Synthesis,Characterization, and DNA Interaction Studies of the Ruthenium(II) Complexes [Ru(bpy)2(ipbp)]2+ and [Ru(ipbp)(phen)2]2+ (ipbp=3‐(1H‐Imidazo[4,5‐f][1,10]phenanthrolin‐2‐yl)‐4H‐1‐benzopyran‐2‐one; bpy=2,2′‐Bipyridine; phen=1,10‐Phenanthroline)

A novel ligand 3‐(1H‐imidazo[4,5‐f][1,10]phenanthrolin‐2‐yl)‐4H‐1‐benzopyran‐4‐one (ipbp) and its ruthenium(II) complexes [Ru(bpy)₂(ipbp)]²⁺ ( 1 ) and [Ru(ipbp)(phen)₂]²⁺ ( 2 ) (bpy=2,2′‐bipyridine, phen=1,10‐phenanthroline) were synthesized and characterized by elemental analysis and mass, ¹H‐NMR, and electronic‐absorption spectroscopy. The electrochemical behavior of the complexes was studied by cyclic voltammetry. The DNA‐binding behavior of the complexes was investigated by spectroscopic methods and viscosity measurements. The results indicate that complexes 1 and 2 bind with calf‐thymus DNA in an intercalative mode. In addition, 1 and 2 promote cleavage of plasmid pBR 322 DNA from the supercoil form I to the open circular form II upon irradiation.     

Synthesis,characterization, and DNA binding of ruthenium(II) complexes with 2-benzo[b] furan-2-yl-1H-imidazo[4,5f][1,10]phenanthroline as an intercalative ligand

DNA-binding properties of a number of ruthenium complexes with different polypyridine ligands are reported. The new polypyridine ligand BFIP (=2-benzo[b] furan-2-yl-1H-imidazo[4,5-f][1,10]phenanthroline) and its ruthenium complexes [Ru(bpy)₂BFIP]²⁺ (bpy = 2,2′-bipyridine), [Ru(dmb)₂BFIP]²⁺ (dmb = 4,4′-dimethyl-2,2′-bipyridine), and [Ru(phen)₂BFIP]²⁺ (phen = 1,10-phenanthroline) have been synthesized and characterized by elemental analysis, mass spectra, IR, UV-Vis, ¹H- and ¹³C-NMR, and cyclic voltammetry. The DNA binding of these complexes to calf-thymus DNA (CT-DNA) was investigated by spectrophotometric, fluorescence, and viscosity measurements. The results suggest that ruthenium(II) complexes bind to CT-DNA through intercalation. Photocleavage of pBR 322 DNA by these complexes was also studied, and [Ru(phen)₂BFIP]²⁺ was found to be a much better photocleavage agent than the other two complexes.     

DNA Interactions of a Dinuclear Ruthenium(II) Complex Bridged by 1,3-bis(1,10-phenanthroline[5,6-d]imidazol-2-yl)benzene

A novel dinuclear ruthenium(II) complex [(phen)₂Ru(mbpibH₂)Ru(phen)₂]⁴⁺ [phen = 1,10-phenanthroline; mbpibH₂ = 1,3-bis(1,10-phenanthroline[5,6-d]imidazol-2-yl)-benzene] has been synthesized and characterized. The DNA-binding behavior of this complex has been studied by spectroscopic and viscosity measurements. Results suggest that the dinuclear ruthenium(II) complex intercalates into DNA base pairs via its bridging moiety. It has also been found that the dinuclear ruthenium(II) complex displays the enantiopreferential DNA-binding after equilibrium dialysis.     

Synthesis,DNA interaction and photocleavage studies of ruthenium(II) complexes with 2-(pyrrole) imidazo[4,5-f]-1,10-phenanthroline as an intercalative ligand

Three Ru(II) complexes, namely [Ru(bipy)₂PRIP]²⁺ (1), [Ru(dmb)₂PRIP]²⁺ (2), and [Ru(phen)₂PRIP]²⁺ (3) (dmb = 4,4′-dimethyl-2,2′-bipyridine; PRIP = 2-(pyrrole) imidazo [4,5-f]-1,10-phenanthroline) have been synthesized and characterized by elemental analysis, mass spectra, IR, ¹H NMR and ¹³C NMR. The DNA-binding properties of the three complexes with calf-thymus DNA (CT-DNA) were investigated by spectrophotometry, fluorescence methods and viscosity measurements. The results suggest that all three complexes bind to CT-DNA through intercalation. Also, when irradiated at 365 nm, the three complexes promote the photocleavage of plasmid pBR-322 DNA. Under comparable experimental conditions, complex 3 cleaves DNA more effectively than complexes 1 and 2.     

