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 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.     

Interpretation of the Electronic Spectra of Ruthenium Nitrosyl Complexes with Nitrogen-containing Heterocyclic Ligands

The electronic absorption spectra of ruthenium nitrosyl complexes with nitrogen-containing heterocyclic ligands were analyzed on the basis of ab initio and CINDO/CI semiempirical calculations of free ligands L and complexes trans-[Ru(NO)(NH₃)₄(L)]^{3 +} (L = pyridine, pyrazine, nicotinamide, isonicotinamide, l-histidine, imidazole). Spectral manifestations of a strong covalent Ru-NO bond were observed to conclude that the oxidation states of Ru and NO in the RuNO^{3 +} group are expedient to represent as Ru(III) and NO⁰. Introduction of a nitrosyl group into the inner coordination sphere of Ru(II) complexes with nitrogen-containing heterocyclic ligands much affects the entire spectral patterns and denudes these ligands of the capacity to exhibit chromophoric properties.     

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.     

Formation of Oligo-Nuclear Carboxylate Nickel(II) Complexes with Nitrogen-Containing Ligands. Quantum-Chemical Simulation

Using the DFT method PBE0/6-31G(d, p) and taking into account the solvent, the formation of bi- and pentahedral Ni(II) complexes with carboxylate and N-containing ligands in the gas phase was studied, and ΔG° of their formation from simple compounds was estimated. The functional role of bridging groups and hydrogen bonds in the formation of polynuclear structures was revealed. A model of self-organization of penta-nuclear coordination compounds [Ni^II₅(O₂CR)₈L_2n(μ-OH)₂]⁰ from binuclear complex [Ni^II₂(O₂CR)₄L_n(μ-H₂O)]⁰ was proposed, into the structure of which mononuclear Ni^II cations are embedding and promote proton transfer from bridging aqua ligands.

     

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: IX. Nitro-Nitrosyl Equilibrium in cis-[Ru(2,2'-bpy)2(L)NO2]+ Complexes

Ruthenium(II) bisbipyridyl complexes cis-[Ru(bpy)₂(L)NO₂](BF₄) (bpy is 2,2'-bipyridyl) with 4-substituted pyridine ligands L = 4-(Y)py (Y = NH₂, Me, Ph, and CN) were obtained. The equilibrium constants of the reversible nitro-nitrosyl transition [Ru(bpy)₂(L)NO₂]⁺ + 2H⁺ [Ru(bpy)₂(L)NO]^{3 +} + H₂O were measured in solutions with pH 1.5-8.5 (ionic strength 0.4). The constants correlate with the protonation constants of free ligands 4-(Y)py.     

Ruthenium(II) Complexes with Three Different Diimine Ligands

The synthesis of tri-heteroleptic complex of Ru(II) with diimine ligands is describe. Ten compounds [Ru(R₂bpy) (biq) (L)][PF₆]₂ (R = H, CH₃); L = 2,2′-bipyridine (bpy), 4,4′-dimethyl-2,2′-bipyridine (Me₂bpy), 2,2′-bipyrimidine (bpm), 2,2′-biisoquinoline (biiq), 1,10-phenanthroline (phen), dipyrido[3,2-c:2′,3′-e]pyridazine (taphen), 2,2′-biquinoline (biq), 6,7-dihydrodipyrido[2,3-b:3,2-j][1,10]-phenanthroline (dinapy), 2-(2[pyridyl)quinoline (pq), 1-(2-pyrimidyl)pyrazole] (pzpm), 2,2′-biimidazole (H₂biim) are characterized by elemental analysis, electronic and ¹H-NMR spectroscopy. The relative photosustitution rates of biq in MeCN are given at three temperatures.     

Cationic Ruthenium(II) Carbonyl Complexes with Nitrile Ligands

Stable cationic complexes of the type [RuCO(PPh₃)₂(L)(RCN)]⁺[ClO₄]^? derived from acetonitrile and acrylonitrile have been synthesized. The bidentate ligands (LH) used are acetylacetone, benzoylacetone, dibenzoylmethane, trifluorothenoyl acetone and 8-hydroxyquinoline. The complexes have been characterized by elemental analysis, IR, conductivity, ¹H and ³¹P NMR and ESCA studies, and possible stereochemistry has been established.     

