Horowitz Metzeger Research Articles

Characterization and biological activity of Pefloxacin–imidazole mixed ligands complexes

Solid complexes [M(PEF)(HIm)Clx(H2O)m]_nH2O, [M=Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cr(III)] and [Ag(PEF)(HIm)]·2H2O; PEF=Pefloxacin, HIm=imidazole were prepared and characterized using elemental analyses, IR spectroscopy, conductance measurements, UV–Vis spectra, ESR of the copper complex, magnetic moments measurements and 1H NMR spectra. The results have shown that Pefloxacin reacts as a bidentate ligand and is bound to the metal ions through the pyridone oxygen and one carboxylic oxygen, except for the silver(I) complex where the metal ion is chelated to the piperazinyl nitrogen. Thermal studies including TGA and DTA were also performed on the complexes in order to study their stabilities and activation energies, ΔE∗, entropies ΔS∗; enthalpies ΔH∗ and order of reactions n have been derived using Horowitz–Metzeger method calculations. The mixed ligands complexes were evaluated for their antibacterial activity against two bacterial species, namely Staphylococcus aureus (S. aureus), Escherichia coli (E. coli). Antifungal screening was studied against two species (Aspergillus flavus and Candida albicans). The complexes under investigation were found to possess better antibacterial effects than uncomplexed Pefloxacin as well as antifungal activity.

Synthesis, Spectral, Characterization, DFT and Biological Studies of New 3-[(3-Chlorophenyl)-hydrazono]-pentane-2,4-dione Metal Complexes

A new series of metal complexes of V(IV), Pd(II), Pt(IV), Ce(IV) and U(VI) with 3-[(3-chlorophenyl)-hydrazono]-pentane-2,4-dione (Cphpd) were synthesized and characterized by elemental analysis, molar conductivity, magnetic moment measurements, UV-vis, FT-IR and <TEX>$^1H$</TEX> NMR as well as TG-DTG techniques. The data indicated that the Cphpd acts as a bidentate ligand through the hydrazono nitrogen and one keto oxygen. The kinetic parameters have been evaluated by using Coats Redfern (CR) and Horowitz-Metzeger (HM) methods. The thermodynamic data reflected the thermal stability for all complexes. The calculated bond length and the bond stretching force constant, F(U=O), values for <TEX>$UO_2$</TEX> bond are <TEX>$0.775{\AA}$</TEX> and <TEX>$286.95Nm^{-1}$</TEX>. The bond lengths, bond angles, dipole moment and the lowest energy model structure of the complexes have been determined with DFT calculations. The antimicrobial activity of the synthesized ligand and its complexes were screened.

Interaction of vanadium (IV) solvates (L) with second-generation fluoroquinolone antibacterial drug ciprofloxacin: Spectroscopic, structure, thermal analyses, kinetics and biological evaluation (L = An, DMF, Py and Et3N)

The preparation and characterization of the new solid complexes [VO(CIP)2L]SO4⋅nH2O, where L=aniline (An), dimethylformamide (DMF), pyridine (Py) and triethylamine (Et3N) in the reaction of ciprofloxacin (CIP) with VO(SO4)2·2H2O in ethanol. The isolated complexes have been characterized with their melting points, elemental analysis, IR spectroscopy, magnetic properties, conductance measurements, UV–Vis. and 1H NMR spectroscopic methods and thermal analyses. The results supported the formation of the complexes and indicated that ciprofloxacin reacts as a bidentate ligand bound to the vanadium ion through the pyridone oxygen and one carboxylato oxygen. The activation energies, E*; entropies, ΔS*; enthalpies, ΔH*; Gibbs free energies, ΔG*, of the thermal decomposition reactions have been derived from thermo gravimetric (TGA) and differential thermo gravimetric (DTG) curves, using Coats–Redfern and Horowitz–Metzeger methods. The lowest energy model structure of each complex has been proposed by using the density functional theory (DFT) at the B3LYP/CEP-31G level of theory. The ligand and their metal complexes were also evaluated for their antibacterial activity against several bacterial species, such as Bacillus Subtilis (B. Subtilis), Staphylococcus aureus (S. aureus), Nesseria Gonorrhoeae (N. Gonorrhoeae), Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli).

