THE EXTRACTION OF CATIONIC RUTHENIUM COMPLEXES FROM AQUEOUS MEDIA BY α-TIN(IV) HYDROGEN PHOSPHATE

ABSTRACT

The ruthenium species [Ru(NH₃)₆]³⁺ was adsorbed by the surface of (α-Sn(HPO₄)₂.2H₂O [SnP]) α-tin(IV) hydrogen phosphate. The ruthenium(II)-containing cation [Ru(NH₃)₆]²⁺, however, has been directly intercalated into (SnP). Since the corresponding ruthenium(III) complex cation was not so intercalated, a new self-catalysed intercalation mechanism involving labile ammonia ligands from the ruthenium(II) has been proposed. At high loadings, guest ruthenium(II) species were oxidised to ruthenium(III).     

Novel drug delivery system for photoinduced nitric oxide (NO) delivery

A hybrid material (AB-1) was obtained by immobilizing photolabile ruthenium nitrosyl complex [Ru(L^SBH)(PPh₃)₂(NO)Cl](ClO₄) (1) into alginate polymer. A controlled release of nitric oxide was observed when a suspension of AB-1 was exposed to visible light. The amount of photoreleased NO from polymeric hybrid material was estimated using Griess reagent assay.     

Homoleptic complexes [Ru(L-L)3]2+ (L-L=diphosphine,diarsine)

Homoleptic Ru(II)–diphosphine and Ru(II)–diarsine complexes [Ru(L-L)₃](OTf)₂ (L-L=Me₂P(CH₂)_nPMe₂; n=1, dmpm; n=2, dmpe) and 1,2-C₆H₄(AsMe₂)₂ (diars) have been isolated, in which the Ru(II) state is stabilised to an unprecedented degree, and the crystal structure of [Ru(diars)₃]Cl₂ has been determined.     

Electropolymerization and characterization of terpyridinyl iron (II) and ruthenium (II) complexes

Electroactive 2,2′: 6,2″-terpyridinyl ligands ( 3, 5, 6 ) and their iron(II) ( 7a–9a ) and ruthenium(II) complexes ( 7b–9b ) were synthesized. Bis[3-(aminophenyl)-2,2′ :6,2″-terpyridinyl]metal(II) complexes ( 7a, 7b ) and bis[2-(hydroxyphenyl)-2,2′ :6,2″-terpyridinyl]metal(II) complexes ( 8a, 8b ) were electropolymerized on to the surface of Pt or In-SnO₂ (ITO) electrodes in acetonitrile containing Bu₄NCIO₄ by scanning the potential between O and + 1.6V (for 7a and 7b ), and ?0.8 and +1.6V (for 8a and 8b ) versus saturated calomel electrode. The electrodes obtained by electropolymerization exhibited reversible electrochromism based on Fe(II)/Fe(III) or Ru(II)/Ru(III) redox couple. Photoresponses to visible light were found in the modified electrode obtained by electropolymerization of ruthenium complex 7b in an aqueous LiClO₄ solution containing methylviologen (cation MV²⁺) under an O₂ atmosphere. The mechanism for the photoresponded cathodic current was explained in terms of an excitation of bis(terpyridinyl)ruthenium(II) complex [Ru(terpy)²₂⁺] by visible light, an electron transfer from the excited state [Ru(terpy)^2+*₂] to MV²⁺, reduction of Ru(terpy)³⁺₂ at an electrode, and oxidation of MV^+* with O₂.     

Study of a gold electrode modified by trans-[Ru(NH3)4(Ist)SO4] to produce an electrochemical sensor for nitric oxide

The modification of a gold electrode surface by electropolymerization of trans-[Ru(NH₃)₄(Ist)SO₄]⁺ to produce an electrochemical sensor for nitric oxide was investigated. The influence of dopamine, serotonin and nitrite as interferents for NO detection was also examined using square-wave voltammetry (SWV). The characterization of the modified electrode was carried out by cyclic voltammetry, electrochemical quartz crystal microbalance (EQCM) and SERS techniques. The gold electrode was successfully modified by the trans-[Ru(NH₃)₄(Ist)SO₄]⁺ complex ion using cyclic voltammetry. The experiments show that a monolayer of the film is achieved after ten voltammetric cycles, that NO in solution can coordinate to the metal present in the layer, that dopamine, serotonin and nitrite are interferents for the detection of NO, and that the response for the nitrite is much less significant than the responses for dopamine and serotonin. The proposed modified electrode has the potential to be applied as a sensor for NO.     

