Thermal decomposition and biological activity studies of some transition metal complexes derived from mixed ligands sparfloxacin and glycine

The synthetic method of novel ternary M(II)/(III)/(IV) complexes, with fluoroquinolone drug sparfloxacin (HSFX) and glycine (HGly) containing nitrogen and oxygen donor ligand have been synthesized and characterized. The prepared complexes fall into stoichiometric formulae of [M(SFX)(Gly)(H₂O)₂]Cl (M = Cr(III) and Fe(III), [M(SFX)(Gly)(H₂O)₂] (M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and UO₂(II) and [Th(SFX)(Gly)(H₂O)₂]Cl₂. The chelate rings are six-membered and six coordinate with 1:1:1 [M]:[SFX]:[Gly]. The important bands in the IR Spectra and main ¹H NMR signals are tentatively assigned and discussed in relation to the predicted molecular structure. The IR data of the HSFX and HGly ligands suggested the existing of a bidentate binding involving carboxylate O and carbonyl O for HSFX ligand and amino N and carboxylate O atoms for HGly ligand. The coordination geometries and electronic structures are determined from the diffused reflectance spectra and magnetic moment measurements. The complexes exist in octahedral form. The complexes decomposed in four to six steps within the temperature range 30–1,000 °C with metal oxides as residues of decomposition. The decomposition steps are accompanied by endothermic or exothermic peaks in the DTA. The HSFX drug, HGly and metal complexes have been screened for their in vitro antibacterial activities against Staphylococcus aureus and Escherichia coli, and antifungal activities against Aspergillus niger and Candida albicans by MIC method. The metal complexes were found to have higher antimicrobial activity than the HSFX drug and HGly ligand and their activity are comparable with the antibacterial and antifungal standards.     

Spectroscopic, cyclic voltammetric and biological studies of transition metal complexes with mixed nitrogen-sulphur (NS) donor macrocyclic ligand derived from thiosemicarbazide

The complexation of new mixed thia-aza-oxa macrocycle viz., 2,12-dithio-5,9,14,18-tetraoxo-7,16-dithia-1,3,4,10,11,13-hexaazacyclooctadecane containing thiosemicarba-zone unit with a series of transition metals Co(II), Ni(II) and Cu(II) has been investigated, by different spectroscopic techniques. The structural features of the ligand have been studied by EI-mass, (1)H NMR and IR spectral techniques. Elemental analyses, magnetic moment susceptibility, molar conductance, IR, electronic, and EPR spectral studies characterized the complexes. Electronic absorption and IR spectra of the complexes indicate octahedral geometry for chloro, nitrato, thiocyanato or acetato complexes. The dimeric and neutral nature of the sulphato complexes are confirmed from magnetic susceptibility and low conductance values. Electronic spectra suggests square-planar geometry for all sulphato complexes. The redox behaviour was studied by cyclic voltammetry, show metal-centered reduction processes for all complexes. The complexes of copper show both oxidation and reduction process. The redox potentials depend on the conformation of central atom in the macrocyclic complexes. Newly synthesized macrocyclic ligand and its transition metal complexes show markedly growth inhibitory activity against pathogenic bacterias and plant pathogenic fungi under study. Most of the complexes have higher activity than that of the metal free ligand.     

Spectroscopic studies of some thiosemicarbazide compounds derived from Girard's T and P

Three new derivatives of thiosemicarbazides, derived from the reactions of ethyl-, allyl- and phenyl isothiocyanates with Girard's T [(carboxymethyl) trimethylammonium chloride hydrazide] and P [1-(carboxymethyl) pyridinium chloride hydrazide], have been isolated and characterized by chemical analyses, conductivities, spectral (IR, 1H NMR) and molecular weight measurements. The most important assignments of the functional groups in the isolated solid organic compounds have been determined using IR spectra. Also, the main functional groups in the skeleton of these compounds have been characterized using 1H NMR spectra. Moreover, a comparative studies between the three thiosemicarbazide derivatives have been carried out. The role of the existence of ethyl-, allyl-, phenyl-, [(CH3)3N+-] and [C5H5N+-] on the position of the functional groups has been investigated. Finally, the absence of any type of hydrogen bonding (inter- and/or intra-) within these compounds is discussed on the basis of the data of melting points, IR and 1H NMR spectra and molecular weight measurements.     

