咔唑及其N-取代衍生物的气相He I紫外光电子能谱与量子化学研 究

首次系列报道了9-H咔唑及其系列N-取代衍生物的气相HeI紫外光电子能谱,借助于Gauss-94采用RHF/3-21G基组对它们的几何构型进行优化,并用RHF/6-31G基组计算分子轨道及能级,计算的分子轨道特征和能量很好地反映了各谱带的特点和分子间电离能的变化规律。依计算结果,以及同系列分子间谱带及相应电离能的相互比较,对每个分子的UPS谱带给予指认,讨论了N-烷基化对π分子轨道的选择性去稳定化作用,并讨论了分子之间电离能的变化规律,得到一系列有益的结论。     

咔唑及其N-取代衍生物的气相HeⅠ紫外光电子能谱与量子化学研究

首次系列报道了9-H咔唑及其系列N-取代衍生物的气相HeI紫外光电子能谱,借助于Gauss-94采用RHF/3-21G基组对它们的几何构型进行优化,并用RHF/6-31G基组计算分子轨道及能级,计算的分子轨道特征和能量很好地反映了各谱带的特点和分子间电离能的变化规律.依计算结果,以及同系列分子间谱带及相应电离能的相互比较,对每个分子的UPS谱带给予指认,讨论了N-烷基化对π分子轨道的选择性去稳定化作用,并讨论了分子之间电离能的变化规律,得到一系列有益的结论.     

N-(2-溴乙基)咔唑与N-乙烯基咔唑的气相HeI紫外光电子 能谱与电子结构研究

首次报道了N-(2-溴乙基)咔唑和N-乙烯基咔唑的气相HeI紫外光电子能谱(UPS),借助于Gaussian94采用RHF/6-31G基组优化几何构型,并用RHF/6-31G^*基组计算分子轨道及能级.在对咔唑和N-烷基咔唑系列分子UPS电离能变化规律研究的基础上,对这2个分子的UPS谱带给予指认,并讨论其电子结构.结果表明N-(2-溴乙基)咔唑的UPS谱与N-烷基咔唑的不同之处是在10.295,10.540eV处出现2个Br原子的孤对轨道;N-乙烯基咔唑的UPS谱带与咔唑的相比,电离能变化的特殊性说明乙烯基与咔唑环共平面。     

N-(2-溴乙基)咔唑与N-乙烯基咔唑的气相HeI紫外光电子能谱与电子结构研究

首次报道了N-(2-澳乙基)咔唑和N-乙烯基咏唑的气相Hel紫外光电子能谱(UPS),借助于Gaussian 94采用RHF/6-3lG基组优化几何构型,并用RHF/6-31G基组计算分子轨道及能级.在对咔唑和N-烷基咔唑系列分子UPS电离能变化规律研究的基础上,对这2个分子的UPS谱带给予指认,并讨论其电子结构.结果表明N-(2-溴乙基)咔唑的UPS谱与N-烷基咔唑的不同之处是在10.295,10.540Ve处出现2个Br原子的孤对轨道;N-乙烯基咔唑的UPS谱带与咔唑的相比,电离能变化的特殊性说明乙烯基与咔唑环共平面.     

双对苯氰基系列分子气相HeI紫外光电子能谱和量子化学研究

测定了4,4′-二氰基联苯(1),4,4′-二氰基二苯醚(2),4,4′-二氰基二苯甲烷(3),4,4′-二氰基二苯酮(4),4,4′-二氰基二苯砜(5)的气相HeI紫外光电子能谱,借助于Gauss-94采用RHF/6-31G方法对其几何构型作全优化,计算分子轨道及能级,对其低电离能区的谱带给予指认,得到通过空间和通过键作用的相对强弱直接影响分子轨道次序的结论. 将立体效应和电子效应分开讨论,得到该系列分子电离能的变化规律.     

