Ruthenium(II) complexes of pyrrol-azo ligands: cytotoxicity,interaction with calf thymus DNA and bovine serum albumin

Two ruthenium(II) complexes of newly designed pyrrol-azo ligands(L) and bipyridine(bpy) formulated as [Ru(L)(bpy)₂]ClO₄, where HL^1?=?(4-chloro-phenyl)-(1H-pyrrol-2-yl)-diazene (1) complex 1 and HL^2?=?(4-nitro-phenyl)-(1H-pyrrol-2-yl)-diazene for 2, were isolated in pure form. The complexes were characterized by physicochemical and spectroscopic methods. The electrochemical behavior of the complexes showed the Ru(III)/Ru(II) couple at different potentials with quasi-reversible voltammograms. The study of cytotoxicity effects of 1 and 2 on human breast cancer cells (MCF 7, MDA-MB 231) and cervical cancer cell (HeLa) taking Cisplatin as a positive reference showed that 1 exhibited higher cytotoxicity against cancer cell lines than 2, but less activity than Cisplatin. The interaction of 1 with calf thymus DNA (CT-DNA) using absorption, emission spectral studies, viscosity-measurement, and electrochemical techniques has been used to determine the binding constant K _b and the linear Stern–Volmer quenching constant K _SV. The results indicate that 1 strongly interacts with CT-DNA in groove binding mode. The interaction of bovine serum albumin (BSA) with 1 was also investigated with the help of spectroscopic tools. Absorption spectroscopy proved the formation of a BSA-[Ru(L¹)(bpy)₂]ClO₄ complex.     

Antiproliferative Activity of Gold(I) N-Heterocyclic Carbene and Triphenylphosphine Complexes with Ibuprofen Derivatives as Effective Enzyme Inhibitors

A series of gold(I) complexes of ligand ibuprofen-alkynyl (but-3-yn-1-yl 2-(4-isobutylphenyl)propanoate, LE) with N-heterocyclic carbene (LC: 1,3-dimethylimidazol-2-ylidene) and triphenylphosphine (PPh₃) ligands with formula (LE)Au (LC) (complex 1 ) and (LE)Au (PPh₃) (complex 2 ) were synthesized and fully characterized by spectroscopic methods. In order to reveal the cytotoxicity mechanism, the interaction of complex 1 or 2 with cysteine (HCys) has been studied by experimental and density functional theory (DFT) methods. The compounds were investigated for their anticancer activity against MCF-7, MDAMB 231 breast cancer cells, HT-29 colon cancer cells and MCF-10A non-tumor breast cell line. The results were compared with cisplatin and auranofin as reference drugs. The complex 2 showed more cytotoxic activity than complex 1 . The complex 2 was 4.2, 3.7, and 1.7 fold more active than cisplatin against HT-29, MDA-MB-231, MCF-7 cancer cell lines, respectively. The inhibition of thioredoxin reductase of complexes 1 and 2 including cytosolic (TrxR1) and mitochondrial (TrxR2) thioredoxin reductase and also the inhibition of glutathione reductase (GR) were studied in detail. Moreover, the cellular uptake and reactive oxygen species (ROS) generation of compounds were investigated. Based on the DFT calculations a relationship between the σ-donor ability of the isolated ligands and cytotoxicity is suggested.     

Synthesis, DNA binding, antioxidant and cytotoxic activities of ruthenium(II) complexes of a Schiff base ligand

Three ruthenium(II) complexes, [Ru(CO)Cl(PPh₃)L], [Ru(CO)Cl(AsPh₃)L] and [Ru(CO)Cl(Py)L], were synthesized from the reactions of 2-(benzothiazol-2-yliminomethyl)-phenol (HL) with [RuHCl(CO)B(EPh₃)₂], where B = PPh₃, AsPh₃ or pyridine, and E = P or As. All the complexes have been characterized by physicochemical and spectroscopic methods. The structure of the free ligand HL was determined by single crystal X-ray diffraction. The binding of the free ligand and its complexes with CT-DNA was studied using electronic absorption spectroscopy. In addition, the free ligand and its complexes were subjected to antioxidant activity tests, which showed that they all possess significant scavenging effects against DPPH and OH radicals. The in vitro cytotoxicities of the compounds were assessed using tumor (HeLa and MCF-7) cell lines.     