Synthesis,spectral characterization,electrochemical studies of pesticide and biological evaluation of transition metal complexes of azo dye derived from substituted phenyl pyrazole

Diazotization of p-nitro aniline followed by coupling with 3-methyl-1-phenyl pyrazole to procure biologically active azo-dye ligand 3-methyl-4-[(E)-(4-nitrophenyl) diazenyl]-1-phenyl-1H-pyrazol-5-ol (NDP) and also the array of transition metal complexes of aforementioned azo-dye ligand has been carried off along with the use of metal complex to detect pesticides electrochemically. Structural verification of synthesized compounds was carried out via ¹H and ¹³C NMR along with the percentage of C,H,N, molecular weights, Infra-red, UV-Visible spectra and molar conductance of ligand and its complexes was observed. Also TGA, P-XRD and CV measurements were noted. An antimicrobial potency was evaluated by well diffusion method and antioxidant efficacy by DPPH technique. Molecular docking studies was used and MTT tests were conducted on MCF-7 and Hela cell lines to investigate anticancer potency. Upon utilizing physical and spectroscopic techniques to characterize the novel azo-dye ligand and its transition coordinated compounds justified the bi-dentate nature of ligand. Further CV measurements showed that the synthesized Co(II) complex exhibited excellent electrocatalysis properties for the electrochemical sensing of pesticide(Ammonium salt of glyphosate 71% SG) with wider linear range of 0.1 μM–0.8 μM and detection limit 0.033 μM. Mn(II) and Co(II) complex displayed good anti-microbial activity along with cytotoxic potency whereas Co(II) and Cu(II) compounds indicated good anti-oxidant activity. Thus, NDP and its complexes being structurally supported via spectral data and CV studies affirms that Co(II) is strongly useful in detecting pesticide. And lastly it was found that all metal complexes have admirable bioefficacy when compared to ligand.     

Spectroscopic characterization and biological activity of metal complexes with an ONO trifunctionalized hydrazone ligand

A series of Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), La(III), Ru(III), Hf(IV), Zr(IV) and U(VI) complexes of phenylamino acetoacetylacetone hydrazone have been synthesized and characterized by elemental analyses, IR, UV–Vis, magnetic moments, conductances, thermal analyses (DTA and TGA) and ESR measurements. The IR data show that the ligand is neutral bidentate, monobasic bidentate, monobasic tridentate or dibasic tridentate towards the metal ion. Molar conductances in DMF indicate that the complexes are non-electrolytes. The ESR spectra of solid [(L)(HL)Cu₂(NO₃)(H₂O)]·1/2H₂O (10) and [(H₂L)Cu(Cl)₂(H₂O)₂] (11) show axial spectra with g_∥ >?g_⊥ >?2.0023 indicating d_(x²???y²) ground state with significant covalent bond character. However, [(HL)₂Mn₂(Cl)₂(H₂O)₄·H₂O (13) shows an isotropic spectrum, indicating manganese(II) to be octahedral. Antibacterial and antifungal tests of the ligand and some of its metal complexes revealed that the complexes are more potent bactericides and fungicides than the ligand.     

Synthesis and spectroscopic studies of some transition metal complexes of a novel Schiff base ligands derived from 5-phenylazo-salicyladehyde and o-amino benzoic acid

Cu(II), Mn(II), Ni(II), and Zn(II) metal complexes with novel heterocyclic Schiff base derived from 5-phenyl azo-salicyladehyde and o-amino benzoic acid have been synthesized and characterized on the basis of elemental analyses, electronic, IR, and (1)H NMR spectra, and also by aid of scanning electron microscopy (SEM), X-ray powder diffraction, molar ratio measurements, molar conductivity measurements, and thermogravimetric analyses. It has been found that the Schiff base behaves as neutral tridentate (ONO) ligand forming chelates with 1:1 (metal:ligand) stoichiometry.     

