Density functional theory and time‐dependent density functional theory study on a series of iridium complexes with tetraphenylimidodiphosphinate ligand

A series of heteroleptic cyclometalated Ir(III) complexes for organic light‐emitting diodes (OLEDs) application have been investigated theoretically to explore their electronic structures and spectroscopic properties. The geometries, the electronic structures, the lowest‐lying singlet absorptions and triplet emissions of Ir(dfppy)₂(tpip), Ir(tfmppy)₂(tpip), and theoretically designed models of Ir(ppy)₂(tpip) were investigated with the density functional theory (DFT)‐based approaches, where ppy = 2‐phenylpyridine, dfppy = 4,6‐difluorophenylpyridine, tfmppy = 4‐trifluoromethylphenylpyridine, and tpip = tetraphenylimidodiphosphinate. Their structures in the ground and their excited states have been optimized at the DFT/Becke 3‐parameter Lee Yang Parr (B3LYP)/Los Alamos National Laboratory 2‐double‐z (LANL2DZ) and time‐dependent DFT/B3LYP/LANL2DZ levels, and the lowest absorptions and emissions were evaluated at B3LYP and M062X level of theory, respectively. Furthermore, the energy transfer mechanism together with the advantage of low efficiency roll‐off for these complexes also can be analyzed here. Copyright © 2013 John Wiley & Sons, Ltd.     

骨显像放射性药物锝-双膦酸盐配合物99mTc-MDP的结构

运用密度泛函理论方法对锝标记双膦酸盐配合物^99mTc-MDP进行了结构预测和计算, 其中MDP代表亚甲基双膦酸. 根据几何异构、构象异构、电荷异构和自旋态异构等特性预测该化合物共有14种异构体. 基于B3LYP/LANL2DZ水平优化的分子结构和计算的总能量,确定了两种稳定异构体,并与实验结构进行了比较. 运用B3LYP/6-31G*(LANL2DZ用于Tc, cc-pVDZ-pp用于Tc)和B3LYP/DGDZVP方法对化合物的稳定结构进行了计算. 理论计算值与实验值吻合较好,而基     

DFT study of the effect of different metals on structures and electronic spectra of some organic-metal compounds as sensitizing dyes

Ruthenium polypyridined-derivative complexes are used in dye-sensitized solar cell [DSSC] as a light to current conversion sensitizer. In order to lower the cost of the DSSC the normal transition metals were used to replace the noble metal ruthenium, and some compounds [ML₂L′] (M = Pt, Fe, Ni, Zn; L = isonicotinic acid, L′ = maleonitriledithiolate, I = PtL₂L′, II = FeL₂L′, III = NiL₂L′, IV = ZnL₂L′) were selected as the replacement. The geometries, electronic structures and optical absorption spectra of these compounds have been studied by using density functional theory (DFT) calculation at the B3LYP/LANL2DZ, B3P86/LANL2DZ, B3LYP/GEN level of theory. All the geometric parameters are close to the experimental values. The HOMOs are mainly on the maleonitriledithiolate groups mixed with fewer characters of the metal atom, the LUMOs are mainly on the two pyridine ligands. This means that the electron transition is attributed to the LLCT. The maximum absorptions of complexes are found to be at 351 nm, 806 nm for compound I, and 542 nm for compound II. The maximum absorptions of complexes are found to be at 884 nm for compound III, and 560 nm for compound IV. This means that those compounds may be as a suitable sensitizer for solar energy conversion applications.     

铱催化甲醇羰基化制乙酸循环反应的理论探究

采用密度泛函理论DFT-B3LYP方法,对铱、碘元素采用相对论校正赝势基组SDD,对C、O、H采用6-311+G(2d,p)基组,优化了各反应物、中间体和过渡态的构型特征,通过能量和振动分析证实了过渡态的真实性.理论研究了阴离子循环中铱催化甲醇羰基化制乙酸的循环反应机理.运用能量跨度模型获得了反应的动力学信息,确定了各反应的决速中间体和决速过渡态和各催化剂的能量跨度和转化频率.通过对cis-[Ir(CO)_2I_2]~-和trans-[Ir(CO)_2I_2]~-催化剂电荷密度的分析比较,得到中心金属的富电子性提高了其催化能力,以上计算结论与文献假设相符.     

