8-羟基喹啉铍及其衍生物电子光谱性质的含时密度泛函理论研究

运用密度泛函理论(DFT)B3LYP方法和abinitioHF单激发组态相互作用(CIS)法分别优化了有机金属配合物8-羟基喹啉铍(BeQ₂)及其3种衍生物分子的基态及最低激发单重态几何结构.系统分析了分子结构、前线分子轨道特征和能级分布规律以探索电子跃迁机理.应用含时密度泛函理论(TD-DFT)计算分子的电子光谱,揭示了BeQ₂及其衍生物的发光源于配体中π→π^*电子跃迁,指出通过配体修饰可以有效地影响配合物前线分子轨道分布,调整发光波段,并有效提高电荷转移量.     

Theoretical design of a fluorescence sensor with configuration-transformed metal ion recognition of aza-18-crown-6

A novel configuration-transformed metal-ion-recognizing fluorescent molecular sensor was designed. The ground state geometries of the free ligand L(L₁, L₂)and their metal ion complex L/Mⁿ⁺ have been investigated theoretically by density functional theory (DFT). The interaction of L and a series of alkaline earth metal ions have been carried out by the natural bond orbital (NBO) and mayer bond order. The calculated results reveal that the metal ion Sr²⁺ has strong interaction with the free ligand L. The excited states, absorption spectra and fluorescence emission spectra of the free ligands L₁, L₂ and their complexes L/Mⁿ⁺ were performed by the time-density functional theory (TD-DFT). The UV-vis results show that the absorption peak of L₂/Sr²⁺ has an obvious change compared with that of L₂, which indicates that the free ligand L₂ can specifically identify the metal ion Sr²⁺. Furthermore, L₂/Sr²⁺ is superior fluorescent molecular sensor compared with other molecules.     

TD-DFT Studies on Electronic and Spectral Properties of Platinum(II) Complexes with Phenol and Pyridine Groups

The molecular structures of the ground and the lowest triplet states for a series of Pt(II) complexes PtLCl(1)[L=6-(2-hydroxyphenyl)-2,2′-bipyridine], Pt(pp)₂[pp=2-(2-hydroxyphenyl)pyridine](2), PtbpyCl₂(bpy=2,2′- bipyridine)(3), and the free tridentate L ligand(4) were optimized by the density functional theory B3LYP and UB3LYP methods, respectively. On the basis of optimized geometries, the spectral properties were investigated with time-dependent density functional theory(TD-DFT). In comparison with those of complexes 2 and 3, the more rigid structure of complex 1 together with its low rate of the radiationless decay via nonemissive d-d state leads to higher photoluminescence quantum efficiency. And the phosphorescence quantum efficiency of complex 1 can be easily controlled by modifying auxiliary ligands. The introduction of fluorine ligand into complexes can effectively increase the radiation transition rate and decrease the radiationless d-d transition rate, and as a result, a novel complex PtLF(5) might be a good phosphorescent material suitable for organic electronic devices.     

新型硫靛染料发色体吸收光谱的理论研究

靛族染料作为一类重要的还原染料,广泛应用于印染及食品等工业领域,同时在太阳能的贮存和利用、信息记录、液晶材料以及医药等方面也有重要应用前景[1-5]。前人的实验和理论研究表明,靛族染料的颜色源于其分子结构中的给电子-受电子基本发色体(参见图式1),给电子基团X(X=NH,O,S     

几个荧光蛋白发色团双光子吸收性质的理论研究

实验测得的荧光蛋白的单、双光子吸收光谱在低频和高频区域都表现出明显不同的特征。为了揭示这些不同点的起源和研究荧光蛋白的构–效关系,我们详细研究了三种荧光蛋白发色团(一种增强型蓝绿色荧光蛋白的中性发色团和两种红色荧光蛋白的阴离子发色团)的单、双光子吸收特性,分别计算了纯的和振动分辨的电子谱。计算结果表明：光谱线形与计算采用的交换相关密度泛函及谱截面计算所采用的近似关系密切;如果在计算光谱截面时,我们利用长程修正的交换相关泛函CAM-B3LYP来计算几何和电子结构参数,然后把Franck-Condon (FC)效应和包含Herzberg-Teller (HT)效果的电-声耦合效应都考虑进去,理论计算的光谱与实验测定的光谱可以很好地符合;对于两种离子态的发色团,HT电-声耦合效应使得对应于基态到第一激发态跃迁的双光子吸收最强峰相对于单光子吸收的最强峰发生了蓝移,但HT电-声耦合效应对高频的双光子吸收谱没有太大的影响;分子内电荷转移是导致高频区的双光子吸收明显强于单光子吸收的主要原因。     

