Synthesis and photoelectrochemical properties of cyclometallated ruthenium(II) complex

A new ruthenium complex, (4-carboxy-1,10-phenantroline-7-carboxylate)(4,7-dicarboxy-1,10-phenantroline)(2-phenylpyridino-²C,N) ruthenium(II), was obtained for the application as a sensitizer in photoelectrochemical converters (PECC). Electrochemical and spectral characteristics of the compound were studied. It was found that the illumination of PECC with AM 1.5 100 mW/cm² solar spectrum simulator provides short circuit current density of 3.9 mA cm^?2 and broken circuit voltage of 0.47 V. PECC efficiency is 1.4% at fillfactor 76%. The lifetimes of charge carriers (electrons) and their transit time determined by modulation spectroscopy were found to be 28 and 4 ms, respectively.     

Synthesis,spectroscopic characterization and antibacterial studies of some derivatives of chlorodimethylsulphoxide/tetramethylenesulphoxide ruthenium(II) and ruthenium(III) with 4-aminoantipyrine

We report the synthesis of five complexes of three different formulations viz. [cis-RuCl₂(4-antp)₂], [trans-RuCl₂(4-antp)₂] and [X]⁺[trans-RuCl₄(4-antp)₂]^? (X⁺ = [(DMSO)₂H]⁺, Na⁺, or [(TMSO)H]⁺ and 4-antp = 4-aminoantipyrine) from different routes. These complexes were characterized on the basis of elemental analyses, molar conductance measurements, magnetic susceptibility, electronic spectra, FTIR, ¹H-NMR and ¹³C{¹H}-NMR spectroscopy. Complexes were screened for antibacterial activity and found to be potent against gram negative bacteria Escherichia coli.     

Synthesis and spectroscopic studies of some halogen-dimethylsulphoxide/tetramethylenesulphoxide-ruthenium(II) and ruthenium(III) complexes with 2-aminobenzimidazole

Synthesis and characterization of seven ruthenium(II) and ruthenium(III) complexes of sulphoxide with 2-aminobenzimidazole are reported. Three different formulations exist; [cis-RuCl₂(SO)₃(2-ABZ)]; [trans-RuCl₂(SO)₃)(2-ABZ)]; and [trans-RuCl₄(SO)(2-ABZ (where SO?=?dimethylsulphoxide(DMSO)/tetramethylenesulphoxide(TMSO); 2-ABZ?=?2-aminobenzimidazole). These complexes are characterized by elemental analysis, conductivity magnetic susceptibility, ¹H-NMR, ¹³C{¹H}-NMR and electronic spectroscopy.     

Synthesis,structural, electrochemical,and spectroscopic studies of some (diimine)ruthenium nitrile complexes

The syntheses of cationic ruthenium(II) complexes [Ru(Me₂-bpy)(PPh₃)₂RR?][PF₆]_x {Me₂-bpy = 4,4?-dimethyl-2,2?-bipyridine, (3) R = Cl, R? = N≡CMe, x = 1, (4) R = Cl, R? = N≡CPh, x = 1, (5) R = R? = N≡CMe, x = 2} and [Ru(Me₂-bpy)(κ²-dppf)RR?][PF₆]_x {dppf = 1,1?-bis(diphenylphosphino)ferrocene, (6) R = Cl, R? = N≡CMe, x = 1, (7) R = Cl, R? = N≡CPh, x = 1, (8) R = R? = N≡CMe, x = 2} are reported, together with their structural confirmation by NMR (³¹P, ¹H) and IR spectroscopy and elemental analysis, and, in the case of trans-[Ru(Me₂-bpy)(PPh₃)₂(N≡CCH₃)Cl][PF₆] (3), by X-ray crystallography. Electronic absorption and emission spectra of the complexes reveal that all complexes except 4 and 6 are emissive in the range 370–400 nm with 8 exhibiting an emission in the blue. Cyclic voltammetry studies of 3–8 show reversible or quasi-reversible redox processes at ca. 1 V, assigned to the Ru(II/III) couple.     

