Synthesis, physico-chemical and DNA interaction studies of homo- and hetero-trinuclear complexes

Synthesis and characterization of three new trinuclear metal complexes of type Cu3, Cu2Zn and Cu2Ni have been achieved by assembling simple mononuclear complexes, namely 2,2'-bipyridyl 3,4-dihydroxo benzaldehyde copper(II) complex and diethylenetriamine complexes of copper(II), nickel(II) and zinc(II) ions, through the reaction of coordinated ligands. The FAB mass spectra for the complexes show fragmentation pattern in accordance with the molecular formula. The frozen electron paramagnetic resonance (EPR) spectrum of tricopper complex shows two sets of parallel lines with approximately 2:1 ratio. The simulation has been carried out by considering dipolar interaction between the two types of copper ions present in the complex. The trimetallic complexes, Cu3, Cu2Ni and Cu2Zn show strong intercalation type of interaction with Calf thymus DNA in 0.02 mol L(-1) of phosphate buffer containing 60 mmol sodium chloride at pH 7.0 at room temperature. The binding constant is found to be in the order Cu3相似文献   

Ligational behavior of a bidentate coumarin derivative towards CoII,NiII, and CuII: synthesis,characterization, electrochemistry,and antimicrobial studies

A series of new Co(II), Ni(II), and Cu(II) complexes of Schiff base derived from coumarin have been prepared and characterized by analytical and spectral methods. The Schiff base is synthesized by the condensation of 2,6-diaminopyridine and 3-acetylcoumarin in 1 : 1 stoichiometric ratio. All complexes have 1 : 1 metal : ligand ratio except the nickel complex, where it was found to be 1 : 2. UV-Vis spectra and magnetic moment studies confirm the existence of tetrahedral and octahedral geometries around cobalt(II) and nickel(II) metal ions, respectively, but copper(II) chloride/nitrate/sulfate complexes have square-planar geometry and copper(II) acetate complex is distorted octahedral. ESR spectra of copper complexes at room temperature and liquid nitrogen temperature were tetragonal. All the complexes were found to be more active against bacteria except Ni(II) complex; only CuLSO₄ and CuL(CH₃COO)₂ have shown the enhanced activity against fungi.     

Synthesis,characterization, thermal decomposition studies and dyeing properties of some novel transition metal complexes of an azo derivative formed from 2-aminothiophene

An azo derivative was synthesized by coupling diazotized 2-amino-3-carbethoxy-4,5-dimethylthiophene with 2-naphthol and this new ligand formed a series of metal complexes with Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) salts. These complexes were characterized on the basis of elemental analyses, molar conductance, magnetic susceptibility measurements, UV-Visible, IR and ¹H NMR spectral data. Analytical data revealed that all the complexes exhibited 1: 1 metal-ligand ratio. Spectral studies showed that the ligand existed in an internally hydrogen bonded azo-enol form rather than the keto-hydrazone form and coordinated to the metal ion in a tridentate fashion. On the basis of electronic spectral data and magnetic susceptibility measurements, suitable geometry was proposed for each complex. The ligand and its cobalt(II) complex were subjected to X-ray diffraction study. The thermal behaviour of the ligand and its copper(II) complex was examined by thermogravimetry. The ligand and its copper(II) and nickel(II) complexes were applied to silk fabric and their fastness properties were evaluated.     

Complexes of cobalt(II), nickel(II) and copper(II) with the benzenedicarboxylic acids. Thermal properties

The thermal properties of the complexes of phthalic, isophthalic and terephthalic acid with cobalt(II), nickel(II) and copper(II) are determined by thermogravimetry (TG), differential thermogravimetry (DTG) and differential scanning calorimetry (DSC).The thermal stability of the anhydrous compounds gives, for the metal ions, a sequence Co > Ni > Cu.The thermal stability series as a function of the ligand for each metal is terephthalate > isophthalate > phthalate.     

