双核Au(I)磷硫配合物激发态性质和金属间弱相互作用的从头算研究

采用MP2和CIS方法分别优化双核Au(I)磷硫配合物, [Au₂(SHCH₂SH)₂]^2＋ (1), [Au₂(SHCH₂SH)(PH₂CH₂PH₂)]^2＋(2), [Au₂(PH₂CH₂PH₂)₂]^2＋ (3), [Au₂(SHCH₂SH)(SCH₂S)] (4), [Au₂(PH₂CH₂PH₂)(SCH₂S)] (5)和[Au₂(SCH₂S)₂]^2－ (6), 基态和激发态的结构. 计算结果表明基态时1～6中存在Au(I)-Au(I)弱吸引作用, 激发态时1～5的金属间相互作用明显增强而6则减弱, 这与实验研究结果一致. 单激发组态相互作用计算揭示: 磷硫配体的更替使得Au(I)配合物跃迁性质呈现MC→MMLCT→MLCT的规律性变化(MC: 金属中心; MMLCT: 金属金属到配体电荷转移; MLCT: 金属到配体电荷转移).     

具有膦配体的异核d10-d8配合物结构:Au-Pt 配合物激发态性质的理论研究

采用MP2和DFT方法优化一系列d10-d8配合物, [MM’(CN)2(PH2CH2PH2)2]＋[M＝AuI, M′＝PtII (1), PdII (2), NiII (3); M’＝PtII, M＝AgI (4), CuI (5)]的基态结构, 其中BH&;H方法得到的金属间距离最接近相应的实验值. 对于经典Au-Pt配合物: 使用多种方法优化[AuPt(CN)2(PMe2CH2PMe2)2]＋(1Me)的结构以验证取代基近似的合理性, 采用单激发组态相互作用方法优化了1的两个低能三重激发态并且考查了环境效应(抗衡离子和溶剂分子)对其较低能激发态发射光谱的影响. 计算结果显示1的两个低能三重激发态分别产生399和234 nm发射, 属于金属中心(Metal-centered, MC)跃迁和分子内电荷转移(Intramolecular Charge Transfer, ICT)的混合性质; 由于电子激发到成键轨道, 使得激发态金属间距离相对基态变短; 环境效应使得较低能的MC/ICT激发态的发射光谱红移, 如1•ClO的发射在473 nm处, 与实验测得[AuPt(CN)2(PCy2CH2PCy2)2]•ClO4的451 nm固体发射相对应.     

金属配合物与DNA的弱相互作用

介绍了金属配合物与DNA相互作用的嵌入、沟槽和静电3种主要模式,并介绍了目前常用的研究方法,包括紫外-可见吸收光谱法、荧光光谱、黏度法、循环伏安法。     

含dppm桥的双核过渡金属配合物中金属─金属间的相互作用

应用ＥＨＭＯ法研究了一系列含ｄｐｐｍ双二苯基膦甲烷桥的双核过渡金属配合物［ＰｄＢｒ（ｄｐｐｍ）］_２，Ｍ_２Ｃｌ_２（μ－ＣＯ）（ｄｐｐｍ）_２（Ｍ＝Ｐｄ，Ｒｈ），［ＲｈＣｌ（ＣＯ）（ｄｐｐｍ）］_２，Ｍ_２－（μ－Ｃｌ）_２Ｃｌ_４（ｄｐｐｍ）_２（Ｍ＝Ｎｂ、Ｔａ、Ｒｅ、Ｒｕ）的电子结构。根据配合物的成键特征，对其金属－金属的相互作用进行了分析。计算结果可以作为解释这类配合物的某些物理化学性质的理论依据。     