Synthesis, structure, catalytic transfer hydrogenation and biological activity of cyclometallated ruthenium(III)2-(arylazo)phenolate complexes

A series of mononuclear organoruthenium complexes of the type [RuX(PPh₃)₂(L)] (X = Cl or Br; L = 2-(arylazo)phenolate ligand) have been synthesized from the reaction of five 2-(arylazo)phenol ligands with ruthenium(III) precursors, viz. [RuCl₃(PPh₃)₃] and [RuBr₃(PPh₃)₂(CH₃OH)] in benzene under reflux. In all these reactions, the 2-(arylazo)phenolate ligand replaces one triphenylphosphine molecule, two chlorides or bromides and one methanol from the precursors leading to five-membered cyclometallated species. The 2-(arylazo)phenol ligands behave as dianionic tridentate C, N, O donors and coordinated to ruthenium by dissociation of the phenolic proton and the phenyl proton at the ortho position of the phenyl ring. The compositions of the complexes have been established by elemental analysis, magnetic susceptibility measurement, FT-IR, UV-Vis and EPR spectral data. These complexes are paramagnetic and shows intense d-d and charge transfer transitions in chloroform. The solution EPR spectrum of the complex 7 in dichloromethane at 77 K shows rhombic distortion around the ruthenium ion. The structural conformation of the complex 1 has been carried out by X-ray crystallography. The redox behavior of the complexes has been investigated by cyclic voltammetry and the potentials are observed with respect to the electronic nature of substituents (R) in the 2-(arylazo) phenolate ligands. These complexes catalyze transfer hydrogenation of benzophenone to benzhydrol with up to 99.5% in the presence of i-prOH/KOH. Further, these complexes have shown great promise in inhibiting the growth of both Gram +ve and Gram −ve bacteria, viz. Staphylococcus aureus NCIM 2079 and Escherichia coli NCIM 2065 and fungus Candida albicans NCIM 3102.     

Synthesis,spectroscopic characterization and antibacterial sensitivity of some chloro dimethylsulfoxide/tetramethylenesulfoxide ruthenium(II) and ruthenium(III) complexes with 2-aminobenzothiazole

Synthesis and characterization of seven ruthenium(II) and ruthenium(III) complexes of sulfoxide with 2-aminobenzothiazole are reported. Three different formulations exist: [cis,cis,cis-RuCl₂(SO)₂(2-abtz)₂] and [trans,trans,trans-RuCl₂(SO)₂(2-abtz)₂] and [trans-RuCl₄(SO)(2-abtz)] ^? [X]⁺ (where SO?=?dimethyl sulfoxide (dmso) or tetramethylenesulfoxide (tmso); 2-abtz?=?2-aminobenzothiazole and [X]⁺?=?[H(abtz)]⁺, [Na⁺]. These complexes were characterized by elemental analyses, conductivity measurements, magnetic susceptibility, FTIR, ¹H NMR, ¹³C{¹H} NMR and electronic spectroscopy. Some of the complexes were screened for their antibacterial activity and are found to be potent against the gram negative bacteria Escherichia coli.     

Synthesis and characterization of a mononuclear ruthenium(III) triazole complex

A mononuclear ruthenium(III) complex containing ethylenediaminetetraacetate (edta), [Ru(Hedta)(Htrz)] · 4H₂O (1) (Htrz = 1H-1,2,4-triazole), has been synthesized and the structure was determined by single-crystal X-ray diffraction. The complex crystallizes in the triclinic space group P 1, with the unit cell parameters a = 7.212(3) Å, b = 9.873(4) Å, c = 13.806(6) Å, α = 91.945(6)°, β = 100.078(6)°, γ = 97.230(7) and Z = 2. The complex was also characterized by elemental analysis, IR, UV–Vis and ESR spectra. Cyclic voltammetry for the complex shows a ruthenium(III)/ruthenium(IV) oxidation and a ruthenium(III)/ruthenium(II) reduction within the range of ?1.5–0.5 V. Magnetic susceptibility data give an effective moment of 1.81 B.M. at room temperature.     

Synthesis,characterization, spectroscopic study,and catalytic behavior of ruthenium(II) o-phenanthroline complex with dipicolinate

A new dipicolinate complex of Ru(II), cis-[Ru(phen)₂dipic]?·?9.5H₂O (1), where dipic is dipicolinate or pyridine-2,6-dicarboxylate and phen is 1,10-phenanthroline, has been synthesized and characterized by elemental analysis, spectroscopic (IR, UV-Vis), cyclic voltammetry, and single-crystal X-ray diffraction. ORTEP drawing of cis-[Ru(phen)₂dipic]?·?9.5H₂O shows that the coordination geometry around Ru(II) is a distorted octahedron. It crystallizes in the triclinic system, with space group P 1, a?=?10.4633(2)?Å, b?=?13.6332(4)?Å, c?=?13.6637(4)?Å, α?=?67.516(3)°, β?=?69.757(2)°, γ?=?77.201(2)°, V?=?1680.74(8)?ų, Z?=?2, and R _int?=?0.0311. In 1, two phen are bidentate N,N′ ligands. The Ru(II) in 1 is bonded to dipicolinate through pyridine nitrogen and one oxygen of carboxylate groups, thus pyridine-2,6-dicarboxylate is a bidentate N,O ligand. Efficient and selective oxidation of alcohols with NaIO₄ as oxidant was conducted by this complex catalyst in CH₃OH/H₂O as solvents under air at room temperature.     

