Redox processes of ruthenium (II) polypyridine complexes induced by fast-atom bombardment mass spectrometry

Fast-atom bombardment (FAB) mass spectrometry in the negative ionization mode enables the sputtering into the gas phase of the ruthenium complexes [Ru(2,2′-bipyridine[bpy])₂(2,5-bis) (pyrydil)pyrazine[dpp])](PF₆)₂; [Ru(bpy)₂,(2,3dpp)](PF₆)₂;[Ru(bpy)₂,(2,3-dpp-Me)]( PF₆)₃; and [Ru(bpy)₂(?-2,3-dpp)]₂ RuCl₂(PF₆)₄ as intact radical anions. These data, combined with those avaiiable from the positive FAB spectra allow a full characterization of the analytes.     

New Ruthenium(II) Complexes Functionalized with Coumarin Derivatives: Synthesis,Energy‐Transfer‐Based Sensing of Esterase,Cytotoxicity, and Imaging Studies

Two new bichromophoric ruthenium(II) complexes, [Ru(bpy)₂(bpy‐CM)](PF₆)₂ and [Ru(bpy)₂(bpy‐CM343)](PF₆)₂ (bpy=2,2′‐bipyridine, CM=coumarin) with appended coumarin ligands have been designed and synthesized. The energy‐transfer‐based sensing of esterase by the complexes has been studied by using UV/Vis and luminescence spectroscopic methods. The cytotoxicity and the cellular uptake of one of the complexes have also been investigated.     

系列含4，5-二氮杂-9，9’-螺二芴配体的钌配合物的合成及其性能研究

本文合成了3个新钌（Ⅱ）配合物,[Ru（bpy）₂（SB）]（PF₆）₂、[Ru（bpy）（SB）₂]（PF₆）₂和[Ru（SB）₃]（PF₆）₂（bpy=2,2’-bipyridine,SB=4,5-diaza-9,9’-spirobifluorene）,通过核磁和元素分析对配合物的结构进行了确定。[Ru（bpy）₂（SB）]（PF₆）₂通过X射线单晶衍射确认了结构。研究了配合物的光物理性能。结果表明[Ru（bpy）₂（SB）]（PF₆）₂在乙腈中的发桔红光,波长为606nm,量子产率约为0.0012。在同样条件下[Ru（bpy）（SB）₂]（PF₆）₂和[Ru（SB）₃]（PF₆）₂的发光非常微弱甚至几乎没有发光。还研究了这些配合物的电致化学发光性能。随着配体中SB含量的增加,发光的峰电压从1.36V增加到1.58V,相对发光强度从731降低到52。     

系列含4,5-二氮杂-9,9′-螺二芴配体的钌配合物的合成及其性能研究(英文)

合成了3个钌髤配合物,[Ru(bpy)2(SB)](PF6)2、[Ru(bpy)(SB)2](PF6)2和[Ru(SB)3](PF6)2(bpy=2,2′-bipyridine,SB=4,5-diaza-9,9′-spirobifluorene),通过核磁和元素分析对配合物的结构进行了确定。[Ru(bpy)2(SB)](PF6)2通过X射线单晶衍射确认了结构。研究了配合物的光物理性能。结果表明[Ru(bpy)2(SB)](PF6)2在乙腈中的发桔红光,波长为606 nm,量子产率约为0.001 2。在同样条件下[Ru(bpy)(SB)2](PF6)2和[Ru(SB)3](PF6)2的发光非常微弱甚至几乎没有发光。还研究了这些配合物的电致化学发光性能。随着配体中SB含量的增加,发光的峰电压从1.36 V增加到1.58 V,相对发光强度从731降低到52。     

Crystallographic report: A synthetic precursor for hetero‐binuclear metal complexes, [Ru(bpy)(dppy)2(CO)2](PF6)2 (bpy = 2,2′‐bipyridine,dppy = 2‐(diphenylphosphino)pyridine)

In the title complex, [Ru(bpy)(dppy)₂(CO)₂](PF₆)₂ (bpy = 2,2′‐bipyridine, dppy = 2‐(diphenylphosphino)pyridine), the ruthenium atom exhibits a slightly distorted octahedral coordination with the carbonyl ligands in cis positions. In addition, two dppy ligands coordinate to the ruthenium center through the phosphorus atoms in mutually trans positions and two pyridyl nitrogen atoms of the dppy direct toward two carbonyl ligands. Copyright © 2004 John Wiley & Sons, Ltd.     

