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The luminescent, mono-diimine ruthenium complexes [(H)Ru(CO)(PPh3)2(dcbpy)][PF6] (1) (dcbpy = 4,4'-dicarboxy-2,2'-bipyridyl) and [(H)Ru(CO)(dppene)(5-amino-1,10-phen)][PF6] (2) (dppene = bis(diphenylphosphino)ethylene; phen = phenanthroline) were conjugated with 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (DPPE) and with cholesterol in the case of complex 2. Using standard conjugation techniques, compound 1 gives the bis-lipid derivative [(H)Ru(CO)(PPh3)2(dcbpy-N-DPPE2)][PF6] (3), while 2 provides the monolipid conjugate [(H)Ru(CO)(dppene)(1,10-phen-5-NHC(S)-N-DPPE)][PF6] (4) and the cholesterol derivative [(H)Ru(CO)(dppene)(1,10-phen-5-NHC(O)Ocholesteryl)][PF6] (5). These compounds were characterized by spectroscopic methods, and their photophysical properties were measured in organic solvents. The luminescence of lipid conjugates 3 and 4 is quenched in organic solvents while compound 4 shows a weak, short-lived, blue-shifted emission in aqueous solution. The cholesterol conjugate 5 shows the long-lived, microsecond-time scale emission associated with triplet metal-to-ligand charge-transfer excited states. Incorporation of conjugate 3 in lipid bilayer vesicles restores the luminescence, but with blue shifts (~80 nm) accompanied by nanosecond-time scale lifetimes. In the vesicles conjugate 4 shows a short-lived and blue-shifted emission similar to that observed in solution but with increased intensity. Conjugation of the complex [(H)Ru(CO)(PhP2C2H4C(O)O-N-succinimidyl)2(bpy)][PF6] (6") (bpy = 2,2'-bipyridyl) with DPPE gives the phosphine-conjugated complex [(H)Ru(CO)(PhP2C2H4C(O)-N-DPPE)2(bpy)][PF6] (7). Complex 7 also exhibits a short-lived and blue-shifted emission in solution and in vesicles as observed for complexes 3 and 4. We have also conjugated the complex [Ru(bpy)2(5-amino-1,10-phen)][PF6]2 (8) with both cholesterol (9) and DPPE (10). Neither complex 9 nor the previously reported complex 10 exhibited the blue shifts observed for complexes 3 and 4 when incorporated into large unilamellar vesicles (LUVs). The anisotropies of the emissions of complexes 3, 4, and 7 were also measured in LUVs, and those of complex 5 were measured in both glycerol and LUVs. High fundamental anisotropies were observed for complexes 3, 4, and 7.

The complex [Ru(tpy)(CO)(2)TFA]+[PF(6)]- (where tpy = 2,2':6',2' '-terpyridine and TFA = CF(3)CO(2)-) (1) has been synthesized and fully characterized spectroscopically. The X-ray structure of the complex has been determined. The photopysical properties of the ruthenium complex and the free ligand tpy have been investigated at room temperature and at 77 K in acetonitrile solution and in the solid state. Their electronic spectra are highly influenced by intermolecular stacking interactions, both in solution and in the solid state. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations have been performed to characterize the electronic structure and the excited states of [Ru(tpy)(CO)(2)TFA]+[PF(6)]- and tpy. TDDFT calculations on three different conformations of free ligand have been performed as well. Absorption and emission spectra of tpy have been studied at different temperatures and concentrations in order to have a better understanding of this ruthenium derivative's properties. The absorption spectrum of 1 is characterized by metal-perturbed ligand-centered (LC) bands in the UV region. No metal-to-ligand charge transfer (MLCT) bands are observed in the visible for the complex. Only at high concentrations (10(-4) M) does a very weak band appear at 470 nm. At 77 K and low concentrations, solutions of 1 exhibit a major 3LC emission band centered at 468 nm (21.4 x 10(-3) cm(-1)). When the concentration of the complex is increased, an unstructured narrow emission at 603 nm (16.6 x 10(-3) cm(-1)), with a lifetime of 10 micros, dominates the emission spectrum in glassy acetonitrile. This emission originates from a pi-pi stacked dimeric (or oligomeric) species. TDDFT calculations performed on a tail-to-tail dimer structure, similar to that seen in the solid state, ascribe the transition to a triplet excited state, where intermolecular metal (d) --> ligand (pi*, polypyridine) charge transfer occurs. A good estimate of the transition energy is also obtained (623 nm, 1.94 eV).

