Nickel(II)-, cobalt(II)-, copper(II)-, and zinc(II)-phthalate and 1-methylimidazole coordination compounds: synthesis, crystal structures and magnetic properties

Three new coordination polymers [M(Pht)(1-MeIm)₂]_n (where M=Cu (1), Zn (2), Co (3); Pht²⁻=dianion of o-phthalic acid; 1-MeIm=1-methylimidazole) and two compounds [M(1-MeIm)₆](HPht)₂ · 2H₂O (M=Co (4), Ni (5)) have been synthesized and characterized by X-ray crystallography. The structures of 1-3 (2 is isostructural to 3) consist of [M(1-MeIm)₂] building units connected by 1,6-bridging phthalate ions to form infinite chains. In complex 1, each copper(II) center adopts a square coordination mode of N₂O₂ type by two O atoms from different phthalate ions and two N atoms of 1-MeIm, whereas in 3 two independent metal atoms are tetrahedrally (N₂O₂) coordinated to a pair of Pht ligands and a pair of 1-MeIm molecules. There are only van der Waals interactions between the chains in 1, while the three-dimensional network in 3 is assembled by C-H?O contacts. In contrast to polymers 1-3 the structures of 4 and 5 (complexes are also isostructural) are made up of the [M(1-MeIm)₆]²⁺ cation, two hydrogen phthalate anions (HPht⁻) and two H₂O solvate molecules. The coordination around each metal(II) atom is octahedral with six nitrogen atoms of 1-MeIm. Extended hydrogen bonding networks embracing the solvate water molecules and a phthalate residue as well as the weak C-H?O interactions stabilize the three-dimensional structures. Magnetic studies clearly show that the magnetic ions do not interact with each other. Furthermore, in compound 4 we have another example of a highly anisotropic Co²⁺ ion with a rhombic g-tensor and large zero-field-splitting. The complexes were also characterized by IR and ¹H NMR spectroscopy, thermogravimetric analysis, and all data are discussed in the terms of known structures.     

Antifungal cobalt(II), copper(II), nickel(II) and zinc(II) complexes of furanyl-,thiophenyl-, pyrrolyl-, salicylyl- and pyridyl-derived cephalexins

Some novel cephalexin-derived furanyl, thiophenyl, pyrrolyl, salicylyl and pyridyl Schiff's bases and their cobalt (II), copper (II), nickel (II) and zinc (II) complexes have been synthesized and studied for their antifungal properties against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. The presence of metal ions in the investigated Schiff's base complexes reported here lead to significant antifungal activity, whereas the parent ligands were generally less active.     

Acetazolamide-M(II) [M(II) = Co(II),Ni(II),Cu(II)] complexes with ethylamine, diethylamine, triethylamine, and potassium hidroxide

Complexes of Co(II), Ni(II), and Cu(II) with dideprotonated Acm are synthesized and characterized. Acm acts as bidentate ligand through the N-sulfonamido atom and the N-thiadiazole atom except for K6CoAcm4.6H2O in which Acm behaves as monodentate through the N-sulfonamido atom.     

Antifungal Cobalt(II), Copper(II), Nickel(II) and Zinc(II) Complexes of Furanyl-,Thiophenyl-, Pyrrolyl-, Salicylyl- and Pyridyl-derived Cephalexins

Some novel cephalexin-derived furanyl, thiophenyl, pyrrolyl, salicylyl and pyridyl Schiff's bases and their cobalt (II), copper (II), nickel (II) and zinc (II) complexes have been synthesized and studied for their antifungal properties against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. The presence of metal ions in the investigated Schiff's base complexes reported here lead to significant antifungal activity, whereas the parent ligands were generally less active.     

