Theoretical studies on the electronic structure and spectral properties of versatile diarylethene-containing 1,10-phenanthroline ligands and their rhenium(I) complexes

The structures of versatile diarylethene-containing 1,10-phenanthroline ligands (L₁ and L₂) and their rhenium(I) complexes [Re(CO)₃(L)Cl] (1 and 2) in the ground and low-lying excited states have been optimized at the B3LYP functional and the ab initio configuration interaction singlets (CIS) level, respectively. The spectral properties are predicted with use of time-dependent density functional theory (TDDFT). As shown, the transition character of the strongest absorption band and luminescent spectrum for closed-ring complex 1 is different from that of 2, the former has ππ^∗ character and the latter has MLCT and LLCT character. We presume the second triplet excited state contributes to the phosphorescence of 1, while the lowest triplet excited state accounts for the phosphorescence of 2. Spin-orbit coupling influences the excitation energies for d(Re)-joined transitions whereas it has negligible effect on the transition character for complexes 1 and 2.     

磷光三核Cu(I)吡唑配合物光学性质的理论研究

用TD-B3LYP方法研究了{[3-(CF3),5-(Me)Pz]Cu}3的单体以及二聚体的光学性质,同时揭示了Cu…Cu相互作用对光谱性质的影响.     

单核和双核钴羰基-亚硝基配合物的理论研究

利用密度泛函理论研究了钴羰基-亚硝基配合物Co(NO)(CO)n (n=1～4) 和Co2(NO)2(CO)n(n=2～5)体系.Co(NO)(CO)n (n=1～4)的低能构型和前人研究的等电子体Ni(CO)n+1类似,并且理论预测还可能存在热力学不稳定的具有弯曲的NO配体的Co(NO)(CO)4.理论预测Co2(NO)2(CO)n (n=2～5)的各不同异构体的构型非常相似,能量也很接近,因此其势能面非常复杂,但是其异构体的构型与前人理论预测的等电子体Ni2(CO)n+2非常类似,即Co2(NO)2(CO)5,Co2(NO)2(CO)4和Co2(NO)2(CO)3分别有1,2和3个桥配体.离解能计算表明,对双核钴化合物,羰基解离将比Co-Co键断裂更容易.     

Bipyridyl/carbazolate silver(I) and gold(I) N-heterocyclic carbene complexes: A systematic study of geometric constraints and electronic properties

A series of silver(I) and gold(I) carbene complexes of the type [M(L)(2,2′-bipyridine)][PF₆] (L = 1-benzyl-3-(2-pyridylmethyl)benzimidazolylidene; M = Ag ( 1 ); M = Au ( 3 )) and [M(L)(carbazole)] (M = Ag ( 2 ); M = Au ( 4 )) were synthesized and analyzed using a range of spectroscopic and crystallographic techniques. Inspection of the solid-state structures of 1 , 2 and 4 revealed a number of intermolecular noncovalent interactions. In the solid-state structure adopted by 1 , π–π and Ag–Ag interactions directed the complexes to orient in a head-to-tail fashion. The photophysical properties were found to be influenced by the ancillary ligands in solution as well as in the solid-state. Calculations were performed to support the aforementioned structural and optoelectronic assignments.     

Theoretical study of {Au3(CH3NCOCH3)3}n·{2,4,7‐trinitro‐9‐fluorenone} (n = 1,2) complexes

The interaction between {Au₃(CH₃N?COCH₃)₃} and {2,4,7‐trinitro‐9‐fluorenone} and the electronic structure and spectroscopic properties of {Au₃(CH₃N = COCH₃)₃}_n·{2,4,7‐trinitro‐9‐fluorenone} (n = 1,2) are studied at the HF, MP2, and PBE levels. Secondary π‐interactions (Au‐fluorenone) were found to be the main contribution to short‐range stability in the {Au₃(CH₃N?COCH₃)₃}_n·{2,4,7‐trinitro‐9‐fluorenone} complex. At the MP2 and PBE levels, Au‐C equilibrium distances of 292.3 and 304.0 pm and interaction energies of 105.3 and 24.9 kJ/mol were found, respectively. The absorption spectra of these complexes were calculated by the single excitation time‐dependent method at the PBE level. The theoretical values obtained are in agreement with the experimental range. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Effect of water on zinc (II), cadmium (II) complexes with pyridylimidazole: Theoretical study of stability and electronic spectrum