Heterogenization of catalytically important homogeneous catalysts on solid supports has become an expanding area of research. PNN and PONOP ruthenium pincer complexes were immobilized on a silica poly(allylamine) composite, BP-1 by a two-step Mannich reaction. The complexes on BP-1 were characterized by solid state NMR, FT-IR, elemental analysis, and metal digestion studies. Model solution experiments were carried out to determine the site of electrophilic substitution on the pyridine ring of the pincer complexes and revealed substitution in both the meta - and para -position. The catalytic reactivity of immobilized (PNN)RuH(Cl)(CO) and (PONOP)RuH(Cl)(CO) on BP-1 was studied for the dehydrogenative coupling of alcohols to esters with the liberation of H 2 . Moderate to good ester yields were realized with both immobilized systems without using the base required for the homogeneous reaction and also in the presence of KOH. The homogeneous model reactions required a base for ester formation. The amine functionality on BP-1 served as the base to generate the active pincer catalyst on the BP-1 surface. Both immobilized catalysts were recycled for multiple alcohol reaction cycles. Four-step control experiments were carried out using an alcohol and both immobilized systems. The results revealed the heterogeneity of the alcohol catalysis by both BP-1-Ru-PNN and BP-1-Ru-PONOP systems. This study has opened a new catalytic methodology for reactions where base is required for catalyst activation, by using a solid support with basic functionality. [ABSTRACT FROM AUTHOR]

Luminescent ruthenium diimine complexes have been covalently bound to the surface of a silica polyamine composite (SPC) using peptide coupling agents. The loading of the complexes using this route is quite low (∼0.01-0.04 mmol/g) leaving sufficient surface amines to coordinate added metal ions. When the composite particles containing the Ru complexes are exposed to solutions of Cu2+, Ni2+ or Zn2+, luminescence is quenched with efficiencies that follow concentration dependence and the relative binding affinities of the ions. When heavy metal ions such as mercury or lead are adsorbed onto the same surface, luminescence is enhanced by a factor of ∼3.5. When the complexes are exposed to these metals in solution, no quenching or enhancement is observed. Both phenomena were shown to be the result of adsorption of the cations onto the polyamine surface by using the Stern-Volmer relationship. The mechanism of both quenching and enhancement is discussed and the options for further development of this novel metal sensing technique are presented. [ABSTRACT FROM AUTHOR]

Novel catalysts consisting of ruthenium nanoparticles encapsulated in cross-linked matrices based on the poly(propylene imine) dendrimers of the 1st and 3rd generations have been synthesized with a narrow particle size distribution (3.8 and 1.0 nm, respectively). The resulting materials showed high activity for the hydrogenation of phenols in aqueous media (specific catalytic activity reached turnover frequencies of 2975 h−1 with respect to hydrogen uptake). It has been shown that the use of water as a solvent leads to a 1.5 to 50-fold increase in the reaction rate depending upon the nature of the substrate. It has been established that unlike the traditional heterogeneous catalysts based on ruthenium, during the hydrogenation of dihydroxybenzenes, the hydrogenation rate decreases in the order: resorcinol>hydroquinone≫catechol. The maximum specific activity for resorcinol was a turnover frequency of 243150 h−1 with respect to hydrogen uptake. The catalyst based on the dendrimer of the 3rd generation containing finer particles has significantly inferior activity to the catalyst based on the dendrimer of the 1st generation by virtue of steric factors, as well as the need for prereduction of the ruthenium oxide contained on the surface. These catalysts showed resistance to metal leaching and may be reused several times without loss of activity. [ABSTRACT FROM AUTHOR]