DNA-Targeting RuII-Polypyridyl Complex with a Long-Lived Intraligand Excited State as a Potential Photodynamic Therapy Agent

Subtle ligand modifications on Ru^II-polypyridyl complexes may result in different excited-state characteristics, which provides the opportunity to tune their photo-physicochemical properties and subsequently change their biological functions. Here, a DNA-targeting Ru^II-polypyridyl complex (named Ru1 ) with highly photosensitizing ³IL (intraligand) excited state was designed based on a classical DNA-intercalator [Ru(bpy)₂(dppz)] ⋅ 2 PF₆ by incorporation of the dppz (dipyrido[3,2-a:2′,3′-c]phenazine) ligand tethered with a pyrenyl group, which has four orders of magnitude higher potency than the model complex [Ru(bpy)₂(dppz)] ⋅ 2 PF₆ upon light irradiation. This study provides a facile strategy for the design of organelle-targeting Ru^II-polypyridyl complexes with dramatically improved photobiological activity.     

Chemistry of ruthenium in N2P2X2 (X = Cl, Br) coordination sphere: Synthesis, characterization and reactivities

Reaction of 2-(phenylazo)pyridine (pap) with [Ru(PPh₃)₃X₂] (X = Cl, Br) in dichloromethane solution affords [Ru(PPh₃)₂(pap)X₂]. These diamagnetic complexes exhibit a weakdd transition and two intense MLCT transitions in the visible region. In dichloromethane solution they display a one-electron reduction of pap near − 0.90 V vs SCE and a reversible ruthenium(II)-ruthenium(III) oxidation near 0.70 V vs SCE. The [Ru^III(PPh₃)₂(pap)Cl₂]⁺ complex cation, generated by coulometric oxidation of [Ru(PPh₃)₂(pap)Cl₂], shows two intense LMCT transitions in the visible region. It oxidizes N,N-dimethylaniline and [Ru^II(bpy)₂Cl₂] (bpy = 2,2′-bipyridine) to produce N,N,N′,N′-tetramethylbenzidine and [Ru^III(bpy)₂Cl₂]⁺ respectively. Reaction of [Ru(PPh₃)₂(pap)X₂] with Ag⁺ in ethanol produces [Ru(PPh₃)₂(pap)(EtOH)₂]²⁺ which upon further reaction with L (L = pap, bpy, acetylacetonate ion(acac⁻) and oxalate ion (ox²⁻)) gives complexes of type [Ru(PPh₃)₂(pap)(L)]ⁿ⁺ (n = 0, 1, 2). All these diamagnetic complexes show a weakdd transition and several intense MLCT transitions in the visible region. The ruthenium(II)-ruthenium(III) oxidation potential decreases in the order (of L): pap > bpy > acac⁻ > ox²⁻. Reductions of the coordinated pap and bpy are also observed.     

Synthesis, photochemistry, and electrochemistry of ruthenium(II) polypyridyl complexes anchored by dicobalt carbonyl units

A novel hybrid complex system of ruthenium polypyridyl complexes anchored by dicobalt carbonyl units, [Ru(bpy)₂{phen-C{Co₂(CO)₄(dppm)}C-tolyl}](PF₆)₂ (1) and [Ru(bpy)₂{tolyl-C{Co₂(CO)₄(dppm)}C-phen-C{Co₂(CO)₄(dppm)}C-tolyl}](PF₆)₂ (2), has been prepared from the dicobalt carbonyl complex Co₂(CO)₆(dppm) (dppm = bis(diphenylphosphino)methane) and the ruthenium complex [Ru(bpy)₂(phen--tolyl)](PF₆)₂ (3) or [Ru(bpy)₂(tolyl--phen--tolyl)](PF₆)₂ (4).The present Ru-Co₂ hybrid complexes 1 and 2 are nonluminescent at room temperature, although precursor ruthenium polypyridyl complexes, such as 3 and 4, clearly show phosphorescence from the ³MLCT excited state. The emission quenching of these hybrid complexes indicates the intramolecular energy transfer from the ruthenium polypyridyl unit to the dicobalt carbonyl unit(s) and then to the ground state by a radiationless deactivation process accompanied by a vibrational relaxation of the dicobalt carbonyl unit(s). This interpretation is supported by spectral change measurements along with constant potential electrolysis and electrochemical data.     

