Investigation of Gallium(III) Complexes with Thiouracil Derivatives: Effects of pH on Coordination and Stability.

This study explores the formation and properties of new complexes involving gallium(III) and thiouracil derivatives-2-thiouracil (TU), 6-methyl-2-thiouracil (MTU), 6-propyl-2-thiouracil (PTU), 5-carboxy-2-thiouracil (CTU), and 6-methoxymethyl-2-thiouracil (MMTU). Conducted in aqueous solutions at relatively low concentrations, this research enabled the formation of soluble complexes, identified and described here for the first time. The influence of metal-to-ligand ratios on species distribution and their fluorescence properties was examined through potentiometric titration, alongside visible and fluorescence spectroscopy.

Influence of d-Electron Divalent Metal Ions in Complex Formation with L-Tartaric and L-Malic Acids.

Binary complexes of α-hydroxy acids (L-Tartaric acid and L-Malic acid) with d-electron metal ions (copper, cobalt, nickel) were investigated. Potentiometric measurements have been performed in aqueous solution with computer analysis of the data for determination of the stability constants of complexes formed in the studied systems. The coordination mode of the complexes was defined using spectroscopic methods: electron paramagnetic resonance (EPR), ultraviolet-visible (UV-Vis), circular dichroism (CD), and infrared (IR).

Thermodynamic and Spectroscopic Studies of the Complexes Formed in Tartaric Acid and Lanthanide(III) Ions Binary Systems.

Binary complexes of tartaric acid with lanthanide(III) ions were investigated. The studies have been performed in aqueous solution using the potentiometric method with computer analysis of the data for detection of the complexes set, determination of the stability constants of these compounds. The mode of the coordination of complexes found was determined using spectroscopy, which shows: Infrared, circular dichroism, ultraviolet, visible as well as luminescence spectroscopy.

New coordination compounds of citric acid and polyamines with lanthanide ions - potential application in monitoring the treatment of cancer diseases.

Non-covalent interaction in the binary systems of polyamines (putrescine, spermidine, spermine) with citric acid and complex formation in the binary as well as ternary systems of lanthanide(III) ions, citric acid and polyamine have been investigated. The studies were performed in aqueous solution. The overall stability constants of the complexes were determined using the potentiometric method with computer analysis of the data.

Coordination properties of ,'-bis(5-methylsalicylidene)-2-hydroxy-1,3-propanediamine with d- and f-electron ions: crystal structure, stability in solution, spectroscopic and spectroelectrochemical studies.

Template reaction between 5-methylsalicylaldehyde and 2-hydroxy-1,3-propanediamine in the presence of copper ion led to dinuclear and mononuclear copper(ii) complexes [CuL(CHCOO)(CHOH)](CHOH) (1) and [CuHL](CHOH) (2), where HL is ,'-bis(5-methylsalicylidene)-2-hydroxy-1,3-propanediamine. The result of the reactions between 5-methylsalicylaldehyde and 2-hydroxy-1,3-propanediamine in the presence of lanthanide ions and/or copper(ii) ion was ,'-bis(5-methylsalicylidene)-2-hydroxy-1,3-propanediamine (HL B) or [CuHL](CHOH) (2), respectively. Structures of the compounds were determined by single-crystal X-ray diffraction and physicochemical methods.

Carboxyl groups of citric acid in the process of complex formation with bivalent and trivalent metal ions in biological systems.

Binary complexes of citric acid (HL - protonated form, HL and HL - partly protonated forms, L - fully deprotonated) with d- and f-electron metal ions were investigated. The studies have been performed in aqueous solution using the potentiometric method with computer analysis of the data, electron paramagnetic resonance, infrared, visible as well as luminescence spectroscopies. The overall stability constants of the complexes were determined.

The trimorphic structure of N,N'-bis(5-methylsalicylidene)-4-methyl-1,3-phenylenediamine.

The new Schiff base ligand, N,N'-bis(5-methylsalicylidene)-4-methyl-1,3-phenylenediamine (H2L), has been prepared by condensation of 5-methylsalicylaldehyde with 4-methyl-1,3-phenylenediamine. It was found that this ligand crystallizes in the monoclinic space group P21/c, with Z' = 1. Further studies showed that - as a result of the one-pot metal-promoted reactions - three different polymorphic forms of H2L were obtained, with different numbers (1, 3 or 4) of symmetry-independent molecules depending on the lanthanide metal ion present in the reaction media: La (Z' = 3), Nd (Z' = 4), Sm, Tb, Ho and Yb (all Z' = 1); the last form is identical with that obtained by crystallization of the ligand itself.