Studies on Optical Properties of Si220 Nanoclusters via Time-dependent Density Functional Theory Calculations

The optical properties of bare and hydrogen passivated Si₂₂₀ nanoclusters(NCs) in four typical motifs(i.e., bulk-like, onion-like, bucky-diamond and icosahedral motifs) were studied via time-dependent density functional theory(TD-DFT) calculations. The calculation results show that there is a significant blue shift in the optical absorption spectra when the Si NCs are passivated with hydrogen. A strong absorption peak in the visible light region appears for the hydrogenated bulk-like, onion-like and bucky-diamond Si NCs.     

Accurate Control of Deuterated Locations and Amount of Deep Blue Ir(dfpypy)2pic for Phosphorescent Efficiency Enhancement: Evaluations from Theoretical Aspect

A well-known deep-blue emitting iridium(Ⅲ) complex was selected for deuterium isotope effect evaluation, both on deuterated locations and numbers, through theoretical investigation. It was revealed that the containment of the d site deuteriation of ancillary ligand picolinate enabled the non-radiative deactivation process to be repessed, and thereby improving the quantum efficiency through such a simple and controllable approach.     

三(4-硝基苯基)甲烷衍生物的结构和振动光谱的理论研究（英文）

用密度泛函理论优化了三苯甲烷(1)和一系列三(4-硝基苯基)甲烷衍生物2,3和4的几何结构,并计算了其红外光谱和拉曼光谱;通过与实验光谱的对比,对实验光谱中的谱峰进行了指认,并从理论上纠正了部分对3和4红外光谱谱峰不合适的实验指认;同时预测了2,3和4的拉曼光谱.结果表明,几种化合物的振动光谱计算结果与相应的实验结果吻合良好;且化合物2,3和4的拉曼光谱具有相似性.     

Theoretical studies on the spectroscopic properties and the substituent effects of pyridyl triazole Os(II) complexes

To explore the spectroscopic properties of pyridyl triazole Os(II) complexes and how the substituent effects affect the spectroscopic properties of [Os(ptz)₂L₂] (L=PH₃; ptzH=(2-pyridyl)-1,2,4-triazole) (1), [Os(bptz)₂L₂] (bptzH=3-tert-butyl-5-(2-pyridyl)-1,2,4-triazole) (2), [Os(fptz)₂L₂] (fptzH=3-(trifluoreomethyl)-5-(2-pyridyl)-1,2,4-triazole) (3), and [Os(fbtz)₂L₂] (fbtzH=3-(trifluoreomethyl)-5-(4-tert-butyl- 2-pyridyl)-1,2, 4-triazole) (4), the density functional theory (DFT) method at the B3LYP level was used to optimize the geometrical structures in the ground and excited state. The absorption and emission properties of the dichloromethane solution were predicted at the time-dependent density functional theory (TD-DFT, B3LYP) level associated with the PCM solvent effect model, the transitions characters of them were assigned. Important correlations between substituent effects and emission spectra and the quantum yield have been obtained by comparing and analyzing the calculated results.     

线型和星型平面噻吩类低聚物衍生物分子结构及光电性质研究

运用密度泛函DFT B3LYP／6-31G(d)方法对线型(a)和星型(b)平面噻吩类低聚物衍生物分别进行了几何构型优化,并采用含时密度泛函TD-DFT B3LYP／6-31G(d)方法计算了其紫外吸收光谱．计算结果表明:用TD-DFT．方法计算体系的紫外吸收光谱值与实验数据吻合;通过对噻吩类低聚物衍生物分子几何结构和前线分子轨道能级的分析,并从理论上解释了线型(a)和星型(b)衍生物光谱性质的差异:后者与前者相比较吸收光谱发生红移,这是由于星型结构使其相应HOMO能级升高,电离能(IP)降低,成为很好的电子给体和空穴传输材料．     