Ruthenium(II) complexes of aroylhydrazones: structural,electrochemical and electrostatic interactions with DNA

Four Ru(II) complexes with tridentate ligands viz. (4-hydroxy-N′-(pyridin-2-yl-ethylene) benzohydrazide [Ru(L¹)(PPh₃)₂(Cl)] (1), N′-(pyridin-2-yl-methylene) nicotinohydrazide [Ru(L²)(PPh₃)₂(Cl)] (2), N′-(1H-imidazol-2-yl-methylene)-4-hydroxybenzohydrazide [Ru(L³)(PPh₃)₂(Cl)] (3), and N′-(1H-imidazol-2-yl-methylene) nicotinohydrazide [Ru(L⁴)(PPh₃)₂(Cl)] (4) have been synthesized and characterized. The methoxy-derivative of L³H (abbreviated as L³H*) exists in E configuration with torsional angle of 179.4° around C₇-N₈-N₉-C₁₀ linkage. Single crystal structures of acetonitrile coordinated ruthenium complexes of 1 and 3 having compositins as [Ru(L¹)(PPh₃)₂(CH₃CN)]Cl (1a) and [Ru(L³)(PPh₃)₂(CH₃CN)]Cl (3a) revealed coordination of tridentate ligands with significantly distorted octahedral geometry constructed by imine nitrogen, heterocyclic nitrogen, and enolate amide oxygen, forming a cis-planar ring with trans-placement of two PPh₃ groups and a coordinated acetonitrile. Ligands (L¹H-L⁴H) and their ruthenium complexes (1–4) are characterized by ¹H, ¹³C, ³¹P NMR, and IR spectral analysis. Ru(II) complexes have reversible to quasi-reversible redox behavior having Ru(II)/Ru(III) oxidation potentials in the range of 0.40–0.71 V. The DNA binding constants determined by absorption spectral titrations with Herring Sperm DNA (HS-DNA) reveal that L⁴H and 1 interact more strongly than other ligands and Ru(II) complexes. Complexes 1–3 exhibit DNA cleaving activity possibly due to strong electrostatic interactions while 4 displays intercalation.     

Synthesis and characterization of dinuclear (Hedta)Ru(III) complexes with N-heterocyclic ligands: magnetic properties and DNA-binding studies

Two ruthenium(III) complexes containing ethylenediaminetetraacetate(edta), viz. [{Ru(Hedta)}₂L]·xH₂O L = 4,4′-bipyridine(bpy) (1) and 4,4′-azopyridine(Azpy) (2), have been synthesized by the reaction between K[Ru(Hedta)Cl]·1.5H₂O and the corresponding N-heterocycles. Complex 1 was determined by single-crystal X-ray diffraction. The products were characterized by IR, UV–vis, cyclic voltammetry, and magnetic techniques. Their DNA-binding activities were investigated using electronic absorption spectroscopic methods and ?uorescence quenching; the experimental results show that these two ruthenium complexes may bind to CT-DNA through intercalation modes.     

Cellular Mechanistic Considerations on Cytotoxic Mode of Action of Phosphino Ru(II) and Ir(III) Complexes

Two piano-stool ruthenium(II) complexes Ru(η⁶-p-cymene)Cl₂PPh₂CH₂OH ( RuPOH ) and Ru(η⁶-p-cymene)Cl₂P(p-OCH₃Ph)₂CH₂OH ( RuMPOH ) and two half-sandwich iridium(III) complexes Ir(η ⁵-Cp*)Cl₂PPh₂CH₂OH ( IrPOH ) and Ir(η ⁵-Cp*)Cl₂P(p-OCH₃Ph)₂CH₂OH ( IrMPOH ) have been studied in terms of potential anticancer activity on previously selected cell line (human lung adenocarcinoma). Based on experimental results obtained in monoculture in vitro model mechanistic considerations on the possible cellular modes of action have been carried out. ICP-MS analysis revealed the higher cellular uptake for less hydrophobic Ir(III) complexes in comparison to the corresponding Ru(II) compounds. Cytometric analysis showed a predominance of apoptosis over the other types of cell death for all complexes. The apoptotic pathway was confirmed by a decrease in mitochondrial membrane potential and the activation of caspases-3/9 for both Ru(II) and Ir(III) complexes. It was concluded that in the case of Ru(II) complexes the intense ROS generation is mainly responsible for the resulting cytotoxicity. The corresponding Ir(III) complexes trigger simultaneously at least three different cytotoxic pathways i. e., depletion of mitochondrial potential, activation of caspases-dependent apoptosis, and ROS-associated oxidation. Thus, it can be assumed that the final accumulation of toxic effects over time via parallel activation of different pathways results in the highest cytotoxicity in vitro exhibited by Ir(III) complexes when compared with Ru(II) complexes.     