Synthesis, Characterization, DFT Modeling and Antimicrobial Studies on the Ti(IV), Y(III) and Ce(IV) Ofloxacin Solid Complexes

A new solid complexes of Ti(IV), Y(III) and Ce(IV) have been synthesized with ofloxacin. The formulae and structure of the complexes have been proposed in the light of analytical, spectral ( 1 H NMR, IR and UV-Visible), magnetic, molar conductivities and thermal studies. The complexes are soluble in DMSO-d6 and DMF. The measured molar conduc- tance values indicate that, the three complexes are electrolyte in nature. The results support the formation of the complexes and indicated that ofloxacin reacts as a bidentate ligand chelate to the metal ion through the pyridone oxygen and one carboxylato oxygen. The kinetic parameters of thermogravimetric and its differential have been evaluated by using Coats Redfern (CR) and Horowitz-Metzeger (HM) methods. The thermodynamic data reflect the thermal stability for all complexes. The metal- ligand binding of the Ti(IV), Y(III) and Ce(IV) complexes is predicted using density funcational theory at the B3LYP-CEP-31G level of theory and total energy, dipole moment estimation of different Ti(IV), Y(III) and Ce(IV) ofloxacin structures. The biologi- cal activities of the ofloxacin, inorganic salts and their metal complexes were assayed against different bacterial species.

Metal complexes of moxifloxacin–imidazole mixed ligands: Characterization and biological studies

Solid complexes [M(MOX)(HIm)Clx]·nH2O, [M=Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cr(III)] and [Ag(MOX)(HIm)·2.5H2O]; MOX=moxifloxacin, HIm=imidazole were prepared and characterized using elemental analyses, IR spectroscopy, conductance measurements, UV–Vis spectra, ESR of the copper complex, magnetic moments measurements, 1H and 13C NMR for the nickel (II) complex and thermal analyses. The results indicate that moxifloxacin reacts as a bidentate ligand and is bound to the metal ions through the pyridone oxygen and one carboxylic oxygen, except for the silver (I) complex where the metal ion is chelated to the hydro pyridinium nitrogen. The activation energies, ΔE∗; entropies ΔS∗; enthalpies ΔH∗ and order of reactions have been derived from differential thermogravimetric (DTA) curves, using Horowitz–Metzeger method. The mixed ligands complexes were evaluated for their antibacterial activity against two bacterial species, namely Staphylococcus aureus (S. aureus), Escherichia coli (E. coli). Antifungal screening was studied against two species (Aspergillus flavus and Condida albicans). The complexes under investigation were found to possess better antibacterial agents than uncomplexed Moxifloxacin and have antifungal activity as well.

Metal Complexes of Enrofloxacin Part I: Preparation, Spectroscopic, Thermal Analyses Studies and Antimicrobial Evaluation

The interaction of titanium (IV), yttrium (III), zirconium (IV), palladium (II) and cerium (IV) with deproto- nated enrofloxacin leads to the formation of the neutral or cationic mononuclear complexes. The isolated solid complexes have been characterized with physicochemical and spectroscopic techniques and thermogravimeteric analyses. The spectro- scopic data indicate that the enrofloxacin ligand is on the deprotonated mode acting as bidentate ligand coordinated to the metal ions through the ketone oxygen and a carboxylato oxygen and the metal ions completed the coordination number with water molecules. The thermal decomposition mechanisms proposed for enrofloxacin and their metal complexes were discussed. The activation energies, E * , enthalpies, ∆H * , entropies, ∆S * and Gibbs free energies, ∆G * , of the thermal decomposition reactions have been derived from thermogravimetric (TG) and differential thermogravimetric (DTG) curves, using Coats-Redfern (CR) and Horowitz-Metzeger (HM) methods. The antimicrobial activity has been evaluated against six different microorganisms.

