Bis(2,2′-bipyridine)cobalt(III) complexes containing asymmetric ligands: Synthesis,DNA-binding and photocleavage studies

Three new Co^III complexes: [Co(bpy)₂(pdtb)]³⁺ (1), [Co(bpy)₂(pdta)]³⁺ (2) and [Co(bpy)₂(pdtp)]³⁺ (3) have been synthesized and characterized. The DNA binding behavior of the Co^III complexes has been investigated by spectroscopic methods and viscosity measurements. The results indicate that the size and shape of the intercalated ligand have a marked effect on the binding affinity of complexes involving CT-DNA. Complexes (2) and (3) have been found to promote cleavage of plasmid pBR 322 DNA from the supercoiled form I to the open circular form II upon irradiation. Photocleavage mechanisms are proposed.     

Unusually facile syntheses of [RuII(bpy)3]2+ (bpy = 2,2′-bipyridine) and [RuII(phen)3]2+ (phen = 1,10-phenanthroline)

The salts [Ru^II(L–L)₃](CF₃SO₃)₂ (L–L = bpy or phen) have been prepared in high yields via reactions of [Ru^II(DMF)₆](CF₃SO₃)₂ (DMF = N,N-dimethylformamide), generated in situ by reduction of [Ru^III(DMF)₆]-(CF₃SO₃)₃, with an excess of bpy or phen at room temperature in DMF solutions.     

Synthesis,characterization and crystal structure determination of iron(III) complexes containing 4,4′-dimethyl-2,2′-bipyridine,dimethyl sulfoxide and chloride, [Fe(dmbipy)Cl4][dmbipyH] and [Fe(dmbipy)Cl3(DMSO)]

[Fe(dmbipy)Cl₄][dmbipyH], 1 (dmbipy is 4,4′-dimethyl-2,2′-bipyridine), was prepared from reaction of FeCl₃ · 6H₂O with 4,4′-dimethyl-2,2′-bipyridine in 0.1 molar aqueous HCl. Treatment of 1 with dimethyl sulfoxide in methanol produced [Fe(dmbipy)Cl₃(DMSO)], 2 (DMSO is dimethyl sulfoxide). Both complexes were characterized by IR, UV-vis, and ¹H-NMR spectroscopies and their structures were studied by single crystal diffraction. Compounds 1 and 2 are high-spin with spin multiplicity of six.     

Synthesis,spectral and antimicrobial studies of chloroantimony(III)di[3(2′-hydroxyphenyl)-5-(4-substitutedphenyl)pyrazolinates]

Dichloroantimony(III) pyrazolinates and chloroantimony(III) dipyrazolinates of the type SbCl₂(C₁₅H₁₂N₂OX) and SbCl(C₁₅H₁₂N₂OX)₂ [where C₁₅H₁₂N₂OX = 3(2′-hydroxyphenyl)-5-(4-X-phenyl)pyrazoline, X=H in1 and5;–CH₃ in2 and6;–OCH₃ in3 and7 and–Cl in4 and8] have been synthesized by reaction of SbCl₃ and sodium salt of pyrazolines in 1 : 1 and 1 : 2 molar ratio in anhydrous benzene at elevated temperature. These newly synthesized derivatives have been characterized by elemental analysis (C, H, N, Cl and Sb), molecular weight measurement and spectral studies [IR and¹H and¹³C NMR]. The free pyrazoline and some dichloroantimony(III) pyrazolinates and chloroantimony(III) dipyrazolinates have been screened for antibacterial and antifungal activities, with some dichloroantimony(III) pyrazolinates and chloroantimony(III) dipyrazolinates exhibiting higher antibacterial and antifungal effects than free pyrazoline and some antibiotics.     