含dppm桥的双核过渡金属配合物中金属─金属间的相互作用

应用ＥＨＭＯ法研究了一系列含ｄｐｐｍ双二苯基膦甲烷桥的双核过渡金属配合物［ＰｄＢｒ（ｄｐｐｍ）］_２，Ｍ_２Ｃｌ_２（μ－ＣＯ）（ｄｐｐｍ）_２（Ｍ＝Ｐｄ，Ｒｈ），［ＲｈＣｌ（ＣＯ）（ｄｐｐｍ）］_２，Ｍ_２－（μ－Ｃｌ）_２Ｃｌ_４（ｄｐｐｍ）_２（Ｍ＝Ｎｂ、Ｔａ、Ｒｅ、Ｒｕ）的电子结构。根据配合物的成键特征，对其金属－金属的相互作用进行了分析。计算结果可以作为解释这类配合物的某些物理化学性质的理论依据。     

一系列d8配合物1,3[(dz2)(pz)]激发态和金属间相互作用的理论研究

采用MP2和CIS方法分别优化trans-[M₂(CN)₄(PH₂CH₂PH₂)₂] [M＝Pt (1), Pd (2)和Ni (3)]和trans-[M(CN)₂(PH₃)₂] [M＝Pt (4), Pd (5)和Ni (6)]的基态和^1,3[(d_z2)(p_z)]激发态结构. CIS计算显示1的激发态Pt-Pt距离相对基态变短, 而2和3的金属间距离却增长. TD-DFT方法合理地预测了1～6发射能, 如: 1在CH₂Cl₂溶液中分别拥有348和404 nm的荧光和磷光发射, 与实验的386和448 nm相对应. 在1～3的激发态中, d⁸-d⁸相互作用依次递减, 相应的发射跃迁能增加; 与单核配合物4～6相比, 金属间相互作用使得双核Pt配合物的发射波长红移, 而对双核Pd和Ni配合物影响很小.     

Na-噻吩荷移配合物弱相互作用的理论研究

利用 B3LYP法在 6-31 1 +G* 水平上研究了 Na-噻吩体系可能存在的 3种 Na-噻吩复合物 A,B和 C分子结构 .结果表明 :Na-噻吩体系存在 2个能量极小结构 A和 C;结构 B未得到证实 .结构 A中 ,Na的 3s1电子直接和噻吩杂环的所有重原子进行弱相互作用形成一个具有 Cs对称性的金属有机复合物 ;结构 C中 ,Na原子的 3s1电子主要通过和与 S原子不直接相连的 C2和 C3进行弱相互作用 ,因而在原有的大 π键基础上形成一个新的大 π键 ,其结构为 C2 v对称性 .结构 A较结构 C稳定 78.0 k J/ mol.结构 A中的 Na—S之间的距离为 0 .4 0 7nm,键角∠ CSC为 91°,金属 Na和噻吩之间的弱相互作用使整个噻吩分子平面稍微变形 ,S原子向 Na所在的一侧稍微偏离 C环平面 .结构 C中 Na-S之间的距离为 0 .82 5 nm,∠ CSC为 91°,金属 Na原子和杂环中所有的原子在同一个平面内 .在 B3LYP、 MP2、 MP3和 MP4水平上 ,分别用 6-31 1 +G* 和 6-31 1 ++G* * 基组精确计算了最稳定结构 A的结合能 ΔE为 8.3～ 1 0 .9k J/ mo     

含吩噻嗪金属配合物的合成及非线性光学性质研究

本文报道了一种新的配体:10-乙基-3-甲酰吩噻嗪缩肼基二硫代甲酸甲酯(HL)及其金属配合物的合成。采用了元素分析、质谱、核磁共振、红外光谱对配体及其金属配合物进行了表征。此外,并应用紫外、荧光和Z-扫描技术,测定了配体及其金属配合物的荧光最佳发射波长(λ_max^em)、荧光量子产率(Φ_f)、寿命(τ)和非线性光学性质。结果表明它们在DMF溶液中都能发射出较强的橄榄色荧光,配体及其金属配合物都有双光子吸收,并且金属配合物的非线性光学效应比配体明显增强。用半经验量子化学方法(RHF/PM3)计算结果与实验值较为吻合。     