EXAFS Study on Structural Change of Charcoal-supported Ruthenium Catalysts during Lignin Gasification in Supercritical Water

Lignin gasification in supercritical water over charcoal supported ruthenium trivalent salts was studied using a batch reactor at 673 K. Ruthenium (III) nitrosyl nitrate on charcoal (Ru(NO)(NO₃)₃/C) was more active than ruthenium (III) chloride on charcoal (RuCl₃/C) for the gasification reaction. EXAFS analysis revealed that ruthenium metal particles were formed in both RuCl₃/C and Ru(NO)(NO₃)₃/C catalysts during the lignin gasification and that the size of ruthenium metal in Ru(NO)(NO₃)₃/C was smaller than that in RuCl₃/C. It was concluded that well-dispersed ruthenium metal particles were active for the lignin gasification in supercritical water.     

Ruthenium Catalysts for Controlled Mono‐ and Bis‐Allylation of Active Methylene Compounds with Aliphatic Allylic Substrates

The allylation of 1,3‐dicarbonyl compounds and malononitrile with aliphatic allylic substrates is achieved under mild conditions in the presence of new ruthenium catalysts. The ruthenium complex [Ru(C₅Me₅)(2‐quinolinecarboxylato)(CH₂CHCH‐n‐Pr)] [BF₄] as a precatalyst, allows the synthesis of mono‐allylated branched derivatives. On the other hand, the parent complex [Ru(C₅Me₅)(MeCN)₃] [PF₆] as a precatalyst, straightforwardly favours the bis‐allylation of the procarbonucleophiles leading to bis‐allylated bis‐linear products. The involvement of the two precatalysts provides a sequential synthesis of unsymmetrical mixed linear‐branched bis‐allylated derivatives.     

Experimental and DFT calculated structure of the diruthenium(2.5) complex [(Me3TACN)Ru(μ-Cl)3Ru(Me3TACN)](PF6)2

The diruthenium(2.5) complex [(Me₃TACN)Ru(μ-Cl)₃Ru(Me₃TACN)]-(PF₆)₂, Me₃TACN = 1,4,7-trimethyl-1,4,7-triazacyclononane, has been crystallized for structural characterization. The results are reproduced by density functional theory (DFT) calculations and confirm the sensitivity of the central Ru(μ-Cl)₃Ru core to contacts between the Cl bridging atoms and the co-ligands. The singly occupied MO is characterized as a σ* MO involving the metal d_z² orbitals and a small halide contribution by DFT calculations and EPR.     

Homonuclear tris-dithiocarbamato ruthenium(III) complexes as single-molecule precursors for the synthesis of ruthenium(III) sulfide nanoparticles

Tris(N-phenyldithiocarbamato) ruthenium(III) complexes, [Ru(L¹)₃] (1); tris(N-(4-methylphenyl)dithiocarbamato)) ruthenium(III), [Ru(L²)₃] (2); and tris(N-(4-methoxyphenyl)dithiocarbamato)) ruthenium(III), [Ru(L³)₃] (3) were synthesized and characterized by elemental analysis, thermogravimetric analysis, FTIR, UV–VIS and NMR spectroscopy. TGA analyses show major degradation of all complexes in the range 120–350°C, leading to the formation of residual weight corresponding to ruthenium (III) sulfides. The ¹H-NMR spectra of the ligands and complexes are in agreement with the proposed structures. FTIR studies confirmed that the ligands coordinate the Ru³⁺ ion in a bidentate chelating mode. The complexes were thermolysed at 180°C to prepare hexadecylamine-capped Ru₂S₃ nanoparticles. Powder X-ray diffraction patterns revealed the formation of hexagonal-phase Ru₂S₃ nanoparticles with average crystallite sizes ranging from 8.3 to 9.5?nm. TEM images showed the crystalline clusters with shapes ranging from square to hexagonal, while SEM images elucidated that the particles were agglomerated. Energy-dispersive X-ray spectra confirmed the presents of Ru₂S₃ nanoparticles.     