[M(N)X2]-(M=Ru, Os; X=S2C6H4, mnt)的电子结构和光谱性质的理论研究

利用密度泛函理论(DFT)中的B3LYP方法优化了氮化钌和氮化锇配合物[M(N)X2]-[M=Ru, Os; X=S2C6H4, mnt(maleonitriledithiolate)]的基态几何结构, 得到的几何参数与实验结果吻合得很好. 采用TD-DFT方法, 得到了配合物在CH3CN溶液中的激发态电子结构和电子吸收光谱. 利用SCRF方法中的CPCM模型来模拟溶剂化效应. 研究结果表明, 配合物1~4在CH3CN溶液中的吸收跃迁性质相似, 低能吸收均被指认为LMCT和LLCT的混合跃迁, 高能吸收均被指认为ILCT/LLCT跃迁.     

TD-DFT Study on Pyrazoline Derivatives

1 INTRODUCTION Pyrazoline compounds have been widely used in industry due to their good photoconductivity and high fluorescence quantum productivity[1]. In recent years, pyrazoline derivatives with high vitrification temperature Tg have been found to act as hole trans- fer materials in the electroluminescence device, which has captured the intensive interest of che- mists[2]. But so far, the electron transfer mechanism of these compounds is still unclear[3~7]. Some resear- ches have attr…     

1, 2-二硒方酸气相酸性和芳香性的理论研究

在RHF/6-311G^*^*水平优化得到1,2-二硒方酸(3,4-二羟基-3-环丁烯-1,2-二硒酮)三种平面构象异构体的平衡几何构型。进一步用MP2(full)/6-311G^*//RHF/6-311G^*^*方法计算三种异构体的单点能量,发现ZZ型异构体是能量最低构象,且ZZ和ZE型能量非常接近。用优化的最稳定构象ZZ型异构体在RHF/6-311G^*^*//RHF/6-311G^*^*,RHF/6-311+G^*^*//RHF/6-311+G^*^*,MP2(full)/6-311+G^*^*//RHF/6-311+G^*^*和B3LYP/6-311+G^*^*//B3LYP/6-311+G^*^*水平计算其气相酸性[ΔGⅲ~(~2~9~8~K~)]和同键反应芳香性稳定化能(HASE)。用基团加和法(groupincrementapproach)在RHF/6-311+G^*^*//RHF/6-311+G^*^*和B3LYP/6-311+G^*^*//B3LYP/6-311+G^*^*水平计算其磁化率增量(Λ)。计算结果指出标题化合物的键长发生了平均化,同键反应芳香性稳定化能和磁化率增量均为负值,表明它具有芳香性,实现了标题化合物芳香性的几何、能量和磁性的判定。     

氮混杂金属卟啉吸收光谱性质的理论研究

采用密度泛函理论在B3LYP/6-31+G(d)水平上研究了4种金属Mg, Ni, Cu, Zn配位的自由卟啉(FBP)及氮混杂卟啉(NECP)的几何结构及分子轨道能级. 采用含时密度泛函理论(TD-DFT)方法计算了金属与2种卟啉配位后在气体条件下的电子吸收光谱, 包括激发能、 吸收波长、 跃迁组成和振子强度.计算结果表明, 与金属配位的FBP(M-FBP)具有D_4h对称性, 分子轨道能级HOMO/HOMO-1和LUMO/LUMO+1因能级相近发生简并, HOMO-LUMO轨道能级差大约3.0 eV, 在Soret带出现较强吸收峰.由于C/N原子位置的改变, 非对称性结构的M-NECP前线轨道组成发生改变, 轨道能级差(HOMO-LUMO)减小至2.6 eV左右, 且能级发生分裂, Soret带出现多个电子吸收谱峰, Q带也出现吸收峰. 本文研究了水、 氯仿和苯3种不同极性溶剂对M-FBP和M-NECP的分子轨道及电子吸收光谱的影响, 结果表明, 随溶剂极性减弱金属配合物的电子吸收光谱发生红移, 并且吸收峰强度增强.     