Half-sandwich ruthenium(II)-arene complexes: synthesis,spectroscopic studies,biological properties,and molecular modeling

In search for antitumor metal-based drugs that would mitigate the severe side-effects of cisplatin, Ru(II) complexes are gaining increasing recent interest. In this work, we report on the synthesis, characterization (¹H- and ¹³C-NMR, FT-IR), and cytotoxicity studies of two new half-sandwich organometallic Ru(II) complexes of the general formula [Ru(η⁶-arene)(XY)Cl](PF₆) where arene?=?benzene or toluene and XY?=?bidentates: dipyrido[3,2-a:2′,3′-c]phenazine (dppz) or 2-(9-anthryl)-1H-imidazo[4,5-f][1,10]phenanthroline (aip), which are bound to Ru(II) via two phenanthroline-N atoms in a characteristic “piano-stool” configuration of Ru(II)-arene complexes—as confirmed by vibrational and NMR spectra. In addition, cytotoxic studies were performed for similar half-sandwich organometallic [Ru(η⁶-p-cymene)(Me₂dppz)Cl]PF₆ complex (Me₂dppz = 11,12-dimethyl-dipyrido[3,2-a:2′,3′-c]phenazine). This study is complemented with elaborate modeling with density functional theory (DFT) calculations, which provided insight into reactive sites of Ru(II) structures, further detailed by molecular docking on the B-DNA dodecamer, which identified binding sites and affinities: most pronounced for the [Ru(η⁶-benzene)(aip)Cl](PF₆) in both A-T and G-C regions of the DNA minor groove. Cytotoxic activity was probed versus tumor cell lines B16, C6, and U251 (B16 mouse melanoma, C6 rat glioma, U251 human glioblastoma) and non-tumor cell line HACAT (HACAT normal human keratinocytes).     

Synthesis,characterization, electrochemistry,catalytic, and antimicrobial studies of ruthenium(III) complexes containing ONO donor ligands

A series of ruthenium(III) complexes [RuX(EPh₃)₂L] (where X = Cl or Br; E = P or As; L = deprotonated dibasic tridentate ligand) were prepared by the reaction of [RuX₃(EPh₃)₃] with Schiff bases (H₂L¹–H₂L⁴). The ligands were prepared by the condensation of N-4 phenyl/methyl semicarbazide with o-vanillin/o-hydroxy acetophenone. The complexes were characterized by elemental, physico-chemical, and electrochemical methods. Catalytic studies of these complexes for the oxidation of alcohols and aryl–aryl coupling were carried out. Antimicrobial experiments were also carried out.     

Synthesis,characterization, and antitumor properties of ruthenium(II) anthraquinone complexes

Three new Ru(II) complexes, [Ru(dmb)₂(ipad)](ClO₄)₂ (dmb = 4,4′-dimethyl-2,2′-bipyridine, ipad = 2-(anthracene-9,10-dione-2-yl) imidazo[4,5-f][1,10]phenanthroline, 1), [Ru(dmp)₂(ipad)](ClO₄)₂ (dmp = 2,9-dimethyl-1,10-phenanthroline, 2), and [Ru(dip)₂(ipad)](ClO₄)₂ (dip = 4,7-diphenyl-1,10-phenanthroline, 3), have been synthesized and characterized. The three Ru(II) complexes intercalate with the base pairs of DNA. The in vitro antiproliferative activities and apoptosis-inducing characteristics of these complexes were investigated. The complexes exhibited cytotoxicity against various human cancer cell lines. BEL-7402 cells displayed the highest sensitivity to 1, accounted for by the greatest cellular uptake. Complex 1 was shown to accumulate preferentially in the nuclei of BEL-7402 cells and cause DNA damage and induce apoptosis, which involved cell cycle arrest and reactive oxygen species generation.     

Synthesis,spectroscopic and structural characterization of new complex of ruthenium(II) with Hmtpo ligand

The [(PPh₃)₂RuHCl(CO)(Hmtpo)] complex has been prepared and studied by IR, NMR, UV–VIS spectroscopy and X-ray crystallography. The complex was prepared in reactions of [RuHCl(CO)(PPh₃)₃] with 7-hydroxy-5-methyl[1,2,4]triazolo[1,5-a]pyrimidine in methanol. The electronic structure and UV–Vis spectrum of the obtained compound have been calculated using the TD–DFT method.     