Copper(II), cobalt(II) and nickel(II) complexes of lapachol: synthesis,DNA interaction,and cytotoxicity

Three novel copper(II), cobalt(II), and nickel(II) complexes of lapachol (Lap) containing 110-phenanthroline (phen) ligand, [M(Lap)₂(phen)] (M=Cu(II), 1, Co(II), 2, and Ni(II), 3), have been synthesized and characterized using, elemental analysis and spectroscopic studies. Their interactions with calf thymus DNA (CT DNA) were investigated using viscosity, thermal denaturation, circular dichorism, fluorescence quenching, and electronic absorption spectroscopy. The DNA cleavage abilities of 1–3 have been studied, where cleavage activity of copper complex 1 is more than the complexes 2 and 3. The in vitro cytotoxic potential of the complexes 1–3 against human cervical carcinoma (HeLa), human liver hepatocellular carcinoma (HepG-2), and human colorectal adenocarcinoma (HT-29) cells indicated their promising antitumor activity with quite low IC₅₀ values in the range of .15–2.41 μM, which are lower than those of cisplatin.     

Antibacterial cobalt (II), copper (II), nickel (II) and zinc (II) complexes of mercaptothiadiazole--derived furanyl, thienyl, pyrrolyl, salicylyl and pyridinyl Schiff bases

A series of Co (II), Cu (II), Ni (II) and Zn (II) complexes of mercaptothiadiazole-derived furanyl, thienyl, pyrrorlyl, salicylyl and pyridinyl Schiff bases were synthesized, characterized and screened for their in vitro antibacterial activity against four Gram-negative, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Shigella fexneri, and two Gram-positive; Bacillus subtilis and Staphylococcus aureous bacterial strains. The results of these studies show the metal complexes to be more antibacterial as compared to the prepared un-complexed Schiff bases.     

Synthesis, structures and magnetic properties of oxamido-bridged trinuclear Cu(II)-Mn(II)-Cu(II) complexes

Based on self-assembly of the dissymmetrical mononuclear entity CuL(CH₃OH) [H₂L = (E)-N¹-(2-((2-aminocyclohexydiimino)(phenyl)methyl)-4-chlorophenyl)-N²-(2-benzyl-4-chlorophenyl)oxalamide] with Mn(II), two trinuclear complexes were prepared. They are of the formula [(LCuN₃)₂Mn(CH₃OH)₂] · 2CH₃OH · 2H₂O (1) and [(LCuSCN)₂Mn(H₂O)₂] · 4CH₃OH (2). Their magnetic properties were studied by susceptibility versus temperature measurement, the best fitting of the experimental data led to J = −14.40 cm⁻¹ for 1 and J = −15.48 cm⁻¹ for 2. Hydrogen bonds help complex 1 to produce a novel S type one-dimensional chain-like supramolecular structure. In complex 2, Cl?Cl interaction also results in the formation of a one-dimensional structure.     

Synthesis,characterization, DNA interaction,and cytotoxicity of novel Pd(II) and Pt(II) complexes

Four complexes [Pd(L)(bipy)Cl]·4H₂O (1), [Pd(L)(phen)Cl]·4H₂O (2), [Pt(L)(bipy)Cl]·4H₂O (3), and [Pt(L)(phen)Cl]·4H₂O (4), where L = quinolinic acid, bipy = 2,2’-bipyridyl, and phen = 1,10-phenanthroline, have been synthesized and characterized using IR, ¹H NMR, elemental analysis, and single-crystal X-ray diffractometry. The binding of the complexes to FS-DNA was investigated by electronic absorption titration and fluorescence spectroscopy. The results indicate that the complexes bind to FS-DNA in an intercalative mode and the intrinsic binding constants K of the title complexes with FS-DNA are about 3.5?×?10⁴ M^?1, 3.9?×?10⁴ M^?1, 6.1?×?10⁴ M^?1, and 1.4?×?10⁵ M^?1, respectively. Also, the four complexes bind to DNA with different binding affinities, in descending order: complex 4, complex 3, complex 2, complex 1. Gel electrophoresis assay demonstrated the ability of the Pt(II) complexes to cleave pBR322 plasmid DNA.     