Reactions of 2-(arylazo)aniline with ruthenium substrates: Isolation, characterizations and reactivities of delocalized diazoketiminato and orthometallated Ru(II) chelates

Reactions of 2-(arylazo)aniline, HL-NH₂ [H represents the dissociable protons upon complexation and HL-NH₂ is p-RC₆H₄NNC₆H₄-NH₂; R = H for HL¹-NH₂; CH₃ for HL²-NH₂ and Cl for HL³-NH₂] with Ru(H)(CO)(PPh₃)₃Cl and Ru(CO)₃(PPh₃)₂ afforded products of compositions [(HL-NH)Ru(CO)Cl(PPh₃)₂] and [(L-NH)Ru(PPh₃)₂(CO)], respectively. All the complexes were characterized unequivocally. The X-ray structures of the complexes 4c and 5c have been determined. The cyclic volatammograms exhibited one reversible oxidative response in the range of 0.56–0.16 V versus SCE for [(L-NH)Ru(PPh₃)₂(CO)] and a quasi reversible oxidative response within 0.56–0.70 V versus SCE for [(HL-NH)Ru(CO)Cl(PPh₃)₂]. The conversion of ketones to corresponding alcohols has been studied in presence of newly synthesized ruthenium complexes.     

Binuclear Ru(III) Schiff base complexes: synthesis,spectral characterization,oxidation, C?C coupling reactions and antibacterial activities

New hexa‐coordinated binuclear Ru(III) Schiff base complexes of the type {[(B)₂X₂Ru]₂L} (where B = PPh₃ or AsPh₃; X = Cl or Br; L = binucleating N₂O₂ Schiff bases) were synthesized and characterized by elemental analysis, magnetic susceptibility measurement, FT‐IR, UV–vis, ¹³C{¹H}‐NMR, ESR at 300 and 77 K, cyclic voltammetric technique, powder X‐ray diffraction pattern and SEM. The new complexes were used as catalysts in phenyl–phenyl coupling reaction and the oxidation of alcohols to their corresponding carbonyl compounds using molecular oxygen atmosphere at room temperature. Further, the new Schiff base ligands and their Ru(III) complexes were also screened for their antibacterial activity against K. pneumoniae, Shigella sp., M. luteus, E. coli and S. typhi. From this study, it was found that the activity of the ruthenium(III) Schiff base complexes almost reaches the effectiveness of the conventional bacteriocide standards. Copyright © 2009 John Wiley & Sons, Ltd.     

Chemistry of a family of semiquinone monochelates of carbonyl ruthenium(II) generated by reacting quinones with hydridic species

The reactions of [Ru(H)(Cl)(CO)(PPh₃)₃] with 3,5-di-tert-butyl-o-benzoquinone (dbq) and 3,4,5,6-tetrachloro-o-benzoquinone (tcq) have afforded the corresponding semiquinone complexes [Ru^II(dbsq)(Cl)(CO)(PPh₃)₂] and [Ru^II(tcsq)(Cl)(CO)(PPh₃)₂], respectively. The reaction of [Ru(H)₂(CO)(PPh₃)₃] with tcq has furnished [Ru^II(tcsq)(H)(CO)(PPh₃)₂]. Structure determination of [Ru(dbsq)(Cl)(CO)(PPh₃)₂] has revealed that it is a model semiquinonoid chelate with two equal C---O lengths ( 1.291(6) and 1.296(6) Å). The complexes are one-electron paramagnetic (1.85μ_B) and their EPR spectra in fluid media display a triplet structure (g2.00) due to superhyperfine coupling with two trans-³¹P atoms (A_iso17 G). The stretching frequency of the CO ligand increases by 20 cm⁻¹ in going from [Ru(dbsq)(Cl)(CO)(PPh₃)₂] to [Ru(tcsq)(Cl)(CO)(PPh₃)₂] consistent with electron withdrawal by chloro substituents. For the same reason the E_1/2 values of the cyclic voltammetric quinone/semiquinone and semiquinone/catechol couples undergo a shift of 500 mV to higher potentials between [Ru(dbsq)(Cl)(CO)(PPh₃)₂] and [Ru(tcsq)(Cl)(CO)(PPh₃)₂].     

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.     