Synthesis, spectroscopic characterization and biological activity of the metal complexes of the Schiff base derived from phenylaminoacetohydrazide and dibenzoylmethane

A new series of mono and binuclear Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), La(III), Ru(III), Hf(IV), ZrO(II) and UO(2)(II) complexes of phenylaminodibenzoylhydrazone have been synthesized and characterized by elementals analyses, IR UV-vis spectra, magnetic moments, conductances, thermal analyses (DTA and TGA) and electron spin resonance (ESR) measurements. The IR spectral data show that, the ligand behaves as a neutral bidentate type (15 and 16), monobasic bidentate type (6), or monobasic tridentate type (5, 7, 8, 10, 11, 13, 14, 17-21) or dibasic tridentate type 2-4, 9 and 12 towards the metal ion. Molar conductances in DMF solution indicate that, the complexes are non-electrolytes. The ESR spectra of solid complexes (9 and 10) show axial and non-axial types indicating a [Formula: see text] ground state with significant covalent bond character. However, complexes (11 and 12), show isotropic type, indicating manganese(II) octahedral geometry. Antibacterial and antifungal tests of the ligand and its metal complexes are also carried out and it has been observed that the complexes are more potent bactericides and fungicides than the ligand.     

Synthesis, spectral and biological studies of nitrogen–sulphur donor macrocyclic ligands and their transition metals complexes

Mn(II), Co(II), Ni(II) and Cu(II) complexes have been synthesized with 22 and 24 membered tetramide macrocyclic ligands viz; 1,9,12,20-tetraaza-2,8,13,19-tetraone-5,16-dithiacyclodocosane [L¹] and 1,9,13,21-tetraaza-2,8,14,20-tetraone-5,17-dithiacyclotetracosane [L²] and characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, mass, IR, electronic EPR spectral studies and electrochemical properties. The molar conductance of all the complexes in DMSO solution is corresponding to 1:2 electrolyte. Thus these complexes may be formulated as [M(L′)]Cl₂ [where M = Mn(II), Co(II), Ni(II) and Cu(II) L′ = L¹ and L²]. On the basis of spectral studies a distorted octahedral geometry has been assigned for all the complexes. The ligands and their complexes were also screened in vitro against two pathogenic fungi (F. moniliformae and R. solani) to assess their growth inhibiting potential.     

Spectroscopic characterization of some metal complexes derived from 4-acetylpyridine nicotinoylhydrazone

Coordination compounds of Mn^II, Cu^II, Fe^III and Zn^II ions with 4-acetylpyridine nicotinoylhydrazone (4-APNH) were synthesized and characterized by elemental analyses, molar conductivity, magnetic moments, i.r., u.v./vis., m.s., ¹H-n.m.r. and thermal analyses. I.r. spectra show that the ligand can act either in the enol form as monovalent bidentate or in the keto form as neutral bidentate depending on the metal salt used. Octahedral structures are proposed for Fe complex and square – planar for the Cu complex, while tetrahedral structures were suggested for Zn and Mn complexes on the basis of magnetic and spectral evidences. Semi-empirical calculations ZINDO/1 have been used to study the molecular geometry and the harmonic vibrational spectra with the purpose to assist the experimental assignment of the complexes. In memory of the late Professor Dr. Abdel Hamid M. Shallaby 2/5/2006     

