Studies on the synthesis, spectra, catalytic and antibacterial activities of binuclear ruthenium(II) complexes

Association thermodynamic parameters for nano Cu(NO3)2·2.5H2O with ligands at different temperatures

Association thermodynamic parameters are important because they give information about the nature of ion-ion interaction in solution, the dielectric constant of the medium and the intermolecular hydrogen bonding between the solvent molecules. The different association thermodynamic parameters for nano copper(ii) nitrate hemi pentahydrate in the presence of 4,6-diacetylresorcinol and 4,6-bis(1-hydrazonoethyl)benzene-1,3-diol as ligands were calculated. Conductance measurements were used in different concentrations of binary mixed solvents (DMF and water) at different temperatures, 293.15, 303.15, 313.15 and 323.15 K. A comparison between association thermodynamic parameter data such as association constants (K _A), degree of dissociation (α), free energies of association (ΔG _A), enthalpies of association (ΔH _A) and entropies of association (ΔS _A) in the case of using the two ligands was done. Different calculated thermodynamic parameters indicate that the association is more favorable with 4,6-diacetylresorcinol as a ligand than 4,6-bis(1-hydrazonoethyl)benzene-1,3-diol due to the large size of 6-bis(1-hydrazonoethyl)benzene-1,3-diol.

Development of ruthenium(II) complexes as topical antibiotics against methicillin resistant Staphylococcus aureus

A series of ruthenium(II) bis(2,2'-bipyridyl) complexes containing N-phenyl-substituted diazafluorenes (Ru-C1, Ru-C6, Ru-C7 and Ru-F) was synthesized and their potential antibacterial activity against methicillin resistant Staphylococcus aureus (MRSA) was investigated. The Ru-C7 complex showed significant improvement in both minimum inhibitory concentration (MIC, 6.25 μg mL(-1)) and minimum bactericidal concentration (MBC, 25 μg mL(-1)) towards MRSA when compared with those of methicillin (positive control) (MIC = 25 μg mL(-1) and MBC = 100 μg mL(-1)). The Ru-C7 complex possessed much stronger antibacterial effects than the Ru-C6 complex (MIC, 25 μg mL(-1), MBC, >100 μg mL(-1)). Both Ru-C6 and Ru-C7 complexes were also demonstrated to be biologically safe when tested on normal human skin keratinocytes.

Synthesis, spectroscopic studies, molecular modeling and antimicrobial activity of binuclear Co(II) and Cu(II) complexes of 4,6-diacetylresorcinol

Reactions of 4,6-diacetylresorcinol with different cobalt(II) and copper(II) salts viz., OAc(-), Cl(-), NO3(-) and SO4(2-), yielded a new series of binuclear metal complexes. Reactions of the ligand with these metal ions in the presence of a secondary ligand (L') [O,O-donor; acetylacetone, N,O-donor; 8-hydroxyquinoline or N,N-donor; 1,10-phenanthroline and N,N,N',N'-tetramethylethylenediamine] in 1:2:2 (L:M:L') molar ratio yielded mixed-ligand complexes with different molar ratios. The metal complexes were characterized by elemental and thermal analyses, IR, electronic, ESR and mass spectra as well as conductivity and magnetic susceptibility measurements. The analytical and spectroscopic data suggested that the H2L ligand behaves as a neutral, monobasic or dibasic tetradentate ligand, depending on the type of the anion and secondary ligand used, through the two phenolic and two carbonyl groups. Electronic spectra, magnetic and conductivity measurements showed that all complexes are octahedral with non-electrolytic nature. The profile of ESR spectra of copper(II) complexes suggested the octahedral geometry and the spin Hamiltonian parameters of the complexes were calculated and discussed. Molecular orbital calculations were performed for metal complexes using Hyperchem 7.52 program on the bases of PM3 level and the results correlated with the experimental data. The free ligand and some of its metal complexes showed antimicrobial activity towards some of Gram-positive and Gram-negative bacteria, yeast (Candida albicans) and fungus (Aspergillus fumigatus).