, has been isolated.     

Palladium-catalyzed tandem dimerization and cyclization of acetylenic ketones: a convenient method for 3,3'-bifurans using PdCl2(PPh3)2

Alkynones undergo tandem dimerization and cyclization in the presence of PdCl2(PPh3)2 and triethylamine in tetrahydrofuran at room temperature to give 3,3'-bifurans predominantly. Other palladium catalysts while under similar conditions, by rearrangement, lead to 2,5-disubstituted furans. This distinguished property of PdCl2(PPh3)2 has been attributed to the involvement of hydridopalladium halide. This method provides a simpler route to a variety of furans and a regioselective synthesis of polysubstituted 3,3'-bifurans using easily accessible acetylenic ketones.     

A Computational Study on the Mechanism for the K_2CO_3-catalyzed Reaction of Carbon Dioxide and 1-Chlo-2-propanol

The microcosmic reaction mechanism of K2CO3-catalyzed 1-chlo-2-propanol and carbon dioxide has been investigated by density functional theory(DFT) at the GGA/PW91/DNP level.We optimize the geometric configurations of reactants,intermediates,transition states,and products.The energy analysis calculation approves the authenticity of intermediates and transition states.According to our calculations,four feasible reaction pathways are found.The main pathway of the reaction is ReA → IMA1 → TSA1 → IMA2 → IMA5 → TSA5 → P.Besides,we also in-vestigate the reaction mechanism of 1-chlo-2-propanol and carbon dioxide without K2CO3-catalyzation by the same theory and level.The computational results indicate that the activation barrier with K2CO3-catalyzed is smaller than the activation barrier without K2CO3-catalyzed.That is to say,K2CO3 can promote the reaction to give the product in a high yield,which is in agreement with the experimental results.     

An efficient Approach to Modify the Catalyst Activity for the Hydrogenation of Nitrobenzene

Transition metal complexes have been used extensively for the hydrogenation in homogeneous system probably due to their high catalytic selectivities under mild operating conditions. In order to improve the homogeneous catalyst system, some studies on the homogeneous or soluble polymer-supported bimetallic catalysts have been recently carried out and enhanced activity, better selectivity were observed in selective hydrogenation, hydrodehalogenation, carbonylation, hydroformylation and regioselec…     

Synthesis,spectroscopic characterization and EPR studies on electron transfer reactions of bis[N-(2,5-di-tert-butylphenyl)salicylaldiminato]copper complexes with PPh3

New bidentate N-(2,5-di-tert-butylphenyl)salicylaldimines bearing X = H, HO, CH3O, Br, NO2, 3,5-di-Br, 3-NO2-5-Br and 5,6-benzo substituents on the salicylaldehyde moiety, LxH, and their mononuclear bis[N-(2,5-di-tert-butylphenyl)salicylaldiminato]copper(II) complexes, Cu(Lx)2, have been prepared and investigated by IR, UV-Visible, 1H NMR, ESR spectroscopy, magnetic measurements, as well as reactions of Cu(LX)2 with PPh3 were studied. It has been found that some complexes with X = HO and CH3O unlike their electron-withdrawing and unsubstituted analogues are readily reduced by PPh3 via intramolecular electron transfer from ligand to copper(II) to give Cu-stabilized radical intermediates. The spectra of the primary radicals interpreted in terms of couplings of unpaired electron with (63,65)Cu, 31P, 14N nuclei and aromatic protons.     

Preparation of Poly(p-Phenylene), Poly(m-Phenylene), and Poly(2,5-Thienylene) Via Electron Transfer from Aryl Grignard Reagents to 2,3-Dichloropropene

Three polymers including poly(p-phenylene), poly(m-phenylene), and poly(2,5-thienylene) were synthesized in good yields from the corresponding aryldimagnesium bromide with two equiv of 2,3-dichloropropene. The polymerization process involving electron transfer from the Grignard reagent to 2,3-dichloropropene is proposed.     

Evaluation of functionalized silica's for the adsorptive recovery of homogenous catalysts through interaction with the metal centre

The goal of this paper is the evaluation of functionalized silica's for the recovery of homogeneous catalysts by adsorption via its metal centre. As model catalysts, we selected bis(triphenylphosphine)cobalt(II)dichloride (CoCl(2)(PPh(3))(2)), bis(triphenylphosphine)palladium(II)dichloride (PdCl(2)(PPh(3))(2)) and tris(triphenylphosphine)rhodium(I)dichloride (RhCl(PPh(3))(3)). Twelve functionalized groups selected from four classes containing one or more N-, O-, P- or S-atoms were evaluated. A preliminary selection of the adsorbents was done by investigating the adsorption of the metal salts for the cobalt and the palladium complex. The results could be explained by the Hard and Soft Acid Base (HSAB) theory. For the most suitable functionalized adsorbents, these experiments were extended by introducing the ligand in the system which promoted the competition of the functionalized groups on adsorbent and the ligands present in solution. These experiments demonstrated that different complex species are adsorbed. 2-(2pyridyl)ethyl-functionalized silica is selected as a promising adsorbent for adsorption of the CoCl(2)(PPh(3))(2) from acetonitrile, while 3-(mercapto)propyl-functionalized silica is selected as a promising adsorbent for adsorption of the PdCl(2)(PPh(3))(2) and RhCl(PPh(3))(3) from DMF. The presence of a ligand, an increase of the temperature and the presence of a solvent with the donor properties can decrease the adsorption equilibrium and need to be taken into account.     

己烯氢羧基化反应中钯膦催化剂作用机理的原位红外光谱研究

用原位红外光谱研究了在合成气压力下钯-膦催化剂(PdCl2(PPh3)/PPh3和2-乙基己醇存在下己烯的氢羧基化.结果表明羰基钯中间体最先形成并和醇反应形成氢羧基化钯.然后是连续地进行烯烃插入,羰基配位和醇解得到酯,并重新生成(R'O)Pd(CO)(PPh3)2中间体.