Ruthenium(III) complexes with N-(acetyl)-N′-(5-R-salicylidene)hydrazines: Syntheses,structures and properties

The reactions of 1 mol equiv. each of [Ru(PPh₃)₃Cl₂] and N-(acetyl)-N′-(5-R-salicylidene)hydrazines (H₂ahsR, R = H, OCH₃, Cl, Br and NO₂) in alcoholic media afford simultaneously two types of complexes having the general formulae [Ru(HahsR)(PPh₃)₂Cl₂] and [Ru(ahsR)(PPh₃)₂Cl]. The complexes have been characterized by elemental analysis, magnetic, spectroscopic and electrochemical measurements. Molecular structures of [Ru(HahsH)(PPh₃)₂Cl₂] and [Ru(ahsH)(PPh₃)₂Cl] have been confirmed by X-ray crystallography. In both species, the PPh₃ ligands are trans to each other. The bidentate HahsH⁻ coordinates to the metal ion via the O atom of the deprotonated amide and the imine–N atom in [Ru(HahsH)(PPh₃)₂Cl₂]. In HahsH⁻, the phenolic OH is involved in a strong intramolecular hydrogen bond with the uncoordinated amide N atom forming a seven-membered ring. In [Ru(ahsH)(PPh₃)₂Cl], the tridentate ahsH²⁻ binds to the metal ion via the deprotonated amide O, the imine N and the phenolate O atoms. In the electronic spectra, the green [Ru(HahsR)(PPh₃)₂Cl₂] and brown [Ru(ahsR)(PPh₃)₂Cl] complexes display several absorptions in the ranges 385–283 and 457–269 nm, respectively. Both complexes are low-spin and display rhombic EPR spectra in frozen solutions. Both types of complexes are redox active and display a quasi-reversible ruthenium(III) to ruthenium(II) reduction which is sensitive to the polar effect of the substituent on the chelating ligand. The reduction potentials are in the ranges −0.21 to −0.12 and −0.42 to −0.21 V (versus Ag/AgCl) for [Ru(HahsR)(PPh₃)₂Cl₂] and [Ru(ahsR)(PPh₃)₂Cl], respectively.     

Organoruthenium(II) compounds with pyridyl benzoxazole/benzthiazole moiety: studies on DNA/protein binding and enzyme mimetic activities

We report herein synthesis and characterization of four new organoruthenium(II) complexes of the type [RuH(CO)(PPh₃)₂(L_1,2)]Cl (1, 3) and [Ru(CO)(Cl)₂(AsPh₃)(L_1,2)] (2, 4) derived from the reaction of [RuHCl(CO)(EPh₃)₃] (E = P or As) with 2-(pyridine-2yl)benzoxazole (L₁) and 2-(pyridine-2yl)benzthiazole (L₂). Single-crystal X-ray diffraction data of 2 proved octahedral geometry of the complexes with a 1?:?1 ratio between the metal and the coordinated ligands. The binding affinities of 1–4 toward calf-thymus DNA (CT-DNA) and BSA were thoroughly studied by various spectroscopic techniques. Furthermore, the coordination compounds exhibit catecholase-like activities in the aerial oxidation of 3,5-di-tert-butylcatechol to the corresponding o-quinone and phosphatase-like activities in the hydrolysis of 4-nitrophenyl phosphate to 4-nitrophenolate ion. The kinetic parameters have been determined using Michaelis–Menten approach. The highest k_cat values suggested that coordination compounds exhibit higher rates of catalytic efficacy.     

Oxovanadium(IV) and ruthenium(II) carbonyl complexes of ONS‐donor ligands derived from dehydroacetic acid and dithiocarbazate: Synthesis,characterization, antioxidant activity,DNA binding and in vitro cytotoxicity

