Walaa H. El-Shwiniy

Metal complexes of the third generation quinolone antibacterial drug sparfloxacin: preparation, structure, and microbial evaluation

The interactions of yttrium chloride, zirconium chloride, and uranium nitrate with sparfloxacin (SPAR) in ethanol, methanol, and acetone were studied. The isolated solid complexes were characterized by elemental analysis, infrared, 1H-NMR and electronic spectra, and thermogravimetric analysis. The results support the formation of [Y(SPAR)2Cl2]Cl ⋅ 12H2O, [ZrO(SPAR)2Cl]Cl ⋅ 15H2O, and [UO2(SPAR)3](NO3)2 ⋅ 5H2O. Infrared spectra of the isolated solid complexes indicate that SPAR is bidentate through the ring carbonyl oxygen and one oxygen of carboxylate. The calculated bond length and force constant, F(U=O), in the uranyl complex are 1.747 Å and 655.29 Nm−1, respectively. The antimicrobial activities of the ligand and metal complexes have been tested against bacteria Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) and fungi Penicillium rotatum (P. rotatum) and Trichoderma sp., showing that the complexes exhibit higher antibacterial activity than SPAR.

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(H2O)2]Cl(3)·10H2O and [ZrO(CIP)2Cl]Cl·15H2O formed in the reaction of ciprofloxacin (CIP) with YCl3 and ZrOCl(2)·8H2O 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, ΔS*; enthalpies, ΔH*; Gibbs free energies, ΔG*, 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.

Synthesis, characterization and antimicrobial investigation of some moxifloxacin metal complexes

The new complexes of moxifloxacin (MOX), with Ti(IV), Y(III), Pd(II) and Ce(IV) have been synthesized. These complexes were then characterized by melting point, magnetic studies and spectroscopic techniques involving infrared spectra (IR), UV-Vis, (1)H NMR. C, H, N and halogen elemental analysis and thermal behavior of complexes also investigated. The results suggested that the molar ratio for all complexes is M: MOX=1:2 where moxifloxacin acts as a bidentate via one of the oxygen atoms of the carboxylate group and through the ring carbonyl group and the complexes have the following formula [Ti(MOX)(2)](SO(4))(2)·7H(2)O, [Y(MOX)(2)Cl(2)]Cl·12H(2)O, [Pd(MOX)(2)(H(2)O)(2)]Cl(2)·6H(2)O and [Ce(MOX)(2)](SO(4))(2)·2H(2)O. The activation energies, E*, enthalpies, ΔH*, entropies, ΔS* and Gibbs free energies, ΔG*, of the thermal decomposition reactions have been derived from thermogravimetric (TGA) and differential thermogravimetric (DrTG) curves, using Coats-Redfern (CR) and Horowitz-Metzger (HM) methods. The antimicrobial activity of these complexes has been evaluated against three Gram-positive and three Gram-negative bacteria and compared with the reference drug moxifloxacin. The antibacterial activity of Ti(IV) complex is significant for E. coli K32 and highly significant for S. aureus K1, B. subtilis K22, Br. otitidis K76, P. aeruginosa SW1 and K. oxytoca K42 compared with free moxifloxacin.

Spectroscopic, thermal analysis, and antimicrobial evaluation of new Y(III), Zr(IV), and U(VI) ibuprofen complexes

New complexes of Y(III), Zr(IV), and U(VI) with the anti-inflammatory drug ibuprofen (IBU) have been synthesized and characterized by elemental analysis, spectroscopic techniques (UV-Visible, IR, and 1H NMR), magnetic moment determination, conductance measurements, and thermal analyses (thermogravimetric and differential thermogravimetric). The anti-inflammatory drug acts as bidentate chelate bound to metal ions through the deprotonated carboxylate. The calculated bond length and force constant, F(U=O), in the uranyl complex are 1.815 Å and 671.69 Nm−1, respectively. The metal–ligand binding of the Zr(IV) and Y(III) complexes is predicted using density functional theory at the B3LYP-CEP-31G level of theory and total energy, dipole moment estimation of different Zr(IV) and Y(III) ibuprofen structures. The antibacterial activity of the ligand, metal salts, and metal complexes have been tested, showing that the complexes are significant against all six bacterial species compared with IBU and metal salts.

Synthesis and characterization of new 2-cyano-2-(p-tolyl-hydrazono)-thioacetamide metal complexes and a study on their antimicrobial activities.

2-Cyano-2-(p-tolyl-hydrazono)-thioacetamide (Cthta) reacted with V(IV), Zr(IV), Pd(II), Pt(IV), Ce(IV) and U(VI) in acetone as a solvent at room temperature to form a solid complexes with characteristic color for metal ion. The molar ratio for all synthesized complexes is M:Cthta=1:2 which was established from the results of chemical analysis. The isolated complexes have been characterized with their melting points, elemental analysis, magnetic properties, conductance measurements, mass, IR, UV-Vis. and (1)H NMR spectroscopic methods and thermal analyses. The results supported the formation of the complexes and indicated that the Cthta reacts as a bidentate ligand. The thermogravimetric and infrared spectroscopic data confirmed the presence of water in the composition of the complexes. The molar conductance values of all complexes in (DMSO) were found in the range 150.71-328.85S cm(2) mol(-1) at room temperature. The magnetic moments of the complexes were measured at room temperature. The kinetic parameters of thermogravimetric and its differential have been evaluated by using Coats Redfern (CR) and Horowitz-Metzeger (HM) methods. The ligand as well as their metal complexes were also evaluated for their antibacterial and antifungal activities.