Green synthesis of biologically active transition metal nanoparticles containing novel Schiff base via catalyst free hydrothermal reaction: Structural,biological and morphology study

Novel cobalt, nickel and copper complexes were synthesized by regular reflux method and nano sized Co(II), Ni(II) and Cu(II) metal complexes were synthesized by a facile hydrothermal method using green solvent at various temperatures without the addition of any capping agent. The structural characterization was done by magnetic susceptibility, molar conductance, elemental analysis, thermal analysis, FT‐IR, ¹H NMR, ¹³C NMR, ESI mass, UV–Visible analysis. The morphology and size of the nano metal complexes were determined using FE‐Scanning electron microscopy, powder X‐ray diffraction data and atomic force microscopic techniques. All the spectral and analytical results reveal 1:2 metal to ligand ratios having [ML₂(H₂O)₂] stoichiometry, here M=Co(II), Ni(II) and Cu(II), L=deprotonated ligand. The non‐electrolytic nature of the compound was confirmed by molar conductance experiment. The synthesized Schiff base and its metal complexes (7, 8 and 9) were tested for their biological activity. All the tested compounds exhibit decent anticancer and DNA cleavage activity and copper complex shows better activity results than other tested compounds.     

Synthesis and characterization of a new Schiff base derived from 2,3-diaminopyridine and 5-methoxysalicylaldehyde and its Ni(II), Cu(II) and Zn(II) complexes. Electrochemical and electrocatalytical studies

We describe the synthesis and characterization of a new tetradentate Schiff base ligand obtained from 2,3-diaminopyridine and 5-methoxysalicylaldehyde. This ligand (H₂L) reacted with nickel(II), copper(II), and zinc(II) acetates to give complexes. The ligand and its metal complexes were characterized using analytical, spectral data (UV–vis, IR, and mass spectroscopy), and cyclic voltammetry (CV). The crystal structure of the copper complex was elucidated by X-ray diffraction studies. The electrochemical behavior of these compounds, using CV, revealed that metal centers were distinguished by their intrinsic redox systems, e.g. Ni(II)/Ni(I), Cu(II)/Cu(I), and Zn(II)/Zn(I). Moreover, the electrocatalytic reactions of Ni(II) and Cu(II) complexes catalyze the oxidation of methanol and benzylic alcohol.     

Coordination compounds of biological interest: Thermal properties of some compounds of saccharin (o-benzoic sulphimide) with nickel(II) and zinc(II)

The thermal properties of nickel(II) and zinc(II) complexes of saccharin (sacc) (o-benzoic sulphimide) have been studied and compared both with those of cobalt(II) and copper(II) previously studied and with those of ternary complexes of nickel(II) and zinc(II) having both saccharin and pyridine as ligands. The thermal behaviour is discussed in terms of the interaction between metal and ligands, interaction studied by IR spectroscopy, and by reflectance spectroscopy.The classical thermal stability scale Co(II) > Ni(II) > Cu(II) > Zn(II) is always obtained.     

Synthesis,characterization, fluorescence and redox features of new <Emphasis Type="Italic">vic</Emphasis>-dioxime ligand bearing pyrene and its metal complexes

A new vic-dioxime ligand, N,N′-bis(aminopyreneglyoxime) (LH₂), and its copper(II), nickel(II) and cobalt(II) metal complexes were synthesized and characterized by elemental analyses, IR, UVVIS and ¹H and ¹³C NMR spectra (for the ligand). Mononuclear complexes were synthesized by a reaction of ligand (LH₂) and salts of Co(II), Ni(II), and Cu(II) in ethanol. The complexes have the metal-ligand ratio of 1: 2 and metals are coordinated by N,N′ atoms of vicinal dioximes. The ligand acts in a polydentate fashion bending through nitrogen atoms in the presence of a base, as do most vic-dioximes. Detection of a H-bonding in the Co(II), Ni(II), and Cu(II) complexes by IR revealed the square-planar MN₄ coordination of mononuclear complexes. Fluorescent properties of the ligand and its complexes arise from pyrene units conjugated with a vic-dioxime moiety. Fluorescence emission spectra of the ligand showed a drastic decrease in its fluorescence intensity upon metal binding. The electrochemical properties of the complexes were studied by the cyclic voltammetry technique. The nickel complex displayed an irreversible oxidation process while the copper complex exhibited a quasi-reversible oxidation and reduction processes based on the copper Cu(II)/Cu(III) and Cu(II)/Cu(I) couples, respectively.     

