Dioxochromium(V) complexes with 1,10-phenanthroline and 2,2′-bipyridine ligands

cis-[Cr^III(phen)₂(H₂O)₂]³⁺ and cis-[Cr^III(bipy)₂(H₂O)₂]³⁺ (phen = 1,10-phenanthroline and bipy = 2,2-bipyridine) were readily oxidized by either PbO₂ or PhIO to form the chromium(V) complexes [Cr^V(phen)₂(O)₂]⁺ and [Cr^V(bipy)₂(O)₂]⁺ respectively, which were characterized by elemental analysis, i.r. and e.s.r. spectroscopy.     

Synthesis,characterization, and cytotoxicity of Pt(IV) complexes containing 1,10-phenanthroline and 2,2′-bipyridine and diaminocyclohexane ligands

Four platinum(IV) complexes containing intercalating ligands [1,10-phenanthroline (phen) and 2,2′-bipyridine (bpy)] and ancillary ligands [(1S,2S)-diaminocyclohexane (SS-DACH) and (1R,2R)-diaminocyclohexane (RR-DACH)] were synthesized and characterized by ¹H nuclear magnetic resonance, electrospray ionization mass spectrometry, X-ray crystal structure analysis, elemental analysis, ultraviolet absorption spectroscopy, circular dichroism spectroscopy, and electrochemical analysis. The reactions between [Pt(phen)(SS-DACH)Cl₂]²⁺ and glutathione and Ac-CPFC-NH₂ were investigated by high-performance liquid chromatography. [Pt(phen)(SS-DACH)Cl₂]²⁺ was reduced to its corresponding Pt(II) complex [Pt(phen)(SS-DACH)]²⁺, while glutathione and Ac-CPFC-NH₂ were oxidized to glutathione-disulfide and a peptide containing an intramolecular disulfide bond, respectively. The cytotoxicities of the Pt(IV) complexes against a human non-small cell lung cancer cell line (A549) and the corresponding cisplatin-resistant cell line (A549cisR) were evaluated. These Pt(IV) complexes showed a higher activity toward A549 and A549cisR than did cisplatin. Also, the cytotoxicities of the Pt(IV) complexes were higher for A549cisR than for A549 cells. Moreover, the cytotoxicities of the (SS-DACH)-liganded platinum complexes were higher than those of the (RR-DACH)-liganded platinum complexes in either A549 or A549cisR cells. Phen-liganded platinum complexes were more cytotoxic than the bpy-liganded platinum complexes. The cytotoxicities of these Pt(IV) complexes had no correlation with reduction potentials.     

Binuclear cluster complexes of molybdenum containing 2,2′-bipyridine and 1,10-phenanthroline: Synthesis and structure

By the interaction between (Et₄N)₂[Mo₂O₂S₈] and I₂ in DMF with a subsequent addition of 2,2′-bipyridine or 1,10-phenanthroline, new binuclear complexes [Mo₂O₂S₂I₂(bipy)₂] (1) and [Mo₂O₂S₂I₂(phen)₂] (2) are obtained. The structure of [Mo₂O₂S₂I₂(bipy)₂] is determined using single crystal X-ray diffraction. The compounds are characterized by elemental analysis and IR spectra. The [MoO(S₂)₂(bipy)] complex as a product of oxidative destruction of 1 is isolated and characterized.     

Synthesis,spectroscopic, photophysical and electrochemical behaviour of ruthenium(II) and copper(I) isocyano-bridged complexes with polypyridine ligands: 2,2′-bipyridine and 1,10-phenanthroline

New binuclear complexes with [Cu(PPh₃)₃]⁺ and [Cu(PPh₃)(N—N)]⁺ (N—N – 2,2-bipyridine, 1,10-phenanthroline) moieties connected via the isocyanide group to [Ru(bpy)₂(py)]⁺ and [Ru(phen)₂(py)]⁺ have been prepared and isolated as PF₆ ^– salts. In addition, new trinuclear complexes, [{(PPh₃)₃Cu(-NC)}₂Ru(bpy)₂](PF₆)₂ and [{(N—N)-(PPh₃)Cu(-NC)}₂Ru(bpy)₂](PF₆)₂, have been synthesized using [Ru(bpy)₂(CN)₂]. The complexes have been characterized by elemental analyses, i.r., n.m.r., u.v.–vis., FAB mass spectra and by conductivity measurements. The i.r. spectra reveal an increase in v;(CN) in the isocyano-bridged complexes compared to the mononuclear parent complexes. The complexes are luminescent with emission wavelengths in the 458–550 and 600–636 nm ranges. The half wave reduction potentials in MeCN are always more positive than those of the parent complexes. It is observed that the isocyano-bridged complexes are more powerful excited state reductants than the cyano-bridged, Cu^(I)(-CN)Ru^(II) complexes.     

