Synthesis, Characterization, and Electrochemistry of Biorelevant Photosensitive Low-Potential Orthometalated Ruthenium Complexes
摘要:
Redox potentials of photosensitive cyclometalated Ru" derivatives of 2-phenylpyridine or 2-(4-tolyl)pyridine are controllably decreased by up to 0.8 V within several minutes. This is achieved by irradiation of the ruthena(II)cycles cis-[Ru(o-X-2-py)(LL)(MeCN)(2)]PF6 (2, X = C6H4 (a) or 4-MeC6H3 (b), LL = 1,10-phenanthroline or 2,2'-bipyridine). The cis geometry of the MeCN ligands has been confirmed by the X-ray structural studies. The sigma-bound sp(2) carbon of the metalated ring is trans to LL nitrogen. Complexes 2 are made from [Ru(o-X-2-py)(MeCN)(4)]PF6 (1) and I-L. This "trivial" ligand substitution is unusual because la reacts readily with phen in MeCN as solvent to give cis-[Ru(o-C6H4-2-py)(phen)(MeCN)(2)]PF6 (2c) in a 83% yield, but bpy does not afford the bpy-containing 2 under the same conditions. cis-[Ru(o-C6H4-2-py)(bpy)(MeCN)(2)]PF6 (2e) has been prepared in CH2Cl2 (74%). Studies of complexes 2c,e by cyclic voltammetry in MeOH in the dark reveal Ru-II/III quasy-reversible redox features at 573 and 578 mV (vs Ag/AgCl), respectively. A minute irradiation 2c and 2e converts them into now species with redox potentials of -230 and 270 mV, respectively. An exceptional potential drop for 2c is accounted for in terms of a photosubstitution of both MeCN ligands by methanol. ESR, H-1 NMR, and UV-vis data indicate that the primary product of photolysis of 2c is an octahedral monomeric low-spin (S = 112) Ru-III species, presumably cis-[Ru-II(o-C6H4-2-py)(phen)(MeOH)2]2+. The primary photoproduct of bpy complex 2e is cis-[Ru-II(O-C6H4-2-py)(bpy)(MeCN)(MeOH)](+), and this accounts for a lower decrease in the redox potential. Irradiation of 2c in the presence of added chloride affords [(phen)(o-C6H4-2-py)(ClRuORuCl)-O-III-Cl-IV(o-C6H4-2-py)(phen)]PF6, a first mu-oxo-bridged mixed valent dimer with a cyclometalated unit. The structure of the dimer has been established by X-ray crystallography.
Synthesis, Characterization, and Electrochemistry of Biorelevant Photosensitive Low-Potential Orthometalated Ruthenium Complexes
作者:Alexander D. Ryabov、Ronan Le Lagadec、Hebert Estevez、Ruben A. Toscano、Simon Hernandez、Larissa Alexandrova、Viktoria S. Kurova、Andreas Fischer、Claude Sirlin、Michel Pfeffer
DOI:10.1021/ic048270w
日期:2005.3.1
Redox potentials of photosensitive cyclometalated Ru" derivatives of 2-phenylpyridine or 2-(4-tolyl)pyridine are controllably decreased by up to 0.8 V within several minutes. This is achieved by irradiation of the ruthena(II)cycles cis-[Ru(o-X-2-py)(LL)(MeCN)(2)]PF6 (2, X = C6H4 (a) or 4-MeC6H3 (b), LL = 1,10-phenanthroline or 2,2'-bipyridine). The cis geometry of the MeCN ligands has been confirmed by the X-ray structural studies. The sigma-bound sp(2) carbon of the metalated ring is trans to LL nitrogen. Complexes 2 are made from [Ru(o-X-2-py)(MeCN)(4)]PF6 (1) and I-L. This "trivial" ligand substitution is unusual because la reacts readily with phen in MeCN as solvent to give cis-[Ru(o-C6H4-2-py)(phen)(MeCN)(2)]PF6 (2c) in a 83% yield, but bpy does not afford the bpy-containing 2 under the same conditions. cis-[Ru(o-C6H4-2-py)(bpy)(MeCN)(2)]PF6 (2e) has been prepared in CH2Cl2 (74%). Studies of complexes 2c,e by cyclic voltammetry in MeOH in the dark reveal Ru-II/III quasy-reversible redox features at 573 and 578 mV (vs Ag/AgCl), respectively. A minute irradiation 2c and 2e converts them into now species with redox potentials of -230 and 270 mV, respectively. An exceptional potential drop for 2c is accounted for in terms of a photosubstitution of both MeCN ligands by methanol. ESR, H-1 NMR, and UV-vis data indicate that the primary product of photolysis of 2c is an octahedral monomeric low-spin (S = 112) Ru-III species, presumably cis-[Ru-II(o-C6H4-2-py)(phen)(MeOH)2]2+. The primary photoproduct of bpy complex 2e is cis-[Ru-II(O-C6H4-2-py)(bpy)(MeCN)(MeOH)](+), and this accounts for a lower decrease in the redox potential. Irradiation of 2c in the presence of added chloride affords [(phen)(o-C6H4-2-py)(ClRuORuCl)-O-III-Cl-IV(o-C6H4-2-py)(phen)]PF6, a first mu-oxo-bridged mixed valent dimer with a cyclometalated unit. The structure of the dimer has been established by X-ray crystallography.
