共轭CN与非共轭CF3吸电子取代基对PPV类衍生物分子结构及光电性质的影响

运用密度泛函DFT B3LYP／6-31G(d)方法对CN和CF3吸电子基团取代的PPV类衍生物的三聚体进行了几何构型优化,并采用含时密度泛函TD-DFT、B3LYP／6-31G(d)方法计算了其相应化合物的紫外吸收光谱．通过对CN和CF3取代的PPV类衍生物的分子几何结构、前线分子轨道能级、电子云分布规律的分析,从理论上解释了共轭CN与非共轭CF3吸电子取代基对其光谱性质影响的差异：前者使相应PPV类衍生物的吸收光谱发生红移,后者则发生蓝移．计算结果还表明用TD-DFT方法计算该体系的紫外吸收光谱值与实验数据吻合得很好;另外引入CN和CF3基团之后,使其相应的PPV衍生物的LUMO能级降低,电子亲合势增加,都是很好的电子传输材料．     

取代基对4-N,N-二苯胺基均二苯乙烯类电致发光材料光电特性的影响

用紫外吸收光谱、荧光发射光谱、循环伏安法(CV)、微分脉冲伏安法(DPV)等手段研究了4个4-N,N-二苯胺基均二苯乙烯类化合物的光电性能, 计算出它们的电离势(P_I)在5.70～5.90 eV, 带隙值(E_g)在2.78～2.88 eV, 分析了电化学行为, 讨论了取代基对吸收光谱、发射光谱和电子结构的影响. 结果表明, 引入供电子基团OCH₃后, 分子氧化电位降低, HOMO能量升高, 电离势降低; 引入吸电子基团—Cl后, 氧化电位升高, LUMO能量降低, 电子亲和势增加. 取代基—Cl和—OCH₃都使化合物的带隙(E_g)减小, 紫外-可见光谱的吸收峰和荧光光谱的发射峰均发生红移.     

甲基取代对聚吡咯结构和性能的影响

本文采用量化学ＳＣＦ－ＭＮＤＯ和ＣＮＤＯ／２－ＣＯ方法对三种聚甲基取代吡咯的结构进行优化，分析了它们的电子能带结构，探讨了甲基取代对聚吡咯结构和性能的影响。     

推拉电子取代基对二茂铁衍生笺性质及电子结构的影响

根据前线轨道理论分析３种具有推拉电子取代基的二茂铁衍生物循环伏安曲线，电子上光谱衣光谱电子化学行为，为给出了分子轨道能级图。实验结果表明，ＰⅡ有两对可逆氧化还原峰，Ｅ＾ｏｘ１，Ｅ＾ｏｘ２分别为０．３３，０．５９Ｖ，第一氧化态ＰⅡ＾＋（Ｄ－Ｆｃ＾＋－Ｒ）在６１３ｎｍ有强的ＬＭＣＴ（ｌｉｇａｎｄ－ｔｏ－ｍｅｔａｌ－ｃｈｇａｒｇｅ－ｔｒａｎｓｆｅｒ）带，是一种良好的光学特性氧化还原开关。ＰⅡ在３５４ｎｍ     

推拉电子取代基对二茂铁衍生物性质及电子结构的影响

根据前线轨道理论分析３种具有推拉电子取代基的二茂铁衍生物循环伏安曲线、电子吸收光谱及光谱电化学行为，并给出了分子轨道能级图，实验结果表明，ＰⅡ有两对可逆氧化还原峰，Ｅ１、Ｅ２分别为０．３３、０．５９Ｖ，第一氧化态ＰⅡ＋￣（Ｄ—Ｆｃ￣＋—Ｒ）在６１３ｎｍ有强的ＬＭＣＴ（ｌｉｇａｎｄ－ｔｏ－ｍｅｔａｌ－ｃｈａｒｇｅ－ｔｒａｎｓｆｅｒ）带，是一种良好的光学特性氧化还原开关．ＰⅡ在３５４ｎｍ处出现强的ＬＭＣＴ带，ＰⅢ在３５６ｎｍ和３２０ｎｍ处分别出现强的ＬＭＣＴ和π→πＣＴ带，应具有较高的二阶分子极化系数，应当是较好的ＳＨＧ材料．     

亚胺氯化物介导一锅法合成3-吸电子基团取代吲哚衍生物

以3-氰基/酯基吲哚为代表的3-吸电子基团取代吲哚结构存在于多种生物活性分子中,常作为优势骨架构建类药性化合物库用于新药发现.本文设计并发展了一种基于亚胺氯化物活性中间体的串联反应,从邻卤苯乙腈/酯和酰胺出发,在碱和CuBr催化下,一锅法构建结构多样性3-吸电子基团取代吲哚骨架的新合成方法.该反应原料简单易得、反应快速...     