The reactions of [Ru3(CO)10(μ-dppm)] 4 with quinolines afforded [Ru3 (μ-CO)(CO)7{μ3-η2-P(C6H5)CH2P(C6H5)2)}{μ-η2-C9H5(R)N}] ( 8, R = 4-Me; 9, R = H) as the major products along with small amounts of known compound [Ru3(CO)9{μ3-η3-P(C6H5)CH2P(C6H5)(C6H4)}] 5. The molecular structure of 8 has been determined by single crystal X-ray studies. The reaction of 5 with 4-methylquinoline in refluxing cyclohexane afforded 8 and two known dinuclear compounds, [Ru2(CO)6{μ-CH2P(C6H5)(C6H4)P(C6H5}] 10 and [Ru2(CO)6 {μ-(C6H4)P(C6H5)(CH2)P(C6H5}] 11, in 40, 12, and 10% yields, respectively. The compounds 10 and 11 are also formed from the thermolysis of 4 in addition to the major compound 5. The solid state structure of the previously reported [Ru3(CO)10(η-H){μ-η2-C9H6N}] 2a is also reported for comparison. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of the ruthenium(II) diimine complexes [Ru(CO)(CF 3 CO 2 )(dppene)(5-R-phen)][PF 6 ] (dppene = 1,2-diphenylphosphinoethene; phen = 1,10-phenanthroline; R = H, 1 ; R = NH 2 , 2 ; R = cholestoryl carbamate, 3 ; R = 1,2-dihexadecanoyl- sn -glycero-3-phosphoethanolamine, 4 ), [Ru(CO)(H)(4,4′-R-bpy)(R′Ph 2 P) 2 ][PF 6 ] (bpy = 2,2′-bipyridine; R = H, R′ = Ph, 5 ; R = H, R′ = 1,2-dihexadecanoyl- sn -glycero-3-phosphoethanolamine, 6 ; R = 1,2-dihexadecanoyl- sn -glycero-3-phosphoethanolamine, R′ = Ph, 7 ), [Ru(bpy) 2 (5-R-phen)][PF 6 ] 2 (R = NH 2 , 8 ; R = cholestoryl carbamate, 9 ; R = 1,2-dihexadecanoyl- sn -glycero-3-phosphoethanolamine, 10 ) is reported. Complexes 1 – 6 give cyclovoltammetric (CV) responses with multiple ill-defined reduction waves and one oxidation wave, all of which were chemically irreversible. Complexes 5 and 7 , containing axially coordinating phosphines, showed reversible oxidation and reduction CV responses, while 6 showed redox waves similar to 3 . Complexes 8 – 10 show a metal-centered irreversible oxidation around +1.4 V that, in the case of 8 and 9 , is heavily modified by adsorption phenomena. In the negative part of the CV, 9 and 10 show a single chemically and electrochemically reversible 1e − reduction both at E °′ = −1.29 V, about 500 mV cathodically shifted with respect to 8 . The interactions of complexes 1 and 2 with bovine serum albumin (BSA) and double stranded DNA (ds-DNA) were also studied by electrochemical methods. Both complexes showed strong binding to BSA. Evidence for intercalation of both complexes with DNA is presented, with 1 showing a stronger interaction than 2 . [ABSTRACT FROM AUTHOR]

The reactions of [Os3(CO)10(MeCN)2], [Ru3(CO)12], [(μ-H)Os3(CO)8{Ph2PCH2P(Ph)C6H4}], [Os3(CO)10(μ-dppm)] and [Ru3(CO)10(μ-dppm)] with 2-mercapto-1-methylimidazole are reported. The labile cluster [Os3(CO)10(MeCN)2] reacts with 2-mercapto-1-methylimidazole at 25 °C to give [(μ-H)Os3(CO)10{μ-SC&z.dbnd6;NCH&z.dbnd6;CHN(CH3)}] (1) whereas the corresponding reaction of [Ru3(CO)12] with the ligand at 68 °C gives [(μ-H)Ru3(CO)9{μ3-η2-SC&z.dbnd6;NCH&z.dbnd6;CHN(CH3)}] (2). Both [(μ-H)Os3(CO)8{Ph2PCH2P(Ph)C6H4}] and [Os3 (CO)10(μ-dppm)] react with 2-mercapto-1-methylimidazole at 25 and 110 °C, respectively, to give [(μ-H)Os3(CO)8{μ-SC&z.dbnd6;NCH&z.dbnd6;CHN(CH3)(μ-dppm)] (3). In contrast [Ru3(CO)10(μ-dppm)] reacts with 2-mercapto-1-methylimidazole at 68 °C to yield the known compound [Ru3(CO)7(μ3-CO)(μ3-S)(μ-dppm)] (4). The structures of 1–3 have been determined by X-ray crystallography. [Copyright &y& Elsevier]