Spectroscopic,morphology and electrical conductivity studies on Co(II), Ni(II), Cu(II) and Mn(II)-oxaloyldihydrazone complexes

Cobalt (II), nickel (II), copper (II) and manganese (II) complexes of dihydrazone derived from the condensation of oxaloyldihydrazide with 2-hydroxybenzaldehyde have been synthesized. The dihydrazone ligand/chelates were characterized on the basis of their elemental analyses, spectral (UV–Vis., FT-IR, mass, ¹H NMR), magnetism, thermal (TGA) measurements and structures of the compounds have been established. The surface morphology of the desired complexes was studied by SEM. The ligand is coordinated to the Ni(II), Co(II), Mn(II) and Cu(II) centers in bi, tetra, penta and hexadentate way giving mono-nuclear complexes except in case of manganese and copper the bi-nuclear complexes were formed. The nickel complex has tetrahedral geometry while the other complexes are suggested to have octahedral configurations. The prepared samples have been assayed for their electrical activities. The electrical activity (DC and AC conductivity) for ligand and its metal complexes has been examined at different frequencies (1, 10, 100 kHz) in the temperature ranges 303–573 and 300–625 K, respectively. The DC and AC conductivity are viewed as thermally activated process at higher temperatures and a marked increment was seen in case of Mn(II) complex. The dielectric permittivity was determined in the temperature area of 300–625 K and diminished with augmentation of frequency proposing a typical behavior of dielectrics.     

Theoretical study on the gas-phase acidity of multiple sites of Cu+-adenine and Cu2+-adenine complexes

The acidities of multiple sites in Cu(+)-adenine and Cu(2+)-adenine complexes have been investigated theoretically. To compare, the acidities of adenine (A) and adenine radical cation (A(*+)) have also been included. The results clearly indicate that the acidities of C-H and N-H groups in Cu(+/2+)-adenine are significantly enhanced relative to the neutral adenine. The acidic order for a given site on adenine and adenine derivatives is as follows: Cu(2+)-adenine > A(*+) > Cu(+)-adenine > A. For Cu(+)-adenine and Cu(2+)-adenine, N3-coordination exhibits N9-H acid, and N1- and N7-coordination exhibits N6-H(a) and N6-H(b) acid, respectively. Additionally, it is found that C2-H group is surprisingly acidic in the coordination complexes. Calculations in aqueous solution reveal that our results can be extrapolated to aqueous solution. Analyses of the electronic properties interpret the highest acidity of Cu(2+)-adenine among the adenine derivatives studied. Also, Electrostatic potential calculations of [A(-H(+))](-) and [A(-H(+))](*) indicate that the removal of H(a) or H(b) from the amino group favors the bidentate coordination, which provides a dative bond from the deprotonated N and the original coordination ligand to copper ion besides the electrostatic interaction between them and thereby stabilizes the [A(-H(+))](-)/[A(-H(+))](*). NBO analysis confirms the electrostatic potential result.     

Studies on DNA cleavage and antimicrobial screening of transition metal complexes of 4-aminoantipyrine derivatives of N2O2 type

A new series of transition metal complexes of Cu(II), Ni(II), Zn(II) and VO(IV), were synthesized from the Schiff base (L) derived from 4-aminoantipyrine, 3-hydroxy-4-nitrobenzaldehyde and acetylacetone. The structural features were arrived from their elemental analyses, magnetic susceptibility, molar conductance, Mass, IR, UV-Vis., ¹H NMR and ESR spectral studies. The data show that the complexes have composition of [ML]X type. The UV-Vis., magnetic susceptibility and ESR spectral data of the complexes suggest a square-planar geometry around the central metal ion except for VO(IV) complex which has square-pyramidal geometry. The redox behavior of copper and vanadyl complexes were studied by cyclic voltammetry. The antimicrobial screening tests were also recorded and gave good results in the presence of metal ion in the ligand system. The nuclease activity of the above metal complexes shows that the copper and nickel complexes cleave DNA through redox chemistry, whereas other complexes are not effective.     