Formation of a covalently-linked bimetallic compound upon irradiation of tris(1,4,5,8-tetraazaphenanthrene)ruthenium(II) in the presence of 5′-guanosine-monophosphate

A new type of binuclear Ru(II) complex [Ru(TAP)₂(TAP-TAP)Ru(TAP)₂]⁴⁺ (1) (TAP-TAP=2,2′-bis(1,4,5,8-tetraazaphenanthrene)) produced by photo-reaction of Ru(TAP)₃²⁺ in the presence of 5′-guanosine-monophosphate (5′-GMP) has been isolated and characterised. The formation of 1 is proposed to proceed via mono-reduced Ru(TAP)₃²⁺, i.e. [Ru²⁺(TAP)₂(TAP^⋅−)]⁺. The emission lifetime of 1 is much greater than that of Ru(TAP)₃²⁺, consistent with an increased energy gap between the ³MLCT and ³MC states in 1. This arises because of stabilisation of its ³MLCT state due to the localisation of the excited state electron on the TAP-TAP ligand.     

Synthesis and cytotoxicity of a ruthenium nitrosyl nitric oxide donor with isonicotinic acid and a cell penetrating peptide

The syntheses and properties of trans-[Ru(NH₃)₄(L)(NO)](BF₄)₃ (L = isonicotinic acid (inaH) (I) or ina-Tat48–60 (II)) are described. Tat48–60, a cell penetrating peptide fragment of the Tat regulatory protein of the HIV virus, was linked to the ruthenium nitrosyl through inaH. I and II release NO after reduction forming trans-[Ru(NH₃)₄(L)(H₂O)]^3 +. The IC₅₀ values against B16-F10 melanoma cells of I and II (21 μmol L^− 1 and 23 μmol L^− 1, respectively) are close to that of the commercially available cisplatin (33 μmol L^− 1) and smaller than similar complexes. The cytotoxicity is assigned to the NO released from I and II.     

HPLC separation,NMR and QTOF/MS/MS structure elucidation of a prominent nitric oxide donor agent based on an isomeric composition of a nitrosyl ruthenium complex

A new and promising nitrosyl ruthenium complex, [Ru(NO)(bdqi-COOH)(terpy)](PF₆)₃, bdqi-COOH is 3,4-diiminebenzoic acid and terpy is 2,2′-terpyridine, has been synthesized as a NO donor agent. The procedure used for [Ru(NO)(bdqi-COOH)(terpy)](PF₆)₃ synthesis has, apparently, yielded the formation of two isomers in which the ligand bdqi-COOH appears to be coordinated in its reduced form (bdcat-COOH), which could have differences in their pharmacological properties. Therefore, it was intended to separate the two possible isomers by high-performance liquid chromatography (HPLC) and to characterize them by high resolution mass spectrometry (QTOF MS) and by magnetic nuclear resonance spectroscopy (NMR). The results obtained by MS showed that the ESI-MS mass spectra of both HPLC column fractions, e.g. peak 1 and peak 2, are essentially equal, showing that both isomers display nearly identical gas-phase behavior with clusters of isotopologue ions centered at m/z 573, m/z 543 and m/z 513. Regarding the NMR analysis, the results showed that the positional isomerism is located in the bdqi-COOH ligand. From the observed results it can be concluded that the synthesis procedure that has been used results in the formation of two [Ru(terpy)(bdqi-COOH)NO](PF₆)₃ isomers.     

Ionic conduction of novel polymer composite films based on partially phosphorylated poly(vinyl alcohol)