Tailored synthesis,spectroscopic, catalytic,and antibacterial studies of dinuclear ruthenium (II/III) chloro sulfoxide complexes with 5-nitro-o-phenanthroline as a spacer

A dinucleating spacer incorporating o-phenanthroline has been synthesized and characterized. The reaction of this spacer with ruthenium precursors resulted in formation of dinuclear complexes, [cis,fac-RuCl₂(SO)₃ (μ-nphen)cis,cis-RuCl₂(SO)₂], [trans,mer-RuCl₂(SO)₃ (μ-nphen)trans, cis-RuCl₂(SO)₂], and [X]⁺[trans-RuCl₄(SO)(μ-nphen)mer-RuCl₃(SO)]^?, where SO = dimethylsulfoxide/tetramethylenesulfoxide, nphen = 5-nitro-o-phenanthroline, and X⁺ = [(dmso)₂H]⁺, Na⁺, and [(tmso)H]⁺. These complexes were characterized by elemental analyses, conductivity measurements, magnetic susceptibility, FT-IR, FAB-Mass, ¹H-NMR, ¹³C{¹H}-NMR, and electronic spectroscopy. [trans,mer-RuCl₂(dmso)3(μ-nphen)trans,cis-RuCl₂(dmso)₂] was also characterized on the basis of ¹H–¹H COSY NMR. The coordination of one ruthenium is through heterocyclic nitrogen of the o-phenanthroline and the second is through the oxygen of the nitrito group. Catalytic activity of these complexes has been investigated in hydrolysis of benzonitrile. All the complexes possess antibacterial activity against Escherichia coli and are compared to Chloramphenicol.     

Synthesis, spectroscopic, electrochemical and luminescence studies of ruthenium (II) polypyridyls containing multifunctionalized 1,2,4-triazole as co-ligand

Ruthenium (II) 2,2′-bipyridyl and 1,10-phenanthroline complexes with 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (LH₂) as co-ligand were synthesised and characterized by elemental analysis, IR, UV/Vis,¹H NMR spectra and FAB-mass data. The electrochemical and luminescent properties of the complexes were also studied.     

Synthesis,characterization, and catalytic properties of some new ruthenium(II)/(III) complexes containing N,N-donor ligands

This article describes the preparation and characterization of cis-[Ru(bipy)₂L](ClO₄)₂ and trans-[RuCl₂L₂]?·?Cl (bipy?=?2,2′-bipyridyl and L?=?ortho-phenylenediamine (o-phd), 2-aminopyridine (2-apy) and 2-aminobenzonitrile (2-abn), and examines the catalytic oxidations of benzyl alcohol, benzohydrol and pipronyl alcohol by cis-[Ru(bipy)₂ (o-phd)](ClO₄)₂ and trans-[RuCl₂(o-phd)₂]?·?Cl complexes at room temperature and in the presence of N-methyl morpholine-N-oxide (NMO) as co-oxidant.     

A cyclometallated iridium(III) dimethylphenylphosphine complex

[Ir(cod)Cl]₂ (cod = 1,5-cyclooctadiene) reacts with PMe₂Ph in CH₃CN to give the red cation [Ir(PMe₂Ph)₄]⁺. This complex in CH₃CN reacts with H₂ to give cis-[IrH₂(PMe₂Ph)₄]⁺, but on reflux for 6 h in the absence of H₂, it gives the first example of a cyclometallated PMe₂Ph complex fac-[IrH(PMe₂C₆H₄)(PMe₂Ph)₃]⁺, as shown by PMR spectroscopy and preliminary X-ray crystallographic data.     

Coordination of di- and triimine ligands at ruthenium(II) and ruthenium(III) centers: structural,electrochemical and radical scavenging studies

Herein, we explore the coordination of di- and triimine chelators at ruthenium(II) and ruthenium(III) centers. The reactions of 2,6-bis-((4-tetrahydropyranimino)methyl)pyridine (thppy), N¹,N²-bis((3-chromone)methylene)benzene-1,2-diamine (chb), and tris-((1H-pyrrol-2-ylmethylene)ethane)amine (H₃pym) with trans-[Ru^IICl₂(PPh₃)₃] afforded the diamagnetic ruthenium(II) complex cis-[RuCl₂(thppy)(PPh₃)] (1) and the paramagnetic complexes [mer-Ru₂(μ-chb)Cl₆(PPh₃)₂] (2), and [Ru(pym)] (3), respectively. The complexes were characterized by IR, NMR, and UV–vis spectroscopy and molar conductivity measurements. The structures were confirmed by single crystal X-ray diffraction studies. The redox properties of the metal complexes were probed via cyclic- and squarewave voltammetry. Finally, the radical scavenging capabilities of the metal complexes towards the NO and 2,2-di(4-tert-octylphenyl)-1-picrylhydrazyl (DPPH) radicals were investigated     