Coordination behaviour in transition metal complexes of asymmetric NPN ligands

Two bicyclic, chiral aminophosphine ligands, namely 4R, 9R-1,3-bis(pyridin-2-ylmethyl)-2-(2-propyl)octahydro-1H-1,3,2-benzodiazaphosphole (1) and 4R, 9R-1,3-bis(pyridin-2-ylmethyl)-2-(2-ethoxy)octahydro-1H-1,3,2-benzodiazaphosphole (2) have been prepared from 1R, 2R-diaminocyclohexane and the appropriate dichlorophosphine and the nature of their coordination to a number of transition metals explored. Ligand 1 coordinates to Pd(II) and Pt(II) as a terdentate donor to give complexes of the type [M(κ³-N,P,N-1)Cl]⁺ whereas ligand 2 favours bidentate κ²-P,N coordination to give the complexes M(κ²-P,N-2)Cl₂. The study of the coordination chemistry of the NPN ligand 1 is frustrated by its ready decomposition to an unknown species which appears to be promoted by transition metals. The ligand 2 does not undergo such a transformation and its metal chemistry is more readily examined. Aside from the Pt(II) and Pd(II) complexes above, 2 has been coordinated to Cr(0) and Mo(0) in the octahedral complexes M(κ²-P,N-2)(CO)₄ and Au(I) in linear Au(κ¹-P-2)Cl. All the complexes have been fully characterised by spectroscopic and analytical techniques including a single-crystal X-ray structure analysis of [Pt(κ³-N,P,N-1)Cl]Cl, 3.     

Polymer complexes. LV. Spectroscopic,thermal studies,and coordination of metal ions N-[3-(5-amino-1,2,4-triazolo)] acrylamide polymer complexes

Novel polymeric complexes with a potentially bidentate ligand formed by amidation of 3,5-diamino-1,2,4-triazole with acryloyl chloride were synthesized and characterized on the basis of elemental analyses, IR, ¹H-NMR, UV-Vis, magnetic susceptibility measurements, molar conductance, and thermal analyses. The molar conductance data reveal that all the polymer complexes are non-electrolytes. Spectral studies reveal that the free ligand coordinates bidentate to the metal ion through the oxygen of the carbonyl and azomethine of the heterocyclic ring. Elemental analyses of the polychelates indicate the metal to ligand ratio of 1?:?1/1?:?2. On the basis of electronic spectral data and magnetic susceptibility measurements, suitable geometry has been proposed for each polymeric complex. The electron spin resonance spectral data of the Cu(II) complex showed that the metal–ligand bonds have considerable covalent character. The thermal behavior of these chelates shows that the polymer complexes lose coordinated water in the first step immediately followed by decomposition of the anions and ligand molecules in a subsequent step.     

Redox, thermodynamic and spectroscopic of some transition metal complexes containing heterocyclic Schiff base ligands

Complexes of two series of Schiff base ligands, H₂L_a and H₂L_bderived from the reaction of 2,6-diacetyl pyridine with semicarbazide, H₂L_a and thiosemicarbazide, H₂L_b, with the metal ions, Co(II), Ni(II), Cu(II), VO(IV) and UO₂(VI) have been prepared. The ligands are characterized by elemental analysis, IR, UV–vis and ¹H NMR. The structures of the complexes are investigated with the IR, UV–vis, X-band ESR spectra, ¹H NMR and thermal gravimetric analysis as well as conductivity and magnetic moment measurements. The IR-spectra reveal the presence of variable modes of chelation for the investigated ligands. A variety of binuclear or mononuclear complexes were obtained with the two ligands in tri-, tetra or pentadentate forms. The bonding sites are the pyridine nitrogen, two azomethine nitrogen atoms and ketonic oxygen in case of H₂L_a or sulphur atoms in case of H₂L_b. The Coats–Redfern equation has been used to calculate the kinetic and thermodynamic parameters for the different thermal decomposition steps of some complexes. Cyclic voltammograms of Co(II) and Ni(II) show quasi-reversible peaks. The redox properties and the nature of the electro-active species of the complexes have been characterized.     