Synthesis,structure and DNA-binding studies on the 2-(3-chlorophenyl)imidazo[4,5-f]1,10-phenanthroline-bis(2,2′-bipy ridine)-ruthenium(II) complex

A new polypyridyl ligand, MCP {MCP = 2-(3-chlorophenyl)imidazo[4,5-f]1,10-phenanthroline} and its ruthenium(II) complex, [Ru(bpy)2(MCP)](ClO4)2· 0.5MeCN (bpy = 2,2-bipyridine), have been synthesized and characterized. The structure of the complex was determined by single crystal X-ray diffraction techniques. The MCP ligand is essentially planar and the stacking interactions between the ligands were observed in the crystal. [Ru(bpy)2(MCP)]2+ can strongly bind to Calf thymus DNA through intercalation of MCP ligand. The Cl substitute group has no significant effect on the spectral properties and DNA-binding behaviour of the complex.     

Nickel(II) complex containing 5,5′-dimethyl-2,2′-bipyridine: Crystal structure and luminescent properties

[Ni(5,5′-dmbipy)₂Cl₂]·3H₂O (1) complex was obtained from the reaction of NiCl₂·6H₂O with 5,5′-dimethyl-2,2′-bipyridine (5,5′-dmbipy) in a mixture of CH₃OH/CH₃CN. This complex was characterized by elemental analysis, IR, UV-Vis and luminescence spectroscopy, and its structure was determined by the single-crystal diffraction method. The Ni atom has a distorted octahedral coordination by four N atoms from two 5,5′-dmbipy ligands and two Cl^– anions.     

[Sn 2 (H 2 O) 2 Br 2 (CH 3 ) 4 {μ-(CH 2 ) 3 }·2bpy]: A Layered,Hetero Bimolecular Composite (bpy=2,2′-bipyridine)

Reaction of (Me 2 SnBr) 2 w -(CH 2 ) 3 with 2,2'-bipyridine (bpy) in benzene affords, in the presence of small amounts of water, crystals of the novel composite [Sn 2 (H 2 O) 2 Br 2 Me 4 { w -(CH 2 ) 3 }2bpy] ( 1 ). The crystal structure of 1 consists of alternating layers of either organotin bromide or bipyridine molecules, each bpy molecule being configured cis oid and linked with the organotin layer via one O-H > N hydrogen bond. The mutual disposal of the molecules in the bpy bilayer differs from that known for pure, crystalline bpy. Cell parameters: a 24.3499(1), b 6.5112(1), c 23.3262(1) Å; g 119.557(1). Monoclinic, space group C 2/ c , D calc =1.750 g/cm 3 , Z =4; final R 1: 0.0529; wR 2=0.1374 for 3638 unique reflections [ R (int)=0.0676; I >2 ( I )].     

Syntheses,crystal structures and magnetic properties of complexes based on [Ni(L-L)3]2+ complex cations with dimethylderivatives of 2,2′-bipyridine and TCNQ

From the aqueous-methanolic systems Ni(NO₃)₂ – LiTCNQ – 5,5′-dmbpy and Ni(NO₃)₂ – LiTCNQ – 4,4′-dmbpy three novel complexes [Ni(5,5′-dmbpy)₃](TCNQ)₂ (1), [Ni(4,4′-dmbpy)₃](TCNQ)₂ (2) and [Ni(4,4′-dmbpy)₃]₂(TCNQ-TCNQ)(TCNQ)₂∙0.60H₂O (3), were isolated in single crystal form. The new compounds were identified using chemical analyses and IR spectroscopy. Single crystal studies of all samples corroborated their compositions and have shown that their ionic structures contain the complex cations [Ni(5,5′-dmbpy)]²⁺ (1) or [Ni(4,4′-dmbpy)]²⁺ (2 and 3). The anionic parts of the respective crystal structures 1–3 are formed by TCNQ^⋅- anion-radicals and in 3 also by a σ-dimerized dianion (TCNQ-TCNQ)^2- with a C-C distance of 1.663(5) Å. The supramolecular structures are governed by weak hydrogen bonding interactions. The variable-temperature (2–300 K) magnetic studies of 1 and 3 confirmed the presence of magnetically active Ni(II) atoms with S = 1 and TCNQ^⋅- anion-radicals with S = 1/2 while the (TCNQ-TCNQ)^2- dianion is magnetically silent. The magnetic behavior was described by a complex magnetic model assuming strong antiferromagnetic interactions between some TCNQ^⋅- anion-radicals.     

