Ten new stable 4-(49-pyridyl)pyridinium disubstituted monoylides were synthesized by the reaction of 4-(49-pyridyl)pyridinium monosubstituted ylides with electrophiles as aromatic isocyanates and isothiocyanates. The facile synthesis and high stability of the new ylides were attributed not only to the delocalization of both negative and positive charges, but also to the intramolecular hydrogen bond. This bond was proved to be present both in solution (by NMR) and solid phase (by X-ray crystallography). The computational studies using density functional theory calculations (DFT) suggest, as well, an important charge delocalization in gas-phase structures for simplified model disubstituted cycloimmonium ylides. The palladium complexation for two of the new ylides was studied using NMR titrations and quantified using UV-visible spectroscopy titrations.
Complexes of uranyl(VI) (U(VI)) with tridentate ligands derived from salicylaldehyde and aminoacids are reported, bis 2-((2-hydroxybenzylidene)amino)acetic acid U(VI), UO 2 (SalGly) 2 (1); tri (4), and tri aqua 2-((2-hydroxybenzylidene)amino)-4-(methylthio)butanoic acid U(VI) nitrate, [UO 2 (SalMet) (H 2 O) 3 ]NO 3 (5). The characterization of the complexes was performed by electrospray mass spectroscopy, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance, fluorescence spectroscopy, and thermal analysis. The complexes are electrolytes (1 : 1) having a molar ratio M : L ¼ 1 : 1, except 1, which is a nonelectrolyte with a molar ratio M : L ¼ 1 : 2. The fluorescence intensity of the complexes is more intense than uncomplexed uranyl, except 1 and 5. High fluorescence of the uranyl SalAla complex (2) was used to assess complexes-DNA interaction based on fluorescence quenching assay. The interaction of 2 with DNA was assessed by measuring the relative fluorescence quenching of the complex when nucleic acids were added.
Abstract:The complexes with manganese(II), iron(II), cobalt(II), nickel(II) and copper(II) of 2-(4, 4'-bipyridin-1-ium-1-yl)-1-(4-bromophenylamino)-3-(4-methoxyphenyl)-3-oxo-1-thioxopropan-2-ide (ylide, Y) were synthesized and characterized. The obtained compounds with 1 : 2 metal/ligand ratios have been characterized by FTIR, UV Vis spectroscopy, ESI MS spectrometry, molecular conductance, magnetic measurements and thermal analysis. The ylide ligand forms chelates with metallic (II) ions through their amide nitrogen and oxygen atoms.
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