Triplet Energy Transfer from Ruthenium Complexes to Chiral Eniminium Ions: Enantioselective Synthesis of Cyclobutanecarbaldehydes by [2+2] Photocycloaddition

Chiral eniminium salts, prepared from α,β‐unsaturated aldehydes and a chiral proline derived secondary amine, underwent, upon irradiation with visible light, a ruthenium‐catalyzed (2.5 mol %) intermolecular [2+2] photocycloaddition to olefins, which after hydrolysis led to chiral cyclobutanecarbaldehydes (17 examples, 49–74 % yield), with high diastereo‐ and enantioselectivities. Ru(bpz)₃(PF₆)₂ was utilized as the ruthenium catalyst and laser flash photolysis studies show that the catalyst operates exclusively by triplet‐energy transfer (sensitization). A catalytic system was devised with a chiral secondary amine co‐catalyst. In the catalytic reactions, Ru(bpy)₃(PF₆)₂ was employed, and laser flash photolysis experiments suggest it undergoes both electron and energy transfer. However, experimental evidence supports the hypothesis that energy transfer is the only productive quenching mechanism. Control experiments using Ir(ppy)₃ showed no catalysis for the intermolecular [2+2] photocycloaddition of an eniminium ion.     

Ruthenium carbonyl derivatives of N-salicylidene-2-hydroxyaniline

The ruthenium tricarbonyl derivative [Ru(CO)₃(sha)] (1), was synthesized from reaction of [Ru₃(CO)₁₂] with N-salicylidene-2-hydroxyaniline (shaH₂) Schiff base. The corresponding reactions of the ruthenium cluster with shaH₂ in presence of a secondary ligand L,L?=?pyridine and triphenyl phosphine resulted in the formation of the dicarbonyl derivatives [Ru(CO)₂(shaH₂)(L)] (2, 3). In the presence of L?=?2-aminobenzimidazole or thiourea, two complexes [Ru(CO)₂(sha)(L)] (4, 5) were formed and the shaH₂ ligand bonded to ruthenium oxidatively. The bipyridine(bpy) derivative had the molecular formula [Ru(CO)₂(shaH)(bpy)] (6), with shaH coordinated bidentate. All complexes were characterized by elemental analysis and mass, IR, ¹H NMR and UV–Vis spectroscopy. The spectroscopic studies of these complexes revealed several structural arrangements and different tautomeric forms.     

Tuning Excited State Isomerization Dynamics through Ground State Structural Changes in Analogous Ruthenium and Osmium Sulfoxide Complexes

The complexes [Ru(bpy)₂(pyESO)](PF₆)₂ and [Os(bpy)₂(pyESO)](PF₆)₂, in which bpy is 2,2′‐bipyridine and pyESO is 2‐((isopropylsulfinyl)ethyl)pyridine, were prepared and studied by ¹H NMR, UV–visible and ultrafast transient absorption spectroscopy, as well as by electrochemical methods. Crystals suitable for X‐ray structural analysis were grown for [Ru(bpy)₂(pyESO)](PF₆)₂. Cyclic voltammograms of both complexes provide evidence for S→O and O→S isomerization as these voltammograms are described by an ECEC (electrochemical‐chemical electrochemical‐chemical) mechanism in which isomerization follows Ru²⁺ oxidation and Ru³⁺ reduction. The S‐ and O‐bonded Ru^3+/2+ couples appear at 1.30 and 0.76 V versus Ag/AgCl in propylene carbonate. For [Os(bpy)₂(pyESO)](PF₆)₂, these couples appear at 0.97 and 0.32 V versus Ag/AgCl in acetonitrile, respectively. Charge‐transfer excitation of [Ru(bpy)₂(pyESO)](PF₆)₂ results in a significant change in the absorption spectrum. The S‐bonded isomer of [Ru(bpy)₂(pyESO)]²⁺ features a lowest energy absorption maximum at 390 nm and the O‐bonded isomer absorbs at 480 nm. The quantum yield of isomerization in [Ru(bpy)₂(pyESO)]²⁺ was found to be 0.58 in propylene carbonate and 0.86 in dichloroethane solution. Femtosecond transient absorption spectroscopic measurements were collected for both complexes, revealing time constants of isomerizations of 81 ps (propylene carbonate) and 47 ps (dichloroethane) in [Ru(bpy)₂(pyESO)]²⁺. These data and a model for the isomerizing complex are presented. A striking conclusion from this analysis is that expansion of the chelate ring by a single methylene leads to an increase in the isomerization time constant by nearly two orders of magnitude.     