铱催化甲醇羰基化制乙酸循环反应的理论探究

采用密度泛函理论DFT-B3LYP方法, 对铱、碘元素采用相对论校正赝势基组SDD, 对C、O、H采用6-311+G(2d, p)基组, 优化了各反应物、中间体和过渡态的构型特征, 通过能量和振动分析证实了过渡态的真实性. 理论研究了阴离子循环中铱催化甲醇羰基化制乙酸的循环反应机理. 运用能量跨度模型获得了反应的动力学信息, 确定了各反应的决速中间体和决速过渡态和各催化剂的能量跨度和转化频率. 通过对cis-[Ir(CO)2I2]- 和 trans-[Ir(CO)2I2]-催化剂电荷密度的分析比较, 得到中心金属的富电子性提高了其催化能力, 以上计算结论与文献假设相符.     

取代基对8-羟基喹啉金属配合物电子光谱和二阶非线性光学性质的影响

在B3LYP/LANL2DZ/6-31G^*水平上优化目标化合物分子的几何结构,并分别在TD- B3LYP/LANL2DZ/6-31++G^**和B3LYP/LANL2DZ/6-31++G^**水平计算目标化合物分子的电子吸收光谱和二阶非线性光学性质.计算结果表明,引入共轭给电子基使配合物分子的最大吸收波长红移,强共轭吸电子基的引入使配合物的最大吸收波长蓝移,取代基的引入使IrQ₃型配合物的二阶非线性光学性质明显增大.对AgQ型配合物,电子跃迁属于配体内部的电荷转移（LLCT）.对PtQ₂和IrQ₃型配合物,电子跃迁属于LLCT和部分金属向配体的电荷转移.取代基对AgQ,PtQ₂,IrQ₃型配合物分子的跃迁性质几乎无影响. 关键词： 8-羟基喹啉金属配合物 电子光谱 二阶非线性光学性质 密度泛函理论     

Understanding the absorption and emission spectra of borondipyrromethene dye and its substituted analogues

Borondipyrromethene (BODIPY) dye possesses a bright and long wavelength emitting fluorescent character with a wide spectral range from visible to near infrared region. In the present work, the spectral properties of BODIPY dyes were analyzed using ab intio and density functional theory methods. The ground and excited state geometries of BODIPY and its substituted analogues in chloroform medium, were optimized using the density functional theory (DFT) and singly excited configuration interaction (CIS) methods. Based on the ground and excited state geometries, the absorption and emission spectra have been calculated using time-dependent density functional theory (TDDFT) method. The TDDFT calculations have been performed using hybrid exchange correlation functionals B3LYP and M06-HF and long-range separated functionals LC-BLYP, LC-BOP, LC-PBE, LC-PBE0 and CAM-B3LYP. The solvent phase calculations were carried out using polarizable continuum model (PCM). The TDDFT investigation reveals that the substitution of acceptor, donor–donor, donor–acceptor–donor and phenyl group in BODIPY dye influence the absorption and emission spectra significantly.     

Density functional theory study of MgnNi2 （n=1-6） clusters

The geometries of Mg n Ni 2(n = 1-6) clusters are studied by using the hybrid density functional theory(B3LYP) with LANL2DZ basis sets.For the ground-state structures of Mg n Ni 2 clusters,the stabilities and the electronic properties are investigated.The results show that the groundstate structures and symmetries of Mg clusters change greatly due to the Ni atoms.The average binding energies have a growing tendency while the energy gaps have a declining tendency.In addition,the ionization energies exhibit an odd-even oscillation feature.We also conclude that n = 3,5 are the magic numbers of the Mg n Ni 2 clusters.The Mg 3 Ni 2 and Mg 5 Ni 2 clusters are more stable than neighbouring clusters,and the Mg 4 Ni 2 cluster exhibits a higher chemical activity.     

Zn2+-Schiff’s Base Complex as an “On–Off-On” Molecular Switch and a Fluorescence Probe for Cu2+ and Ag+ Ions

The present study presents a thorough theoretical analysis of the electronic structure and conformational preference of Schiff’s base ligand N,N-bis(2-hydroxybenzilidene)-2,4,6-trimethyl benzene-1,3-diamine (H₂L) and its metal complexes with Zn²⁺, Cu²⁺ and Ag⁺ ions. This study aims to investigate the behavior of H₂L and the binuclear Zn²⁺ complex (1) as fluorescent probes for the detection of metal ions (Zn²⁺, Cu²⁺ and Ag⁺) using density functional theory (DFT) and time-dependent density functional theory (TDDFT). The six conformers of the H₂L ligand were optimized using the B3LYP/6–311?+??+?G** level of theory, while the L^?2-metal complexes were optimized by applying the B3LYP functional with the LANL2DZ/6–311?+??+?G** mixed basis set. The gas-phase and solvated Enol-cis isomer (E-cis) was found to be the most stable species. The absorption spectra of the E-cis isomer and its metal complexes were simulated using B3LYP, CAM-B3LYP, M06-2X and ωB97X functionals with a 6–311?+??+?G** basis set for C, O, N and H atoms and a LANL2DZ basis set for the metal ions (Zn²⁺, Cu²⁺ and Ag⁺). The computational results of the B3LYP functional were in excellent agreement with the experimental results. Hence, it was adopted for performing the emission calculations. The results indicated that metal complex (1) can act as a fluorescent chemosensor for the detection of Ag⁺ and Cu²⁺ ions through the mechanism of intermolecular charge transfer (ICT) and as a molecular switch “On–Off-On” via the replacement of Cu²⁺ by Ag⁺ ions, as proved experimentally.