Photocytotoxic Activity of Ruthenium(II) Complexes with Phenanthroline-Hydrazone Ligands

This paper reports on the synthesis and characterization of two new polypyridyl-hydrazone Schiff bases, (E)-N′-(6-oxo-1,10-phenanthrolin-5(6H)-ylidene)thiophene-2-carbohydrazide (L¹) and (E)-N′-(6-oxo-1,10-phenanthrolin-5(6H)-ylidene)furan-2-carbohydrazide (L²), and their two Ru(II) complexes of the general formula [RuCl(DMSO)(phen)(Lⁿ)](PF6). Considering that hydrazides are a structural part of severa l drugs and metal complexes containing phenanthroline derivatives are known to interact with DNA and to exhibit antitumor activity, more potent anticancer agents can be obtained by covalently linking the thiophene acid hydrazide or the furoic acid hydrazide to a 1,10-phenanthroline moiety. These ligands and the Ru(II) complexes were characterized by elemental analyses, electronic, vibrational, ¹H NMR, and ESI-MS spectroscopies. Ru is bound to two different N-heterocyclic ligands. One chloride and one S-bonded DMSO in cis-configuration to each other complete the octahedral coordination sphere around the metal ion. The ligands are very effective in inhibiting cellular growth in a chronic myelogenous leukemia cell line, K562. Both complexes are able to interact with DNA and present moderate cytotoxic activity, but 5 min of UV-light exposure increases cytotoxicity by three times.     

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.     

新型不对称三齿多吡啶配体及其混配钌(II)配合物的合成、表征及与DNA相互作用研究

合成了两个新型不对称三齿多吡啶配体 ,3 ( 1,10 菲咯啉基 2 ) 1,2 ,4 三唑 (PHT) ,3 ( 1,10 菲咯啉基 2 ) 5 甲基 1,2 ,4 三唑 (PHMT) ,及其混配配合物 [Ru(tpy) (PHT) ] 2 + (Ru1)和 [Ru(tpy) (PHMT) ] 2 + (Ru2 ) ,通过元素分析、FAB MS ,ES MS ,1HNMR ,IR ,UV vis ,发射光谱和电化学对它们进行了表征 .运用电子吸收光谱、竞争性结合实验和粘度测试等方法研究了配合物与DNA的作用机理 ,结果显示它们均是通过静电作用与DNA结合 ,且Ru2与DNA的作用比Ru1与DNA的作用更强 .     

Ru(II) Chloro-Bis(bipyridyl) Complexes with Substituted Pyridine Ligands: Interpretation of Their Electronic Absorption Spectra

A number of complexes were synthesized with the general formula cis-[Ru(Bipy)₂(L)(Cl)](BF₄), where Bipy is 2,2"-bipyridine, L is pyridyne (Py), 4-aminopyridine (4-NH₂py), 4-picoline (4-Mepy), nicotin-amide (3-CONH₂py), isonicotinamide (4-CONH₂py), 3- and 4-cyanopyridine (3-CNpy, 4-CNpy), 4,4"-bipyridine (4,4"-Bipy), trans-1,2-bis(4-pyridyl)ethylene (Bpe), 4,4"-azopyridine (Azpy), pyrazine (Pyz), imidazole (Imid), and NH₃. The semiempirical CINDO-CI method was used to calculate the energies and intensities of transitions in the electronic absorption spectra. The differences observed in the spectra of these compounds are mainly due to the positions of the charge-transfer transitions d (Ru) *(L). Depending on the positions of these transitions, ligands L can be divided into three groups: 1) transitions Ru L lie in the region of the first long-wavelength band d (Ru) *(Bipy) (L = Azpy, Pyz); 2) transitions Ru L lie between the first and second bands due to the charge transfer to Bipy (L = 3-CONH₂py, 4-CONH₂py, 4,4"-Bipy, Bpe, 4-CNpy), and 3) transitions Ru L lie in the region of the second band d (Ru) *(Bipy) (L = Py, 4-Mepy, 3-CNPy, 4-NH₂py, Imid).     

Effect of Nonchromophoric Ligands on the Spectral Characteristics of Ruthenium(II) (2,2'-Bipyridine)diphosphine Complexes

The electronic absorption and luminescence spectra of the complexes cis-[Ru(bpy)(dppe)X₂] [bpy is 2,2'-bipyridine, dppe is 1,2-bis(diphenylphosphino)ethane] in 4 : 1 ethanol-methanol mixtures at 77 and 293 K were measured, and the luminescence decay times were determined. As the field strength of the nonchromophoric ligand X increases in the order I^- < Br^- < Cl^- < 1/2(CO₃ ^{2 -}) < NCS^- < NO₂ ^- < CN^-, the electronic transitions are blue-shifted, and the luminescence decay time becomes longer.     

Cyclopentadienyl Ruthenium(II) Complexes with Bridging Alkynylphosphine Ligands: Synthesis and Electrochemical Studies

