Chemistry of Polypyridine Ruthenium Complexes: VII. Electronic Structure and Photochemistry of cis-[Ru(2,2'-bpy)2(L)(Cl)]+ Complexes

The electronic absorption spectra and photochemical behavior of the complexes of cis-[Ru(bpy)₂ · (L)(Cl)]⁺ (bpy is 2,2'-bipyridyl) with pyridine (L = py) and 4-substituted pyridines [L = methyl-, amino-, and cyanopyridine, and 4,4'-bipyridyl (bipy)]. Photoirradiation of acetonitrile solutions of the complexes results in substitution of ligand L by a solvent molecule. A correlation was revealed between the photolysis quantum yield and the coordination-induced ligand L-to-metal charge transfer.     

Chemistry of Ruthenium Polypyridine Complexes: VIII. Electronic Structure and Reactivity of cis-[Ru(2,2'-Bpy)2(L)Cl]+ Complexes in Excited States

Ab initio and semiempirical CINDO/CI calculations of free ligands L and complexes cis-[Ru(bpy)₂(L)Cl]⁺ [bpy = 2,2'-bipyridyl, L = pyridine, 3-cyanopyridine, 4-picoline, nicotinamide, isonicotinamide, 4-picoline, 4-aminopyridine, 4,4'-bipyridyl (bipy), trans-1,2-bis(4-pyridyl)ethene, 4,4'-azopyridine, pyrazine (pyz), and imidazole] were used to study the interrelation between the electronic structures of the ligands and the complexes in the ground and electronically excited states and to interpret the electronic absorption spectra of the complexes. The quantum yields for photosubstitution of a solvent molecule for a ligand L were measured; for L = pyz and bipy, photolysis quantum yields as a function of irradiation wave-length were studied. The possibility of population of ligand-field photoactive states from overlying charge-transfer states and the associative mechanism of ligand photosubstitution were discussed.     

Chemistry of Electronically Excited Ruthenium Polypyridine Complexes: III.1 Electronic Structure of Complexes cis-[Ru(2,2'-bpy)2(4,4'-bipy)(X)]q

The results of ab initio quantum-chemical calculations of isolated ruthenium(II) complexes cis- [Ru(bpy)₂(bipy)(X)]⁴4q (bpy is 2,2'-bipyridyl, bipy is 4,4'-bipyridyl; X = NH₃, Cl^-, Br^-, CN^-, NO^- ₂, ONO^-, MeCN, and NO⁺) are presented. Analysis of the charge distributions and the orbital structures of the complex ions points to absence of strong -acceptor bonds Ru-bpy, Ru-bipy, and Ru-X (X = NO⁺), to delocalization of -electron density under the action of strong donors X, to localized nature of lowest unoccupied molecular orbitals, and to special position of the nitrosyl complexes in this series.     

Chemistry of Ruthenium Polypyridine Complexes: VI. Synthesis and Photochemistry of cis-[Ru(bpy)2(bipy)X]q Complexes

Complexes cis-[Ru(bpy)₂(bipy)(X)] ^{n +} [bpy = 2,2'-bipyridyl, bipy = 4,4'-bipyridyl, X = Br^-, ONO^-, CN^- (n = 1); MeCN, PPh₃ (n = 2), and NO⁺ (n = 3)] were synthesized. Irradiation of acetonitrile solutions of the complexes with X = Cl^-, Br^-, ONO^-, NO₂-, CN^-, NH₃, MeCN, and PPh₃ by visible light results in photosubstitution of 4,4'-bipyridyl by a solvent molecule. The electronic absorption spectra of the complexes were assigned on the basis of quantum-chemical calculations. A correlation was revealed between photolysis quantum yields and charges transferred from ligands X upon their coordination.     

Chemistry of Ruthenium Polypyridine Complexes: V. Electronic Structure of Ruthenium(II) Bipyridine-Diphosphine Mixed-Ligand Complexes

Comparative analysis of the donor-acceptor capacities of diphosphine ligands in two series of complexes: cis-[Ru(bpy)2(LL)]^{q +} [LL = 2,2'-bipyridine (bpy), o-benzoquinonediimine (bqdi), cis-1,2-bis(diphenylphosphino)ethane, cis-1,2-bis(diphenylphosphino)ethylene (dppen), (NH3)2, and (CO)2] and [Ru(NH₃)₄. (LL)]^{2 +} (LL = bpy, dppen, and bqdi), was performed. Diphosphines are the strongest donors; they compare in -acceptor capacity which is associated with phosphorus d orbitals with 2,2'-bipyridine and fall far short of o-benzoquinonediimine and carbonyl.     