     

WmCn(m+n≤7)团簇的几何结构与稳定性

利用密度泛函理论(DFT)中的杂化密度泛函B3LYP方法在LANL2DZ基组水平上对W_mC_n(m+n≤7)团簇进行几何构型全优化,得出它们的基态结构,并计算基态结构的平均结合能、二阶能量差分、能隙及键级.结果表明:随着W原子个数的增加,团簇的结构由线性转变为平面,再转变为立体结构,其中自旋多重度未超过5;C原子的掺杂增强团簇的稳定性;分析团簇Wiberg键级可知,团簇中W-C键级明显大于W-W和C-C键级,表明W_mC_n(m+n≤7)团簇最容易形成W-C键.     

密度泛函理论对ZrnPd团簇结构和性质的研究

用B3LYP/LANL2DZ方法对Zr_nPd(n =1—13)团簇的平衡几何结构、能量、频率、电子性质和磁性进行了计算.研究表明,Pd原子位于表面的异构体更为稳定,其中Zr₇Pd,Zr₁₂Pd团簇稳定性高,是幻数团簇,此外,相对于Zr_nCo与Zr_nFe团簇,Zr_nPd团簇参与化学反应的能力较弱,化学稳定性更     

中性循环中铱催化甲醇羰基化合成乙酸的理论研究

采用密度泛函理论研究了中性循环中Ir(CO)_3I催化甲醇羰基化制乙酸的反应机理,计算得到了反应路径上各驻点的几何构型与频率,通过能量和振动分析证实了过渡态的真实性.结果表明,Ir(CO)_2I与CH_3I作用后,亲核加成过程出现反应路径中最大能垒(40. 3 kJ/mol),使用能量跨度模型分析了反应过程的动力学信息,确定了反应的能量跨度和决速中间体和决速过渡态分别为IM1和TS12,亲核加成过程为反应的决速步骤,得到了298 K催化剂的转化频率3. 2×10~(-6)s~(-1).     

Modeling excitation properties of iridium complexes

Five iridium Ir(III) complexes have been studied using B3P86, B3LYP, M05, M06, M05‐2X, and M06‐2X functionals within configuration interaction singles (CIS) and time dependent density functional theory (TDDFT) formalisms with the aim of finding theory level that would allow for reliable prediction of emission properties. Knowledge of these properties prior to synthesis may significantly facilitate rational design of organic light‐emitting diodes (OLEDs). Our results indicate that the M05‐2X functional gives excellent results in this respect for the class of complexes studied here with the exception of the (bsn)₂Ir(acac) complex. We have shown that the discrepancy between the theoretical and experimental values for this complex is due to the presence of the sulfur atom. Copyright © 2009 John Wiley & Sons, Ltd.     

DFT/TDDFT investigation on the photophysical properties of a series of phosphorescent cyclometalated complexes based on the benchmark complex FIrpic

The photophysical properties of four Ir(III) complexes have been investigated by means of the density functional theory/time-dependent density functional theory (DFT/TDDFT). The effect of the electron-withdrawing and electron-donating substituents on charge injection, transport, absorption and phosphorescent properties has been studied. The theoretical calculation shows that the lowest-lying singlet absorptions for complexes 1–4 are located at 387, 385, 418 and 386 nm, respectively. For 1–4, the phosphorescence at 465, 485, 494 and 478 nm is mainly attributed to the LUMO → HOMO and LUMO → HOMO-1 transition configurations characteristics. In addition, ionisation potential (IP), electron affinities (EAs) and reorganisation energy have been investigated to evaluate the charge transfer and balance properties between hole and electron. The balance of the reorganisation energies for complex 3 is better than others. The difference between hole transport and electron transport for complex 3 is the smallest among these complexes, which is beneficial to achieve the hole and electron transfer balance in emitting layer.     