A series of new complexes of oxovanadium(IV) [VO(L)(B)] and ruthenium(II) [Ru(CO)(PPh₃)₂(L)] ( 1.1- 1.3,  2.1–2.3 ) (H₂L = dehydroacetic acid Schiff base of S‐methyldithiocarbazate, H₂smdha ( 1 ) or S‐benzyldithiocarbazate, H₂sbdha ( 2 ); B = 2,2′‐bipyridine (bpy) or 1,10‐phenanthroline (phen)) have been synthesized. The structure of these complexes was authenticated using elemental analyses and spectroscopic techniques, and their magnetic properties and electrochemical behaviour were studied. The molecular structures of oxovanadium(IV) complexes [VO(smdha)(bpy)]?CH₂Cl₂ ( 1.1 ) and [VO(sbdha)(phen)]?2H₂O ( 2.2 ) were confirmed using single‐crystal X‐ray crystallography. Analytical data showed that the ligands 1 and 2 are chelated to the metal centres in a bi‐negative tridentate fashion through azomethine N, thiol S and deprotonated hydroxyl group. The antioxidant activity of the synthesized compounds was tested against 2,2‐diphenyl‐1‐picrylhydrazyl) radical, which showed that the complexes demonstrate a better scavenging activity than their corresponding ligands. The cupric ion reducing antioxidant capacity method was also employed and the total equivalent antioxidant capacity values were found to be higher for the oxovandium(IV) complexes. DNA binding affinity of the compounds was determined using UV–visible and fluorescence spectra, revealing an intercalation binding mode. Higher cytotoxicity for the complexes compared to their ligands was found against human liver hepatocellular carcinoma (HepG2) and breast adenocarcinoma (MCF7) cell lines using MTT assay.     

Metal(II) complexes of bioactive aminonaphthoquinone-based ligand: synthesis,characterization and BSA binding,DNA binding/cleavage,and cytotoxicity studies

An aminonaphthoquinone ligand, L, and its metal complexes of general formula [MLCl₂] {M = Co(II), Ni(II), Cu(II) and Zn(II)} have been synthesized and characterized by analytical and spectral techniques. Tetrahedral geometry has been assigned to Ni(II) and Zn(II) complexes and square planar geometry to Co(II) and Cu(II) complexes on the basis of electronic spectral and magnetic susceptibility data. The binding of complexes with bovine serum albumin (BSA) is relatively stronger than that of free ligand and alters the conformation of the protein molecule. Interaction of these complexes with CT-DNA has been investigated using UV-Vis and fluorescence quenching experiments, which show that the complexes bind strongly to DNA through intercalative mode of binding (K_app 10⁵ M^?1). Molecular docking studies reiterate the mode of binding of these compounds with DNA, proposed by spectral studies. The ligand and its complexes cleave plasmid DNA pUC18 to nicked (Form II) and linear (Form III) forms in the presence of H₂O₂ oxidant. The in vitro cytotoxicity screening shows that Cu(II) complex is more potent against MCF-7 cells and Zn(II) complex exhibits marked cytotoxicity against A-549 cells equal to that of cisplatin. Cell imaging studies suggested apoptosis mode of cell death in these two chosen cell lines.     

Ruthenium(III) tetradentate Schiff-base complexes: spectral,catalytic, and its biocidal efficacy

New six-coordinate ruthenium(III) Schiff-base complexes of general formula [Ru(X)(PPh₃)(L)] (where X = Cl/Br and L = mononucleating bibasic tetradentate ligand derived by condensing actetoacetanilide/acetoacetotoludide with o-aminophenol/o-aminothiophenol/o-aminobenzoic acid in 1 : 2 molar ratio in ethanol) have been synthesized and characterized by physico-chemical and spectroscopic methods. The new ruthenium(III) complexes possess 2NO/2NS metal binding sites and are catalysts for the oxidation of alcohols using molecular oxygen as co-oxidant and in C–C coupling reactions. These complexes possess good biocidal (antibacterial and antifungal) activity.     

Ruthenium(II) complexes of NSO donor ligands in the form of ring-substituted 4-phenyl-thiosemicarbazones of salicylaldehyde and o-hydroxyacetophenone

This work describes the preparation and characterisation of ruthenium(II) complexes of several ONS donor ligands in the form of ring-substituted 4-phenylthiosemicarbazones of salicylaldehyde and o-hydroxyacetophenone. Reactions of these thiosemicarbazone ligands with [Ru(PPh₃)₃]Cl₂ in refluxing MeOH furnished ruthenium(II) complexes of general formula [Ru(PPh₃)₂(LH)Cl] where the ligands acted as monoanionic tridentate ONS donors attached to the ruthenium(II) acceptor centre through the deprotonated phenolic oxygen, thione sulphur and azomethine nitrogen.     