配位化合物中配体分子间的弱相互作用

配合物分子内和分了间的弱相互作用是从配位化学到超分子化学的桥梁，本文混配配合物中的配体间相互作用与其稳定性的关系入手，讨论了配合物中可能存在的各类非共价作用情况及其影响因素，关重讨论了配合物分子间的弱相互和与超分子化学的关系。     

DNA与金属锇配合物相互作用的表面电化学研究

采用自己建立的DNA表面电化学研究微量方法, 研究了单双链DNA与两种锇配合物(联吡啶锇和二氯菲咯啉锇)的相互作用. 研究发现, 两种锇配合物都是通过静电作用与DNA结合, 其作用方式不受溶液离子强度的影响. 并计算得到了联吡啶锇和二氯菲咯啉锇与dsDNA和ssDNA相互作用的多个热力学和动力学参数, 如结合常数K_3＋或K_2＋, 结合常数比K_3＋/K_2＋, 离子强度为零时的极限比 , 结合自由能ΔG_b, 解离速度常数k, 结合位点数s.     

Syntheses,structures, photoluminescence,and theoretical studies of a novel class of d10 metal complexes of 1H-[1,10]phenanthrolin-2-one

A novel asymmetric monosubstituted 1,10-phenanthroline, Hophen.0.5 H(2)O (1, Hophen=1H-[1,10]phenanthrolin-2-one), was generated by a facile route, and a novel class of crystalline, d(10)-metal, monomeric or oligomeric complexes of this ligand, namely [Hg(ophen)(2)].4 H(2)O.CH(2)Cl(2) (2), [Cd(3)Cl(ophen)(5)].1.5 H(2)O.2 CH(2)Cl(2) (3), and [Zn(4)O(ophen)(4)(OAc)(2)].4H(2)O.2 CH(2)Cl(2) (4), were obtained by means of liquid diffusion, and were characterized by X-ray crystallography and photoluminescence studies. Complex 1 exhibits a hydrogen-bonded dimeric structure, 2 is a neutral monomeric complex, 3 has a trinuclear structure with the ophen ligand acting as a bridge through the ketone groups, and 4 features a tetranuclear Zn(4)O core that is consolidated further by bridging ophen and acetate ligands. All the complexes display photoluminescent properties in the blue/green region. The photoluminescent mechanisms were investigated by means of molecular orbital calculations, which showed that the photoluminescent properties are ligand-based and can be tuned upon ligation to different metal ions.     

Excited-state properties and environmental effects for protonated schiff bases: a theoretical study.

Complete active space self-consistent field (CASSCF), multireference configuration interaction (MRCI), density functional theory (DFT), time dependent DFT (TDDFT) and the singles and doubles coupled-cluster (CC2) methodologies have been used to study the ground state and excited states of protonated and neutral Schiff bases (PSB and SB) as models for the retinal chromophore. Systems with two to four conjugated double bonds are investigated. Geometry relaxation effects are studied in the excited pipi* state using the aforementioned methods. Taking the MRCI results as reference we find that CASSCF results are quite reliable even though overshooting of geometry changes is observed. TDDFT does not reproduce bond alternation well in the pipi* state. CC2 takes an intermediate position. Environmental effects due to solvent or protein surroundings have been studied in the excited states of the PSBs and SBs using a water molecule and solvated formate as model cases. Particular emphasis is given to the proton transfer process from the PSB to its solvent partner in the excited state. It is found that its feasibility is significantly enhanced in the excited state as compared to the ground state, which means that a proton transfer could be initiated already at an early step in the photodynamics of PSBs.     

Electrochemical and quantum chemical investigation of the CuI and CuII complexes with biquinolyl monomer and polymer ligands

Structural reorganization of polyamide (PA) and low-molecular-weight Cu^I and Cu^II complexes with biquinolyl (biQ) ligands during their mutual redox transformations in solution was studied using the electrochemical methods (cyclic voltammetry and preparative electrolysis) and quantum chemical DFT calculations. The influence of electronic factors and geometry distortions in the complexes on the ionization energy on going from Cu^I to Cu^II was evaluated in comparison. The catalytically active form of the [Cu^I(PA)L₂]BF₄ complex can be synthesized in situ from the stable tetrahedral complex [Cu^I(PA)₂]BF₄ by the series of successive redox transitions Cu^I → Cu^II → Cu^I accompanied by the loss of one biQ-containing macroligand. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1331–1340, July, 2007.     