The geometry structures of complexes such as [Zn(PIm)₂(H₂O)] and [Cd(PIm)₂(H₂O)₂] [PIm = (2‐(2′‐pyridyl) imidazole)] are optimized by density functional theory (DFT) B3LYP methods. On the basis of their stable structures, the stability of the coordinated water existing in the complexes is analyzed quantitatively in terms of the interaction between the central metal and the coordinated water. The interaction energy of the Zn pyridylimidazole complex increased obviously by considering the intermolecular hydrogen bond (O? H…N). The theoretical calculation well explained penta‐ and hexa‐coordinated conformation, respectively, in Zn and Cd pyridylimidazole complexes. The spectral properties of the Zn Cd complexes have been studied by time‐dependent density functional theory (TD‐DFT). The calculation results show that the coordinated waters in Cd complexes have little effect on their spectral properties. While the axially coordinated waters in Zn pyridylimidazole cause a red shift in the absorption wavelength and change the pattern of charge transfer as a result of the effect of polarization from intermolecular hydrogen bond. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

Synthesis, characterization, electrochemistry and luminescence studies of heterometallic gold(I)-rhenium(I) alkynyl complexes

The present work provides a brief summary review of the chemistry of luminescent gold(I) alkynyls and their ability to form heterometallic complexes. A series of luminescent heterometallic gold(I)-rhenium(I) alkynyl complexes has been synthesized and characterized. Their electrochemical and photophysical properties have been studied and their emission origins elucidated.     

位阻效应对N-(4-脱氢苯基)吡啶离子与氮氧自由基反应的理论计算研究

应用量子化学密度泛函理论(DFT),在B3LYP/cc-pVDZ基组水平上,对N-(4-脱氢苯基)吡啶离子与不同结构的氮氧自由基反应进行了热动力学研究.优化了反应通道上反应物、中间体、过渡态和产物的几何构型并计算出它们的零点振动能( Ezpv)和焓值,分析数据研究位阻效应对反应的影响.研究表明3类氮氧自由基均与N-(4...     

二阶非线性光学活性分子——咪唑类衍生物的设计与性质的理论研究

采用B3LYP方法在6-31G*水平上优化了6种F,Cl和Br取代的咪唑类衍生物分子几何构型,在此基础上采用TD-DFT的方法计算了它们的前线轨道能级和电子光谱,并用CPHF方法研究了此类衍生物二阶非线性光学系数性质.计算结果表明:此类化合物具有平面结构,共轭性较强;分子内设计的推拉电子基团增强分子内电荷转移,使前线分子轨道间的电子跃迁更容易;各体系具有较大的vβec和良好的透明性;咪唑环的引入增强了体系的热稳定性.这些结论对分子设计具有一定的指导意义.     

Cross-coupling reactions of gold(I) alkynyl and polyyndiyl complexes

Gold(I) alkynyl complexes are shown to efficiently couple with aryl iodides under mild conditions in the presence of both Pd(II) and Cu(I) co-catalysts. The reaction is not gold catalysed, but rather the Au(I) centre serves to transfer the alkynyl moiety to Cu(I), which then enters the conventional Sonogashira cycles. Using this method, a small range of 1,4-disubstituted diynes, including examples of differentially substituted compounds ArCCCCAr′, have been prepared directly from [(Ph₃P)AuCCCCAu(PPh₃)] and aryl iodides ArI.     

Effect of the axial cysteine ligand on the electronic structure and reactivity of high-valent iron(IV) oxo-porphyrins (Compound I): a theoretical study

The effect of axial ligands on the reactivity of high-valent iron(IV) oxo-porphyrins (Compound I) was investigated using the B3LYP hybrid density functional method. We studied alkane hydroxylation using four models: Compound I with thiolate, imidazole, phenolate, and chloride anions as axial ligands. The first three ligands were employed as models for cysteinate, histidine, and tyrosinate, respectively. Our calculations show that anionic ligands and neutral ligands favor different electronic states for stationary points in the reaction coordinate, and the calculated energy barrier and energy of several reaction intermediates show similar values. A remarkable effect of axial ligands was found in the final product release step. Our calculations show that the thiolate ligand weakens a bond between heme and an alcohol. In contrast, the imidazole ligand significantly increases the interaction between heme and an alcohol, which causes the catalytic cycle to be less efficient.     