New ion-conducting polymer composite films have been prepared, and their ionic conducting properties have been investigated. The polymer composite films are fabricated from partially phosphorylated poly(vinyl alcohol) with tetramethylammonium salt (P-PVA·Me₄N⁺) and poly(acrylic acid) (PAA) or poly(ethylene glycol) (PEG). For P-PVA·Me₄N⁺/PEG composite films, the ionic conductivity and carrier density sharply increased, and carrier mobility sharply decreased around [PEG]/[PO₃]_P-PVA of 2. The ionic conductivity is dominated by both carrier density and carrier mobility at [PEG]/[PO₃]_P-PVA<2 and only by carrier density at [PEG]/[PO₃]_P-PVA>2. This is attributed to the fact that the ionic conduction in P-PVA·Me₄N⁺/PEG composite films occurred through the PEG-Me₄N⁺ complex which was independent of the carrier mobility. On the other hand, the ionic conductivity in P-PVA·Me₄N⁺/PAA composite films showed a bell-shaped dependence on the PAA contents with a maximum value at [CO₂H]_PAA/[OH]_P-PVA=1. FTIR spectrum measurements demonstrated that part of the carboxylic acid residues was dissociated in the composite films. This fact implied that the ionic conduction was mediated by PAA at the low PAA content. At high PAA content, however, an excess of the carboxylic acid residues formed trapping sites for the Me₄N⁺ ion, leading to a decrease in the ionic conductivity. Furthermore, we proposed a unique mechanism of the ionic conduction.     

Aldehyde-decorated 2,2′-bipyridine and 2,2′:6′,2″-terpyridine ruthenium(II) complexes: Convenient scaffolds for supramolecular chemistry

Two new aldehyde-decorated tpy and bpy-containing ruthenium(II) complexes, [Ru(1)(bpy)₂][PF₆]₂ and [Ru(1)(tpy)Cl][PF₆] in which 1 is 5,5′-bis(4-formylphenyl)-2,2′-bipyridine, have been prepared and fully characterized. The packing in both solid state structures involves extensive O_aldehyde···HC_pyridine contacts, but π-stacking interactions are important only between [Ru(1)(tpy)Cl]⁺ cations.     

Arene–RuII Complexes of Curcumin Exert Antitumor Activity via Proteasome Inhibition and Apoptosis Induction

Organometallic ruthenium(II) complexes of general formula [(η⁶‐arene)Ru(curcuminato)Cl], with arene being p‐iPrC₆H₄Me ( 1 ), C₆H₆ ( 2 ), and C₆Me₆ ( 3 ), were synthesized, characterized, and evaluated for their antitumor effects. Specifically, we explored their ability to regulate the proteasome, a validated pharmacological target in cancer treatment. Ruthenium complexes inhibited isolated proteasomes to various extents, with the biological activity of these complexes depending on the nature of the bound arene; in particular, [(η⁶‐arene)Ru(curcuminato)Cl] 2 suppressed proteasomal activities more potently than 1 , 3 , or free curcumin. Each complex also inhibited proteasomes in cultured colon cancer cells and consequently triggered apoptosis, with the [(η⁶‐benzene)Ru(curcuminato)Cl] complex 2 being the most active. The influence on the oxidative status of HCT116 cells and the DNA binding ability of the [(η⁶‐arene)Ru(curcuminato)Cl] complexes were studied. Complex 2 showed the highest antioxidant capacity; moreover, complexes 1 and 2 were shown to bind isolated DNA with higher affinity (up to threefold) than free curcumin. Collectively, our results demonstrate that the complexation of curcumin with ruthenium(II) is a promising starting point for the development of curcumin‐based anticancer drugs.     

Spectroscopic and computational studies on a new Pd(II)-bis(pyrazol-1-yl)methane aqua-complex

By reacting a stoichiometric amount of BPM or Me₂BPM (BPM = bis(pyrazol-1-yl)methane, Me₂BPM = bis(3,5-dimethylpyrazol-1-yl)methane) with Pd(OAc)₂ (OAc = acetate) in CH₂Cl₂, the new neutral complexes [Pd(OAc)₂(BPM)] (1) and [Pd(OAc)₂(Me₂BPM)] (1^Me) were isolated and characterized by NMR and IR spectroscopy. Acidolysis of one Pd-OAc bond of compound 1 by using aqueous perchloric acid in methanol led to the formation of the stable cationic aqua-complex [Pd(OAc)(H₂O)(BPM)](ClO₄) (2-ClO₄). The [Pd(OAc)(H₂O)(BPM)]⁺ cation was obtained also by reacting 1 with trifluoromethanesulfonic acid. NMR studies on inter- and intra-molecular hydrogen bonding of the aqua-ligand have been carried out and the data obtained have been interpreted on the basis of the results of DFT calculations.     