Selective Preparation of a Heteroleptic Cyclometallated Ruthenium Complex Capable of Undergoing Photosubstitution of a Bidentate Ligand

Cyclometallated ruthenium complexes typically exhibit red-shifted absorption bands and lower photolability compared to their polypyridyl analogues. They also have lower symmetry, which sometimes makes their synthesis challenging. In this work, the coordination of four N,S bidentate ligands, 3-(methylthio)propylamine (mtpa), 2-(methylthio)ethylamine (mtea), 2-(methylthio)ethyl-2-pyridine (mtep), and 2-(methylthio)methylpyridine (mtmp), to the cyclometallated precursor [Ru(bpy)(phpy)(CH₃CN)₂]⁺ (bpy=2,2′-bipyridine, Hphpy=2-phenylpyridine) has been investigated, furnishing the corresponding heteroleptic complexes [Ru(bpy)(phpy)(N,S)]PF₆ ([ 2 ]PF₆–[ 5 ]PF₆, respectively). The stereoselectivity of the synthesis strongly depended on the size of the ring formed by the Ru-coordinated N,S ligand, with [ 2 ]PF₆ and [ 4 ]PF₆ being formed stereoselectively, but [ 3 ]PF₆ and [ 5 ]PF₆ being obtained as mixtures of inseparable isomers. The exact stereochemistry of the air-stable complex [ 4 ]PF₆ was established by a combination of DFT, 2D NMR, and single-crystal X-ray crystallographic studies. Finally, [ 4 ]PF₆ was found to be photosubstitutionally active under irradiation with green light in acetonitrile, which makes it the first cyclometallated ruthenium complex capable of undergoing selective photosubstitution of a bidentate ligand.     

2Rotaxane based on terpyridyl bimetal ruthenium complexes and β-cyclodextrin as organic sensitizer for dye-sensitized solar cells

The conjugated carboxy-functionalized terpyridyl bimetal ruthenium complex [(tdctpy)Ru(dctpy-(ph)₄-dctpy)Ru(tdctpy)][PF₆]₄ and [2]rotaxane by self-assembly of [(tdctpy)Ru(dctpy-(ph)₄-dctpy)Ru(tdctpy)][PF₆]₄ with β-cyclodextrin are reported as sensitizer for dye-sensitized solar cells (DSSCs), where tdctpy?=?4′-p-tolyl-4,4″-dicarboxy-2,2′?:?6,2″-terpyridine, dctpy?=?4,4″-dicarboxy-2,2′?:?6,2″-terpyridine and dctpy-(ph)₄-dctpy represents a bridging ligand where two 4,4″-dicarboxy-2,2′?:?6′,2″-terpyridine units are connected through four phenyl spacers in the 4′-position. The DSSCs fabricated utilizing these materials give typical electric power conversion efficiency of 0.013–0.523% under air mass (AM) 1.5, 100?mW?cm^?2 irradiation at room temperature. The terpyridyl bimetal ruthenium complex [(tdctpy)Ru(dctpy-(ph)₄-dctpy)Ru(tdctpy)][PF₆]₄ with conjugated-bridge chains displayed much higher conversion efficiency compared with the carboxy-functionalized terpyridyl monometal ruthenium complex [tdctpy-Ru-(idctpy)][PF₆]₂, where idctpy?=?4′-p-iodophenyl-4,4″-dicarboxy-2,2′?:?6,2″-terpyridine. [2]Rotaxane displayed the highest electric power conversion efficiency of 0.523% when β-cyclodextrin was introduced into the conjugated terpyridyl bimetal ruthenium complex and formed [2]rotaxane.     

Heterodinuclear Ruthenium(II) Complexes of the Bridging Ligand 1,6,7,12‐Tetraazaperylene with Iron(II), Cobalt(II), Nickel(II), as well as Palladium(II) and Platinum(II)