Chemistry of Ruthenium Polypyridine Complexes: IV. Quantum-Chemical Simulation of the Effect of Solvation Shell on the Electronic Structure of Ru(II) Complexes with Nitrogen-containing Ligands

Ab initio quantum-chemical calculations of Ru(II) complexes have been fulfilled with consideration for solvation within the framework of the polarized continuum model. Energy levels of fragments of Ru(II) complexes with organic ligands are shifted relative to each other by electrostatic interactions with the solvation shells.     

[99Tcm(NO)Cl(PL)2]＋类配合物的定量构效关系

用半经验量子化学方法中的ZINDO/1对15种[99Tcm(NO)Cl(PL)2]＋类配合物的结构进行了优化，得到各种物理化学参数和电性参数，并将这些参数对心肌初始摄取值进行多元线性回归分析，得到了4个方程.利用所得方程，提出了该类配合物的心肌摄取机理主要为氧化还原反应机理.     

Substituents effects on two related families of dyes for dye sensitized solar cells: [Ru(4,4'-R,R-2,2'-bpy)(3)]2+ and [Ru(4,4'-COOH-2,2'-bpy)(4,4'-R,R-2,2'-bpy)(2)]2+

We studied the influence of the substituents over the composition of the molecular orbitals, electronic transitions, and reactivity of several ruthenium derivatives. We found a good agreement with the previously reported experimental data. In these theoretical calculations including spin-orbit coupling, we study several ruthenium-tris-(2,2'-bipyridine) substituted dyes, which do or do not have an anchoring group to get attached to the semiconductor surface. It was observed that the complexes that have electron-donor substituents might be more efficient to donate electrons if they are anchored to a semiconductor than those complexes that have electron-acceptor substituents. Therefore, the results suggest that these dyes with electron-donor substituents will give better yields in photocurrent generation. Also, the localization of the lowest unoccupied molecular orbital over the ligand that has the anchoring will help to improve electron injections into the TiO(2) nanoparticles. We propose here several not yet synthetized dyes, which could be used in this kind of device, due to their interesting molecular properties.     

Photoinduced electron-transfer processes based on novel bipyridine-Ru(II) complex: properties of cis-[Ru(2,2'-bipyridine)2(5,6-bis(3-amidopyridine)-7-oxanorbornene)](PF6)2 and cis-[Ru(2,2'-bipyridine)2(3-aminopyridine)2](PF6)2 complexes

This paper presents the synthesis, MO calculations, and photochemical and photophysical properties of cis-[Ru(bpy)2(3Amdpy2oxaNBE)](PF6)2 (2), where bpy is 2,2'-bipyridine and 3Amdpy2oxaNBE is the novel 5,6-bis(3-amidopyridine)-7-oxanorbornene chelate-ligand (1). Complex 2 is considered in relation to the cis-[Ru(bpy)2(3Amnpy)2](PF6)2 (3) analogous complex, where 3Amnpy is 3-aminopyridine. Complexes 2 and 3 exhibit absorptions near 350 nm and in the 420-500 nm region attributable to a contribution from MLCT transitions (dpi-->bpy and dpi-->L; L=3Amdpy2oxaNBE or 3Amnpy). Whereas complex 3 is photochemically reactive, complex 2 shows luminescence either at 77 K or at room temperature in fluid solution. The emission of 2 assignable as an MLCT (Ru-->bpy) emission is characterized by a long lifetime at room temperature (650 ns in CH3CN and 509 ns in H2O). It is independent of lambdairr, but it is temperature dependent; i.e., it increases as the temperature is lowered. Considering the chelate ring of 1 contributes to the stability of the complex 2 under continuous light irradiation, the difference in the primary photoprocesses of 3 (loss of 3Amnpy) and 2 (luminescence) may be caused by a lowering of the lowest excited state from 3 to 2. The surface crossing to the lowest MC state value of 987 cm-1 (similar to that of [Ru(bpy)3]2+) will be prevented in the case of complex 2, and as a result, efficient 3Amdpy moiety loss cannot occur. The electronic depopulation of the {Ru(bpy)2} unit and population of a bpy* orbital upon excitation are evident by comparing the photophysical properties with those of a [Ru(bpy)3]2+ related complex. Moreover, a reduction of a bpy ligand in the MLCT excited state is indicated by time-resolved spectra that show features typical of bpy*-. The photocatalytic property of 2 is spectroscopically demonstrated by oxidative quenching using either methylviologen2+ or [RuCl(NH3)5]+2 electron-acceptor ions.     

Synthesis of Ruthenium(II) Tris(2,2'-bipyridine) Complexes

A procedure for preparing Ru(II) tris(2,2'-bipyridine) complexes containing one functionalized bipyridine ligand was developed.     