Ruthenium complexes of hexakis(cyanophenyl)[3]radialenes and their di(cyanophenyl)methane precursors: synthesis,photophysical, and electrochemical properties

The coordination chemistry of cross-conjugated ligands and the effect of cross-conjugation on the nature of metal–metal and metal–ligand interactions have received limited attention. To explore the effects of cross-conjugation eight ruthenium complexes were synthesized, mononuclear complexes of two isomeric cross-conjugated [3]radialenes [RuCp(PPh₃)₂(L)]PF₆ and [{RuCp*(dppe)}(L)]PF₆ (L?=?hexakis(4-cyanophenyl)[3]radialene, 2; hexakis(3-cyanophenyl)[3]radialene, 3), and dinuclear complexes [{RuCp(PPh₃)₂}₂(L)](PF₆)₂ and [{RuCp*(dppe)}₂(L)](PF₆)₂ of the diarylmethane precursors (L?=?4,4′-dicyanodiphenylmethane, 4; 3,3′-dicyanodiphenylmethane, 5) to the [3]radialenes. Considerable synthetic challenges allowed only clean isolation of mononuclear complexes of the multidentate radialenes 2 and 3. As expected, coordinating a positively charged metal induces a red shift for the π–π* transition in complexes of ligand 2, but unexpectedly a blue shift for the same transition in complexes of 3 was observed. This points to conformational differences for the [3]radialene in the ruthenium complexes of the para- (2) versus meta- (3) substituted hexaaryl[3]radialenes. Cyclic voltammetry indicates that the methylene spacer in 4 and 5 does not enable any interaction between metal centers and the absorption behavior is essentially as observed for [Ru(NCPh)(PPh₃)₂Cp]PF₆ and [Ru(NCPh)(dppe)Cp*]PF₆ but generally with a slight red shift in absorbance maxima.     

Synthesis and characterization of chloro-bis(quinoline-2-carboxylato-κ2N,O)gallium(III)

The preparation and characterization of a new gallium(III) complex with quinoline-2-carboxylate, of formula [Ga(quin-2-c)₂Cl], are described. The crystal structure of the complex has been determined by X-ray diffraction, crystallizing in monoclinic space group P2₁/n with Ga(III) adopting a distorted tetragonal pyramid. Gallium(III) coordinates two quinoline-2-carboxylates and one chloride with a Cl,N₂,O₂ donor set. In the crystal the 2-D supramolecular structure is generated by weak intermolecular interactions, C–H?···?O, C–H?···?Cl, and C–H?···?π. The cytotoxicity assays against several human cancer cell lines (Du145, A549, MCF-7, A498, HT-29) and against mouse fibroblasts (BALB/3T3) revealed moderate antiproliferative activity of the complex.     

Norfloxacin La(III)-based complex: synthesis,characterization, and DNA-binding studies

A La(III) complex, [La^IIICl₂(NOR)₂]Cl (2), containing norfloxacin (NOR) (1), a synthetic fluoroquinolone antibacterial agent, has been synthesized and characterized by elemental analysis, IR, UV–vis spectra and ¹H NMR spectroscopy, and molar conductance measurements. The interaction between 2 and CT-DNA was investigated by steady-state absorption and fluorescence techniques in different pH media, and showed that 2 could bind to CT-DNA presumably via non-intercalative mode and the La(III) complex showed moderate ability to bind CT-DNA compared to other La(III) complexes. The binding site number n, and apparent binding constant K_A, corresponding thermodynamic parameters ΔG^#, ΔH^#, ΔS^# at different temperatures were calculated. The binding constant (K_A) values are 0.23 ± 0.05, 0.56 ± 0.05, and 0.18 ± 0.08 × 10⁵ L mol^?1 for pH 4, 7, and 11, respectively. It was also found that the fluorescence quenching mechanism of CT-DNA by La(III) complex was a static quenching process.     

Spectroscopic characterization and electrochemical studies of ruthenium(II) carbonyl complexes containing bidentate Schiff bases and triphenylphosphine or a nitrogen heterocycle

Reactions of ruthenium(II) carbonyl complexes of the type [RuHCl(CO)(PPh₃)₂(B)] [B?=?PPh₃, pyridine (py), piperidine (pip) or morpholine (mor)] with bidentate Schiff base ligands derived from the condensation of 2-hydroxy-1-naphthaldehyde with aniline, o-, m- or p-toluidine in a 1?:?1 mol ratio in benzene resulted in the formation of complexes formulated as [RuCl(CO)(L)(PPh₃)(B)] [L?=?bidentate Schiff base anion, B?=?PPh₃, py, pip, mor]. The complexes were characterized by analyses, IR, electronic and ¹H NMR spectroscopy, and cyclic voltammetric studies. In all cases, the Schiff bases replace one molecule of phosphine and a hydride ion from the starting complexes, indicating that Ru–N bonds in the complexes containing heterocyclic nitrogenous bases are stronger than the Ru–P bond to PPh₃. Octahedral geometry is proposed for the complexes.