Fernando R.G. Bergamini

Synthesis, spectroscopic characterization, DFT studies, and initial antibacterial assays in vitro of a new palladium(II) complex with tryptophan

A new palladium(II) complex with the amino acid L-tryptophan (Pd-TRP) was synthesized in aqueous solution and characterized by chemical and spectroscopic methods. Elemental, ESI-QTOF mass spectrometric, and thermal analyses of the solid compound permitted proposing the [Pd(C11H11N2O2)2] · 2H2O composition. Infrared, Raman, and UV-Vis spectroscopic data indicate the coordination of the ligand to Pd(II) through monodentate oxygen of carboxylate and through nitrogen of the amino group. The 1H and 13C NMR spectroscopic data confirm coordination through the carboxylate, while 15N NMR data confirm coordination of nitrogen of NH2. Density functional theory studies confirmed nitrogen and oxygen coordination to palladium(II) as a minimum of the potential energy surface with calculations of the hessians showing no imaginary frequencies. Biological studies were performed to provide information concerning the antibacterial activities of the compound. The Pd-TRP complex was shown to be active against Gram-positive and Gram-negative pathogenic bacterial strains.

Synthesis, spectroscopic studies, and preliminary antibacterial assays of a palladium(II) complex with 2-mercaptothiazoline

In this article, synthesis of a palladium(II) complex with 2-mercaptothiazoline in aqueous solution is presented. Composition of the complex was defined as 1 : 2 (metal : ligand). Infrared and solid-state nuclear magnetic resonance indicate ligand coordination to Pd(II) through nitrogen of thiazole ring and sulfur of thiol. ESI–QTOF–mass spectrometric analysis shows primarily the dimeric form in solution. An antibiogram assay of the complex was performed by the disc diffusion method. The compound did not show antibacterial activity against the considered bacterial cells in the tested concentrations.

A binuclear silver complex with l -buthionine sulfoximine: synthesis, spectroscopic characterization, DFT studies and antibacterial assays

A binuclear silver(I) complex with the amino acid L-buthionine sulfoximine (BSO) of composition Ag2C8H16N2O3S was synthesized and characterized by chemical and spectroscopic measurements, and DFT (density functional theory) studies. Solid-state 13C nuclear magnetic resonance (SSNMR) and infrared vibrational spectroscopy (IR) analyses indicate the coordination of the nitrogen and carboxylate groups of the amino acid moiety to one of the silver atoms, while coordination to the second silver atom occurs through the nitrogen of the sulfoximine group. ESI-QTOF-MS measurements show the maintenance of the binuclear structure in solution. DFT studies confirm the proposed structure as a minimum of the potential energy surface (PES) with calculations of the hessians showing no imaginary frequencies. Raman spectroscopic measurements of the [Ag2(BSO)] complex led to the assignments of the Ag–N bonds. Biological assays of BSO and [Ag2(BSO)] were performed by the well-diffusion method over Staphyloccocus aureus (Gram-positive), Escherichia coli and Pseudomonas aeruginosa (Gram-negative) bacterial strains. The ligand was inactive under the tested concentration (100 μg mL−1). The [Ag2(BSO)] complex was active against the Gram-negative and Gram-positive bacteria tested, with MIC values of 3.125 μg mL−1.

Synthesis and crystal structure of a palladium(II) complex with the amino acid L-citrulline

Synthesis and structural characterization of a novel palladium Pd(II) complex with the amino acid L-citrulline (Cit, C 6 H 13 N 3 O 3 ) are presented in this paper. Elemental analysis indicates a 1:2 metal/ligand molar composition for the complex, with the molecular formula PdC 12 H 24 N 6 O 6. The compound was also characterized by infrared (IR) spectroscopic measurements and the crystal structure has been solved by powder X-ray diffraction data with simulated annealing strategy in real space. The Pd(II) complex crystallizes in the triclinic system with space group P-1 and cell parameters a = 4.6493(4) A, b = 5.222(4) A, c = 18.040(2) A, α = 77.41(6)°, β = 94.72(7),° and γ = 101.45(7)°. The crystal structure confirms the presence of Pd(II) ions in a nearly square planar environment and the molecular formula with deprotonated citrulline as proposed by analytical and spectroscopic data.

N,N′,N′′ versus N,N′,O imine-containing coordination motifs: ligand-directed synthesis of mononuclear and binuclear CuII compounds

It is shown that tridentate imine ligands can control the nuclearity of copper(II) complexes based on the donor atoms present in the ligand. While the N,N′,N′′-donating imine ligand led to a mononuclear compound, the N,N′,O-donating imine ligand produced a binuclear metal complex.