Nanoparticles of manganese oxides as efficient catalyst for the synthesis of pyrano[2,3-d]pyrimidine derivatives and their complexes as potent protease inhibitors

Novel pyrano[2,3-d] pyrimidine derivatives were synthesized via the three-component reaction of thiophene-2-carbaldehyde, malononitrile and barbituric or thiobarbituric acid in the presence of Mn2O3 nanoparticles. This method has been found to be eco-friendly and economical. Compound 1 was used as a precursor for the synthesis of new pyranopyrimidine derivatives 2–5. Moreover, 7-amino-2,3,4,5-tetrahydro-4-oxo-5-(thiophen-2-yl)-2-thioxo-1H-pyrano[2,3-d]pyrimidine-6-carboxamide 4 was then converted into another set of novel compounds 6–8. On the other hand, a series of Mn(II) complexes with pyrano[2,3-d]pyrimidine derivatives have been prepared. The synthesized compounds and its complexes were characterized by elemental analysis, magnetic and spectroscopic methods (IR, XRD, SEM, TEM, 13C, 1HNMR) as well as thermal analysis. The spectrophotometric determinations suggest a distorted octahedral geometry for all complexes. The organic compounds and its chelates as inhibitors exhibited remarkable effects on the enzyme activity of an extracellular toxic protease, KB76 from Brevibacterium otitidis as well as against different bacterial and fungal strains.Graphical abstract

Design and synthesis of new thiobarbituric acid metal complexes as potent protease inhibitors: spectral characterization, thermal analysis and DFT calculations

Five novel metal complexes of thiobarbituric acid (TBAH) have been prepared with the general formulae: [Ti(TBA)2(H2O)2]Cl2·2H2O, [Pd(TBA)2]·4H2O, Na[Ag(TBA)2(H2O)2]·4H2O, [Hg(TBA)2(H2O)2] and [Ce(TBA)2(H2O)3]SO4·H2O. The complexes have been fully characterized employing physicochemical and diverse spectroscopic techniques (IR, UV–Vis, mass and 1H NMR) as well as thermal analysis. Elemental analyses and spectroscopic data have showed that the stoichiometries of all complexes were 1:2. Thermal analysis measurements indicated that the complexes have good thermal stability. Density functional theory calculations were carried out at the B3LYP levels of theory with a double basis set, LANL2DZ basis set for titanium, palladium, cerium atoms, or LANL2MB basis set for silver, mercury atoms and 6-31+G(d,p) basis set for the other atoms. The optimized geometry of the ligand and its complexes was obtained based on the optimized structures. The ligand and its metal complexes act as protease inhibitors and repressed their enzymatic activity significantly.

Synthesis, spectral, DFT modeling, cytotoxicity and microbial studies of novel Zr(IV), Ce(IV) and U(VI) piroxicam complexes

The Zr(IV), Ce(IV) and U(VI) piroxicam anti-inflammatory drug complexes were prepared and characterized using elemental analyses, conductance, IR, UV-Vis, magnetic moment, IHNMR and thermal analysis. The ratio of metal: Pir is found to be 1:2 in all complexes estimated by using molar ratio method. The conductance data reveal that Zr(IV) and U(VI) chelates are non-electrolytes except Ce(IV) complex is electrolyte. Infrared spectroscopic confirm that the Pir behaves as a bidentate ligand co-ordinated to the metal ions via the oxygen and nitrogen atoms of ν(CO)carbonyl and ν(CN)pyridyl, respectively. The kinetic parameters of thermogravimetric and its differential, such as activation energy, entropy of activation, enthalpy of activation, and Gibbs free energy evaluated using Coats-Redfern and Horowitz-Metzger equations for Pir and complexes. The geometry of the piroxicam drug in the Free State differs significantly from that in the metal complex. In the time of metal ion-drug bond formation the drug switches-on from the closed structure (equilibrium geometry) to the open one. The antimicrobial tests were assessed towards some types of bacteria and fungi. The in vitro cell cytotoxicity of the complexes in comparison with Pir against colon carcinoma (HCT-116) cell line was measured.

Synthesis of Pd(II), Ag(I), Pt(IV), and Hg(II) Complexes with Nifuroxazide, Their Structure, DFT Modeling, and Antimicrobial and Anticancer Activity

New mononuclear complexes of Pd(II), Ag(I), Pt(IV), and Hg(II) with nifuroxazide were synthesized by the reaction of the metals salts with the drug. The complexes were characterized by elemental and thermal analysis and FT-IR, 1H NMR, and UV–Vis spectra. Stoichiometry of the complexes was determined to be 1: 2. Nifuroxazide (Nif.) drug is coordinated to the metal ions as a bidentate ligand via oxygen and nitrogen atoms of the C=O and hydrazone groups. Density functional theory (DFT) calculations were carried out at the B3LYP levels with LANL2DZ basis set for Ag(I) and Hg(II) ions, LANL2MB basis set for Pd(II) and Pt(IV) ions, and 6-31G(d,p) basis set for the other atoms. The complexes had high thermal stability. Tests for anticancer activity, breast cancer cell line (MCF7), demonstrated that Hg(II), Pt(IV), and Pd(II) metal complexes had higher activity than the free ligand.