Synthesis, characterization and DNA-binding studies of ruthenium(II) mixed-ligand complexes containing dipyrido[1,2,5]oxadiazolo[3,4-b]quinoxaline

A novel ligand dipyrido[1,2,5]oxadiazolo[3,4-b]quinoxaline (dpoq) and its complexes [Ru(bpy)₂(dpoq)]²⁺ and [Ru(phen)₂(dpoq)]²⁺ (bpy = 2,2′-bipyridine; phen = 1,10-phenanthroline) have been synthesized and characterized by elemental analysis, electrospray mass spectra and ¹H NMR. The interaction of Ru(II) complexes with calf thymus DNA (CT-DNA) was investigated by absorption spectroscopy, fluorescence spectroscopy, thermal denaturation and viscosity measurements. Results suggest that two Ru(II) complexes bind to DNA via an intercalative mode.     

DNA interactions of ruthenium(II) complexes with a polypyridyl ligand: 2-(2, 5-dimethoxyphenyl)-1<Emphasis Type="Italic">H</Emphasis>-imidazo[4,5-<Emphasis Type="Italic">f</Emphasis>]1,10-phenanthroline

This article describes the synthesis of a polypyridyl ligand, namely 2-(2, 5-dimethoxyphenyl)-1H-imidazo[4,5-f]1,10-phenanthroline (DMPIP) and its Ru(II) complexes, namely [Ru(bipy)₂DMPIP]²⁺ (1), [Ru(dmb)₂DMPIP]²⁺ (2) and [Ru(phen)₂DMPIP]²⁺ (3) ((bipy = 2,2′-bipyridine, dmb = 4,4′-dimethyl-2,2′-bipyridine, phen = 1,10-phenanthroline). The complexes were characterized by elemental analysis, plus IR, ¹H-NMR and ¹³C [¹H]-NMR spectra. The interactions of the complexes with calf thymus DNA were investigated. The results indicate that the three complexes can intercalate into DNA. Under irradiation at 365 nm, all three complexes promote the photocleavage of plasmid pBR 322 DNA. Inhibitor studies suggest that singlet oxygen plays a significant role in the cleavage mechanism for the complexes.     

Study of the interaction between ruthenium(II) complexes and CT-DNA: synthesis,characterisation, photocleavage and antimicrobial activity studies

Two polypyridyl ligands 6-fluro-3-(1H-imidazo [4,5-f] [1,10]-phenanthroline-2-yl)-4H-chromen-4-one (FIPC), 6-chloro-3-(1H-imidazo [4,5-f] [1,10]-phenanthroline-2-yl)-4H-chromen-4-one (ClIPC) polypyridyl ligands and their Ru(II) complexes [Ru(bipy)₂FIPC]²⁺(1), [Ru(dmb)₂FIPC]²⁺(2), [Ru(phen)₂FIPC]²⁺(3), [Ru(bipy)₂ClIPC]²⁺(4), [Ru(dmb)₂ClIPC]²⁺(5) and [Ru(phen)₂ClIPC]²⁺(6) ((bipy = 2,2′-bipyridine, dmb = 4,4′-dimethyl-2,2′-bipyridine and phen = 1,10-phenanthroline) have been synthesised and characterised by elemental analysis, Mass spectra, IR, ¹H and ¹³C-NMR. The DNA-binding of the six complexes to calf-thymus DNA (CT-DNA) has been investigated by different spectrophotometric, fluorescence and viscosity measurements. The results suggest that 1–6 complexes bind to CT-DNA through intercalation. The variation in binding affinities of these complexes is rationalised by a consideration of electrostatic, steric factors and nature of ancillary ligands. Under irradiation at 365 nm, the three complexes have also been found to promote the photocleavage of plasmid pBR 322 DNA. Inhibitor studies suggest that singlet oxygen (¹O₂) plays a significant role in the cleavage mechanism of Ru(II) complexes. Thereby, under comparable experimental conditions [Ru(phen)₂FIPC]²⁺(3), [Ru(phen)₂ClIPC]²⁺(6) cleaves DNA more effectively than 1, 2, 4 and 5 complexes do. The Ru(II) polypyridyl complexes (1–6) have been screened for antimicrobial activities.     

