共查询到17条相似文献,搜索用时 187 毫秒
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运用量子化学中的密度泛函和含时密度泛函理论法,计算了四种加共轭环的脱氢苯[15]轮烯衍生物的几何构型、电子结构、前线分子轨道和电子光谱性质。计算结果表明当脱氢苯[15]轮烯分子(M)被杂环取代或增加分子的共轭性,对轮烯的键长和键角等结构参数的影响不大,这与轮烯具有较强的共轭性有关。当母体中的苯环被嘧啶环取代时,最大吸收波长蓝移;当母体中的苯环被萘取代时,最大吸收波长与母体中的苯被吡嗪取代时的最大吸收波长相近。 相似文献
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运用量子化学中的密度泛函和含时密度泛函理论法,计算了苯[15]轮烯分子1号位被CH3、NH2、OH、Cl、CN和NO2取代后的衍生物几何构型、电子结构、前线分子轨道和电子光谱性质。计算结果表明取代基性质的改变,对苯[15]轮烯的键长和键角等结构参数的影响不大,这与轮烯具有较强的共轭性有关。在1号位取代时,NO2取代物的最大吸收波长红移最多。主要是因为对LUMO轨道而言,硝基取代物的LUMO轨道电子云在硝基附近分布较多。 相似文献
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本文运用量子化学中的密度泛函理论在B3LYP/6-31+G(d)水平下首先对含N杂环的四种化合物嘧啶、咪唑、吡唑和吡咯的电子几何结构、振动分析和化合物的分子能量进行的理论计算,根据振动分析结果显示均能稳定存在,后对稳定存在的结构利用含时密度泛函理论在B3LYP/6-31+G(d)水平下对嘧啶、咪唑、吡唑和吡咯的分子最大吸收光谱和前线分子轨道进行了理论数值比较研究,研究发现四种含N杂环芳香化合物中吡咯的最大吸收波长对应的跃迁为HOMO-1→LUMO跃迁,嘧啶、咪唑和吡唑的最大吸收波长均为HOMO→LUMO跃迁,所有化合物最大吸收波长对应的轨道跃迁均为π→π*。 相似文献
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烈性炸药的探测是一项重要的研究课题,基于金属有机骨架化合物(MOFs)的荧光探针近年来受到研究者的广泛关注。本文采用密度泛函理论(DFT)和含时密度泛函理论(TDDFT)研究了金属有机骨架化合物[Zn(sfdb)(bpy)(H2O)]n的发光机理及其与硝基苯分子之间的氢键相互作用。运用TDDFT方法探究氢键在激发态下的行为,结果表明分子间氢键在激发态下增强,促进分子间电荷转移,导致荧光淬灭。这项研究工作表明分子间氢键对于荧光过程具有重要影响,这为设计合成探测炸药分子的MOFs荧光探针提供了新的思路。 相似文献
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捅姜:采用密度泛函方法从理论上研究了一类[Os(PH3):(CN):(N^N)][N^N=bpy(1);N^N=phbpy(2);bpy=2,2’-联吡啶;phbpy=4,4-双苯基-2,2'-联吡啶]配合物的几何结构和光谱性质。采用含时密度泛函方法中的PBE0泛函,得到两个配合物的最低能单态吸收和磷光发射分别在471(1)、487(2)nm和619(1)、661(2)nm。1和2的高能占据分子轨道主要由金属Os和cN配体占据,而低能非占据分子轨道主要受N“N配体成份控制,因此1和2的最低能吸收被指认为MLCT跃迁,并混有少量的LLCT微扰,且其强度最大的高能吸收表现为配体(联吡啶)内部的电荷转移跃迁。计算结果表明,CN和联吡啶配体在跃迁过程中担当两个独立的发色团。与分子1相比,由于2在联吡啶配体上增加了盯共轭效应,导致其吸收和发射产生红移。 相似文献
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采用密度泛函方法,在PBE/DZP水平上,通过与化合物C4R4、Si4[SiR3]4比较,对标题化合物的异常分子结构进行了理论研究,并计算了分子的核排斥能(PBE/6-31g**)、静电势(PBE/6-31g**)、结合能(PBE/TZP),对关键键能进行了能量分解(PBE/TZP)。计算结果表明静电吸引作用和轨道作用是B4R4,Al4[SiR3]4和Ga4[SiR3]4分子存在异常分子结构主要原因。 相似文献
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采用密度泛函理论的B3LYP方法在6-311+G(d,p)基组上,对河豚毒素(TXX)进行了理论计算,得到了它的分子构型、热力学函数、偶极矩、脂水分配系数、红外光谱、核磁共振光谱、福井函数和前线轨道等信息,并对分子的IR谱和1HNMR谱进行了指认。模拟结果表明,TTX为一热力学非常稳定的弱极性且疏水性分子;福井函数和前线轨道计算表明,胍基N和H原子很可能是其发挥药理活性的亲电和亲核反应中心。 相似文献
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MP2 method and different functionals such as M06-HF, M06-2X, CAM-B3 LYP, PBE0, B3 LYP and M06 L incorporating different XC amounts were used to calculate the static first hyperpolarizabilies β(0) of eight molecules which are derivatives of benzene, stilbene and diphenylacetylene. The values were then compared to the experimental ones. The M06-2X functional was then selected for further calculations. NBO calculations were also performed to define the intramolecular charge transfer in each molecule. TD-DFT calculations were performed taking into account the solvent effect using the IEF-PCM formalism. Some parameters characterizing the vertical transitions such as the wavelength of the maximum absorption λ_(max) were compared to the experimental ones. Finally,solvation Gibbs free enthalpy ΔG_(solv) values have also been examined in order to determine which the specific solvent for a given molecule is. 相似文献