Preparation, spectral and biological investigation of formaldehyde-based ligand containing piperazine moiety and its various polymer metal complexes

A novel tetradentate salicylic acid-formaldehyde ligand containing piperazine moiety (SFP) was synthesized by condensation of salicylic acid, formaldehyde and piperazine in presence of base catalyst, which was subjected for the preparation of coordination polymers with metal ions like manganese(II), cobalt(II), copper(II), nickel(II) and zinc(II). All the synthesized polymeric compounds were characterized by elemental analysis, IR, (1)H NMR and electronic spectral studies. The thermal stability was determined by thermogravimetric analysis and thermal data revealed that all the polymer metal complexes show good thermal stability than their parent ligand. Electronic spectral data and magnetic moment values revealed that polymer metal complexes of Mn(II), Co(II) and Ni(II) show an octahedral geometry while Cu(II) and Zn(II) show distorted octahedral and tetrahedral geometry respectively. The antimicrobial screening of the ligand and coordination polymers was done by using Agar well diffusion method against various bacteria and fungi. It was evident from the data that antibacterial and antifungal activity increased on chelation and all the polymer metal complexes show excellent antimicrobial activity than their parent ligand.     

Pyrazolate-based copper(II) and nickel(II) [2 x 2] grid complexes: protonation-dependent self-assembly, structures and properties

The pyrazole-based diamide ligand N,N'-bis(2-pyridylmethyl)pyrazole-3,5-dicarboxamide (H(3)L) has been structurally characterised and successfully employed in the preparation of [2 x 2] grid-type complexes. Thus, the reaction of H(3)L with Cu(ClO(4))2.6H(2)O or Ni(ClO(4))2.6H(2)O in the presence of added base (NaOH) affords the tetranuclear complexes [M(4)(HL(4))].8H(2)O (1: M = Cu, 2: M = Ni). Employment of a mixture of the two metal salts under otherwise identical reaction conditions leads to the formation of the mixed-metal species [Cu(x)Ni(4-x)(HL)(4)].8H(2)O (x相似文献   

Template synthesis and spectral characterization of some Schiff base complexes derived from quinoxaline-2-carboxaldehyde and L-histidine

New Schiff base complexes of Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) were synthesized by template condensation of quinoxaline-2-carboxaldehyde, L-histidine, and the metal compound, and were characterized by elemental analysis, fourier transform infrared spectroscopy, electronic spectra, conductance measurements, magnetic susceptibility measurements, ESR spectra, and thermal analysis. In all the complexes, the Schiff base coordinates through azomethine nitrogen, quinoxaline nitrogen, and carboxylato oxygen. The physicochemical and spectroscopic measurements reveal square planar geometry for the copper(II) complex, tetrahedral geometry for the manganese(II), cobalt(II), and zinc(II) complexes, and octahedral geometry for the iron(III) and nickel(II) complexes.     

Synthesis and characterization of metal(II) complexes of poly(3-nitrobenzylidene-1-naphthylamine-co-succinic anhydride)

The alternating copolymer poly(3-nitrobenzylidene-1-naphthylamine-co-succinic anhydride) was synthesized from the Schiff base, 3-nitrobenzylidene-1-naphthylamine and succinic anhydride using hydroquinone monomethyl ether under nitrogen atmosphere. The molecular weight of the copolymer was determined by gel permeation chromatography. The metal-polymer complexes were synthesized by the reaction of THF solution of the alternating copolymer with aqueous solution of Cu(II) and Ni(II) acetates. The elemental analysis of the metal-polymer complexes suggests that the metal to ligand ratio is 1:2. The IR spectral data indicate that the metal ions are coordinated through the oxygen of the keto and ester groups. The UV-Visible, magnetic moments and ESR studies indicate square planar geometry for Cu(II) and distorted octahedral geometry for Ni(II) complexes. XRD studies revealed that the copolymer and its Cu(II) complex are crystalline, while the Ni(II) complex is amorphous. The intrinsic viscosity of the copolymer, thermal properties of metal-polymer complexes and their catalytic activity are discussed.     

Salisaldehyde-2-aminobenzimidazole schiff base complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)

New metal complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with salicylidine-2-aminobenzimidazole (SABI) are synthesized and their physicochemical properties are investigated using elemental and thermal analyses, IR, conductometric, solid reflectance and magnetic susceptibility measurements. The base reacts with these metal ions to give 1:1 (Metal:SABI) complexes; in cases of Fe(III), Co(II), Cu(II), Zn(II) and Cd(II) ions; and 1:2 (Metal:SABI) complexes; in case of Ni(II) ion. The conductance data reveal that Fe(III) complex is 2:1 electrolyte, Co(II) is 1:2 electrolyte, Cu(II), Zn(II) and Cd(II) complexes are 1:1 electrolytes while Ni(II) is non-electrolyte. IR spectra showed that the ligand is coordinated to the metal ions in a terdentate mannar with O, N, N donor sites of the phenloic -OH, azomethine -N and benzimidazole -N3. Magnetic and solid reflectance spectra are used to infer the coordinating capacity of the ligand and the geometrical structure of these complexes. The thermal decomposition of the complexes is studied and indicates that not only the coordinated and/or crystallization water is lost but also that the decomposition of the ligand from the complexes is necessary to interpret the successive mass loss. Different thermodynamic activation parameters are also reported, using Coats-Redfern method. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and characterization of some pyrimidine, purine, amino acid and mixed ligand complexes

Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes of barbital, thiouracil, adenine, amino acids (methionine, lysine and alanine) and some mixed ligands were prepared and characterized by elemental analyses, IR, electronic spectra, magnetic susceptibility and ESR spectra. Coordination of the metallic centre to the oxygen and nitrogen atoms of barbital, thiouracil, amino acids and coordinate to amino group and nitrogen atom of adenine occurred. Electronic spectra and magnetic susceptibility measurements were utilized to infer the structure of the complexes which are octahedral for Mn(II), Fe(III), Co(II), Ni(II) and Cd(II) and tetrahedral for Mn(II), Cu(II), Zn(II) complexes. ESR spectra were observed for copper complexes with a d(x2)-(y2) ground state with small g(||) values indicating strong interaction between the ligands and their metal ions.     

Studies of Some New Aminocyclodiphosphazane Complexes of Co(II), Ni(II), and Cu(II)

The ligand aminocyclodiphosph(V)azane derivative (III) and its complexes with Co(II), Ni(II), and Cu(II) ions were prepared and characterized by microanalytical, FTIR, ¹H, ¹³C, and ³¹P-NMR, UV/Visible, thermogravimetric (TGA) analysis, and magnetic moments. The ligand acts in a tetrahedral manner forming 2:1 metal to ligand ratio. The copper complex is assigned to be tetrahedral while cobalt and nickel complexes were assigned to be octahedral structure.     

A thermoanalytical study of dipicolinic acid acting as a terdentate ligand in coordination compounds of divalent metal ions

The coordination compounds obtained by reaction of hot solutions of dipicolinic acid with the carbonates of the divalent metal ions manganese(II), iron(II), cobalt(II), nickel(II), copper(II) and zinc(II) are studied using TG, DSC and HTRS techniques. For the thermal stability a sequence Mn > Fe > Zn > Co > Ni > Cu may be observed. This series is compared with the similar series obtained with isocinchomeronic acid. The thermal stability is, for each metal of the series, isocinchomeronic > dipicolinic. Thermal stability is discussed in terms of the intermolecular bonds, of the structures and of the stability constants of the complexes examined.     

某些芳香族羟肟一过渡金属配合物的红外光谱

The preparation and infrared spectroscopic studies of coordination compounds of salicylaldoxime, 2-hydroxy-acetophenone oxime, 2-hydroxy-benzophenone oxime and 2-hydroxy-4-methoxy-benzophenone oxime with copper (II), nickel (II), cobalt (II) and iron (II) have been described. The frquency of the C=N stretching vibration is usually higher in the complex than that in the ligand. The higher the frequency of the C=N vibration is, the larger the stability constant of the complex will be, but there is no quantitative relationship. In the case of complexes of salicylaldoxime with Cu, Ni, Co and Fe, &CC=N values are correlated linearly with the ionization potentials of the central metal ions. The frequency of the OH stretching vibration is closely related to the geometric configuration of the complex. Thus aromatic hydroxyoximes form coordination compound with Co (II) and Fe (II) with cis configuration possessing six membered stronger hydrogen bonding ring. This is indicated in the infrared spectra by the complete absence of the absorption band due to the OH stretching vibration, or by the appearance of an extremely broad and flat band of very low intensity. However, Cu (II) or Ni (II) complex possesses trans configuration with five membered hydrogen-bonding bridge showing characteristic OH absorption band in the infrared region. The &COH of complex investigated is closely related to the polar nature of the substituents on the benzene ring. By examining the spectra of Cu-63 and Cu-65 complexes with 2-hydroxy-4(5)-substituted benzophenone oximes, the characteristic frequencies of M -- O and M -- N in the far infrared region were assigned for a series of aromatic hydroxyoxime-transition metal complexes.