DNA interaction studies of ruthenium(II) polypyridyl complex : [Ru(dmb)2(ITAP)](ClO4)2 (ITAP = isatino [1,2-b]-1,4,8,9-tetraazatriphenylene)

A new ligand ITAP and its complex [Ru(dmb)₂(ITAP)](ClO₄)₂ (ITAP = isatino [1,2-b]-1,4,8, 9-tetraazatriphenylene, dmb = 4,4′-dimethyl-2,2′-bipyridine) have been synthesized and characterized by elemental analysis, Fast atom bombardment mass spectra, Electrospray mass spectra, and ¹H NMR. Thermal denaturation and absorption titration experiments show the complex binds to calf thymus DNA (CT-DNA) with moderate affinities. Viscosity measurements and thermal denaturation indicate that the DNA-binding mode could be intercalative interaction. The Ru(II) complex in the presence of plasmid pBR322 DNA has been found to promote the cleavage of plasmid pBR322 DNA from the supercoiled Form I to the open circular Form II upon irradiation. Mechanisms for DNA cleavage by the complex were also investigated.     

Synthesis,characterization, DNA-binding and DNA-photocleavage studies of [Ru(bpy)2(BPIP)] and [Ru(phen)2(BPIP)] (BPIP = 2-(4′-biphenyl)imidazo[4,5-f][1,10]phenanthroline)

New ligand 2-(4′-biphenyl)imidazo[4,5-f][1,10]phenanthroline (BPIP) and its complexes [Ru(bpy)₂(BPIP)]²⁺ (1) (bpy = 2,2′-bipyridine) and [Ru(phen)₂(BPIP)]²⁺ (2) (phen = 1,10-phenanthroline) have been synthesized and characterized by mass spectroscopy, ¹H NMR and cyclic voltammetry. The interaction of two Ru(II) complexes with calf thymus DNA (CT-DNA) was investigated by spectroscopic and viscosity measurements. Results indicate that both complexes bind to DNA via an intercalative mode and the DNA-binding affinity of complex 2 is much greater than that of complex 1. Furthermore, when irradiated at 365 nm, both complexes have also been found to promote the photocleavage of plasmid pBR 322 DNA.     

Synthesis,DNA‐Binding and Photocleavage Studies of the Ruthenium(II) Complexes [Ru(phen)2(ppd)]2+ and [Ru(phen)(ppd)2]2+ (ppd=Pteridino[6,7‐f] [1,10]phenanthroline‐11,13(10H,12H)‐dione,phen=1,10‐Phenanthroline)

Two new complexes, [Ru(phen)₂(ppd)]²⁺ ( 1 ) and [Ru(phen)(ppd)₂]²⁺ ( 2 ) (ppd=pteridino[6,7‐f] [1,10]phenanthroline‐11,13(10H,12H)‐dione, phen=1,10‐phenanthroline) were synthesized and characterized by ES‐MS, ¹H‐NMR spectroscopy, and elemental analysis. The intercalative DNA‐binding properties of 1 and 2 were investigated by absorption‐spectroscopy titration, luminescence‐spectroscopy studies, thermal denaturation, and viscosity measurements. The theoretical aspects were further discussed by comparative studies of 1 and 2 by means of DFT calculations and molecular‐orbital theory. Photoactivated cleavage of pBR322 DNA by the two complexes were also studied, and 2 was found to be a much better photocleavage reagent than 1 . The mechanism studies revealed that singlet oxygen and the excited‐states redox potentials of the complex may play an important role in the DNA photocleavage.     