Spectroscopic characterization of Co(II)-, Ni(II)-, and Cd(II)-substituted wild-type and non-native retroviral-type zinc finger peptides

The nucleocapsid protein (NCP) from Mason-Pfizer monkey virus (MPMV) contains two evolutionary invariant Cys-X₂-Cys-X₄-His-X₄-Cys retroviral-type zinc finger structures, where the Cys and His residues provide ligands to a tetrahedrally coordinated Zn(II) ion. The N-terminal zinc finger (F1) of NCP from MPMV contains an immediately contiguous Cys in the -1 position relative to the start of this conserved motif: Cys-Cys-X₂-Cys-X₄-His-X₄-Cys. Metal complexes of 18-amino acid peptides which model the native zinc finger sequence, SER-Cys-X₂-Cys-X₄-His-X₄-Cys (F1_SC), and non-native Cys-SER-X₂-Cys-X₄-His-X₄-Cys (F1_CS) and SER-SER-X₂-Cys-X₄-His-X₄-Cys (F1_SS) sequences have been spectroscopically characterized and compared to the native two-zinc-finger protein fragment, MPMV NCP 21-80. All Co(II)-substituted peptide complexes adopt tetrahedral ligand geometries and have S^-MCo(II) ligand-to-metal charge-transfer (LMCT) transition intensities consistent with three Co(II)-S bonds for F1_SC and F1_CS. The non-native F1_CS peptide binds Co(II) with K_Co=1.5᎒⁶ M^-1, comparable to that of the native complex, and 걄-fold tighter than F1_SS. Like the Co(II) derivative, the absorption spectrum of Ni(II)-substituted NCP 21-80 is most consistent with tetrahedral Ni(II) complexes with multiple thiolate donors. In contrast, Ni(II) complexes of F1_SC and F1_CS exhibit a single absorption band in the 400-550 nm region ()겨-300 M^-1 cm^-1), distinct in the two complexes, assignable to a degenerate d-d transition envelope characteristic of non-native square-planar coordination geometry, and an intense LMCT transition in the UV ()₂₅₅ᄾ,000 M^-1 cm^-1). Cd(II) complexes have intense absorption in the UV (5_max=233 nm), with absolute intensities consistent with 񬩈 M^-1 cm^-1 per Cd(II)-S bond. ¹¹³Cd NMR spectroscopy of ¹¹³Cd MPMV NCP gives '=649 ppm, consistent with S₃N coordination. Co(II) and Cd(II) complexes of non-native F1_CS peptides are more sensitive to oxidation by O₂, relative to F1_SC, suggestive of a higher lability in the non-native chelate. The implications of these findings for the evolutionary conservation of this motif are discussed.     

Synthesis, characterization, and antitumor activity of 1,2-bis(diphenylphosphino) ethane platinum(II) and palladium(II) complexes

A number of 1,2-bis(diphenylphosphino)ethane monomeric platinum(II) and palladium(II) complexes have been synthesized in light of their potential antitumor activity. The metal center is coordinated with a number of carboxylate anions in the cis-configuration. These complexes have been characterized by elemental analysis, conductivity measurement, and various spectroscopic techniques [IR and 195Pt NMR]. In vivo screening tests for activity of these complexes were performed against the L1210/0 murine leukemia cancer model, but none displayed a significant level of antitumor activity.     

2,2'-Bipyridinebutyldithiocarbamatoplatinum(II) and palladium(II) complexes: synthesis, characterization, cytotoxicity, and rich DNA-binding studies

Butyldithiocarbamate sodium salt (Bu-dtcNa) and its two complexes, [M(bpy)(Bu-dtc)]NO3 (M=Pt(II) or Pd(II) and bpy=2,2'-bipyridine), have been synthesized and characterized on the basis of elemental analysis, molar conductivities, IR, 1H NMR, and UV-vis spectra. In these complexes, the dithiocarbamato ligand coordinates to Pt(II) or Pd(II) center as bidentate with two sulfur atoms. These complexes show 50% cytotoxic concentration (Cc(50)) values against chronic myelogenous leukemia cell line, K562, much lower than that of cisplatin. The interaction of these complexes with calf thymus DNA was extensively investigated by a variety of spectroscopic techniques. These studies showed that both complexes presumably intercalate in DNA. UV-vis studies imply that they cooperatively bind with DNA and unexpectedly denature the DNA at very low concentrations (approximately 100 microL). Palladium complex breaks the DNA into two unequal fragments and binds stronger to the lighter fragment than to the heavier one. In the interaction studies between the Pt(II) and Pd(II) complexes with DNA, several binding and thermodynamic parameters have been determined, which may provide deeper insights into the mechanism of action of these types of complexes with nucleic acids.     