Synthesis,structure, and DNA-binding studies of a dicopper(II) complex with N-phenolato-N′-[2-(dimethylamino) ethyl]oxamide as ligand

A new µ-oxamido-bridged dicopper(II) complex, [Cu₂(pdmaeox)(bpy)(H₂O)](pic)?·?H₂O [H₃pdmaeox?=?N-phenolato-N′-[2-(dimethylamino)ethyl]oxamide, Hpic?=?2,4,6-trinitrophenol, bpy?=?2,2′-bipyridine], has been synthesized and characterized by elemental analyses, molar conductivity measurement, infrared, and electronic spectra studies, and X-ray single-crystal diffraction. The complex crystallizes in the triclinic system, P 1 space group, with crystallographic data: a?=?10.7815(2)?Å, b?=?11.3598(2)?Å, c?=?14.1389(3)?Å, and z?=?2. In [Cu₂(pdmaeox)(bpy)(H₂O)]⁺, one copper(II) resides in the inner site with a square-planar coordination geometry and the other is chelated by the two exo-oxygen atoms of the cis-pdmaeox^3? ligand in a square-pyramidal environment. The Cu···Cu separation through cis-pdmaeox^3? bridge is 5.1834(4)?Å. The crystal structure is stabilized by hydrogen bonds and π–π stacking interactions. The interaction of the dicopper(II) complex with herring sperm-DNA (HS-DNA) has been investigated by electronic absorption titration, fluorescence titration, electrochemical titration, and viscosity measurements. The results reveal that the interaction of the dicopper(II) complex with HS-DNA might be electrostatic binding. The effects of bridging ligand on the interaction of the dinuclear complex with HS-DNA were preliminarily investigated.     

Syntheses and Crystal Structures of Two Ion Pair Complexes, [Ru(bpy)3]2[Fe(CN)6]I · 7H2O and [Ru(bpy)3]- [Fe(CN)5NO]CH3OH · H2O

Two ion pair complexes, [Ru(bpy)₃]₂[Fe(CN)₆]I [sdot] 7H₃O (1) and [Ru(bpy)₃][Fe(CN)₅NO](CH₃OH) [sdot] H₂O (2) (bpy = 2,2-bipyridine) have been synthesized and structurally characterized. X-Ray crystallographic structures of 1 and 2 both show Fe(III) and Ru(II) in distorted octahedral environments. In both complexes, H-bonding interactions between an uncoordinated water molecule and the nitrogen atom of a cyano group exist.     

Crystal structure and spectroscopic studies of catena-diaqua-tris-μ-(l-proline)neodymium(III) triperchlorate, [Nd(l-pro·H)3(H2O)2](ClO4)3

The crystal structure of the Nd^III l-proline complex [Nd(C₅H₉O₂N)₃(H₂O)₂] (ClO₄)₃ has been determined. The complex crystallizes in the monoclinic space group P2₁, with the following crystal data: a = 13.379(3), b = 21.912(5), c = 9.870(2) Å, β = 91.28(4)°, V= 2892.8 ų, Z = 4, M, = 823.6, d_x = 1.89 g cm^3̄, d_m = 1.91 g cm^3̄, μ(Mo-K_α) = 21.7 cm⁻¹. Absorption and laser excited fluorescence spectra of the mono- crystal were measured along the crystallographic axis a at 300, 123 and 77 K. The probabilities of f-f transitions were analysed, based on the Judd-Ofelt theory. The sig- nificant dependence of intensity on temperature was observed and in such conditions the contribution of possible mechanisms to the hypersensitive transitions was considered. Stark components were determined and energy diagrams for ⁴I _9/2 and ⁴I_11/2 levels were proposed. Bridging coordination bonds from carboxyl groups of the proline molecules create linear polymers and the hydrogen bonds formed stabilize the crystal structure.     

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.     

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.     