Synthesis,characterization, and DNA-binding of [Co(phen)2(CPIA)]3+, [Co(phen)2(BIP)]3+, and [Co(phen)2(CIP)]3+

Three ligands, 2-(3-(carboxymethyl)-1,10-phenanthroline-[5,6-d]imidazole-1-yl)acetate (CPIA), 2-(benzo[d][1,3]dioxol-4-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (BIP), and 2-(9H-carbazol-3-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (CIP), and their complexes, [Co(phen)₂(CPIA)]³⁺ (1) (phen = 1,10-phenanthroline), [Co(phen)₂(BIP)]³⁺ (2), and [Co(phen)₂(CIP)]³⁺ (3), have been synthesized and characterized. Binding of the three complexes with calf thymus DNA (CT-DNA) has been investigated by spectroscopic methods, cyclic voltammetry, and viscosity measurements. The three complexes bind to DNA through an intercalative mode, and the size and shape of the intercalative ligands have significant effects on the binding affinity of complexes to CT-DNA.     

Synthesis, DNA-binding and photocleavage studies of [Ru(phen)2(pbtp)] and [Ru(bpy)2(pbtp)] (phen = 1,10-phenanthroline; bpy = 2,2′-bipyridine; pbtp = 4,5,9,11,14-pentaaza-benzo[b]triphenylene)

Based on the ligand dppz (dppz = dipyrido-[3,2-a:2′,3′-c]phenazine), a new ligand pbtp (pbtp = 4,5,9,11,14-pentaaza-benzo[b]triphenylene) and its polypyridyl ruthenium(II) complexes [Ru(phen)₂(pbtp)]²⁺ (1) (phen = 1,10-phenanthroline and [Ru(bpy)₂(pbtp)]²⁺ (2) (bpy = 2,2′-bipyridine) have been synthesized and characterized by elemental analysis, ES-MS and ¹H NMR spectroscopy. The DNA-binding of these complexes were investigated by spectroscopic methods and viscosity measurements. The experimental results indicate that both complexes 1 and 2 bind to CT-DNA in classical intercalation mode, and can enantioselectively interact with CT-DNA. It is interesting to note that the pbtp ruthenium(II) complexes, in contrast to the analogous dppz complexes, do not show fluorescent behavior when intercalated into DNA. When irradiated at 365 nm, both complexes promote the photocleavage of pBR 322 DNA.     

Synthesis,DNA-binding,and photocleavage properties of Ru(II) complexes containing dppz-based ligand

A ligand ipdp (ipdp?=?indeno[1′,2′?:?5,6]pyrazino[2,3-i]dipyrido[3,2-a?:?2′,3′-c]phenazine-8-one) and its ruthenium complexes, [Ru(L)₂(ipdp)]²⁺ (L?=?bpy (2,2′-bipyridine), phen (1,10-phenanthroline)), have been synthesized and characterized by elemental analysis, electrospray mass spectra, and ¹H NMR. The interaction between the complexes and calf thymus DNA (CT-DNA) has been investigated by spectroscopic methods and viscosity measurements. The results indicate that the complexes can bind to CT-DNA in an intercalative mode. In addition, both complexes promote the photocleavage of plasmid pBR322 DNA under irradiation. The mechanistic studies reveal that singlet oxygen ¹O₂ plays a significant role in DNA photocleavage.     

Synthesis,Characterization, and DNA‐Binding Properties of the Chiral Ruthenium(II) Complexes Δ‐ and Λ‐[Ru(bpy)2(dmppd)]2+ (dmppd = 10,12‐Dimethylpteridino[6,7‐f] [1,10]phenanthroline‐11,13(10H,12H)‐dione; bpy = 2,2′‐Bipyridine)