Synthesis, spectroscopy, structure and photophysical properties of dinaphthylmethylarsine complexes of palladium(II) and platinum(II)

Dinaphthylmethylarsine complexes of palladium(II) and platinum(II) with the formulae [MX₂L₂] (M = Pd, Pt; L = di(1-naphthyl)methylarsine = Nap₂AsMe and X = Cl, Br, I), [M₂Cl₂(μ-Cl)₂L₂], [PdCl(S₂CNEt₂)L], [Pd₂Cl₂(μ-OAc)₂L₂] and [MCl₂(PR₃)L] (PR₃ = PEt₃, PPr₃, PBu₃, PMePh₂) have been prepared. These complexes have been characterized by elemental analyses, IR, Raman, NMR (¹H, ¹³C, ³¹P) and UV-vis spectroscopy. The stereochemistry of the complexes has been deduced from the spectroscopic data. The crystal structures of trans-[PdCl₂(PEt₃)(Nap₂AsMe)] and of [Pd(S₂CNEt₂)₂], a follow-up product, were determined. The UV-vis spectra of [MX₂L₂] complexes show a red shift on going from X = Cl to X = I. The complexes [PdX₂L₂] and [PtX₂L₂] are strongly luminescent in fluid solution and in the solid at ambient temperature.     

Synthesis and properties of trinuclear polypyridyl complexes Ru(II)-Co(II)-Ru(II) and Ru(II)-Co(III)-Ru(II): Their photoinduced interconversion

The trinuclear [{Ru^II(bpy)₂(bpy-terpy)}₂Co^II]⁶⁺ complex (1⁶⁺) in which a Co(II)-bis-terpyridine-like centre is covalently linked to two Ru(II)-tris-bipyridine-like moieties by a bridging bipyridine-terpyridine ligand has been synthesised and characterised. Its electrochemical, photophysical and photochemical properties have been investigated in CH₃CN. The cyclic voltammetry exhibits two successive reversible oxidation processes, corresponding to the Co^III/Co^II and Ru^III/Ru^II redox couples at E_1/2 = −0.06 and 0.91 V vs Ag/Ag⁺ 10 mM, respectively. The one-electron oxidized form of the complex, [{Ru^II(bpy)₂(bpy-terpy)}₂Co^III]⁷⁺ (1⁷⁺) obtained after exhaustive electrolysis carried out at 0.2 V is fully stable. 1⁶⁺ and 1⁷⁺ are only poorly luminescent, indicating that the covalent linkage of the Ru(II)-tris-bipyridine centre to the cobalt subunit leads to a strong quenching of the Ru^II excited state by an intramolecular process. Luminescence lifetime experiments carried out at different temperatures indicate that the transfer is more efficient for 1⁷⁺ compare to 1⁶⁺ due to lower activation energy. Continuous irradiation of 1⁷⁺ performed at 405 nm in the presence of P(Ph)₃ acting as sacrificial electron donor leads to its quantitative reduction into 1⁶⁺, whereas similar experiment starting from 1⁶⁺ with a sulfonium salt as sacrificial electron acceptor converts 1⁶⁺ into 1⁷⁺ with a slower rate and a maximum yield of 80%. These photoinduced electron transfers were followed by UV-Visible spectroscopy and compared with those obtained with a simple mixture of both mononuclear parent complexes i.e. [Ru^II(bpy)₃]²⁺ and [Co^II(tolyl-terpy)₂]²⁺ or [Co^III(tolyl-terpy)₂]³⁺ (tolyl-terpy = 4′-(4-methylphenyl)-2,2′:6′,2′′-terpyridine).     