给、吸电子基团对芳香共轭体系电子结构影响的密度泛函理论研究

采用密度泛函理论,在B3LYP／6—31G^＊方法水平上对8个连接有给、吸电子基团的芳香共轭体系的稳定性、偶极矩、静电荷分布和前线轨道能级进行了研究,并采用TD／DFT方法进一步研究了它们的电子光谱．结果表明a-1,b-1,c-1和d-2分子比它们的同分异构体要稳定;对于苯、呋喃、吡咯与乙烯形成的共轭体系,吸电子基团连接在乙烯一端,给电子基团连接在芳香环上使体系的偶极距增强,而吡啶则相反;前线轨道能级差较小的是吸电子基团连接在芳香环一端的体系,相应的分子最大吸收波长也较大．     

取代基对依布硒啉电子结构及光谱性质影响的理论研究

采用密度泛函理论B3LYP方法在6-311++G**水平对依布硒啉及其6个衍生物进行结构优化,并分析了取代基对分子几何构型、电荷分布、前线轨道能级分布的影响.在相同计算水平上采用含时密度泛函理论方法进行了电子光谱研究,讨论了取代基对电子光谱的影响.计算结果表明,标题化合物分子为非平面结构,苯并异硒唑酮环与苯环之间存在一...     

硅锗酞菁聚合物的电子结构

在自洽场晶体轨道法全略微分重叠(SCFCNDO/2－CO)水平上对氧桥和硫桥一维链硅锗酞菁聚合物的能带结构和电子特性进行了研究,探讨了堆积酞菁环间交错角以及中心原子和桥原子的变化对电子特性的影响.计算结果表明,除前线带宽外,交错角变化对所研究的聚酞菁电子特性影响不大.晶体轨道分析表明,氧桥聚酞菁电荷载流子主要通过垂直酞菁环π轨道的纵向重叠导电通路流动,而硫桥聚酞菁导带电子还可经中心原子和桥原子的d轨道重叠通路迁移.     

卤原子取代苯并噻二唑聚合物给体材料的合成及其光伏性能研究

通过对苯并噻二唑单元进行氟、氯等卤原子取代,并同时调节烷基侧链的长度,设计合成了一系列基于苯并噻二唑四噻吩类的聚合物太阳电池材料.不同卤原子取代以及烷基侧链的长度都会影响聚合物的结晶性和薄膜聚集形貌从而改变其带隙和电荷传输性质.氟、氯原子的引入可调节聚合物的能级结构,而且相对于氟原子而言,具有更大原子半径的氯原子的引入可在更大尺度下调节能级结构,从而大幅提高相应太阳电池的开路电压,同时通过侧链的优化可进一步调节聚合物的微观聚集结构,改善器件能量转换效率.结果表明,在氯原子和氟原子共同作用的情况下,引入较长的侧链有利于提升聚合物的开路电压和短路电流,从而获得较好的器件性能.其中,以氯、氟共同取代的聚合物PCFBT4T-2OD与PC_(71)BM为活性层的器件性能最佳,能量转换效率可达8.84%.     

Synthesis and electrochemical characterization of fluorene and benzimidazole containing novel conjugated polymers: Effect of alkyl chain length on electrochemical properties

The synthesis and characterization of two donor acceptor type conjugated polymers were investigated. Electrochemical properties were examined by cyclic voltammetry, spectroelectrochemistry and kinetic studies. The increase in the alkyl chain length attached to the fluorene unit was investigated in terms of electrochemical properties. The synthesis was carried out via Stille coupling of 4,7-dibromo-4′-(tert-butyl)spiro[benzo[d]imidazole-2,1′ cyclohexane] and 2,5-bis(tributylstannyl)thiophene with 9,9-dihexyl-9H fluorine (P1) and 9,9-didodecyl-9H fluorene (P2) respectively. Both polymers were neutral state green polymers. They had optical band gaps of 1.55 and 1.47 eV respectively. Increasing the chain length resulted in an increase in solubility and processibility of the polymer. Polymers are multichromic, revealing colors from neutral state green to doped state blue.     

Tuning the HOMO–LUMO gap of donor-substituted benzothiazoles

A series of push–pull benzothiazoles were designed and synthesized by the Pd-catalyzed Sonogashira cross-coupling and [2+2] cycloaddition–retroelectrocyclization reactions. The photonic and electrochemical properties of these systems exhibit strong donor–acceptor interaction. The BTs 5–8 show strong intramolecular charge-transfer in the near-infrared (NIR) region. The absorption studies indicate systematic lowering of the optical HOMO–LUMO gap with increase in acceptor strength. The computational studies reveal that incorporation of strong acceptors TCNE and TCNQ results in substantial stabilization of the LUMO level compared to the HOMO level, leading to the low HOMO–LUMO gap and bathochromic shift of the absorption spectrum. The TCBD and DCNQ linked BTs 5–8 exhibit multi-step redox waves and improved thermal stability.     