PbII 4,4,4-trifluoro-1-naphthyl-1,3-butanedione complexes of 1,10-phenanthroline and 2,2′-bipyridine ligands

Lead(II) 4,4,4-trifluoro-1-naphthyl-1,3-butanedione (Htfnb) complexes of 1,10-phenanthroline (phen) and 2,2′-bipyridine (bpy), [Pb₂(bpy)₂(tfnb)₂] (1) and [Pb₂(phen)₂(tfnb)₂] (2), have been synthesized and characterized by elemental analysis, IR, spectroscopy and X-ray crystallography. The self-assembly of 1 and 2 is likely to be caused by C–H ··· F–C, C–H ··· O and π–π stacking interactions.     

Ruthenium(II) complexes containing 2,9-dimethyl-1,10-phenanthroline and 4,4′-dimethyl-2,2′-bipyridine as ancillary ligands: synthesis,characterization and DNA-binding

Two new Ruthenium (II) polypyridyl complexes [Ru(dmp)₂(ipbp)](ClO₄)₂ (1) (dmp = 2,9-dimethyl-1,10-phenanthroline, ipbp = 3-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-4H-1-banzopyran-2-one) and [Ru(dmb)₂(ipbp)](ClO₄)₂ (2) (dmb = 4,4′-dimethyl-2,2′-bipyridine) have been synthesized and characterized by elemental analysis, FAB-MS, ES-MS and ¹H NMR and cyclic voltammetric methods. The DNA-binding behaviors of these complexes were investigated by spectroscopic titration, viscosity measurements, and thermal denaturation. Absorption titration and thermal denaturation studies reveal that these complexes are moderately strong binders of calf thymus DNA (CT-DNA). Viscosity measurements show that the complexes 1 and 2 interact with CT-DNA by intercalative mode. The DNA-binding affinity of the complex 2 is larger than that of complex 1.     

Investigations of ternary complexes of Co(II) and Ni(II) with oxydiacetate anion and 1,10-phenanthroline or 2,2′-bipyridine in solutions

Potentiometric (PT) and conductometric (CT) titration methods have been used to determine the stoichiometry and formation constants in water for a series of ternary complexes of Co(II) and Ni(II) involving the oxydiacetate anion (ODA) and 1,10-phenanthroline (phen) or 2,2′-bipyridine (bipy) ligands, namely [Co(ODA)(phen)(H₂O)], [Co(ODA)(bpy)(H₂O)], [Ni(ODA)(phen)(H₂O)] and [Ni(ODA)(bpy)(H₂O)]. The ternary complex formation process was found to take place in a stepwise manner in which the oxydiacetate ligand acts as a primary ligand and the phen or bipy ligands act as auxiliary ones. The stability of the ternary complexes formed is discussed in the relation to the corresponding binary ones. Furthermore, the kinetics of the substitution reactions of the aqua ligands in the coordination sphere of the Ni-ODA and Co-ODA complexes to phen or bipy were studied by the stopped-flow method. The kinetic measurements were performed in the 288–303 K temperature range, at a constant concentration of phen or bipy and at seven different concentrations of the binary complexes (4–7 mM). The influence of experimental conditions and the kind of the auxiliary ligands (phen/bipy) on the substitution rate was discussed.      

Synthesis,characterization and biological studies on unsymmetrical Schiff-base complexes of nickel(II), copper(II) and zinc(II) and adducts with 2,2′-dipyridine and 1,10-phenanthroline

A series of metal(II) unsymmetrical Schiff-base complexes, {M(C₁₀H₆OCH:N(CH₂)₂N?:?C(CH₃)CH?:?C(CH₃)O), where M=Ni(II), Cu(II) and Zn(II)}, and their 2,2′-dipyridine (bipy) and 1,10-phenanthroline (phen) adducts are synthesized and characterized by microanalysis, magnetic susceptibility, conductance, IR and UV-Vis spectra. The ligand coordinates using the N₂O₂ chromophore to give a two-metal-center four-coordinate square-planar geometry. IR and UV-Vis spectra are consistent with octahedral adducts. The compounds are non-electrolytes in nitromethane and magnetic moments indicate that the complexes are magnetically dilute. The antimicrobial activity of the compounds against ten bacteria and one fungus are reported. The Cu(II) and Zn(II) complexes showed good activity against many of the organisms while their adducts are generally not sensitive. The minimum inhibitory concentrations (MICs) of the sensitive compounds are between 3.0–13.0?mg?mL^?1.     

