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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]

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 series of complexes [XRu(CO)(L–L)(L′)2][PF6] (X = H, TFA, Cl; L–L = 2,2′-bipyridyl, 1,10-phenanthroline, 5-amino-1,10-phenanthroline and 4,4′-dicarboxylic-2,2′-bipyridyl; L′2 = 2PPh3, Ph2PC2H4PPh2, Ph2PCH＝CHPPh2) have been synthesized from the starting complex K[Ru(CO)3(TFA)3] (TFA = CF3CO2) by first reacting with the phosphine ligand, followed by reaction with the L–L and anion exchange with NaPF6. In the case of L–L = phenanthroline and L′2 = 2PPh3, the neutral complex Ru(Ph3P)(CO)(1,10-phenanthroline)(TFA)2 is also obtained and its solid state structure is reported. Solid state structures are also reported for the cationic complexes where L–L = phenanthroline, L2 = 2PPh3 and X = Cl and for L–L = 2,2′-bipyridyl, L2 = 2PPh3 and X = H. All the complexes were characterized in solution by a combination of 1H and 31P NMR, IR, mass spectrometry and elemental analyses. The purpose of the project was to synthesize a series of complexes that exhibit a range of excited-state lifetimes and that have large Stokes shifts, high quantum yields and high intrinsic polarizations associated with their metal-to-ligand charge-transfer (MLCT) emissions. To a large degree these goals have been realized in that excited-state lifetimes in the range of 100 ns to over 1 μs are observed. The lifetimes are sensitive to both solvent and the presence of oxygen. The measured quantum yields and intrinsic anisotropies are higher than for previously reported Ru(II) complexes. Interestingly, the neutral complex with one phosphine ligand shows no MLCT emission. Under the conditions of synthesis some of the initially formed complexes with X = TFA are converted to the corresponding hydrides or in the presence of chlorinated solvents to the corresponding chlorides, testifying to the lability of the TFA Ligand. The compounds show multiple reduction potentials which are chemically and electrochemically reversible in a few cases as examined by cyclic voltammetry. The relationships between the observed photophysical properties of the complexes and the nature of the ligands on the Ru(II) is discussed. [Copyright &y& Elsevier]