DNA Binding to an Anticancer Organo-Ruthenium Complex
Because many anticancer drugs interact with DNA, the determination of their association constants to DNA is essential for quantifying their mechanisms of action. The interactions between a new ruthenium-derived compound [ruthenium(phenanthroline)(kappa-C,N-(2-phenyl-pyridine)(NCMe)(2)PF6, called RDCII] and DNA are studied using different techniques. Fluorescent experiments are used to determine the association and dissociation constants under different salt concentrations. The binding is shown to be reversible and noncovalent. The association constants vary from 1.5 x 10(6) M-1 to 2.9 x 10(3) M-1 when increasing the sodium concentration from 0.1 to 200 mM. Single-molecule stretching methods are used to study the interaction of RDC with longer DNA strands (8.6 kbp home-built dimer of pBR322). The affinities of RDC with DNA under different loads are obtained using McGhee and von Hippel analysis. The affinity constant and thermodynamic parameters are in good agreement with the values found in the literature and lead to the conclusion that this molecule intercalates dsDNA.
Unusual phenomenon in the chemistry of orthometalated ruthenium (II) complexes
作者:Alexander D. Ryabov、Hebert Estevez、Larissa Alexandrova、Michel Pfeffer、Ronan Le Lagadec
DOI:10.1016/j.ica.2005.05.034
日期:2006.2
Yellow cyclometalatated ruthenium (II) complexes [Ru(o-X-2-py)(MeCN)(4)1PF(6) (1, X = C6H4 (a) or 4-MeC6H3 (b)) react readily with 1,10-phenanthroline (LL) in MeCN to give brownish-red species cis-[Ru(o-X-2-py)(LL)(MeCN)(2)]PF6 in high yields. The same reaction of the same complexes under the same conditions with 2,2'-bipyridine results in a significant color change from yellow to brownish-orange suggesting a formation of new species. Surprisingly, X-ray structural studies of these two complexes showed that they are structurally indistinguishable from the starting complexes 1. Referred to as complexes 4a,b, the new compounds are slightly more stable in the air though their spectral characteristics in solution are similar to 1a,b. The diffuse reflectance spectroscopy is so far the only technique that indicated differences between I and 4. (c) 2005 Elsevier B.V. All rights reserved.
Rational Synthesis of Heteroleptic Tris(chelate) Ruthenium Complexes [Ru<sup>II</sup>(2-Ph-2′-Py)(L<sup>∧</sup>L)(L′<sup>∧</sup>L′)]PF<sub>6</sub> by Selective Substitution of the Ligand Trans to the Ruthenated Phenyl Ring
the same N atom was bound to Ru trans to the pyridine of 2-PhPy; these new compounds, in opposition to their well-known isomers, proved to be nicely reactive toward substitutionreactions of the MeCN ligands, by other bidentate N-containing ligands such as 4,4′-R2-2,2′-bipyridine (R = H, OMe, COOH) and 4,7-dimethyl-1,10-phenanthroline. These results question the exact structure of the already reported