Perfluoropoly-ether/peroxide compounds: spectroscopic studies and quantum chemical calculations

Perfluoropolyethers (PFPEs) are a class of high performance materials used in a wide range of applications (refrigeration, lubrication, semiconductor industry, etc.). PFPEs containing peroxidic units are intermediate materials for the preparation of commercial end products. In this work we study the spectroscopic properties of ether and peroxides linkages in this class of compounds; nuclear magnetic resonance (NMR) spectra are discussed, FT-Raman data presented. Quantum chemical calculations on model molecules were used as a tool for the interpretation of the Raman experimental data and physical-chemical properties.     

Unexpected conformational properties of 1-trifluoromethyl-1-silacyclohexane, C5H10SiHCF3: gas electron diffraction, low-temperature NMR spectropic studies, and quantum chemical calculations

The molecular structure of axial and equatorial conformers of 1-trifluoromethyl-1-silacyclohexane, (C5H10SiHCF3), as well as the thermodynamic equilibrium between these species was investigated by means of gas electron diffraction (GED), dynamic nuclear magnetic resonance (DNMR) spectroscopy, and quantum chemical calculations (B3LYP, MP2, and CBS-QB3). According to GED, the compound exists as a mixture of two Cs symmetry conformers possessing the chair conformation of the six-membered ring and differing in the axial or equatorial position of the CF3 group (axial=58(12) mol%/equatorial=42(12) mol%) at T=293 K. This result is in a good agreement with the theoretical prediction. This is, however, in sharp contrast to the conformational properties of the cyclohexane analogue. The main structural feature for both conformers is the unusually long exocyclic bond length Si--C 1.934(10) A. A low-temperature 19F NMR experiment results in an axial/equatorial ratio of 17(2) mol%:83(2) mol% at 113 K and a DeltaG (not equal) of 5.5(2) kcal mol-1. CBS-QB3 calculations in the gas-phase and solvation effect calculations using the PCM(B3LYP/6-311G*) and IPCM(B3LYP/6-311G*) models were applied to estimate the axial/equatorial ratio in the 100-300 K temperature range, which showed excellent agreement with the experimental results. The minimum energy pathways for the chair-to-chair inversion of trifluoromethylsilacyclohexane and methylsilacyclohexane were also calculated using the STQN(Path) method.     

Quantum-chemical and spectroscopic studies of structures of 1 : 2 complexes of carbonyl compounds with aluminum halides

Quantum-chemical calculations of model systems, namely, benzaldehyde and its 1 : 1 and 1 : 2 complexes with AlCl₃, were carried out by the MNDO method. In the 1 : 2 complex, a bridging Al-Cl-Al bond occurs. Apparently, this complex is stabilized through the Coulomb interaction between the positively charged C atom of the carbonyl group and the AlCl₃ fragment, which carries an excessive negative charge and which is not involved in donor-acceptor bonding with the carbonyl O atom. The IR spectra of the 1 : 1 and 1 : 2 complexes of benzophenone with AlBr₃ were recorded, and the differences in the low-frequency regions of these spectra, which are indicative of the presence of the Br₂Al-Br-AlBr₃ fragment in the 1 : 2 complex, are discussed.This article is dedicated to Academician M. G. Voronkov on the occasion of his 75th birthday.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2866–2871, December, 1996.     

Polynuclear sandwich derivatives of [10]annulene: A quantum chemical study

Density-functional theory (DFT) calculations at B3LYP/6-311+G(df,p) and M06/6-311+G(df,p) levels of theory predict the stability of new polynuclear sandwich complexes [Cu₅(C₁₀H₁₀)₂]⁺ and Ni₅(C₁₀H₁₀)₂ based on flat [10]annulene cycles.