Synthesis and Crystal Structure of [Pd(NH_3)_4]Cl_2·2[Pd(NH_3)_3Cl]Cl

PreparahonofsomecomplexcomPOundsof[Pd(NH3)41X2tw,tvhereX=Cl-,Br,I-,X2=Co,:-,RdChl'-,etc.,wasdescribedasearlyl942l'].SynthesisandcryStalstIUCtUreOfthesaltSt'ithamons,Cr2o7",Cro.:',MoO"',andC,o'=',ttcrestillreportedmorcrecenh/'-'j.IPd(NH)4lX2,tvhereX=Cl',BrandNOz,isanotherkindofamndnepalladiumcomplexcompounds.IntheSyStemofIPd(NH).1"-Cl'-H2o,diamlltinedichloridepalladium(II)wasObtalnedbythereachonOfIPd(NH)4lHcomplexionwtthanutebydrogenchloride,andtetrachloridepalladiumaDbythe…     

Structural characterization,photophysical and BSA binding interaction studies of 4,4′-bis(benzimidazolyl)-2,2′-bipyridine

The title compound is synthesized from the precursors 1,2-diaminobenzene and 2,2′-bipyridine-4,4′-dicarboxylic acid (dcbpy) and characterized using ESI-Mass, ¹H NMR, FT-IR and single crystal X-ray analysis. We are the first to report the crystal structure of the 4,4′-bis(benzimidazolyl)-2,2′-bipyridine (bimbpy) ligand. The photophysical properties of the compound in dimethyl sulfoxide and in the aqueous medium are studied. The interaction studies of bimbpy with bovine serum albumin (BSA) were performed with the fluorescence technique and it strongly binds with BSA.     

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.     

Synthesis, crystal structure and properties of a new organic-inorganic hybrid Dawson-like polyoxotungstate [Co(2,2′-bpy)_3]_2[Co(2,2′-bpy)_2Cl][Co(2,2′-bpy)_2]H_2- [SbW_(18)O_(60)]·4H_2O

A new organic-inorganic hybrid polyoxometalate based on Dawson-like polyoxotungstate anion [SbW18O60]9, formulated [Co(2,2′-bpy)3]2[Co(2,2′-bpy)2Cl][Co(2,2′-bpy)2]H2[SbW18O60]·4H2O (2,2′-bpy= 2,2′-bipyridine) has been synthesized from Sb2O3, Na2WO4, CoCl2, and 2,2′-bipyridine materials by hydrothermal method, and which was characterized by elemental analyses, IR, XPS, EPR, TG, and X-ray single crystal diffraction. Structure analysis shows that the polyoxoanion self-assembled under hydrothermal conditions consists of a Dawson-like polyoxotungstate cluster anion [SbW18O60]9 en- capsulating a pyramidal {SbO3} group within the {W18} cluster cage. EPR spectra show that the high-spin octahedral CoII and low-spin CoII ions coexist in the title compound. Magnetic properties in- dicate that the compound is antiferromagnetic.     

Ruthenium(III) mono (2,2′-bipyridine) complexes containing O,O-donor ligands and their oxidation properties for organic compounds

The new complexes [Ru^IIIbpyL₂](PF₆) and [Ru^IIIbpyLCl₂] [bpy = 2,2-bipyridine; HL = acetylacetone, trifluoroacetylacetone, benzoylacetone (Hbac), tropolone or maltol; HL = Hbac or dibenzoylmethane) have been prepared and characterized by spectroscopy. Their redox behaviour was studied by cyclic voltammetry. They effectively catalyze the oxidation of alcohols, alkanes and primary aromatic amines.     

Synthesis and enantiomer separation of a modified tris(2,2′-bipyridine)ruthenium(II) complex

The chiral [5-(4-hydroxybutyl)-5′-methyl-2,2′-bipyridine]-bis(2,2′-bipyridine)-ruthenium(II)-bis(hexafluoroantimonate) complex 3 was prepared and characterized by different NMR techniques and successfully separated into enantiomers by electrokinetic chromatography using anionic carboxymethyl-β-cyclodextrin as chiral mobile phase additive (CMPA). The optimum separation conditions were obtained with 40 mM borate buffer at pH 9.5 and 7.5 mg/mL of the chiral selector at 20°C.