Spectroscopic, and thermal studies of some new binuclear transition metal(II) complexes with hydrazone ligands containing acetoacetanilide and isoxazole

A new chelating ligand, 2-(2-(5-tert-butylisoxazol-3-yl)hydrazono)-N-(2,4-dimethylphenyl)-3-oxobutanamide (HL), and its four binuclear transition metal complexes, M(2)(L)(2) (micro-OCH(3))(2) [M=Ni(II), Co(II), Cu(II), Zn(II)], were synthesized using the procedure of diazotization, coupling and metallization. Their structures were postulated based on elemental analysis, (1)H NMR, MALDI-MS, FT-IR spectra and UV-vis electronic absorption spectra. Smooth films of these complexes on K9 glass substrates were prepared using the spin-coating method and their absorption properties were evaluated. The thermal properties of the metal(II) complexes were investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC). Different thermodynamic and kinetic parameters namely activation energy (E*), enthalpy of activation (DeltaH*), entropy of activation (DeltaS*) and free energy change of activation (DeltaG*) are calculated using Coats-Redfern (CR) equation.     

Spectroscopic studies of bimetallic complexes derived from tridentate or tetradentate Schiff bases of some di- and tri-valent transition metals

Two series of new binuclear complexes with Schiff base ligands, H(4)L(a) or H(2)L(b), derived from the reaction of 4,6-diacetylresorcinol and ethylenediamine, in the molar ratio 1:1 and 1:2 have been prepared, respectively. The two ligands react with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Cr(III) and Fe(III)-nitrates to get binuclear complexes. The ligands were characterized by elemental analysis, IR, UV-vis, (1)H NMR and mass spectra. The complexes were synthesized by direct and template methods. Different types of products were obtained for the same ligand and metal salts according to the method of preparation. The H(4)L(a) ligand behaves as a macrocyclic tetrabasic with two N(2)O(2) sits, while the H(2)L(b) ligand behaves as a dibasic with two N(2)O sites. The H(4)L(a) ligand is a compartmental ligand which hosts the two metal ions at the centers of two cis-N(2)O(2) sites, while the metal complexes of H(2)L(b) ligand are binuclear, where the ligand hosts two metal ions at the centers of two N(2)O sites. In both cases, deprotonation of the hydrogen atoms of the phenolic OH groups occur except in the case of the Ni(II), Fe(III) and Cr(III) complexes. Electronic spectra and magnetic moments of the complexes indicate that the geometries of the metal centers are either octahedral or tetrahedral. The structures are consistent with the IR, UV-vis, ESR, (1)H NMR, mass spectra, and thermal gravimetric analysis (TGA/DTA) as well as conductivity and magnetic moment measurements.     

Molecular orbital studies of some transition metal complexes

A set of molecular orbital calculations based on a particular semi-empirical method, has been undertaken on a homologue series of bis(-2-methylallyl)transition metal (Ni, Co, Fe, Cr) complexes (abbreviated as ML₂). Arguments are found for predicting the stability of the NiL₂ system, which is the only one that could be synthetized.

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Zusammenfassung Eine Reihe von semiempirischen MO-Rechnungen wurde für die homologe Reihe von bis(-2-methylallyl) Metallkomplexen (Ni, Co, Fe, Cr) durchgeführt. Gründe für die Stabilität der Ni-Verbindung, die als einzige synthetisiert wurde, werden angeführt.

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Résumé Un ensemble de calculs par une méthode semi-empirique particulière d'orbitales moléculaires a été effectué sur une série homologue de complexes bis (-2-méthylallyl)-métal de transition (Ni, Co, Fe, Cr): ML₂.Certains arguments sont trouvés en faveur de la stabilité du système NiL₂, le seul à avoir été synthétisé.