系列二羰基化合物的HeI紫外光电子能谱(UPS)及量子化学研究

报道了醌及苯并酸酐等系列二羰基化合物的气相HeI紫外光电子能谱。对各体系利用Gaussian94程序RHF/3-21G进行了构型优化,对得到的优势构型采用STO-6G基组进行了轨道计算。并结合计算结果对各分子体系的UPS谱进行了分析指认。计算结果分析显示:标题化合物的第一个电离峰均是由苯环部分的共轭π键电子电离及羰基的孤对电子电离引起的,且化合物的IP~1值随羰基在HOMO轨道中权重的增大而增大。各化合物的第二、三谱带都与羰基不同类型的孤对电子峰相关联。说明羰基为此类化合物的特征基团。且分子的对称性越高,羰基的孤对电子峰n^-和n^+的平均值越大,分裂值也越大。     

2(5H)呋喃酮二聚体的PES和量子化学研究

报道 2 ( 5H)呋喃酮及其椅式 反式二聚体 (t c DFN)的PES谱 ,谱带的指认借助于谱带形状、类似基团分子的PES结果和对两研究分子的RHF计算 .并提供了二聚体HOMO电离能比单体HOMO电离能低的实验和理论证据 .     

缩胺基脲衍生物HeI PES和电子结构的研究

利用HeI紫外光电子能谱(PES)首次得到一组缩胺基脲衍生物的PES谱图。并利用RHF(6-31G^*^*)计算了它们的电子结构,解析了实验谱,分析和说明与实验电离能所对应的分子轨道的特征。论证了计算结果与实验值间很好的相符关系。并通过实验和计算结果,讨论了这类化合物取代基的影响和为何缺乏生物活性。     

Kr和Kr2的实验和理论研究

利用超声分子束技术、同步辐射和反射式飞行时间质谱仪得到了Kr和Kr2的光电离质谱和光电离效率谱, 确定了Kr和Kr2的电离能. 利用Gaussian-03程序中的MP2(Full)/6-31G*, QCISD/cc-pVTZ以及B3LYP/6-31G方法优化了Kr2的结构, 计算了它们的振动频率和电离能, 计算结果显示: 当采用相同的理论水平和基组时, 随着Kr同位素质荷比(m/z)的增大, 它们结构和电离能保持不变, 而振动频率逐渐变小. 与此同时, 用G2方法计算了Kr (84)和Kr2 (168)的电离能, 它们的电离能的理论值与实验结果符合得比较好.     

哌嗪二酮的气相Hel光电子能谱及其量化计算

给出了哌嗪二酮的气相HeI紫外光电子能谱(UPS), 并进行了化合物分子的HAM/3, MNDO, MINDO/3, INDO, CNDO/2和EHMO等量子化学计算研究. UPS谱低电离能(<11.00 eV)区的四重峰被指认为分子体系中氧-氧, 氮-氮原子孤对轨道间的通过键相互作用导致的分裂峰. 表明HAM/3和MNDO计算法是预指该化合物实验电离能正确次序、轨道对称性类型以及通过键相互作用导致分裂大小的较好方法.     

Synthesis and properties of methoxyphenyl-substituted derivatives of indolo[3,2-b]carbazole

The synthesis and full characterization of new derivatives of indolo[3,2-b]carbazole with differently substituted phenyl groups at nitrogen atoms is reported. Comparative study on their thermal, optical electrochemical, and photoelectrical properties is presented. The synthesized compounds are electrochemically stable. Their highest occupied molecular orbital energy values range from -5.14 to -5.07 eV. The electron photoemission spectra of the films of synthesized materials revealed the ionization potentials of 5.31-5.47 eV. Hole drift mobility of the amorphous film of 5,11-bis(3-methoxyphenyl)-6-pentyl-5,11-dihydroindolo[3,2-b]carbazole exceed 10(-3) cm(2)/V·s at high electric fields, as it was established by xerographic time-of-flight technique. In contrast to diphenylamino substituted derivatives of carbazole, no effect of the position of methoxy groups on the photoelectrical properties was observed for the synthesized methoxyphenyl-substituted derivatives of indolo[3,2-b]carbazole. The indolo[3,2-b]carbazole core has a larger resonance structure that includes 3 phenyl rings, and thus the energy gap of the HOMO and LUMO π orbitals is lower as compared to that of carbazoles. With a larger energy difference between the phenyl substituents and the core moiety, the indolo[3,2-b]carbazole derivatives studied all have a weaker coupling between the phenyl group and a much weaker dependence of the molecular properties on the position of substituents on the phenyl groups as compared to those observed in substituted carbazoles.     

