Optically active Ru(II) complexes with a chiral Tröger’s base ligand and their interactions with DNA (original) (raw)
Related papers
Helvetica Chimica Acta, 2008
The ligand pteridino[6,7-f] [1,10]phenanthroline-11,13-diamine (ppn) and its Ru II complexes [Ru(bpy) 2 (ppn)] 2þ (1; bpy ¼ 2,2'-bipyridine) and [Ru(phen) 2 (ppn)] 2þ (2; phen ¼ 1,10-phenanthroline) were synthesized and characterized by elemental analysis, electrospray MS, 1 H-NMR, and cyclic voltammetry. The DNA-binding behaviors of 1 and 2 were studied by spectroscopic and viscosity measurements. The results indicate that both complexes strongly bind to calf-thymus DNA in an intercalative mode, with DNA-binding constants K b of (1.7 AE 0.4) · 10 6 m À1 and (2.6 AE 0.2) · 10 6 m À1 , respectively. The complexes 1 and 2 exhibit excellent DNA-light switch performances, i.e., they do not (or extremely weakly) show luminescence in aqueous solution at room temperature but are strongly luminescent in the presence of DNA. In particular, the experimental results suggest that the ancillary ligands bpy and phen not only have a significant effect on the DNA-binding affinities of 1 and 2 but also have a certain effect on their spectral properties. [Ru(phen) 2 (ppn)] 2þ (2) might be developed into a very prospective DNA-light switch complex. To explain the DNA-binding and spectral properties of 1 and 2, theoretical calculations were also carried out applying the DFT/TDDFT method.
Inorganica Chimica Acta, 2012
A new family of Ru(II) polypyridyl complexes (C1 to C6) containing furyl-or thienyl-imidazo-phenanthroline ligands (4-6) were synthesized using microwave irradiation and characterized by elemental analysis, 1 H NMR, UV-Vis absorption and fluorescence spectroscopy, FAB, ESI-MS and MALDI-TOF-MS spectrometry. On the other hand, the novel furyl-or thienyl-imidazo-phenanthroline derivatives (5-6) were synthesized through the Radziszewski reaction and completely characterized by the usual spectroscopic techniques. The interaction of the complexes with calf thymus DNA in the absence and in the presence of different quenchers (ethidium bromide, potassium hexacyanoferrate(II) and methyl viologen) has been studied by absorption spectroscopy, steady-state and single-photon timing luminescence measurements. Their electronic spectra show visible absorption peaks at 457-463 nm, with red luminescence at 603-613 nm. The emission quantum yields of these complexes are between 0.006 and 0.016 in air-equilibrated DMSO solution. Luminescence lifetimes in water lie within the 0.4-1.0 ls range, with a non-exponential behavior due to aggregation of the probe. Ru(II) complexes C3, C4, C5 and C6 show intrinsic dsDNA-binding constants of 2.74 Â 10 5 , 3.02 Â 10 5 , 1.32 Â 10 5 and 1.63 Â 10 5 M À1 , respectively. The planar extended structure of the imidazo-phenanthroline ligands and the collected spectroscopic data suggest a partial intercalative binding mode of the novel metal probes to double-stranded DNA.
Inorganica Chimica Acta, 2000
Salicylaldehyde 2-phenylquinoline-4-carboylhydrazone (H 2 L), and its novel copper(II), cobalt(II), and nickel(II) complexes MHL Á Cl Á nH 2 O [M=Cu n = 3 (1), M=Co n = 2 (2), M=Ni n = 3.5 (3)] have been synthesized and characterized by elemental analysis, molar conductivity, spectroscopic, and thermal analysis. The interaction of these complexes with calf thymus DNA was investigated by UV absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and viscosity measurements. The results suggest that these complexes bind to DNA via an intercalation binding mode and their affinity to DNA follows the order of 3 [ 1[ 2.
