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运用密度泛函理论(DFT)方法对7-吡啶吲哚衍生物的结构及电子光谱性质进行了理论研究.在B3LYP/6-31G(d)水平上得到了7-吡啶吲哚(M)以及5种共轭衍生物(a-e)的几何构型、电子布局以及前线分子轨道;应用含时密度泛函理论(TD-DFT)在B3LYP/6-31+G(d)水平上计算了5种衍生物的电子光谱性质.结果表明,共轭体系的π键成分增大,能级差减小,激发能降低,分子的最大激发波长向长波方向移动,即发生红移.但是,如果分子中的空间位阻增大,则共轭程度降低,发生蓝移.前线分子轨道分析表明该类化合物吸收光谱主要对应分子中的HOMO→LUMO电子跃迁,且为π-π*跃迁.为新型含吲哚基团的光电功能材料的设计合成提供了理论参考. 相似文献
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采用ab initio 的HF和DFT的B3LYP方法, 对化合物鸢尾苷元和鸢尾苷基态结构进行优化, 分析了前线分子轨道特征和能级分布. 用含时密度泛函理论(TD-DFT)和半经验的ZINDO方法, 对鸢尾苷元和鸢尾苷的电子光谱进行了研究, 发现该物质主要吸收光谱源于分子内的π→π*的电子跃迁. 计算结果表明, 分子结构改变可影响化合物前线分子轨道分布和吸收光谱, 吸电子基使紫外光谱红移. 相似文献
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CH3和CN取代8-羟基喹啉电子光谱性质的含时密度泛函理论研究 总被引:2,自引:3,他引:2
对8-羟基喹啉QH及其代衍生物MQH和CNQH用密度泛函方法(DFT)在B3LYP/6-31G*水平上进行理论计算,探讨了供电子取代基(-CH3)和吸电子取代基(-CN)对分子电子结构,前线分子轨道能和光谱性质等的影响规律,在此基础上采用含时密度泛涵方法(TD-DFT)计算了电子光谱,计算结果表明,MQH,QH和CNQH的最低激发单重态都是A,激发能分别为3.58,3.72和3.74eV,在高激发态,无论是供电子基团(-CH3)还是拉电子基团(-CN),都导致取代衍生物的电子光谱红移。 相似文献
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聚苯撑醚砜缩聚过程的研究 总被引:1,自引:0,他引:1
本文报导了聚苯撑醚砜碱法缩聚动力学的研究。首先合成了有关的单体及二聚体的模拟化合物,然后进行了反应速率常数的测定。其结果是:(1)两组带有取代基的苯衍生物相互作用时,其反应速率常数等于不带取代基的苯衍生物和带取代基的反应速率常数以及取代基组成相反的另一组速率常数的乘积。(2)对于聚苯撑醚砜缩聚反应必须采用多个反应速率常数来计算动力学过程。 相似文献
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2,5-取代基-3,4-C60吡咯衍生物的电子光谱和非线性光学性质规律的理论研究 总被引:20,自引:2,他引:20
利用量子化学半经验AM1及ZINDO方法研究了2,5-取代基-3,4-C60吡咯衍生物的结构规律和光谱性质.以全自由度优化几何构型为基础,计算了化合物的电子光谱.几种化合物在400 nm以上均产生非C60特征吸收,结果与实验值一致,并对电子跃迁进行了指认,分析了光谱红移的原因.同时用INDO/CI-SOS方法计算了它们的二阶非线性光学系数,其βμ值在-30.14×10-30~-65.49×10-30 esu之间. 相似文献
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卤素取代基不对称变色酸双偶氮胂前线轨道能级和电子光谱 总被引:2,自引:0,他引:2
用HMO法研究卤素取代基不对称变色酸双偶氮胂类化合物Ⅱ电子分子轨道能级和电子光谱.最大吸收峰波长值和实验值相差约为8nm;亲电基取代位置和实验值完全一致.并讨论了电子光谱红移现象和亲电基的取代位置. 相似文献
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The structural and spectroscopic characteristics of the synthesized structurally novel compound 4-chloro-6-methylquinoline-2(1H)-one (4C6MQ) and its isomer 4-chloro-8-methylquinoline-2(1H)-one (4C8MQ) have been examined by means of experimental and computational quantum chemical methods like density functional theory (DFT). The crystal structure of the 4C6MQ compound has been brought to light by single-crystal x-ray diffraction (SCXRD) method which consists of two independent molecules (A and B) in the asymmetric unit with similar conformations. Both the isomer compounds are characterized spectroscopically by FTIR, FT-Raman, UV-Vis, and NMR spectrum and compared with DFT results. The geometries of the isomer compounds have been optimized by using DFT/B3LYP method with the 6-311G++(d,p) basis sets. From the optimized geometry of the compounds, geometric parameters (bond lengths, bond angles, and torsion angles); vibrational analysis; chemical shifts; and electronic absorption of the isomer compounds have been computed and compared with the experimental result. The detailed assignments of vibrational wave numbers have been prepared based on potential energy distribution (PED) which was carried out in the VEDA4 program. In addition, natural bonding orbital analysis, frontier molecular orbital, and molecular electrostatic potential have been explained theoretically. The in silico (absorption, distribution, metabolism, excretion and toxicity) studies were analyzed to identify the potential drug likeliness of the isomer compounds. The implications of the inhibitory activity of isomer compounds against DNA gyrase and lanosterol 14 α-demethylase enzyme by molecular docking are discussed. Further, the isomer compounds were screened for their antibacterial and antifungal activities. 相似文献
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S. A. Beyramabadi M. Javan-Khoshkholgh N. J. Ostad A. Gharib M. Ramezanzadeh M. Sadeghi A. Bazian A. Morsali 《Journal of Structural Chemistry》2018,59(6):1342-1352