Carbazole endcapped heterofluorenes as host materials: theoretical study of their structural, electronic, and optical properties

By mimicking the molecular structure of 4,4'-bis(N-carbazolyl)-2,2'-biphenyl (CBP), which is a widely used host material, a new series of host molecules (carbazole-endcapped heterofluorenes, CzHFs) were designed by linking the hole-transporting carbazole to the core heterofluorene molecules in either meta or para positions of the heterofluorene. The aromatic cores considered in this study are biphenyl, fluorene, silafluorenes, germafluorenes, carbazole, phosphafluorene, oxygafluorene, and sulfurafluorene. To reveal their molecular structures, optoelectronic properties and structure-property relationships of the proposed host materials, an in-depth theoretical investigation was elaborated via quantum chemical calculations. The electronic structures in the ground states, cationic and anionic states, and lowest triplet states of these designed molecules have been studied with emphasis on the highest occupied molecular orbitals (HOMOs), the lowest unoccupied molecular orbitals (LUMOs), energy gaps (E(g)), triplet energy gaps ((3)E(g)), as well as some other electronic properties including ionization potentials (IPs), electron affinities (EAs), reorganization energies (λ), triplet exciton generation fraction (χ(T)), spin density distributions (SD), and absorption spectra. These photoelectronic properties can be tuned by chemical modifications of the heteroatom and the carbazole substitution at different positions. This study provides theoretical insights into the nature of host molecules, and shows that the designed CzHFs can meet the requirements of the host materials for triplet emitters.     

Theoretical studies on the electronic and optical properties of two new alternating fluorene/carbazole copolymers

Poly(fluorene)-type materials are widely used in polymer-based emitting devices. During operation there appears, however, an additional emission peak at around 2.3 eV, leading to both a color instability and reduced efficiency. The incorporation of the carbazole units has been proven to efficiently suppress the keto defect emission. In this contribution, we apply quantum-chemical techniques to investigate two series of alternating fluorene/carbazole oligomers and copolymers poly[2,7-(N-(2-methyl)-carbazole)-co-alt-2,7-m(9,9-dimethylfluorene)], namely, PFmCz (m = 1,2) and gain a detailed understanding of the influence of carbazole units on the electronic and optical properties of fluorene derivatives. The electronic properties of the neutral molecules, HOMO-LUMO gaps (Delta(H-L)), in addition to the positive and negative ions, are studied using B3LYP functional. The lowest excitation energies (E(g)s) and the maximal absorption wavelength lambda(abs) of PFmCz (m = 1,2) are studied, employing the time-dependent density functional theory (TD-DFT). The properties of the two copolymers, such as Delta(H-L), E(g), IPs, and EAs were obtained by extrapolating those of the oligomers to the inverse chain length equal to zero (1/n = 0). The outcomes showed that the carbazole unit is a good electron-donating moiety for electronic materials, and the incorporation of carbazole into the polyfluorene (PF) backbone resulted in a broadened energy gap and a blue shift of both the absorption and photoluminescence emission peaks. Most importantly, the HOMO energies of PF1Cz and PF2Cz are both a higher average (0.4 eV) than polyfluorene (PF), which directly results in the decreasing of IPs of about 0.2 eV more than PF, indicating that the carbazole units have significantly improved the hole injection properties of the copolymers. In addition, the energy gap tends to broaden and the absorption and emission peaks are gradually blue-shifted to shorter wavelengths with an increase in the carbazole content in the copolymers. This is due to the interruption of the longer conjugation length of the backbone in the (F1Cz)(n) series.     