The reaction of [CpRuCl(PPh₃)₂] (Cp=cyclopentadienyl) and [CpRuCl(dppe)] (dppe=Ph₂PCH₂CH₂PPh₂) with bis‐ and tris‐phosphine ligands 1,4‐(Ph₂PC≡C)₂C₆H₄ ( 1 ) and 1,3,5‐(Ph₂PC≡C)₃C₆H₃ ( 2 ), prepared by Ni‐catalysed cross‐coupling reactions between terminal alkynes and diphenylchlorophosphine, has been investigated. Using metal‐directed self‐assembly methodologies, two linear bimetallic complexes, [{CpRuCl(PPh₃)}₂(μ‐dppab)] ( 3 ) and [{CpRu(dppe)}₂(μ‐dppab)](PF₆)₂ ( 4 ), and the mononuclear complex [CpRuCl(PPh₃)(η¹‐dppab)] ( 6 ), which contains a “dangling arm” ligand, were prepared (dppab=1,4‐bis[(diphenylphosphino)ethynyl]benzene). Moreover, by using the triphosphine 1,3,5‐tris[(diphenylphosphino)ethynyl]benzene (tppab), the trimetallic [{CpRuCl(PPh₃)}₃(μ₃‐tppab)] ( 5 ) species was synthesised, which is the first example of a chiral‐at‐ruthenium complex containing three different stereogenic centres. Besides these open‐chain complexes, the neutral cyclic species [{CpRuCl(μ‐dppab)}₂] ( 7 ) was also obtained under different experimental conditions. The coordination chemistry of such systems towards supramolecular assemblies was tested by reaction of the bimetallic precursor 3 with additional equivalents of ligand 2 . Two rigid macrocycles based on cis coordination of dppab to [CpRu(PPh₃)] were obtained, that is, the dinuclear complex [{CpRu(PPh₃)(μ‐dppab)}₂](PF₆)₂ ( 8 ) and the tetranuclear square [{CpRu(PPh₃)(μ‐dppab)}₄](PF₆)₄ ( 9 ). The solid‐state structures of 7 and 8 have been determined by X‐ray diffraction analysis and show a different arrangement of the two parallel dppab ligands. All compounds were characterised by various methods including ESIMS, electrochemistry and by X‐band ESR spectroscopy in the case of the electrogenerated paramagnetic species.     

The Tunable Luminescence of Ruthenium(II) Complexes Containing Different Tetrazolate Ligands

Three luminescent mononuclear Ru^II compounds, [Ru^II(bpy)₂( L¹ )](BF₄) ( 1 ), [Ru^II(bpy)₂( L² )](BF₄) ( 2 ), and the neutral compound [Ru^II(bpy)₂( L³ )] ( 3 ), were obtained, by treatment of [Ru^II(bpy)₂Cl₂] with the tetrazolate (tz)-containing ligands L¹ – L³ . All the compounds were well characterized by IR, UV/Vis, and ¹H NMR and their redox properties were also investigated by cyclic voltammogram. The crystal structure of 3 was determined by X-ray crystallography and it clearly shows that the Ru^II ion is octahedrally coordinated by two bpy ligands and a deprotonated L³ ligand. After introduction of these tz ligands, 1 – 3 are more sensitive towards the change of micro-environment of solvents as compared with that of [Ru^II(bpy)₃]²⁺. This effect is most obvious in 3 , since it contains a 2^– ligand L³ . The slight modification of diimine ligand make these complexes have potential applications as sensors.     

Bioorthogonal Labeling,Bioimaging, and Photocytotoxicity Studies of Phosphorescent Ruthenium(II) Polypyridine Dibenzocyclooctyne Complexes

The synthesis, characterization, photophysics, lipophilicity, and cellular properties of new phosphorescent ruthenium(II) polypyridine complexes functionalized with a dibenzocyclooctyne (DIBO) or amine moiety [Ru(N^N)₂(L)](PF₆)₂ are reported (L=4‐(13‐N‐(3,4:7,8‐dibenzocyclooctyne‐5‐oxycarbonyl) amino‐4,7,10‐trioxa‐tridecanyl‐aminocarbonyl‐oxy‐methyl)‐4′‐methyl‐2,2′‐bipyridine bpy‐DIBO, N^N=2,2′‐bipyridine bpy ( 1 a ), 1,10‐phenanthroline phen ( 2 a ); L=4‐(13‐amino‐4,7,10‐trioxa‐tridecanylaminocarbonyl‐oxy‐methyl)‐4′‐methyl‐2,2′‐bipyridine bpy‐NH₂, N^N=bpy ( 1 b ), phen ( 2 b )). The strain‐promoted alkyne–azide cycloaddition (SPAAC) reaction of the DIBO complexes 1 a and 2 a with benzyl azide were studied. Also, the DIBO complexes 1 a and 2 a can selectively label N‐azidoglycans located on the surface of CHO‐K1 and A549 cells that were pretreated with 1,3,4,6‐tetra‐O‐acetyl‐N‐azidoacetyl‐D ‐mannosamine (Ac₄ManNAz). Additionally, the intracellular trafficking and localization of these biomolecules were monitored using laser‐scanning confocal microscopy. Interestingly, the biolabeling and cellular uptake efficiency of the DIBO complexes 1 a and 2 a were cell‐line dependent, as revealed by flow cytometry and ICP‐MS. Furthermore, the complexes showed good biocompatibility toward the Ac₄ManNAz‐pretreated cells in the dark, but exhibited photoinduced cytotoxicity due to the generation of singlet oxygen.