Two Schiff bases are newly prepared by the condensation of 2-chloro-3-quinolinecarboxaldehyde with ethylenediamine and 1,4-butanediamine. The Schiff bases are characterized by the elemental analysis, IR, 1H and 13CNMR, UV-Vis, and fluorescence spectroscopies. Structural parameters together with the theoretical assignment of their vibrational frequencies and NMR chemical shifts are determined using density functional theory (DFT) approaches. There is good consistency between the DFT-calculated results and the experimental data, confirming the validity of the optimized geometries for the investigated Schiff bases. Optimized geometries of two Schiff bases are not planar, however, the substitutions are essentially in the same plane with the pyridine rings. Shapes of the frontier orbitals are determined using the natural bond orbital (NBO) analysis. Due to a high energy gap between the frontier orbitals, both Schiff bases are stable. Based on the Fukui function analysis, two Cl atoms and two azomethine nitrogen atoms are four suitable donor atoms for coordination to metal ions. Effects of the temperature and pH on the UV-Vis absorbance and fluorescence intensity of the Schiff bases are studied in a DMSO solution. 相似文献
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The conformation of numerous chemical compounds is strongly influenced by solvents. Knowledge of their structure in solution is necessary, especially for a discussion of the biological and pharmacological activity of the molecules. The neurotransmitters and their agonists and antagonists are known to be flexible molecules that interact with quite distinct receptors. The conformational properties of several GABA (γ-aminobutyric acid) mediators have been studied by the MNDO technique. The optimized geometries of the molecules have been used to study the solvent effects on their conformational properties considering the supermolecule approach for their first hydration shell. A conjectural pharmacophoric pattern for several GABA inhibitors has already been suggested from the molecular electrostatic potentials (MEP ) of several molecules using a localized bond orbital technique. In the present work, MEP calculations have been carried out considering a solvent effect on the MNDO optimized geometries to investigate any deviation from the earlier results. 相似文献
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M. Spoliti L. Bencivenni J. J. Quirante F. Ramondo 《Journal of Molecular Structure》1997,390(1-3):139-148
The molecular conformers of the molecule 1,3,5-benzenetriol have been studied by ab initio and density functional methods to determine optimized equilibrium geometries, harmonic vibrational frequencies and relative stability. The results of the quantum-chemical calculations have been used to investigate the functional theory-infrared (FT-IR) spectrum of the 1,3,5-benzenetriol vapors trapped in Ar matrix at 12 K. 相似文献
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ZHANG Ling XIAN Jing ZHANG Tao WANG Xiao-Lan CAI Wan-Fei ZHANG Hong LI Lai-Cai 《结构化学》2011,30(4):524-532
The optimized geometries and vibration frequencies of luteolin,methanol and luteolin-(CH3OH)n complexes have been investigated by density functional theory using B3LYP method.Four stable luteolin-CH3OH complexes,six stable luteolin-(CH3OH)2 complexes and four stable luteolin-(CH3OH)3 complexes have been obtained.The theories of atoms in molecules(AIM) and natural bond orbital(NBO) have been used to analyze the hydrogen bonds of these compounds,and their interaction energies corrected by basis set superposition error are between-8.046 and-76.124 kJ/mol.The calculation results indicate strong hydrogen bonding interactions in the luteolin-(CH3OH)n complexes.Then the nuclear magnetic resonance(NMR) and electronic absorption spectrum of luteolin have been calculated,and the results are in agreement with the experimental data. 相似文献
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N-乙基吩噻嗪及其自由基正离子的结构和电子光谱的理论研究 总被引:1,自引:0,他引:1
用INDO系列方法对N-乙基吩噻嗪及其自由基正离子进行了几何构型优化,得到中性分子为蝶状折叠形,自由基正离子为平面构型。以优化构型为基础计算其电荷密度、自旋密度、键序和电子光谱。对光谱进行理论指认并讨论了从中性分子到离子谱带红移的原因。理论计算结果均与实验结果一致。 相似文献
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The geometries, metal-ligand bond dissociation energies, and heats of formation of twenty sandwich and half-sandwich complexes of the main-group elements of Groups 1, 2, 13, and 14, and Zn have been calculated with quantum chemical methods. The geometries of the [E(Cp)] and [E(Cp)2] complexes were optimized using density functional theory at the BP86 level with valence basis sets, which have DZP and TZP quality. Improved energy values have been obtained by using coupled-cluster theory at the CCSD(T) level. The nature of the metal-ligand bonding has been analyzed with an energy-partitioning method. The results give quantitative information about the strength of the covalent and electrostatic interactions between En+ and (Cp-)n (n = 1, 2). The contributions of the orbitals with different symmetry to the covalent bonding are also given. 相似文献