Theoretical study on the reaction mechanism of(CH_3)_3CO+CO

The global environment pollution includes pho-tochemical smog, acid rain and stratospheric ozonedepletion. The short-lived species/radicals in atmos-phere are closely related to these phenomena. Theshort-lived species/radicals bring the photochemicalsmog,…     

Synthetic and antimicrobial studies on new gold(I) complexes of imidazolidin‐2‐ylidenes

Six new 1,3‐diorganylimidazolidin‐2‐ylidene (NHC) gold(I) complexes of the type [Au(NHC)₂]⁺ (1–6), were synthesized by reacting [AuCl(PPh)₃] with 1,3‐dimesitylimidazolidin‐2‐ylidene or bis(1,3‐dialkylimidazolidin‐2‐ylidene). The complexes 1–6 were fully characterized by elemental analyses and spectroscopic data. The placement of mesityl or para‐substituted benzyl groups on the nitrogen atoms of the ring of the complexes leads to the particularly active antibacterial agents evaluated in this work. It is worth noting that the p‐methoxybenzyl derivative (2) inhibited the growth of Pseudomona aeruginosa, Staphylococcus epidermidis, Staphylococcus aureus and Enterococcus faecalis with minimum inhibitory concentration (MIC) values of 3.12 µg ml^?1, 6.25 µg ml^?1, 3.12 µg ml^?1 and 3.12 µg ml^?1 respectively. In contrast, the analogous p‐dimethylaminobenzyl derivative (3) is effective only against Escherichia coli (MIC = 3.12 µg ml^?1). Copyright © 2004 John Wiley & Sons, Ltd.     

Supramolecular gold(I) compounds with trithiocyanuric acid: Self‐assembly and luminescent properties

[(N₃S₃)Au(AuPMe₃)₂]₂ ( 1 ) and [(N₃S₃)Au(AuPEt₃)₂]₂ ( 2 ) were prepared by treating AuCl(PMe₃) or AuCl(PEt₃) with H₃N₃S₃ upon deprotonation by trimethylamine to give respective Au₆ supermolecules. Using dppm(AuCl)₂ instead of AuCl(PMe₃) or AuCl(PEt₃) to react with H₃N₃S₃ in a similar reaction condition led to a rare heptanuclear supermolecule of [(N₃S₃)₂Au₇(dppm)₄]Cl ( 3 ). It is noted that besides short intramolecular gold(I)?gold(I) distances, both compounds 1 and 2 also show intermolecular gold(I)?gold(I) distances of 3.067(1) and 3.241(1) Å, resulting in two‐dimensional and one‐dimensional polymeric gold(I) solid, respectively. In fact, compound 1 shows a similar two‐dimensional polymeric gold(I) solid to that of the reported [(N₃S₃)Au(AuPPhMe₂)₂]₂ with an intermolecular gold(I)?gold(I) distance of 3.130(2) Å. Significantly, these intermolecular gold(I)?gold(I) distances are well correlated with their cone angles and emission energies. For example, intermolecular gold(I)?gold(I) distances increase in the order of 3.067(1) Å < 3.130(2) Å < 3.241(1) Å for PMe₃ (118°), PPhMe₂ (122°), and PEt₃ (132°), and their emission energies also increase in the order of 542 nm < 530 nm < 504 nm, respectively. This work highlights a very good correlation between intermolecular aurophilic interactions and emission energies for a series of Au₆ supermolecules, where the cone angle plays a vital role in the self‐assembly process as well. Finally, the emissions for 1 – 3 are tentatively assigned to the S → Au charge‐transfer transition, whereas they are most probably modified by gold(I)?gold(I) interactions.     