DNA binding by Ru(II)–bis(bipyridine)–pteridinyl complexes
Journal of Biological Inorganic Chemistry, 2008
The interactions of five bis(bipyridyl) Ru(II) complexes of pteridinyl-phenanthroline ligands with calf thymus DNA have been studied. The pteridinyl extensions were selected to provide hydrogen-bonding patterns complementary to the purine and pyrimidine bases of DNA and RNA. The study includes three new complexes [Ru(bpy)2(L-pterin)]2+, [Ru(bpy)2(L-amino)]2+, and [Ru(bpy)2(L-diamino)]2+ (bpy is 2,2′-bipyridine and L-pterin, L-amino, and L-diamino are phenanthroline fused to pterin, 4-aminopteridine, and 2,4-diaminopteridine), two previously reported complexes [Ru(bpy)2(L-allox)]2+ and [Ru(bpy)2(L-Me2allox)]2+ (L-allox and L-Me2allox are phenanthroline fused to alloxazine and 1,3-dimethyalloxazine), the well-known DNA intercalator [Ru(bpy)2(dppz)]2+ (dppz is dipyridophenazine), and the negative control [Ru(bpy)3]2+. Reported are the syntheses of the three new Ru–pteridinyl complexes and the results of calf thymus DNA binding experiments as probed by absorption and fluorescence spectroscopy, viscometry, and thermal denaturation titrations. All Ru–pteridine complexes bind to DNA via an intercalative mode of comparable strength. Two of these four complexes—[Ru(bpy)2(L-pterin)]2+ and [Ru(bpy)2(L-allox)]2+—exhibit biphasic DNA melting curves interpreted as reflecting exceptionally stable surface binding. Three new complexes—[Ru(bpy)2(L-diamino)]2+, [Ru(bpy)2(L-amino)]2 and [Ru(bpy)2(L-pterin)]2+—behave as DNA molecular “light switches.”
Non-intercalative binding mode of bridged binuclear chiral Ru(II) complexes to native duplex DNA
A pair of chiral binuclear ruthenium(II) complexes were prepared and their binding affinities towards double stranded native DNA were assessed by observing isotropic absorption, polarized light spectra – circular and linear dichroism (CD and LD), fluorescence quenching and DNA thermal denaturation. Upon binding to DNA, the complexes produced LD signals consisting of positive and negative signals in the absorption region, although they exhibited red shift and hypochromism in the absorption spectrum. These contrasting observations indicated that the binding modes of the complexes are largely deviated from classical intercalative binding. Groove binding of the complexes to DNA was found to be more likely than intercalative binding. The small increase of DNA melting temperature in the presence of the complexes indicated a predominance of DNA groove binding. The absence of " molecular light switch effect " further supported non-intercalative binding. The groove binding propensity of complexes was also supported by comparison of the resulting data with the [Ru(phen) 2 (dppz)] 2+ .
Synthesis, characterization, DNA binding and cleavage studies of chiral Ru (II) salen complexes
… Acta Part A: Molecular …, 2009
New symmetrical acyclic binuclear copper (II) complexes [CuL 1-2 ](ClO 4) 2 1 and 2 were synthesized by template method, from bicompartmental ligand 2,6-bis((E)-(2-(2aminoethylamino)ethylimino)methyl)-4-methylphenol (L 1) and 2-((7E)-(2-((Z)-2-((naphthalen-1-yl) methyleneamino)ethylamino)ethylimino)methyl)-6-((9E)-(2-((Z)-2-((naphthalen-1-yl)methyleneamino) ethylamino)ethylimino) methyl)-4-methylphenol (L 2). These complexes were characterized by elemental analysis and spectroscopic techniques. The cyclic voltammogram of binuclear Cu(II) complexes exhibit two quasi-reversible reduction waves. The first reduction potential ranges from-0.6 V to-0.80 V and the second reduction potential lies in the range from-1.0 V to-1.25 V versus Ag/AgCl in Acetonitrile, 0.1 M TBAP. The DNA binding properties have been studied with the complexes 1 and 2 with calf thymus DNA. The complexes show good binding propensity to calf thymus DNA giving binding constant values in the range from 1.4 × 10 5 and 3.67 × 10 6 M-1. The absorption, fluorescence and viscosity measurements spectral data suggests that the complexes are interacting strongly with DNA. These complexes display oxidative cleavage of supercoiled pBR322DNA in the presence of H 2 O 2 at pH 7.2 and 37 •C using singlet oxygen as a reactive species. The binding affinities are in the following order: 2 > 1. Keywords-DNA binding and cleavage studies, copper (II) complexes DNA binding studies, intercalative binding mode and oxidative cleavage studies I.