The first heterodinuclear ruthenium(II) complexes of the 1,6,7,12‐tetraazaperylene (tape) bridging ligand with iron(II), cobalt(II), and nickel(II) were synthesized and characterized. The metal coordination sphere in this complexes is filled by the tetradentate N,N′‐dimethyl‐2,11‐diaza[3.3](2,6)‐pyridinophane (L‐N₄Me₂) ligand, yielding complexes of the general formula [(L‐N₄Me₂)Ru(µ‐tape)M(L‐N₄Me₂)](ClO₄)₂(PF₆)₂ with M = Fe {[ 2 ](ClO₄)₂(PF₆)₂}, Co {[ 3 ](ClO₄)₂(PF₆)₂}, and Ni {[ 4 ](ClO₄)₂(PF₆)₂}. Furthermore, the heterodinuclear tape ruthenium(II) complexes with palladium(II)‐ and platinum(II)‐dichloride [(bpy)₂Ru(μ‐tape)PdCl₂](PF₆)₂ {[ 5 ](PF₆)₂} and [(dmbpy)₂Ru(μ‐tape)PtCl₂](PF₆)₂ {[ 6 ](PF₆)₂}, respectively were also prepared. The molecular structures of the complex cations [ 2 ]⁴⁺ and [ 4 ]⁴⁺ were discussed on the basis of the X‐ray structures of [ 2 ](ClO₄)₄ · MeCN and [ 4 ](ClO₄)₄ · MeCN. The electrochemical behavior and the UV/Vis absorption spectra of the heterodinuclear tape ruthenium(II) complexes were explored and compared with the data of the analogous mono‐ and homodinuclear ruthenium(II) complexes of the tape bridging ligand.     

High yield preparation of a novel tetrakis[ruthenium tris(bipyridine)]calix[6]arene derivative with good diastereomeric purity

In order to develop methodology for the selective preparation of complex molecular structures with potential photochemical or electron transfer functions, the diastereoselective synthesis of multiple ruthenium tris(bipyridine) complexes tethered to a central calix[6]arene core was investigated. Applying recently developed methodology, the resolved precursor cis-Δ-[Ru(bpy)₂(DMSO)Cl]PF₆ (98.6% ee) was efficiently reacted with a novel calix[6]arene derivative, to give the tetrakis[Ru(bpy)₂(bpy′)]calix[6]arene derivative (9) with almost complete retention of absolute stereochemistry at each of the four metal centres, as seen by the unusually strong molar circular dichroism (CD) spectrum. The synthesis of racemic 9 was also carried out, and demonstrated to have an inactive CD spectrum.     

Synthesis,spectral characterization and cytotoxicity of Ru–bipyridyl complexes containing hexakis(pyrazol-1-yl)benzene (hpzb) as a co-ligand

A novel ruthenium bisbipyridine complex, [Ru(bpy)₂(hpzb)](PF₆)₂ (1) (hpzb = hexakis(pyrazol-1-yl)benzene) was obtained in the reaction between [Ru(bpy)₂Cl₂], the tritopic ligand hpzb and NH₄PF₆. A high selectivity has been found in the reaction and when the hpzb ligand was made to react with more than one ruthenium fragment, it coordinated selectively only to the first metallic fragment, and it was not possible to introduce two or three ruthenium centres. A similar complex with a deuterated bipyridine has also been obtained. The reaction with the methylated ligand hexakis(3,5-dimethylpyrazol-1-yl)benzene does not take place. A complete assignment of all the proton and carbon NMR signals of 1 was carried out. The orientation of the free pyrazolyl groups is also discussed. The redox properties and the anticancer activity of complex 1 have been studied.     

Strong Ligand Stabilization Based on π-Extension in a Series of Ruthenium Terpyridine Water Oxidation Catalysts

The substitution behavior of the monodentate Cl ligand of a series of ruthenium(II) terpyridine complexes (terpyridine (tpy)=2,2′:6′,2′′-terpyridine) has been investigated. ¹H NMR kinetic experiments of the dissociation of the chloro ligand in D₂O for the complexes [Ru(tpy)(bpy)Cl]Cl ( 1 , bpy=2,2’-bipyridine) and [Ru(tpy)(dppz)Cl]Cl ( 2 , dppz=dipyrido[3,2-a:2′,3′-c]phenazine) as well as the binuclear complex [Ru(bpy)₂(tpphz)Ru(tpy)Cl]Cl₃ ( 3 b , tpphz=tetrapyrido[3,2-a:2′,3′-c:3′′,2′′-h:2′′′,3′′′-j]phenazine) were conducted, showing increased stability of the chloride ligand for compounds 2 and 3 due to the extended π-system. Compounds 1 – 5 ( 4 =[Ru(tbbpy)₂(tpphz)Ru(tpy)Cl](PF₆)₃, 5 =[Ru(bpy)₂(tpphz)Ru(tpy)(C₃H₈OS)/(H₂O)](PF₆)₃, tbbpy=4,4′-di-tert-butyl-2,2′-bipyridine) are tested for their ability to run water oxidation catalysis (WOC) using cerium(IV) as sacrificial oxidant. The WOC experiments suggest that the stability of monodentate (chloride) ligand strongly correlates to catalytic performance, which follows the trend 1 > 2 > 5 ≥ 3 > 4 . This is also substantiated by quantum chemical calculations, which indicate a stronger binding for the chloride ligand based on the extended π-systems in compounds 2 and 3 . Additionally, a theoretical model of the mechanism of the oxygen evolution of compounds 1 and 2 is presented; this suggests no differences in the elementary steps of the catalytic cycle within the bpy to the dppz complex, thus suggesting that differences in the catalytic performance are indeed based on ligand stability. Due to the presence of a photosensitizer and a catalytic unit, binuclear complexes 3 and 4 were tested for photocatalytic water oxidation. The bridging ligand architecture, however, inhibits the effective electron-transfer cascade that would allow photocatalysis to run efficiently. The findings of this study can elucidate critical factors in catalyst design.     