Quantum chemical study of a new class of sensitisers: influence of the substitution of aromatic rings on the properties of copper complexes

We present a computational study of new copper complexes with potential applications as sensitisers for solar cells. The applied methodology for this study is based on the density functional theory (DFT) and time-dependent DFT, using the B3LYP, PBE0 and M06 functionals with the LANL2DZ (D95V on first row), 6-31G(d,p), 6-311G(d,p) and DZVP basis sets. Optimised molecular structure, the absorption spectra, the molecular orbitals energies and the chemical reactivity parameters that arise from conceptual DFT were calculated. Solvent effects have been taken into account by an implicit approach, namely, the polarisable continuum model (PCM), using the non-equilibrium version of the integral equation formalism of the PCM model. Interesting work for experimentalists in the dye sensitised solar cells’ field.     

PdnPbm(n+m≤5)混合团簇的结构与光谱性质

在相对论有效原子实势(RECP)近似下，用密度泛函中的B3LYP/LANL2DZ方法，对纯Pb_n(n=2—5)团簇、Pd_nPb_m(n+m≤5)混合团簇的各种可能几何构型进行全优化计算，得到它们的基态结构和光谱性质；从结构和振动光谱两个方面分析了其形成规律；最后计算了团簇的能级分布和最高占据轨道(HOMO)与最低空轨道(LUMO)之间的能级间隙(HLG)，分析了团簇的化学活性. 关键词： 团簇 有效原子实势 密度泛函     

CH2F自由基与HNCO反应机理的理论研究

采用密度泛函理论的B3LYP方法,在6-311 G(d,p)基组水平上研究了CH2F自由基与HNCO的微观反应机理,优化了反应过程中的反应物、中间体、过渡态和产物的几何构型,通过振动分析验证了所有可能的过渡态;并且还在QCISD(T)/6- 311 G**//B3LYP/6-311 G(d,p)机组水平上计算了相应单点能．找到了CH2F自由基与HNCO反应的7条可行的反应通道,对结果的分析表明,CH2F HNCO→TS8→IM5→TS9→IM4通道的控制步骤活化能最低,是该反应的主要通道．     

Theoretical and spectroscopic studies of 5‐aminoorotic acid and its new lanthanide(III) complexes

The complexes of cerium(III) and neodymium(III) were synthesized by reaction of the respective inorganic salts with 5‐aminoorotic acid (H₄L) in amounts equal to the metal:ligand molar ratio of 1:3. The structures of the final complexes were determined by means of spectral (IR, Raman, ¹H NMR and ¹³C NMR) and elemental analysis. Significant differences in the IR spectra of the complexes were observed as compared to the spectrum of the ligand. A comparative analysis of the Raman spectra of the complexes with that of the free H₄L allowed a straightforward assignment of the vibrations of the ligand groups involved in coordination. The geometry of H₄L was computed and optimized for the first time with the Gaussian03 program using the B3PW91/6‐311++G**, B3PW91/LANL2DZ, B3LYP/6‐311++G** and B3LYP/LANL2DZ methods. The experimental IR and Raman bands of the ligand were assigned to normal modes on the basis of DFT calculations. The vibrational analysis performed for the studied species, H₄L and its complexes, helped to explain the vibrational behavior of the ligand vibrational modes sensitive to interaction with the lanthanides. The vibrational study gave evidence for the coordination mode of the ligand to lanthanide ions and was in agreement with the other theoretical prediction. Copyright © 2006 John Wiley & Sons, Ltd.     

对全金属La42-团簇芳香性的从头算理论研究

我们将芳香性扩展到全金属阴离子团簇La42-.运用从头算方法(B3LYP/LANL2DZ, B3PW91/LANL2DZ and MP2/LANL2DZ)进行了结构优化.计算结果显示,阴离子团簇有两个同分异构体,一个是C2v结构,另一个是正方形D4h结构.进一步对能量的分析得出,D4h结构比C2v结构更稳定.对最稳定的D4h结构计算了核独立位移(NICS),结果显示正方形的La42-环呈现强芳香性.详细的分子轨道(Mos)分析揭示正方形的La42-环拥有四个独立的离域化成键系统,每一个系统拥有两个电子,分别满足4n + 2芳香性电子计算规则,因此呈现四重芳香性.     

M2Al2(M=Au,Ag,Cu)混合小团簇的密度泛函研究

采用基于密度泛函理论的B3LYP方法,利用小核实赝势LANL2DZ,优化了含重金属二元混合团簇M2Al2(M=Au,Ag,Cu)的稳定结构,并得出具有C2v(1A1)对称性的蝴蝶结构比平面构型更加稳定,其中团簇Au2Al2最稳定.计算了稳定结构的结合能、电离势、电子亲和能、最高占据轨道能级和最低空轨道能级及二者间的能隙,得出参杂团簇M2Al2比非参杂团簇M4(M=Au,Ag,Cu)更稳定的结论.