C78n离子的Jahn-Teller畸变和电子光谱

用INDO系列方法对C78n(D3、D3h、D?h)进行系统研究,表明C78(D3)比C78(D3h、D?h)稳定,与理论计算及实验结果一致;且随n绝对值增大,C78n总能量升高;C78n(D3、D3h、D?h)异构体的部分离子发生了Jahn-Teller畸变.以优化构型为基础,用INDO/SCI方法首次计算了C78n的电子光谱,对电子跃迁进行理论指认,讨论C78n光谱的特征吸收与C78相比发生红移的原因.     

New parametrization scheme for the resonance integrals (Hμν) within the INDO/1 approximation. Main group elements

Among the currently available semiempirical methods, there is still no model equally good for both geometries and spectroscopy. We describe our recent attempt to obtain a set of parameters using the semiempirical INDO/1 model Hamiltonian. We have modified the formula for resonance integrals according to a previous suggestion by Kolb and Thiel for MNDO, and developed a set of parameters for several elements belonging to the first and second rows of the periodic table. This suggested set has been implemented in the latest versions of the ZINDO code and already represents a considerable improvement (relative to Pople's original INDO/1 parametrization) in the calculated geometries. Furthermore, this improved method is shown to be at least competitive with the currently popular NDDO methods. In addition, the results of ionization potentials (calculated at the Koopmans' approximation) and transition energies show that the performance of the INDO/S technique in spectroscopy has been preserved. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 81: 187–201, 2001     

INDOStudiesonElectronicStructuresof（C＿8H＿8）Ln（2，4－C＿4H＿11）（THF）（Ln＝Nd，Sm，Er）

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中间体C60(CH3)-和产物C60(CH3)2的结构及产物

用INDO系列方法对C₆₀^2-与CH₃反应的中间体C₆₀(CH₃)^-进行理论研究,得到具有Cs对称性的构型。结果表明,CH₃加成到C₁₅上,将使与其相邻的双键碳(C₃₀)的电荷密度和自旋密度达极大值,故加成反应部位在C₃₀处;另外,C₁₅的对位C₁₂(或C₂₇)也较其它部位易于反应,且有两个反应场所,因而产物C₆₀(CH₃)₂可能为六元环上的1,2-加成和1,4-加成两种异构体的混合物。同时对两种加成产物的结构和电子光谱进行了理论研究,指认其电子跃迁,并讨论了其光谱红移的原因。     

Theoretical investigation of the heterofullerenes C59N and C69N and their dimers

The heterofullerenes C₅₉N and C₆₉N and their dimers are examined by the intermediate neglect of differential overlap (INDO/1 and INDO/S) models. The results confirm the stability of the (C₅₉N)₂ and (C₆₉)₂ (C_2h) isomers with a 6–6 closure fusion link between the two monomers. The nearest neighbor C of nitrogen, at the hexagon–hexagon fusion in C₅₉N and in C₆₉N where the N replaces one C in the pentagon of the fullerene has the largest electronic spin density, and this is where the two radicals of C₅₉N or C₆₉N link to form dimers. Also the dimers readily dissociate to free radical monomers to react regioselectively with other reagents. The electronic spectra of the radicals are similar to those of the dimers, which suggest essentially identical electronic structures. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 78: 422–436, 2000     

含1,3-二硫-2叶立德烯的系列有机发色团的二阶非线性光学性质的理论研究

设计了12个含有1,3-二硫-2叶立德烯的具有二阶非线性光学性质的有机发色团,对所研究分子用AM1方法进行几何构型优化,用INDO/CI方法获得基态到各激发态的垂直跃迁能和振子强度,即电子光谱;在此基础上用SOS公式计算系列分子的二阶非线性光学系数β_ijk,并从微观上对这一系列分子进行比较,为进一步探索综合性能较好的NLO有机物提供了理论指导.     

C77N+异构体的稳定性和电子光谱研究

All of the possible 21 isomers for C77N+, an isoelectronic molecule of C78, were investigated by the INDO methods based on C78(C2V). It indicates from optimization that the most stable isomer is that the nitrogen atom substitutes C(78) located at the C(78)-C(73) bond passed through by the Y shortest axis and the atoms near the Z longest axis are also easy to substitute, whereas the atoms near the X shortest axis are relatively difficult to substitute. At the same time, C78 was compressed a little and ready to perform the further reaction to form C77 NR at the location of substitution. Electronic spectra of C77N+ were calculated by INDO/SCI method and electronic transition was theoretically assigned. The red shift of absorption peaks for electronic spectra of C77N+ took place compared with that of C78(C2V) because of its narrower LUMO HOMO energy gap. There are great differences in characteristic absorptions among C77N+ isomers, which can be considered as evidence of the formation for each isomer.     

INDO Studies on the Electronic Structure of(2,4-C_7H_(11))_2Yb(DME)

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1π→1π* Ultraviolet Absorption Bands and Electronic Charge Transfers in Singlet Excited States of Sulfur Aromatic Heterocycles

Abstract

Indoline‐2‐thione (BC), benzimidazole‐2‐thione (BN), benzoxazole‐2‐thione (BO), and benzothiazole‐2‐thione (BS) define an interesting series of aromatic compounds containing a NCS synthonic unit in a heterocyclic ring of five centers, substituted by atomic centers of the type C, N, O, or S, where the main electronic absorption bands are localized in the spectral range of ultraviolet A or B.

The first two singlet electronic transitions of this series, ¹S₀→¹S₁(n,π*) and ¹S₀ → ¹S₂(π,π*), determine the main spectroscopic characteristic of these compounds in order to be used as potential photochemical actinometers of solar ultraviolet radiation. Furthermore, the second electronic transition, localized in the 270–360 nm ultraviolet spectral range, presents a hipsochromic spectral shift as function of the electronic nature of the heteroatomic centers in the heterocyclic ring.

In order to determine a spectroscopic assignment of the main absorption bands in aqueous solution and analyze the effect of the substituent on the electronic charge distributions in the ground and the first two singlet excited electronic states, we have used a semiempirical molecular orbital calculation in the INDO/S‐CIS approach. On the other hand, we have carried out a molecular orbital calculation in the AM1 framework, in order to determine the energetic stability of the thiones with respect to the thiol compounds.     

The spectroscopy, dynamics, and electronic structure of pyrenyl-dU nucleosides: P/dU charge transfer state photophysics

Various spectroscopies including UV-vis absorbance, emission, and emission quantum yield are combined with a variety of kinetics measurements including time resolved emission and nanosecond, picosecond, and femtosecond transient absorbance (TA) to systematize the P⁺/dU⁻ charge transfer (CT) state dynamics of a variety of pyrenyl-dU nucleoside conjugates in several solvents of varying polarity. These results are then analyzed further by means of electronic structure computations in vacuum and using two different solvent models. Finally, the excess electron dynamics of a number of DNA duplex structures substituted with two different pyrenyl-dU nucleosides and 5-XdU, where X=Br or F, electron traps are discussed in terms of achieving high yields of long-lived photoinduced CT products in DNA.