对苯二胺和N-取代衍生物正离子自由基的共振喇曼光谱研究

本文中报道了对苯二胺和四种N-烷基取代衍生物正离子自由基的共振喇曼光谱, 揭示了自由基是具有明显C=C和C=N双键性质的半醌式结构, N原子上给电子基团的取代引起上述化学键振动峰低频移动, 反映出结构一端N上有烷基的自由基中与取代基直接相连的N原子失去一个p电子带正电荷, 并吸引环上的π电子形成一定程度C=N双键. 共振喇曼光谱随激发光波长的变化表明, 自由基的两个可见电子吸收带分别主要产生于环结构的π→π*和包含N原子结构的n→π*电子跃迁。     

Calculation of photoelectron spectra of molybdenum and tungsten complexes using Green's functions methods

Green's functions calculations are presented for several complexes of molybdenum and tungsten, two metals that are similar structurally but display subtle, but significant, differences in electronic structure. Outer valence Green's functions IPs for M(CO)6, M(Me)6, MH6, [MCl4O](-), and [MO4](-) (M = Mo, W) are generally within +/-0.2 eV of available experimental photoelectron spectra. The calculations show that electrons in M-L bonding orbitals are ejected at lower energies for Mo while the detachment energy for electrons in d orbitals varies with metal and complex. For the metal carbonyls, the quasiparticle picture assumed in OVGF breaks down for the inner valence pi CO molecular orbitals due to the coupling of two-hole-one-particle charge transfer states to the one-hole states. Incorporation of the 2h1p states through a Tamm-Dancoff approximation calculation accurately represents the band due to detachment from these molecular orbitals. Though the ordering of IPs for Green's functions methods and DFT Koopmans' theorem IPs is similar for the highest IPs for most compounds considered, the breakdown of the quasiparticle picture for the metal carbonyls suggests that scaling of the latter values may result in a fortuitous or incorrect assignment of experimental VDEs.     

共轭效应和芳香性本质的争论和它们的历史发展

“共轭效应是稳定的”是有机化学的最最基本原理之一。但是,自30年代起,键长平均化,4N＋2芳香性理论,苯环D~6~h构架的起因,分子的构象和共轭效应的因果关系,π-电子离域的结构效应等已经受到了广泛的质疑。其中,最引人注目的是Vollhardt等合成了中心苯环具有环己三烯几何特征的亚苯类化合物,Stanger等合成了键长平均化,但长度在0.143～0.148nm的苯并类衍生物。最近(1999年),Stanger又获得了在苯环中具有单键键长的苯并类化合物。在理论计算领域,争论主要表现在计算方法上,集中在如何将作用能分解成π和σ两部分。随着论战的发展,作用能分解法在有机化学中的应用不断地发展和完善,Huckel理论在有机化学中的绝对权威也受到了挑战。为此,简要地介绍了能量分解法的发展史,对kollma法的合理性提出了质疑。此外特别介绍了我们新的能量分解法,及在共轭效应和芳香性的研究中的新观点和新的思维模式。     

Electronic structures of carbazole and its derivatives: A semi-empirical study on the substitution effects of carbazole

The electronic structures of carbazole, N-phenylcarbazole (NPC), cyanophenylcarbazole (CPC) and N-ethylcarbazole (NEC) have been calculated using the quantum chemical semi-empirical MINDO/3 method. In this paper, electronic ground states and first singlet excited states of the systems mentioned were investigated. It is observed that the excitation energy of carbazole based on the calculated difference in heats of formation agrees quite well with experimental data obtained from supersonic expansion studies. Calculated energy levels of molecular orbitals and their graphical forms are used qualitatively in elucidating the S₀ → S₁ excitation electronic origin red shifts observed in carbazole derivatives with respect to the electronic origin of the parent carbazole. It is noted that the red shifts are not just a result of the destabilization of the HOMO of carbazole but are also determined by the nature of the substituting moieties. It is also observed that the LUMO of CPC is not derived from the parent carbazole which partially explains the difference in electronic behaviour as compared with the other derivatives.     

Photoelectron spectroscopy study of the triphenyl derivatives of the group IV elements

The photoelectron He(I) spectra of several phenyl derivatives of the Group IV elements are reported, and the first few bands are assigned to the corresponding MO's. A sizable interaction among the π orbitals of the rings has been found for the carbon derivatives HCPh₃, HC(mesityl)₃ and H₂CPh₂, but not for the Si, Ge and Sn triphenyl derivatives. The exceptional behaviour of the carbon compounds has been attributed to the short central atom—ring distance, by analogy with findings for the Group V triphenyl derivatives.The charge transfer from the rings towards the Si atom is substantially reduced compared with that in H₃SiPh.