Synthesis, physico-chemical characterization and antimicrobial activity of cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes with some acyldihydrazones

Complexes of the type [M(bssdh)]Cl and [M(dspdh)]Cl, where M = Co(II), Ni(II), Cu(II), Zn(II) and Cd(II); Hbssdh = benzil salicylaldehyde succinic acid dihydrazone, Hdspdh = diacetyl salicylaldehyde phthalic acid dihydrazone have been synthesized and characterized with the help of elemental analyses, electrical conductance, magnetic susceptibility measurements, electronic, ESR and IR spectra and X-ray diffraction studies. Magnetic moment values and electronic spectral transitions indicate a spin free octahedral structure for Co(II), Ni(II) and Cu(II) complexes. IR spectral studies suggest that both the ligands behave as monobasic hexadentate ligands coordinating through three > C = O, two > C = N- and a phenolate group to the metal. ESR spectra of Cu(II) complexes are axial type and suggest d(x(2)-y(2)) as the ground state. X-ray powder diffraction parameters for [Co(bssdh)]Cl and [Co(dspdh)]Cl complexes correspond to an orthorhombic crystal lattice. The ligands as well as their metal complexes show a significant antifungal and antibacterial activity against various fungi and bacteria. The metal complexes are more active than the parent ligands.     

Synthesis,physico-chemical characterization and antimicrobial activity of cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes with some acyldihydrazones

Complexes of the type [M(bssdh)]Cl and [M(dspdh)]Cl, where M = Co(II), Ni(II), Cu(II), Zn(II) and Cd(II); Hbssdh = benzil salicylaldehyde succinic acid dihydrazone, Hdspdh = diacetyl salicylaldehyde phthalic acid dihydrazone have been synthesized and characterized with the help of elemental analyses, electrical conductance, magnetic susceptibility measurements, electronic, ESR and IR spectra and X–ray diffraction studies. Magnetic moment values and electronic spectral transitions indicate a spin free octahedral structure for Co(II), Ni(II) and Cu(II) complexes. IR spectral studies suggest that both the ligands behave as monobasic hexadentate ligands coordinating through three > C = O, two > C = N– and a phenolate group to the metal. ESR spectra of Cu(II) complexes are axial type and suggest as the ground state. X–ray powder diffraction parameters for [Co(bssdh)]Cl and [Co(dspdh)]Cl complexes correspond to an orthorhombic crystal lattice. The ligands as well as their metal complexes show a significant antifungal and antibacterial activity against various fungi and bacteria. The metal complexes are more active than the parent ligands.     

Preparation, structural, magnetic and thermal properties of two heterobimetallic cyano-bridged nickel(II)-copper(II)/platinum(II) coordination polymers

Two unique bimetalic Pt(II) coordination polymers of composition [Ni(hydeten)₂Pt(CN)₄] (Ni-Pt) and [Cu(hydeten)₂Pt(CN)₄] (Cu-Pt) [hydeten = N-(2-hydroxyethyl-ethylenediamine) or 2-(2-aminoethylamino)ethanol] have been synthesized and structurally characterized by various methods in this study. The crystal structure of Cu-Pt was determined by single-crystal X-ray diffraction analysis. The structure of Cu-Pt forms of infinite 2,2-TT type [-Cu(hydeten)₂-NC-Pt(CN)₂-CN-] chains containing paramagnetic copper atoms bridged by tetracyanoplatinate species. In this complex, Cu(II) centers display an axially elongated octahedron with two chelating hydeten molecules in the equatorial positions and N-bonded bridging cyano groups in the axial positions, whereas Pt(II) centers are four coordinate with four cyanide-carbon atoms in a square-planar arrangement. The decrease of the moments of these complexes in temperature range of 50 305 K can assigned to the antiferromagnetic interactions in the structures. The thermal decomposition of Cu-Pt comprise of five distinguished stages, while the thermal decomposition of Ni-Pt take place four different stages.     

Spontaneous resolution of binary copper(II) complexes with racemic dipeptides: crystal structures of glycyl-L-alpha-amino-n-butyrato copper(II) monohydrate, glycyl-D-valinato copper(II) hemihydrate, and glycyl-L-valinato copper(II) hemihydrate