Synthesis and tuning of chemical properties by protonation/deprotonation of novel dinuclear ruthenium complexes containing 2,6,2′,6′-tetra(4,5-dimethylbenzimidazol-2-yl)-4, 4′-bipyridine

A novel dinuclear ruthenium complex, [(tpy)Ru(tmbimbpyH₄)Ru(tpy)](ClO₄)₄, has been synthesized to introduce a new proton-induced molecular switching system, where tpy=2,2′:6′,2″-terpyridine and tmbimbpyH₄=2,6,2′,6′-tetra(4,5-dimethylbenzimidazol-2-yl)-4,4′-bipyridine. Both fully protonated and deprotonated forms of the dinuclear Ru complex were isolated and the forms were interchangeable by the addition of acid or base. A longer wavelength shift and a negative oxidation potential shift were observed when the protonated Ru complex was fully deprotonated.     

Ligand dehydrogenation in ruthenium trinitrogen complexes: synthesis,structure and chirality of the cations [Ru(LH4)(L)]2+ [LH4=2,6-bis(pyrrolidin-2-yl)pyridine]

Reaction of 2,6-bis(pyrrolidin-2-yl)pyridine (LH₄) with RuCl₃·3H₂O in refluxing methanol/water mixtures gives rise to the formation of the octahedral complexes [Ru(LH₄)(L)]²⁺, in which one of the two trihapto ligands has been dehydrogenated as 2,6-bis(3,4-dihydro-2H-pyrrol-5-yl)pyridine (L), even if LH₄ was present in excess. With the three stereoisomers of LH₄, the complexes [Ru(R,S-LH₄)(L)]²⁺ (meso), [Ru(R,R-LH₄)(L)]²⁺ and [Ru(S,S-LH₄)(L)]²⁺ have been isolated as the perchlorate salts and characterised by X-ray structure analysis and by CD spectra.     

Design of New Functional Materials Based on Complex Oxides with a Tunnel Structure of the Ramsdellite, Hollandite, and Ba2Ti9O20 Types

The phase relationships in binary, ternary, and more complex Me ₂ ⁺O–Me ²⁺O–Me ₂ ³⁺O₃–Me ⁴⁺O₂–TiO₂ systems (Me ⁺ = Li⁺, K⁺, Rb⁺, Cs⁺; Me ²⁺ = Mg²⁺, Sr²⁺, Ba²⁺, Zn²⁺; Me ³⁺ = Al³⁺, Fe³⁺, Ga³⁺; Me ⁴⁺ = Sn⁴⁺, Zr⁴⁺) are investigated in the concentration regions corresponding to the compositions of titanates with a tunnel structure: Li₂(Me ²⁺,Me ³⁺) _y (Me ⁴⁺,Ti)₄O₈ ramsdellites, (Me ⁺,Me ²⁺) _x (Me ²⁺,Me ³⁺) _y (Me ⁴⁺,Ti)₈O₁₆ hollandites, and (Ba,Me ²⁺)₂(Me ⁴⁺,Ti)₉O₂₀ phases. The homogeneity regions of the solid solutions with the above structures are determined, and their crystal chemical characteristics, phase transformations, and thermal and electrical properties are studied. The results obtained and the data available in the literature are analyzed and generalized. The general approaches to the prediction of changes in the structure and properties of the studied titanates with a variation in the chemical composition due to isomorphous substitutions in different structural positions of the crystal lattice are discussed.     

Enantiopreferential DNA-binding of a novel dinuclear complex [(bpy)2Ru(bdptb)Ru(bpy)2]4+

A novel dinuclear ruthenium(II) complex [(bpy)₂Ru(bdptb)Ru(bpy)₂]⁴⁺ (bpy=2,2^′-bipyridyl; bdptb=2,2^′-bis(5,6-diphenyl-1,2,4-triazin-3-yl)-4,4^′-bipyridine) has been synthesized and characterized. The DNA-binding behaviors of this complex have been studied by viscosity, absorption and circular dichroism (CD) spectra. It has firstly been found that the dinuclear ruthenium(II) complex display the enantiopreferential DNA-binding after equilibrium dialysis.