Absorption spectrum and solvatochromism of the [Ru(4,4'-COOH-2,2'-bpy)2(NCS)2] molecular dye by time dependent density functional theory

We present a combined Density Functional/Time Dependent Density Functional study of the molecular structure, electronic states, and optical absorption spectrum of [Ru(4,4'-COOH-2,2'-bpy)(2)(NCS)(2)], a widely used charge-transfer sensitizer in nanocrystalline TiO(2) solar cells. Calculations have been performed both for the complex in vacuo and in ethanol and water solvents, using a continuum model to account for solute-solvent interactions. Inclusion of the solvent leads to important changes of the energies and composition of the molecular orbitals of the complex; as a consequence, whereas the computed spectrum for the Ru-complex in vacuo deviates from the experimental one in both energy and shape, the spectra calculated in the presence of the solvent are in good agreement with the experiment. The first two absorption bands are found to originate from mixed ruthenium-NCS to bipyridine-pi* transitions rather than to pure metal-to-ligand-charge-transfer (MLCT) transitions, whereas the third band arises from intraligand pi --> pi* transitions. The experimentally observed blue-shift of the spectrum in water with respect to ethanol is well reproduced by our calculations and appears to be related to a decreased dipole moment in the excited state.     

NO Release from trans-[Ru(NH3)4L(NO)]3+ Complexes Upon Reduction (L = 1-Methylimidazole or Benzoimidazole)

The synthesis, characterization and reactivity of trans-[Ru(NH₃)₄(L)NO](PF₆)₃(L = benzoimidazole or 1-methylimidazole in trans position to NO) are presented. ¹H-n.m.r. spectroscopy data indicate that the benzoimidazole and 1-methylimidazole ligands are coordinated to Ru^II through carbon and nitrogen, respectively. The nitrosyl stretching frequencies [(NO) > 1900 cm^–1] suggest that the coordinated nitrosyl has substantial NO⁺ character. The complexes undergo a single-electron reduction (E ⁰–0.245 versus NHE), which involves the coordinated nitrosyl. Dissociation of NO in the reduced species is facilitated by the 1-methylimidazole ligand, which is not observed for the benzoimidazole species. The complex with 1-methylimidazole does not suffer hydroxide attack on the NO⁺, at least at pH values lower than 11.     

钌(Ⅱ)多吡啶配合物的合成、表征及其三阶非线性光学性质研究

合成了三种含咪唑并[4,5-f]邻菲莫咯啉(IP)的钌(Ⅱ)配合物，通过元素分析、FAB-MS、^1HNMR、UV-vis和电化学对它们进行了表征。运用Z-扫描的实验方法研究了钌(Ⅱ)配合物的三阶非线性折射率n~2和非线性吸收系数α~2，并由此计算出它们的三阶非线性系数χ^(^3^)和分子超极化率γ。分析了分子结构对其三阶非线性光学性质的影响。     

Interaction of Sulfonated Ruthenium(II) Polypyridine Complexes with Surfactants Probed by Luminescence Spectroscopy

Novel anionic [RuL₂L′]²⁻ complexes, where L stands for (1,10‐phenanthroline‐4,7‐diyl)bis(benzenesulfonate) (pbbs; 3a ) or (2,2′‐bipyridine)‐4,4′‐disulfonate (bpds; 3b ), and L′ is N‐(1,10‐phenanthrolin‐5‐yl)tetradecanamide (pta; 2a ) or N‐(1,10‐phenanthrolin‐5‐yl)acetamide (paa; 2b ), were synthesized, and their interaction with the prototypical surfactants sodium dodecylsulfate (SDS), cetyl trimethyl ammonium bromide (CTAB), and Triton X‐100 (TX‐100) was investigated by electronic absorption, luminescence spectroscopy, emission‐lifetime determinations, and O₂‐quenching measurements. [Ru(pbbs)₂(pta)]²⁻ ( 5a ) displayed cooperative self‐aggregation in aqueous medium at concentrations above 1.3 μM ; the observed association was enhanced in the presence of either β‐cyclodextrin or NaCl. This amphiphilic Ru^II compound showed the strongest interaction with all the detergents tested: nucleation of surfactant molecules around the luminescent probe was observed below their respective critical micellar concentrations. As much as a 12‐fold increase of the emission intensity and a 3‐fold rise in the lifetime were measured for 5a bound to TX‐100 micelles; the other complexes showed smaller variations. The O₂‐quenching rate constants decreased up to 1/8 of their original value in H₂O (e.g., for [Ru(bpds)₂(pta)]²⁻ ( 6a ) bound to CTAB micelles). Luminescence‐lifetime experiments in H₂O/D₂O allowed the determination of the metal‐complex fraction exposed to solvent after binding to surfactant micelles. For instance, such exposure was as low as 25% for pta complexes⋅CTAB aggregates. The different behaviors observed were rationalized in terms of the Ru^II complex structure, the electrostatic/hydrophobic interactions, and the probe environment.     