     

Spectroscopic and antimicrobial studies of macrocyclic metal complexes derived from 1,8-diaminonaphthalene and dimedone

A new series of macrocyclic metal complexes have been synthesized and characterized by the template condensation reaction of 1,8-diaminonaphthalene and dimedone in presence of divalent transition metals, resulting into the formation of the macrocyclic complexes of the type: [M(C₃₆H₃₆N₄)X₂]; where M = Co(II), Ni(II), Cu(II), Zn(II) and X = Cl^?, NO₃ ^?, CH₃COO^?. The synthesized macrocyclic complexes have been characterized with the aid of elemental analysis, conductance measurements, magnetic susceptibility measurements, electronic, infrared, NMR, Mass and ESR spectral studies. The complexes were also investigated for their fluorescence activity. Electronic spectra along with magnetic moments suggest the six coordinated octahedral geometry for all these complexes. The low value of molar conductance indicates them to be non-electrolyte. The in vitro antimicrobial activities of these macrocyclic complexes have also been investigated against some bacterial strains and yeast. Further minimum inhibitory concentration shown by these complexes against these pathogens was compared with MIC shown by standard antibiotic and standard antifungal drug.     

Coordination polymers of glutaraldehyde with glycine metal complexes: synthesis,spectral characterization,and their biological evaluation

Glycine metal complexes were prepared by the reaction of glycine with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) in 1?:?2 molar ratio. Thereafter their condensation polymerization was done with glutaraldehyde to obtain polymer metal complexes. All the synthesized polymer metal complexes were characterized by elemental analysis, FT-IR, ¹H-NMR, and UV-Vis spectrometry, magnetic susceptibility, and thermogravimetric studies. The analytical data of all the polymers agreed with 1?:?1 molar ratio of metal complex to glutaraldehyde and magnetic moment data suggest that PGG–Mn(II), PGG–Co(II), PGG–Ni(II), and PGG–Cu(II) have an octahedral geometry around the metal atom, whereas the tetrahedral geometry was proposed for PGG–Zn(II) polymer. The PGG–Mn(II) and PGG–Cu(II) showed octahedral geometry. Thermal behavior of the polymer metal complexes was obtained at a heating rate of 10°C?min^?1 under nitrogen atmosphere from 0°C to 800°C. The antimicrobial activities of synthesized polymers were investigated against Streptococcus aureus, Escherichia coli, Bacillus sphaericus, Salmonella sp. (Bacteria), Fusarium oryzae, Candida albicans, and Aspergillus niger (Yeast).     

Spectroscopic, redox and biological activities of transition metal complexes with ons donor macrocyclic ligand derived from semicarbazide and thiodiglycolic acid

A novel macrocyclic Schiff base ligand (2,5,9,12,14,18-hexaoxo-7,16-dithia-1,3,4,10,11,13-hexaazacycloocta-decane (H6L) with N4S2 coordinating sites was prepared by the reaction of the semicarbazide and thiodiglycolic acid. The transition metal complexes with macrocyclic ligand were synthesized and characterized by elemental analyses, magnetic susceptibility measurements, molar conductance, IR, electronic, and EPR spectral studies. Mass, 1H NMR and IR spectral techniques suggest the structural features of macrocyclic ligand. Magnetic and electronic spectral studies suggest an octahedral geometry of complexes. Electrochemical behaviour of cobalt, nickel and copper complexes were determined by cyclic voltammetry. The cyclic voltammogram of the copper complex at room temperature shows a quasi-reversible peaks for Cu(III)-->Cu(II) and Cu(II)-->Cu(I) couples. The macrocyclic ligand and its complexes show growth inhibitory activity against pathogenic bacteria and plant pathogenic fungi A. niger, A. alternata and P. variotii. Most of the complexes have higher activities than that of free ligand.     

Synthesis of some novel divalent transition metal complexes as antimicrobials

A novel series of transition metal complexes have been synthesized from the reaction of 5-((3-(methylthio)-5-(pyridin-4-yl)-4H- 1,2,4-triazol-4-ylamino)melhyl)quinolm-8-ol with transition metal salts.The structures of these compounds have been elucidated by elemental and spectral analysis.Furthermore,compounds were screened for in vitro antimicrobial activity against the representative panel of two Gram-positive and two Gram-negative bacteria and two strains of fungus.The various compounds show potent inhibitory action against test organisms.