A New Luminescent Ruthenium(II) Polypyridine‐derived Dipicolylamine Complex as a Sensor for Cu2+ Ions

A chemo‐sensor [Ru(bpy)₂(bpy‐DPF)](PF₆)₂ ( 1 ) (bpy=2,2′‐bipyridine, bpy‐DPF=2,2′‐bipyridyl‐4,4′‐bis(N,N‐di(2‐picolyl))formylamide) for Cu²⁺ using di(2‐picolyl)amine (DPA) as the recognition group and a ruthenium(II) complex as the reporting group was synthesized and characterized successfully. It demonstrates a high selectivity and efficient signaling behavior only for Cu²⁺ with obvious red‐shifted MLCT (metal‐to‐ligand charge transfer transitions) absorptions and dramatic fluorescence quenching compared with Zn²⁺ and other metal ions.     

5,5′-Bi-5H-cyclopenta[2,1-b;3,4-b′]dipridinylidene,a New Bridging Ligand for Metal Complexes. Preliminary Communication

5,5′-Bi-5H-cyclopenta[2,1-b;3,4-b′]dipyridinylidene( 1 ) was synthesized in three steps from 9,10-phenanthroline and characterized by UV/VIS and NMR spectroscopy, mass spectrometry, and cyclic voltammetry. Its ability to act as a bridging ligand is demonstrated by the synthesis of the complexes [Ru(bpy)₂( 1 )](PF₆)₂ ( 6 ) and [{Ru(bpy)₂}₂( 1 )](PF₆)₄ ( 7 ) (bpy = 2,2′-bipyridine).     

Reactivity of triazolyl Schiff bases with Ru(II)-2,2′-bipyridyl: Synthesis,spectroscopic characterization of isomers and their photo-physical properties

The condensation of 3-amino-1H-1,2,4-triazole with benzaldehyde and terephthalaldehyde provides the bidentate and tetradentate Schiff bases 1,2,4-triazolo-3-imino-benzene L¹H and 1,4-bis(1,2,4-triazolo-3-imino)benzene L²H₂, respectively. The well characterized Schiff bases were allowed to react with cis-Ru(bpy)₂Cl₂ · 2H₂O. Isomers of the mononuclear complexes Ru(bpy)₂L¹]PF₆ · NH₄PF₆ (1a, N4) and [Ru(bpy)₂L¹]PF₆ · 0.5NH₄PF₆ (1b, N2), and the dinuclear Ru(II) complexes [Ru(bpy)₂L²Ru(bpy)₂](PF₆)₂ · NH₄PF₆ (2a, N4N4), [Ru(bpy)₂L²Ru(bpy)₂](PF₆)₂ · NH₄PF₆ · 2H₂O (2b, N2N2) and [Ru(bpy)₂L²Ru(bpy)₂](PF₆)₃ · NH₄PF₆ (2c, Ru(II)-Ru(III)) were separated by column chromatography and characterized by their elemental analysis, FAB mass and spectral (IR, NMR, UV–Vis) data. The data obtained suggest that the ligands are bound to the metal centre via the N4 and N2 atoms of the triazole moiety along with the N (imine) atom. The complexes display metal-to-ligand charge-transfer (MLCT) transitions in the visible region from the dπ(Ru^II) → π^∗L transition. Highly intense ligand-based π→π^∗ transitions are observed in the UV region. A dual emission occurs from the N2 and N2N2 isomers.