Role of cyanide as a bridging ligand in cis-aquocyanoCo(III) complexes containing 2,2′-bipyridine and 1,10-phenanthroline

Cis-aquocyanobis(2,2′-bipyridine)Co(III) and cis-aquocyanobis(1,10-phenanthroline)Co(III) cations present in their IR spectra as cyano-group band in a Nujol mull at ν = 2200 cm⁻¹. To justify the shift in the frequency from 2140 to 2200 cm⁻¹ of cyanide in these compounds, we have hypothesized that the cyano group is a bridge between the metal atom and one hydrogen atom of the water molecule in the cis position on the Co(III) coordination sphere.     

Cadmium(II) diallyldithiocarbamato complexes with 2,2′-bipyridine and 1,10-phenanthroline: spectroscopic and crystal structure analysis

Complexes of Cd(II) with diallyldithiocarbamato (hereafter denoted aldtc) and 2,2′-bipyridine (bipy) and 1,10-phenanthroline (phen) are discussed. Derivatives of general formula [Cd(aldtc)₂(NN)] [NN = bipy, 1 and phen, 2] have been obtained by direct reaction between Cd(NO₃)₂ and a 2 : 1 molar ratio of aldtc and NN. The new complexes have been characterized by IR, ¹H, and ¹³C NMR spectroscopy. Their single crystal structures were also determined. Compounds 1 and 2 have severely distorted octahedral coordination around cadmium, defined by an N₂S₄ donor set. The structure of 1 is isomorphous with the recently reported zinc analogue. The crystal packing of 1 shows different non-classical intermolecular interactions represented in both hydrophilic (π)C–H ··· S and hydrophobic (allyl)C–H ··· C(π) intermolecular interactions. Such interactions result in a chain arrangement of molecules along the crystallographic c-axis. These chains are further connected via π ··· π stacking along with (π)C–H ··· S parallel to b leading to an overall crystal packing that can be regarded as layers of complexes along the bc plane. Molecules in the crystal structure of 2 are arranged into infinite chains, down the b-axis, that are connected by aryl ··· aryl stacking. The chains are further connected to each other in a and c directions via (allyl)C–H ··· S interactions.     

Synthesis,electrochemical properties and electro-oxidative polymerization of copper(II) and nickel(II) complexes with N′-benzoylthiourea ligands containing pyrrole groups

The synthesis of four N-benzoylthioureas containing pyrrole groups are described. The electrochemical behaviour of their copper(II) and nickel(II) complexes has been investigated in aprotic solvents by coulometry and by cyclic voltammetry which indicates that the electrochemical oxidation of copper complexes leads to the formation of Cu^II-benzylureate complexes. The oxidative polymerization of nickel complexes on platinum and a glassy carbon electrode, has been carried out in MeCN.The redox properties of the polymeric films formed have been examined by cyclic voltammetry. The films are catalytically active in the electroreduction of oxygen.     

Syntheses and structures of copper benzene-1,4-dioxydiacetate complexes with 4,4′-bipyridine and 1,10-phenanthroline

Two new copper complexes, [Cu₂(BDOA)(4,4′-bpy)₂] ? 2H₂O (1) and [Cu(BDOA)(phen)] (2) (H₂BDOA = benzene-1,4-dioxydiacetic acid; 4,4′-bpy = 4,4′-bipyridine; phen = 1,10-phenanthroline), were synthesized and characterized by IR, elemental analysis, and single-crystal X-ray diffraction. Complex 1 exhibits a 2-D three-connected network structure with 6³ topology. Complex 2 displays a 1-D chain structure. Furthermore, the 3-D supramolecular networks of 1 and 2 are constructed via rich hydrogen bonds. Thermal stability of 1 is discussed in this article.     

Kinetics and mechanism of substitution of bis(tptz)iron(II) by 2,2′-bipyridine and 1,10-phenanthroline

The kinetics of substitution of Fe(tptz)²+₂ by 2,2-bipyridine and 1,10-phenanthroline have been investigated in acetate buffers in the 3.6–5.6pH range employing stopped-flow spectrophotometry. These reactions are very fast and complete within 5s. The rate of substitution is linearly dependent on [phen] and [bpy]², and increases with the increase in pH. Suitable mechanisms have been proposed involving the unprotonated form of the entering ligand, viz. bipyridine/phenanthroline as the reactive species. The pK_a values of bipyridine and phenanthroline, determined from the kinetic data, are in agreement with the literature values. It is concluded that the substitutions of iron(II)-diimine complexes also occur by an associative mechanism.     