The inducing NO-vasodilation by chemical reduction of coordinated nitrite ion in cis-[Ru(NO(2))L(bpy)(2)](+) complex

The synthesis of [Ru(NO(2))L(bpy)(2)](+) (bpy = 2,2'-bipyridine and L = pyridine (py) and pyrazine (pz)) can be accomplished by addition of [Ru(NO)L(bpy)(2)](PF(6))(3) to aqueous solutions of physiological pH. The electrochemical processes of [Ru(NO(2))L(bpy)(2)](+) in aqueous solution were studied by cyclic voltammetry and differential pulse voltammetry. The anodic scan shows a peak around 1.00 V vs. Ag/AgCl attributed to the oxidation process centered on the metal ion. However, in the cathodic scan a second peak around -0.60 V vs. Ag/AgCl was observed and attributed to the reduction process centered on the nitrite ligand. The controlled reduction potential electrolysis at -0.80 V vs. Ag/AgCl shows NO release characteristics as judged by NO measurement with a NO-sensor. This assumption was confirmed by ESI/MS(+) and spectroelectrochemical experiment where cis-[Ru(bpy)(2)L(H(2)O)](2+) was obtained as a product of the reduction of cis-[Ru(II)(NO(2))L(bpy)(2)](+). The vasorelaxation observed in denuded aortic rings pre-contracted with 0.1 mumol L(-1) phenylephrine responded with relaxation in the presence of cis-[Ru(II)(NO(2))L(bpy)(2)](+). The potential of rat aorta cells to metabolize cis-[Ru(II)(NO(2))L(bpy)(2)](+) was also followed by confocal analysis. The obtained results suggest that NO release happens by reduction of cis-[Ru(II)(NO(2))L(bpy)(2)](+) inside the cell. The maximum vasorelaxation was achieved with 1 x 10(-5) mol L(-1) of cis-[Ru(II)(NO(2))L(bpy)(2)](+) complex.     

Synthesis and Characterization of New Ruthenium (II) Complexes of Stoichiometry [Ru(p-Cymene)Cl2L] and Their Cytotoxicity against HeLa-Type Cancer Cells

When the [Ru(p-cymene)(μ-Cl)Cl]₂ complex is made to react, in dichloromethane, with the following ligands: 2-aminobenzonitrile (2abn), 4-aminobenzonitrile (4abn), 2-aminopyridine (2ampy) and 4-aminopyridine (4ampy), after addition of hexane, the following compounds are obtained: [Ru(p-cymene)Cl₂(2abn)] (I), [Ru(p-cymene)Cl₂(4abn)] (II), [Ru(p-cymene)Cl₂(2ampy] (III) and [Ru(p-cymene)Cl₂(μ-(4ampy)] (IV). All the compounds are characterized by elemental analysis of carbon, hydrogen and nitrogen, proton nuclear magnetic resonance, COSY ¹H-¹H, high-resolution mass spectrometry (ESI), thermogravimetry and single-crystal X-ray diffraction (the crystal structure of III is reported and compared with the closely related literature of II). The cytotoxicity effects of complexes were described for cervical cancer HeLa cells via 3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide (MTT) assay. The results demonstrate a low in vitro anticancer potential of the complexes.     

Experimental and DFT Studies on the DNA-binding Properties of Ruthenium(II) Complexes [Ru(phen)2L]2+(L = o-MOP, o-MP, o-CP and o-NP)

A series of ruthenium(II) complexes with electron-donor or electron-acceptor groups in intercalative ligands, [Ru(phen)₂(o-MOP)]²⁺ (1), [Ru(phen)₂(o-MP)]²⁺ (2), [Ru(phen)₂(o-CP)]²⁺ (3) and [Ru(phen)₂(o-NP)]²⁺ (4), have been synthesized and characterized by elementary analysis, ES-MS, ¹H NMR, electronic absorption and emission spectra. The binding properties of these complexes to CT-DNA have been investigated by spectroscopy and viscosity experiments. The results showed that these complexes bind to DNA in intercalation mode and their intrinsic binding constants (K_b) are 1.1, 0.35, 0.53 and 1.7 × 10⁵ M⁻¹, respectively. The subtle but detectable differences occurred in the DNA-binding properties of these complexes are mainly ascribed to the electron-withdrawing abilities of substituents (–OCH₃ < –CH₃ < –Cl < –NO₂) on the intercalative ligands as well as the intramolecular H-bond (for substituent –OCH₃) which increase the planarity area of the intercalative ligand to some extent. The density functional theory (DFT) calculations were also performed and used to further discuss the trend in the DNA-binding affinities of these complexes.