Two novel chiral ruthenium(II) complexes, Δ‐[Ru(bpy)₂(dmppd)]²⁺ and Λ‐[Ru(bpy)₂(dmppd)]²⁺ (dmppd = 10,12‐dimethylpteridino[6,7‐f] [1,10]phenanthroline‐11,13(10H,12H)‐dione, bpy = 2,2′‐bipyridine), were synthesized and characterized by elemental analysis, ¹H‐NMR and ES‐MS. The DNA‐binding behaviors of both complexes were studied by UV/VIS absorption titration, competitive binding experiments, viscosity measurements, thermal DNA denaturation, and circular‐dichroism spectra. The results indicate that both chiral complexes bind to calf‐thymus DNA in an intercalative mode, and the Δ enantiomer shows larger DNA affinity than the Λ enantiomer does. Theoretical‐calculation studies for the DNA‐binding behaviors of these complexes were carried out by the density‐functional‐theory method. The mechanism involved in the regulating and controlling of the DNA‐binding abilities of the complexes was further explored by the comparative studies of [Ru(bpy)₂(dmppd)]²⁺ and of its parent complex [Ru(bpy)₂(ppd)]²⁺ (ppd = pteridino[6,7‐f] [1,10]phenanthroline‐11,13 (10H,12H)‐dione).     

The photocleavage properties of a novel ruthenium(II) complex on liver cancer cells Bel-7402 DNA

A novel ruthenium(II) complex [Ru(bpy)₂DMHPIP] (DMHPIP = 2-(3,5-dimethoxy-4-hydroxyphenyl)imidazo[4,5-f][1,10]phenanthroline) (1) has been synthesized and characterized by elemental analysis, ¹H-NMR and ESI-MS. The DNA binding properties of the complex has also been investigated by electronic spectra and emission spectra, and the results show that complex (1) bind to DNA with high affinity. On the other hand, the photocleavage property of complex (1) on liver cancer cells lines Bel-7402 DNA has been investigated by electrophoresis agarose gels, and the results show that the complex can promote liver cancer cells Bel-7402 DNA from the supercoiled form to the nicked form excellently.     

Synthesis,characterization and DNA binding studies of ruthenium(II) complexes: [Ru(bpy)<Subscript>2</Subscript>(dtmi)]<Superscript>2+</Superscript> and [Ru(bpy)<Subscript>2</Subscript>(dtni)]<Superscript>2+</Superscript>

Two new ruthenium(II) polypyridyl complexes (1) (dtmi = 3-(pyrazin-2-yl)-as-triazino[5,6-f]-5-methoxylisatin) and (2) (dtni = 3-(pyrazin-2-yl)-as-triazino[5,6-f]-5-nitroisatin) have been synthesized and characterized by elemental analysis, FAB-MS, ES-MS and ¹H-n.m.r. The DNA-binding patterns of complexes were investigated by spectroscopic titration, viscosity measurements and thermal denaturation. The results indicate that the complexes (1) and (2) interact with calf thymus DNA (CT-DNA) by intercalative mode. Due to the withdrawing electronic substitutent in the intercalative ligand, ptni, the DNA-binding affinity of the complexes (2) is larger than that complex (1) does.     

Synthesis and characterization of the [Ru<Subscript>3</Subscript>O(CH<Subscript>3</Subscript>COO)<Subscript>6</Subscript>(py)<Subscript>2</Subscript>(BPE)Ru(bpy)<Subscript>2</Subscript>Cl](PF<Subscript>6</Subscript>)<Subscript>2</Subscript> dimer

The polymetallic [Ru₃O(CH₃COO)₆(py)₂(BPE)Ru(bpy)₂Cl](PF₆)₂ complex (bpy = 2,2′-bipyridine, BPE = trans-1,2-bis(4-pyridil)ethylene and py = pyridine) was assembled by the combination of an electroactive [Ru₃O] moiety with a [Ru(bpy)₂(BPE)Cl] photoactive centre, and its structure was determined using positive ion electrospray (ESI-MS) and tandem mass (ESI-MS/MS) spectrometry. The [Ru₃O(CH₃COO)₆(py)₂(BPE)Ru(bpy)₂Cl]²⁺ doubly charged ion of m/z 732 was mass-selected and subject to 15 eV collision-induced dissociation, leading to a specific dissociation pattern, diagnostic of the complex structure. The electronic spectra display broad bands at 409, 491 and 692 nm ascribed to the [Ru(bpy)₂(BPE)] charge-transfer bands and to the [Ru₃O] internal cluster transitions. The cyclic voltammetry shows five reversible waves at −1.07 V, 0.13 V, 1.17 V, 2.91 V and −1.29 V (vs SHE) assigned to the [Ru₃O]^{−1/0/+1/+2/+3} and to the bpy^0/−1 redox processes; also a wave is observed at 0.96 V, assigned to the Ru^+2/+3 pair. Despite the conjugated BPE bridge, the electrochemical and spectroelectrochemical results indicate only a weak coupling through the π-system, and preliminary photophysical essays showed the compound decomposes under visible light irradiation.     