Di- and trinuclear Ru(II) complexes of 1,10-phenanthroline and 2,2′-bipyridine derivatives; synthesis,photophysical and electrochemical properties

Three heterotopic ligands L¹, L², and L³ based on 1,10-phenanthroline and 2,2′-bipyridine moieties have been synthesized and characterized. The Ru(II) complexes [{Ru(bpy)₂}₃(µ₃-L¹)](PF₆)₆, [{Ru(bpy)₂}₃(µ₃-L²)](PF₆)₆, and [{Ru(bpy)₂}₂(µ₂-L³)](PF₆)₄ (bpy = 2,2′-bipyridine) have been prepared by refluxing Ru(bpy)₂Cl₂·2H₂O with each ligand in ethanol. All three complexes display MLCT absorptions at around 455 nm and emissions at around 618 nm. Electrochemical studies of the complexes reveal one Ru(II)-centered quasi-reversible oxidation at around 1.32 V and three ligand-centered reductions in each case.     

Synthesis of ruthenium and palladium complexes from glycosylated 2,2′-bipyridine and terpyridine ligands

A series of glucosylated mono- and di-(1H-1,2,3-triazol-4-yl)pyridines were prepared from glucosyl azides and 2-ethynyl and 2,6-diethynyl pyridine via Click reaction. Glucosylation of the silver salt of 4-hydroxy-2,2′-bipyridine with acetobromoglucose afforded the corresponding glucosylated 2,2′-bipyridine. Treatment of five examples of the latter pyridine ligands with [cis-Ru(bipy)2Cl₂], [Ru(tpy)Cl₃] or [Pd(COD)Cl₂] gave the corresponding ruthenium(II) and palladium(II) complexes in 62%-quantitative yield.     

Interaction of 3,5-dimethylpyrazole with cobalt(II) carboxylates containing coordinated 1,10-phenanthroline or 2,2′-dipyridyl

The reaction of Co₃(??-OOCBu ^t )₆(NEt₃)₂ with 1,10-phenanthroline or 2,2??-dipyridyl in benzene at room temperature yields L₂Co₂(??-OH₂)(??-OOCBu ^t )₄ complexes (L₂ = Phen (1a) and Dipy (1b)). The reaction of n1a (1b) with 3,5-dimethylpyrazole gives a mixture of L₂Co(Hdmpz)₂(OOCBu ^t )₂ complexes (2a, 2b) and L₂Co(Hdmpz)(OOCBu ^t )₂ (3a, 3b), and their yield is determined by the ratio of the initial reagents. As distinct from pivalates, for cobalt(II) phenanthroline-benzoate, only the (Phen)Co(Hdmpz)₂(OOCPh)₂ complex (4) has been isolated. The structures of the synthesized compounds have been determined by X-ray crystallography.     

Mixed-ligand complexes of iron(II), iron(III), copper(II), and cobalt(II) with pyrazolonic and 2,2′-bipyridine ligands

New mixed-ligand complexes, [M₂(BAMP)(bipy)₂][MCl₄]₂, M=Co⁺²(1), Cu⁺²(2), [M₂(TAMEN)(bipy)₂][MCl₄]₂, M=Fe⁺²(3), Co²⁺(4), and [Fe₂(TAMEN)(bipy)₂][FeCl₆]₂ (5), where BAMP and TAMEN stand for the Mannich bases N,N′-bis(antipyryl-4-methylene)-piperazine and N,N′-tetra(antipyryl-4-methylene)-1,2-ethane-diamine, respectively, have been obtained and characterized by elemental analyses, conductometric and magnetic susceptibility measurements at room temperature, mass spectrometry, UV-Vis, infrared, and mass spectroscopy, and ¹H NMR spectra for the ligands.     

Synthesis and magnetic characterization of Ln(III)–Co(II) complexes with 1,10-phenanthroline ligands

Four heteronuclear complexes, [Ln₂Co₂L₁₀(H₂O)(phen)₂] · n(H₂O) (Ln = La 1, n = 2; Ln = Nd 2, Sm 3, Gd 4, n = 0; HL = α-methylacrylic acid, phen = 1,10-phenanthroline), have been synthesized and characterized by elemental analysis, IR and X-ray diffraction. The complexes with a discrete Co–Ln–Ln–Co tetranuclear molecule are isomorphous in the triclinic space group P 1 and Z = 1, in which all metal ions are bridged by bidentate α-methylacrylato groups. Magnetic measurements of 1, 2 and 3 show antiferromagnetic exchange interaction between paramagnetic centers.