Ring opening of activated cyclopropanes with NIS/NaN3: synthesis of C-1 linked pseudodisaccharides

NIS/NaN₃ mediated ring opening of various donor–acceptor cyclopropanes has been investigated. The study shows the necessity of the donor oxygen lone pair in such ring opening reactions. This methodology has been utilized in the synthesis of C-1 linked pseudodisaccharides through the use of click chemistry.     

ELECTRONIC EFFECTS OF DONOR AND ACCEPTOR SUBSTITUENTS ON DIPYRIDO(3,2-a:2′,3′-c)PHENAZINE (dppz)

Abstract

The chelate ligands 11-R-dipyrido[3,2-a:2′,3′-c]phenazine, dppz-R (R = NH₂, CH₃, H, COOH, NO₂) and the Re(dppz-R)(CO)₃Cl (R = NH₂, COOH, NO₂) complexes were synthesized and characterized by conventional techniques. The influence of the donor and acceptor properties of the R substituents on the ligand properties were studied by spectroscopic techniques such as ¹H-NMR and UV-Vis. Theoretical calculations were also achieved, mainly to interpret and understand the experimental spectra.     

Energy band structure of polymer chains with screw axes of symmetry

The general relations concerning the energy band structure of quasi-one-dimensional crystals possessing screw axes are obtained. The -electron energy bands of an infinite polyene chain are considered within the SCF tight binding approximation.     

Über Reaktionen von Hexachlorodiberyllat mit Trimethylsilyl‐N‐dimethylamid. Die Kristallstrukturen von (Ph4P)3[Be2Cl5(OSiMe3)][BeCl3(Me2NSiMe3)], (Ph4P)[BeCl3(HNMe2)] und (Ph4P)(H2NMe2)[BeCl4]

On Reactions of Hexachlorodiberyllate with Trimethylsilyl‐N‐dimethylamide. Crystal Structures of (Ph₄P)₃[Be₂Cl₅(OSiMe₃)][BeCl₃(Me₂NSiMe₃)], (Ph₄P)[BeCl₃(HNMe₂)], and (Ph₄P)(H₂NMe₂)[BeCl₄] Reactions of bis‐tetraphenylphosphonium hexachlorodiberyllate, (Ph₄P)₂[Be₂Cl₆], with trimethylsilyl‐N‐dimethylamide under different conditions lead to the novel chloroberyllate derivatives (Ph₄P)₃[Be₂Cl₅(OSiMe₃)][BeCl₃(Me₂NSiMe₃)] ( 1 ), (Ph₄P)[BeCl₃(HNMe₂)] ( 2 ), and (Ph₄P)(H₂NMe₂)[BeCl₄] ( 3 ). 1 ‐ 3 were characterized by IR spectroscopy and crystal structure determinations. 1· 4CH₂Cl₂: Space group P1¯, Z = 2, lattice dimensions at 193 K: a = 1115.6(1), b = 2110.7(2), c = 2145.0(3) pm, α = 71.38(1)°, β = 85.66(1)°, γ = 85.24(1)°, R₁ = 0.0732. The [Be₂Cl₅(OSiMe₃)]^2— ion in the structure of 1 is derived from the [Be₂Cl₆]^2— ion by substitution of a μ‐Cl ligand by the oxygen atom of the (OSiMe₃)^— group. The second anion, [BeCl₃(Me₂NSiMe₃)]^—, can be described as donor acceptor complex with a short Be—N bond of 179(1) pm. 2 : Space group P1¯, Z = 2, lattice dimensions at 193 K: a = 1063.1(1), b = 1072.0(1), c = 1238.3(1) pm, α = 87.55(1)°, β = 74.86(1)°, γ = 69.73(1)°, R₁ = 0.0299. The anion of 2 forms a centrosymmetric dimer [BeCl₃(HNMe₂)]₂^2— via N—H···Cl bridges of the two donor acceptor complex units with Be—N separations of 175.2(2) pm. 3 : Space group Pbca, Z = 8, lattice dimensions at 193 K: a = 926.9(1), b = 2164.7(1), c = 2732.7(1) pm, R₁ = 0.0495. The structure of 3 contains centrosymmetric ion quadrupoles [(Me₂NH₂)(BeCl₄)]₂^2— forming by N—H···Cl bridges between (Me₂NH₂)⁺ and [BeCl₄]^2— ions.