Synthesis,characterization, photocleavage,antimicrobial activity and DNA binding of [Co(bpy)2MHPIP]3+, [Co(dmb)2MHPIP]3+, and [Co(phen)2MHPIP]3+ complexes

4-Methyl-2-(2-hydroxyphenyl)imidazo[4,5-f][1,10]phenanthroline) (MHPIP) and its complexes [Co(bpy)₂MHPIP]³⁺ (1) (bpy = 2,2′-bipyridine), [Co(dmb)₂MHPIP]³⁺ (2) (dmb = 4,4′-dimethyl-2,2′-bipyridine), and [Co(phen)₂MHPIP]³⁺ (3) (phen = 1,10-phenanthroline) have been synthesized and characterized by UV/VIS, IR, EA, ¹H, ¹³C-NMR, and mass spectra. The binding of the three complexes with calf-thymus-DNA (CT-DNA) has been investigated by absorption and emission spectroscopy, DNA-melting techniques, viscosity measurements, and DNA cleavage assay. The spectroscopic data and viscosity results indicate that these complexes bind to CT-DNA via an intercalative mode. The complexes also promote photocleavage of plasmid pBR322 DNA and were screened for antimicrobial activity.     

Experimental and density functional theory (DFT) studies on the DNA-binding trend and spectral properties of two new Ru(II) complexes: [Ru(L)2(mip)](ClO4)2 (L = 2,9-dmp and 4,7-dmp)

The new ligand 2′-(3″,4″-methylene-dioxyphenyl)imidazo[4′,5′-f] [1,10]phenanthroline (mip) and its Ru(II) complexes [Ru(2,9-dmp)₂(mip)]²⁺ (1) (2,9-dmp = 2,9-dimethyl-1,10-phenanthrolline) and [Ru(4,7-dmp)₂(mip)]²⁺ (2) (4,7-dmp = 4,7-dimethyl-1,10-phenanthrolline) were synthesized and characterized. The binding properties of the two complexes to calf-thymus DNA (CT-DNA) were investigated by different spectrophotometric methods and viscosity measurements. Both 1 and 2 bind to CT-DNA in an intercalative mode, but with different binding strengths. Complex 2 can emit luminescence in the Tris buffer at ambient temperature, however, complex 1 showed no fluorescence emission, neither alone nor in the presence of CT-DNA. The circular-dichroism signal of the dialysate of the racemic complex against CT-DNA suggests that complexes 1 and 2 interact enantioselectively with CT-DNA. Furthermore, complexes 1 and 2 have been found to be an efficient photosensitiser for cracking DNA plasmid. Theoretical calculations for 1 and 2 were also carried out applying the density functional theory (DFT) method and applied to explain some obtained experimental observations.     

Luminescent Ruthenium(II) Polypyridyl Complexes as Nonviral Carriers for DNA Delivery

Two new luminescent ruthenium(II) polypyridyl complexes, [Ru(bpy)₂(tpt‐phen)]Cl₂ ( 1 ; bpy=2,2′‐bipyridine, tpt‐phen=triptycenyl‐1,10‐phenanthroline) and [Ru(phen)₂(tpt‐phen)]Cl₂ ( 2 ; phen=1,10‐phenanthroline), have been developed as potential nonviral vectors for DNA delivery. Photophysical and electrochemical properties of the complexes have been investigated and corroborated with electronic structure calculations. DNA condensation by these complexes has been investigated by UV/Vis and emission spectroscopy, circular dichroism spectroscopy, atomic force microscopy, dynamic light scattering, confocal microscopy, and electrophoretic mobility studies. These complexes interact with DNA and efficiently condense DNA into globular nanoparticles that are taken up efficiently by HeLa cells. DNA cleavage inability and biocompatibility of complexes have been explored. Both complexes have good gene transfection abilities.