双咔唑间连接方式不同引起的结构和性质变化的理论研究

利用密度泛函方法(DFT)和单激发组态相互作用(CIS)方法, 在6-31G(d,p) 基组水平下优化了咔唑分子和14种双咔唑结构异构体的基态和激发态结构, 在此基础上, 用含时密度泛函(TD-DFT)方法在相同基组水平下计算了模型分子的吸收和发射波长及电荷跃迁性质. 讨论了双咔唑构型的变化带来的性质上的变化, 与实验值相比得到了精确的计算结果. 通过双咔唑的前线轨道能量值、电离能和亲和势及重组能的变化, 全面研究了不同构型的应用, 为实验上的设计和合成提供了思路.     

A Series of Pure Orange-yellow Iridium Complexes with Low Efficiency Roll-off: a Computational Study

The electronic structures and spectroscopic properties of heteroleptic cyclometalated iridium(III) complexes were investigated. The geometries, electronic structures, and the lowest-lying excited states of (DBQ)₂Ir(acac) and (MDQ)₂Ir(acac) were investigated via density functional theory-based approaches. A series of designed models of (DBQ)₂Ir(dpis), (DBQ)₂Ir(tpip), (MDQ)₂Ir(dpis) and (MDQ)₂Ir(tpip) was also calculated for comparison. The structures in the ground and excited states were optimized via B3LYP method. The lowest absorptions and emissions spectra were evaluated via TD-B3LYP and TD-PBE1PBE methods. The computational results reveal that the emission peaks of the designed complexes are at around 585-640 nm, which belong to the orange-yellow wavelength. The frontier molecular orbital properties indicate that the Ir(III) complexes have low efficiency roll-off.     

Theoretical studies on high energetic density nitramine explosives containing pyridine

The insensitive property of explosives containing pyridine is combined with the high energy of nitramine explosives,and the concept of new nitramine explosives containing pyridine is proposed,into which nitramine group with N N bonds is introduced as much as possible.Based on molecular structures of nitramine compounds containing pyridine,density functional theory(DFT) calculation method was applied to study designed molecules at B3LYP/6-31+G(d) level.The geometric and electronic structures,density,heats of formation(HOF),detonation performance and bond dissociation energies(BDE) were investigated and comparable to 1,3,5-trinitro-1,3,5-triazinane(RDX) and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX).The simulation results reveal that molecules B and D perform similarly to traditionally used RDX.Molecule E outperform RDX,with performance that approach that of HMX and may be considered as potential candidate of high energy density compound(HEDC).These results provide basic information for molecular design of novel high energetic density compounds.     

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．     

Application of TD-DFT Theory to Studying Porphyrinoid-Based Photosensitizers for Photodynamic Therapy: A Review

An important focus for innovation in photodynamic therapy (PDT) is theoretical investigations. They employ mostly methods based on Time-Dependent Density Functional Theory (TD-DFT) to study the photochemical properties of photosensitizers. In the current article we review the existing state-of-the-art TD-DFT methods (and beyond) which are employed to study the properties of porphyrinoid-based systems. The review is organized in such a way that each paragraph is devoted to a separate aspect of the PDT mechanism, e.g., correct prediction of the absorption spectra, determination of the singlet–triplet intersystem crossing, and interaction with molecular oxygen. Aspects of the calculation schemes are discussed, such as the choice of the most suitable functional and inclusion of a solvent. Finally, quantitative structure–activity relationship (QSAR) methods used to explore the photochemistry of porphyrinoid-based systems are discussed.     

阿魏酸分子结构和振动光谱的理论研究

阿魏酸是一种有效的天然油脂抗氧化剂.采用密度泛函理论(DFT) B3LYP方法和从头算HF两种方法,在6-311++G**基组水平上对阿魏酸分子的几何结构进行全优化,得到其几何结构参数,进一步计算得到阿魏酸的红外和拉曼振动光谱.计算结果表明,采用B3LYP和HF 2种方法优化得到的几何结构及频率值是一致的,对在B3LYP方法下计算得到的红外和拉曼振动频率进行合理的理论归属并与SDBS数据库实验数据进行比较,发现计算得到的红外和拉曼振动频率与实验测定结果符合较好.阿魏酸分子结构和振动光谱的研究,为研究阿魏酸及其衍生物的化学结构与生理活性之间的构效关系提供依据.