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2-aminothiophenol and 4-methoxybenzaldehyde were cyclized under microwave irridation and solvent free conditions to synthesize 2-(4-methoxyphenyl)benzo[d]thiazole. The molecular structure and vibrational frequencies of the title compound in the ground state have been investigated with ab initio (HF) and density functional theory methods (BLYP, B3LYP, B3PW91 and mPW1PW91) implementing the standard 6–311G(d,p) basis set. Comparison of the observed fundamental vibrational frequencies of title compound and calculated results by HF and DFT methods indicate that B3LYP is superior to the scaled HF approach for molecular problems. 相似文献
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Experimental and Theoretical Study of O-Substituent Effect on the Fluorescence of 8-Hydroxyquinoline
Mohie E. M. Zayed Reda M. El-Shishtawy Shaaban A. Elroby Abdullah Y. Obaid Zahra M. Al-amshany 《International journal of molecular sciences》2015,16(2):3804-3819
The synthesis and characterization of different ether and ester derivatives of 8-hydroxyquinoline have been made. UV-visible and fluorescence spectra of these compounds have revealed spectral dependence on both solvent and O-substituent. The fluorescence intensity of ether derivatives revealed higher intensity for 8-octyloxyquinoline compared with 8-methoxyquinoline, whereas those of ester derivatives had less fluorescence than 8-hydroxyquinoline. Theoretical calculations based on Time-dependent density functional theory (TD-DFT) were carried out for the quinolin-8-yl benzoate(8-OateQ) compound to understand the effect of O-substituent on the electronic absorption of 8-hydroxyquinaline (8-HQ). The calculations revealed comparable results with those obtained from the experimental data. Optimized geometrical structure was calculated with DFT at B3LYP/6-311++G** level of theory. The results indicated that 8-OateQ is not a coplanar structure. The absorption spectra of the compound were computed in gas-phase and solvent using B3LYP and CAM-B3LYP methods with 6-311++G ** basis set. The agreement between calculated and experimental wavelengths was very good at CAM-B3LYP/6-311++G** level of theory. 相似文献
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文章使用DFT法,利用GaussView画图,用Gaussian软件包在b3lyp/6-31G机组下对6种苦参黄酮进行优化计算。从计算结果可推断:8位香叶基或异戊烯基取代,及C2,C3双键、C3羟基是增强黄酮类化合物抗氧化活性的有效部位。 相似文献
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