Copper(II) complexes with glycyl-DL-alpha-amino-n-butyric acid (H2gly-DL-but), glycyl-DL-valine (H2gly-DL-val), glycyl-DL-norleucine (H2gly-DL-norleu), glycyl-DL-threonine (H2gly-DL-thr), glycyl-DL-serine (H2gly-DL-ser), glycyl-DL-phenylalanine (H2gly-DL-phe), and glycyl-L-valine (H2gly-L-val), have been prepared and characterized by IR, powder diffuse reflection, CD and ORD spectra, and magnetic susceptibility measurements, and by single-crystal X-ray diffraction. The crystal structures of the copper complex with H2gly-DL-but, the copper complex with H2gly-DL-val, and [Cu(gly-L-val)]n.0.5nH2O have been determined by a single-crystal X-ray diffraction method. As for the structure of the copper complex with H2gly-DL-but, the configuration around the asymmetric carbon atom is similar to that of [Cu(gly-L-val)]n.0.5nH2O. Therefore it is concluded that the copper complex with H2gly-DL-but is [Cu(gly-L-but)]n.nH2O. On the contrary, as for the structure of the copper complex with H2gly-DL-val, the configuration around the asymmetric carbon atom is different from that of [Cu(gly-L-val)]n.0.5nH2O. Therefore it is concluded that the copper complex with H2gly-dl-val is [Cu(gly-D-val)]n.0.5nH2O. So during the crystallization of the copper(II) complexes with H2gly-DL-but and H2gly-DL-val, spontaneous resolution has been observed; the four complexes have separated as [Cu(gly-D-but)]n.nH2O, [Cu(gly-L-but)]n.nH2O, [Cu(gly-D-val)]n.0.5nH2O, and [Cu(gly-L-val)]n.0.5nH2O, respectively. [Cu(gly-L-but)]n.nH2O is orthorhombic with the space group P2(1)2(1)2(1). [Cu(gly-D-val)]n.0.5nH2O and [Cu(gly-L-val)]n.0.5nH2O are monoclinic with the space group C2. In these complexes, the copper atom is in a square-pyramidal geometry, ligated by a peptide nitrogen atom, an amino nitrogen atom, a carboxyl oxygen atom, and a carboxyl oxygen atom and a peptide oxygen atom from neighboring molecules. So these complexes consist of a two-dimensional polymer chain bridged by a carboxyl oxygen atom and a peptide oxygen atom from neighboring molecules. The axial oxygen atom is located above the basal plane and the side chain of an amino acid is located below it. These polymer chains consist of only one or the other type of optical isomers; no racemic dipeptides are found. Therefore, spontaneous resolution has been observed in the crystallization of copper(II) complexes with H2gly-DL-but and H2gly-DL-val. The crystal structure of [Cu(gly-D-val)]n.0.5nH2O agrees almost completely with that of [Cu(gly-L-val)]n.0.5nH2O, except for the configuration around the asymmetric carbon atom.     

Antibacterial Co(II), Cu(II), Ni(II) and Zn(II) Complexes of Thiadiazole Derived Furanyl,Thiophenyl and Pyrrolyl Schiff Bases

2-Amino-1,3,4-thiadiazole undergoes a condensation reaction with furane-, thiophene- and pyrrole-2-carboxaldehyde to form tridentate NNO, NNS and NNN donor Schiff bases. These Schiff bases were further used to obtain complexes of the type [M(L) 2] X, where M=Co(II), Cu(II), Ni(II) or Zn(II), L=L 1, L 2 or L 3 and X=Cl 2. The new compounds described here have been characterized by their physical, spectral and analytical data, and have been screened for antibacterial activity against several bacterial strains such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The antibacterial potency of the Schiff bases increased upon chelation/complexation in comparison to the uncomplexed Schiff bases against the tested bacterial species thus, opening new approaches to find new ways in the fight against antibiotic-resistant strains.     

Antibacterial Co(II), Cu(II), Ni(II) and Zn(II) complexes of thiadiazole derived furanyl,thiophenyl and pyrrolyl Schiff bases

2-Amino-1,3,4-thiadiazole undergoes a condensation reaction with furane-, thiophene- and pyrrole-2-carboxaldehyde to form tridentate NNO, NNS and NNN donor Schiff bases. These Schiff bases were further used to obtain complexes of the type [M(L)2]X, where M = Co(II), Cu(II), Ni(II) or Zn(II), L = L1, L2 or L3 and X = Cl2. The new compounds described here have been characterized by their physical, spectral and analytical data, and have been screened for antibacterial activity against several bacterial strains such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The antibacterial potency of the Schiff bases increased upon chelation/complexation in comparison to the uncomplexed Schiff bases against the tested bacterial species thus, opening new approaches to find new ways in the fight against antibiotic-resistant strains.