Spectroscopic studies, thermal analyses and biological evaluation of new V(IV), Zr(IV) and U(VI) moxifloxacin complexes

The synthesis and characterization of the new solid complexes [VO(MOX)2H2O]SO4·11H2O, [ZrO(MOX)2Cl]Cl·15H2O and [UO2(MOX)3](NO3)2·3H2O formed in the interaction of moxifloxacin (MOX) with VOSO4·H2O, ZrOCl2·8H2O and UO2(NO3)2·6H2O in methanol and acetone as a solvents at room temperature were reported. The isolated solid complexes have been characterized with melting points, elemental analysis, molar conductance, magnetic moments studies, spectral (UV–Visible, IR and 1HNMR) as well as thermal analyses (TGA and DTG). The results support the formation of the complexes and indicate that moxifloxacin reacts as a bidentate ligand chelate to the metal ion through the pyridone oxygen and one carboxylato oxygen. The kinetic parameters of thermogravimetric (TGA) and its differential (DTG), such as activation energies, E*, enthalpies, ΔH*, entropies, ΔS* and Gibbs free energies, ΔG*, have been evaluated by using Coats–Redfern (CR) and Horowitz–Metzeger (HM) methods. The proposed structure of the ligand and their complexes were detected by using the density functional theory (DFT) at the B3LYP/CEP-31G level of theory. The bond stretching force constant and length of the UO for the [UO2(MOX)3](NO3)2·3H2O complex were calculated. The antibacterial activity of the free moxifloxacin ligand and their metal complexes have been tested against some selected bacterial strains such as: Streptococcus aureus K1, Bacillus subtilis K22, Brevibacterium otitidis K76, Escherichia coli K32, Pseudomonas aeruginosa SW1 and Klebsiella oxytoca K42. The complexes showed good antibacterial effect to the selected bacterial strains as compared to the free ligand and Zr(IV) complex is very highly significant compared with the other two complexes.

Spectroscopic, structure and antimicrobial activity of new Y(III) and Zr(IV) ciprofloxacin

The preparation and characterization of the new solid complexes [Y(CIP) 2(H 2O) 2]Cl 3·10H 2O and [ZrO(CIP) 2Cl]Cl·15H 2O formed in the reaction of ciprofloxacin (CIP) with YCl 3 and ZrOCl 2·8H 2O in ethanol and methanol, respectively, at room temperature were reported. The isolated complexes have been characterized with elemental analysis, IR spectroscopy, conductance measurements, UV–vis and 1H NMR spectroscopic methods and thermal analyses. The results support the formation of the complexes and indicate that ciprofloxacin reacts as a bidentate ligand bound to the metal ion through the pyridone oxygen and one carboxylato oxygen. The activation energies, E*; entropies, Δ S*; enthalpies, Δ H*; Gibbs free energies, Δ G*, of the thermal decomposition reactions have been derived from thermogravimetric (TGA) and differential thermogravimetric (DTG) curves, using Coats–Redfern and Horowitz–Metzeger methods. The proposed structure of the two complexes was detected by using the density functional theory (DFT) at the B3LYP/CEP-31G level of theory. The ligand as well as their metal complexes was also evaluated for their antibacterial activity against several bacterial species, such as Staphylococcus aureus ( S. aureus), Escherichia coli ( E. coli) and Pseudomonas aeruginosa ( P. aeruginosa) and antifungal screening was studied against two species ( Penicillium ( P. rotatum) and Trichoderma ( T. sp.)). This study showed that the metal complexes are more antibacterial as compared to free ligand and no antifungal activity observed for ligand and their complexes.

Metal complexes of the fourth generation quinolone antimicrobial drug gatifloxacin: Synthesis, structure and biological evaluation

Three metal complexes of the fourth generation quinolone antimicrobial agent gatifloxacin (GFLX) with Y(ΙΙΙ), Zr(ΙV) and U(VΙ) have been prepared and characterized with physicochemical and spectroscopic techniques. In these complexes, gatifloxacin acts as a bidentate deprotonated ligand bound to the metal through the ketone oxygen and a carboxylato oxygen. The complexes are six-coordinated with distorted octahedral geometry. The kinetic parameters for gatifloxacin and the three prepared complexes have been evaluated from TGA curves by using Coats–Redfern (CR) and Horowitz–Metzeger (HM) methods. The calculated bond length and force constant, F(U O), for the UO 2 bond in uranyl complex are 1.7522 Å and 639.46 N m −1. The antimicrobial activity of the complexes has been tested against microorganisms, three bacterial species, such as Staphylococcus aureus ( S. aureus), Escherichia coli ( E. coli) and Pseudomonas aeruginosa ( P. aeruginosa) and two fungi species, penicillium ( P. rotatum) and trichoderma ( T. sp.), showing that they exhibit higher activity than free ligand.