Helvetica Chimica Acta, 2008
Complexes [Ru(phen) 2 (ppd)] 2þ and [Ru(phen)(ppd) 2 ] 2þ (ppd ¼ Pteridino[6,7-f] [1,10]phenanthroline-11,13(10H,12H)-dione, phen ¼ 1,10-Phenanthroline)
Inorganica Chimica Acta, 2006
A series of mixed ligand Ru(II) complexes of 5,6-dimethyl-1,10-phenanthroline (5,6-dmp) as primary ligand and 1,10-phenanthroline (phen), 2,2 0-bipyridine (bpy), pyridine (py) and NH 3 as co-ligands have been prepared and characterized by X-ray crystallography, elemental analysis and 1 H NMR and electronic absorption spectroscopy. The X-ray crystal structure of the complex [Ru(phen) 2 (bpy)]Cl 2 reveals a distorted octahedral coordination geometry for the RuN 6 coordination sphere. The DNA binding constants obtained from the absorption spectral titrations decrease in the order, tris(5,6-dmp)Ru(II) > bis(5,6-dmp)Ru(II) > mono(5,6-dmp)Ru(II), which is consistent with the trend in apparent emission enhancement of the complexes on binding to DNA. These observations reveal that the DNA binding affinity of the complexes depend upon the number of 5,6-dmp ligands and hence the hydrophobic interaction of 5,6-dimethyl groups on the DNA surface, which is critical in determining the DNA binding affinity and the solvent accessibility of the exciplex. Among the bis(5,6-dmp)Ru(II) complexes, those with monodentate py (4) or NH 3 (5) co-ligands show DNA binding affinities slightly higher than the bpy and phen analogues. This reveals that they interact with DNA through the co-ligands while both the 5,6-dmp ligands interact with the exterior of the DNA surface. All these observations are supported by thermal denaturation and viscosity measurements. Two DNA binding modes-surface/electrostatic and strong hydrophobic/partial intercalative DNA interaction-are suggested for the mixed ligand complexes on the basis of time-resolved emission measurements. Interestingly, the 5,6-dmp ligands promote aggregation of the complexes on the DNA helix as a helical nanotemplate, as evidenced by induced CD signals in the UV region. The ionic strength variation experiments and competitive DNA binding studies on bis(5,6-dmp)Ru(II) complexes reveal that EthBr and the partially intercalated and kinetically inert [Ru(phen) 2 (dppz)] 2+ (dppz = dipyrido[3,2-a:2 0 ,3 0-c]phenazine) complexes revert the CD signals induced by exciton coupling of the DNA-bound complexes with the free complexes in solution.
Journal of Molecular Structure, 2013
Bis-and tris(2,3-dihydro-4a,12b-(epoxyethanooxy)[1,4]dioxino[2,3-f] [1,10]phenanthroline) complexes of Ru(II): Synthesis, structure and DNA binding properties
Journal of Fluorescence, 2011
The three Ru(II) complexes of [Ru(phen) 2 dppca] 2+ (1) [Ru(bpy) 2 dppca] 2+ (2) and [Ru(dmb) 2 dppca] 2+ (3) (where phen 0 1,10 phenanthroline, bpy 0 2,2-bipyridine, dmb 0 2 ,2-dimethyl 2′,2′-bipyridine and polypyridyl ligand containing a single carboxylate functionality dppca ligand (dipyridophenazine-11-carboxylic acid) have been synthesized and characterized. These complexes have been shown to act as promising calf thymus DNA intercalators and a new class of DNA light switches, as evidenced by UVvisible and luminescence titrations with Co 2+ and EDTA, steady-state emission quenching by [Fe(CN) 6 ] 4− and KI, DNA competitive binding with ethidium bromide, viscosity measurements, and DNA melting experiments. The results suggest that 1, 2, and 3 complexes bind to CT-DNA through intercalation and follows the order 1>2>3. Under irradiation at 365 nm, the three complexes have also been found to promote the photocleavage of plasmid pBR322 DNA.