Synthesis,spectral, and catalytic studies of ruthenium(II) unsymmetrical Schiff-base complexes

Unsymmetrically-substituted ruthenium(II) Schiff-base complexes, [Ru(CO)(B)(L ^x )] [B = PPh₃, AsPh₃ or Py; L ^x = dianion of tetradentate unsymmetrical Schiff-base ligand; x = 4–7, L⁴ = salen-o-hyac, L⁵ = valen-o-hyac, L⁶ = salphen-o-hyac, L⁷ = valen-2-hacn], were prepared and characterized by analytical, IR, electronic, and ¹H NMR spectral studies. The new complexes were tested for their catalytic activity towards the oxidation of benzylalcohol to benzaldehyde.     

Synthesis, spectroscopic analysis and photolabilization of water-soluble ruthenium(III)-nitrosyl complexes

In this paper, the synthesis, structural and spectroscopic characterization of a series of new Ru(III)-nitrosyls of {RuNO}(6) type with the coligand TPA (tris(2-pyridylmethyl)amine) are presented. The complex [Ru(TPA)Cl(2)(NO)]ClO(4) (2) was prepared from the Ru(III) precursor [Ru(TPA)Cl(2)]ClO(4) (1) by simple reaction with NO gas. This led to the surprising displacement of one of the pyridine (py) arms of TPA by NO (instead of the substitution of a chloride anion by NO), as confirmed by X-ray crystallography. NO complexes where TPA serves as a tetradentate ligand were obtained by reacting the new Ru(II) precursor [Ru(TPA)(NO(2))(2)] (3) with a strong acid. This leads to the dehydration of nitrite to NO(+), and the formation of the {RuNO}(6) complex [Ru(TPA)(ONO)(NO)](PF(6))(2) (4), which was also structurally characterized. Derivatives of 4 where nitrite is replaced by urea (5) or water (6) were also obtained. The nitrosyl complexes obtained this way were then further investigated using IR and FT-Raman spectroscopy. Complex 2 with the two anionic chloride coligands shows the lowest N-O and highest Ru-NO stretching frequencies of 1903 and 619 cm(-1) of all the complexes investigated here. Complexes 5 and 6 where TPA serves as a tetradentate ligand show ν(N-O) at higher energy, 1930 and 1917 cm(-1), respectively, and ν(Ru-NO) at lower energy, 577 and 579 cm(-1), respectively, compared to 2. These vibrational energies, as well as the inverse correlation of ν(N-O) and ν(Ru-NO) observed along this series of complexes, again support the Ru(II)-NO(+) type electronic structure previously proposed for {RuNO}(6) complexes. Finally, we investigated the photolability of the Ru-NO bond upon irradiation with UV light to determine the quantum yields (φ) for NO photorelease in complexes 2, 4, 5, and additional water-soluble complexes [Ru(H(2)edta)(Cl)(NO)] (7) and [Ru(Hedta)(NO)] (8). Although {RuNO}(6) complexes are frequently proposed as NO delivery agents in vivo, studies that investigate how φ is affected by the solvent water are lacking. Our results indicate that neutral water is not a solvent that promotes the photodissociation of NO, which would present a major obstacle to the goal of designing {RuNO}(6) complexes as photolabile NO delivery agents in vivo.     

Paramagnetic NMR shift,spectroscopic and molecular modeling studies of lanthanide(III)-morin complexes

Studies on nine-coordinate lanthanide complexes of morin are described. The complexes were characterized by elemental analysis, molar conductance, UV–Vis spectra, IR spectra, thermal analysis and NMR spectra. Molecular modeling studies were also carried out. The complexes are non-electrolytes in DMSO. TGA showed anhydrous nature of the complexes. The electronic spectra of the complexes were recorded in methanol. ¹H NMR spectra of lanthanum, praseodymium, neodymium, samarium and dysprosium complexes have been studied in DMSO-d₆. The complexes do not dissociate in DMSO and retain their coordination. ¹H NMR spectra of paramagnetic and diamagnetic complexes exhibit downfield as well as upfield shifts of morin resonances that shows change in geometry during coordination.