(Phosphine)gold(I) Complexes of Benzenedithioles. Crystal structures of 1,2-benzenedithiolato-bis[triphenyl-phosphinegold(I)] and bis(triethylphosphine)gold(I) bis(1,2-benzenedithiolato)gold(III)

The reaction of 1,2- and 1,3-benzenedithiol C₆H₄(SH)₂ with chloro(phosphine)gold(I) complexes R₃PAuCl (R = Et, Ph) in the presence of triethylamine in tetrahydrofuran gives stable gold(I) complexes 1,2-C₆H₄(SAuPR₃)₂ [R = Et ( 1 ) and Ph ( 2 )] or 1,3-C₆H₄(SAuPPh₃)₂ ( 3 ), respectively, in high yield. The compounds have been characterized by analytical and NMR spectroscopic data. From the reaction of 1,2-C₆H(SH)₂ with Et₃P? AuCl a by-product [(Et₃P)₂Au]⁺ [Au(1,2? C₆H₄S₂)₂]^? ( 4 ) has also been isolated in low yield. The crystal structures of compounds 2 and 4 have been determined by single crystal X-ray diffraction. The gold(I) atoms in complex 2 are two-coordinate with bond angles S? Au? P of 175.2(1) and 159.5(1)°, Au? S bond distances of 2.304(1) and 2.321(1) å, and a short Au…?Au contact of 3.145(1) Å. The gold(I) atom in the cation of complex 4 is also linearly two-coordinate with a P? Au? P angle of 170.1(1) Å and Au? P distances of 2.296(3) and 2.298(3) Å. The geometry of the anion in 4 shows a square-planar coordination of gold(III) by two chelating 1,2-benzenedithiolate ligands with Au? S distances between 2.299(3) and 2.312(3) Å (for two crystallographically independent, centrosymmetrical anions in the unit cell).     

Synthesis, spectroscopic characterization and electronic structure of some new Cu(I) carbene complexes

Reaction of oligomeric Cu(I) complexes [Cu(Μ-S-C(=NR)(O-Ar-CH₃)]_n with Lewis acids gave Cu(I) carbene complexes, which were characterized by¹H and¹³C NMR spectroscopy. Cu(I) carbene complexes could be directly generated from RNCS, Cu(I)-OAr and Lewis acids; this method can be used to prepare Cu(I) carbene complexes with different substitutents on the carbene carbon. The complexes were unreactive towards olefins and do not undergo cyclopropanation. Electronic structure calculations (DFT) show that the charge on the carbene carbon plays an important role in controlling the reactivity of the carbene complex.     

C6F5X＋（X=Cl,Br,I,CH3）离子的理论研究

用DFT B3LYP方法及6-311G（d,p）,6-311＋G（d,p）和LanL2dz基组,对C6F5X＋（X=Cl,Br,I,CH3）阳离子做了理论研究,优化了它们的电子基态的构型,计算了对应分子的垂直电离势（VIP）和绝热电离势（AIP）.结果表明四种离子的构型的对称点群和对应分子相同,但构型参数有明显差别.B...     

A new preparation method of gold nanoparticles by intra-reduction of sodium gold（I） sulfite

In this study, well-dispersed gold nanoparticles were prepared by using intra-molecular reduction of sodium gold sulfite, without using additional reductants and chloride free. The technical parameters including transformation temperature, pH, and concentration were optimized by the single-factor method as 90 C, pH 1, and 0.01 mmol/L [Na3Au（SO3）2], respectively. The resultant colloidal transmission electron microscopy images （TEM） and UV-vis absorption spectrophotometer spectra were acquired to check their properties, and the results show this kind of colloidal gold is controlled to 6 nm in sizes and has good stability in solution.     

Theoretical study of the structure, stability, and infrared spectra of hydrogen-bonded complexes of N-nitrosodiethanolamine (NDELA) with water molecules

A theoretical study of the interaction between the N-nitrosodiethanolamine (NDELA) molecule and one to five water molecules was performed at the B3LYP level using a large polarized basis set. The calculated complexation energies (corrected for BSSE and ZPVE) of NDELA with one, two, three, four, and five water molecules are ?4.62 kcal/mol, ?9.83 kcal/mol, ?15.29 kcal/mol, ?21.60 kcal/mol, and ?25.10 kcal/mol respectively at the B3LYP/6-311++G** level. In all complexes studied, there are red shifts in the vibrational frequencies of the O-Hs of NDELA and water molecules along with increases in the corresponding IR intensities.