Study of complexing properties of mono-derivatives of alkenyl succinic acid with copper(II) and nickel(II) ions.

Mono-derivatives of alkenyl succinic acid are considered in this paper, also their complexes with copper and nickel ions, which structure was studied by IR spectrometry method. Protonization constants and stability constants of complexes of mono-derivatives of succinic acid with copper and nickel ions are calculated by pH-metric titration method. It has been established, that mono-derivatives of succinic acid formed more stable complexes with the copper ion.

STUDY OF COMPLEX FORMATION OF Co (II) WITH TRIGLYCINE IN AQUEOUS SOLUTION

Peptides are an extensive class of both natural and synthetic organic compounds, many of which have high and diverse physiological activity. The relevance of the study of the complexing properties of tripeptides is determined by the large value of these compounds in biological processes, since peptides are a simplified fragment of proteins and are widely used in various sectors of the pharmaceutical industry. One of the representatives of low molecular weight tripeptides is glycyl-glycyl-glycine. In this work, the complex formation of triglycine with Co2+ ions at 298.15 K and I = 0.2 mol/l (KNO3) was studied by potentiometric titration. The study of the complexing properties of triglycine with Co2+ was carried out by the method of potentiometric titration with the ratios M:L = 1:1, 1:2, 1:5. For processing the experimental data, the universal program PHMETR was used, designed to calculate equilibrium constants with an arbitrary number of reactions from the measured equilibrium concentration of one of the particles. The existence of CoL, CoH-1L, CoL2 CoH-2L22–, CoL3–, CoH-3L34– complexes was established. Their stability constants were determined. And the probable structures of the resulting complexes were proposed. The results of this study show that the oxygen and nitrogen atoms of the peptide group are involved in the processes of interaction between Co(II) and triglycine. This significantly changes the thermodynamics of the complex formation of short peptides in comparison with amino acids. The stability constants of cobalt (II) triglycinates obtained in this work allow one to carry out mathematical modeling of equilibria in multicomponent solutions, to predict the behavior of systems in a wide range of concentrations and pH. They can form the basis for generalizations concerning the structure and behavior of low molecular weight peptides in solution, and used for further studies, including calorimetric ones.

Oxidant/complexing properties of the methimazole (MeImHS)/iodine system towards palladium and gold metals. Crystal structure of the complex cation [PdII(MeImHS)4]2+ balanced by a tetraiodide/iodide mixture

The oxidative dissolution of palladium is easily and safely achievable both in dichloromethane and water by the methimazole/I2 mixture.

Mass Spectrometry Reveals Complexing Properties of Modified PNP-Lariat Ether Containing Benzyl Derivative of (S)–Prolinamine

In the investigation presented here the synthesis of new lariat ether derivative obtained from the modification of tetrapyrrolidinyl-PNP-crown ether macrocycle is described. The polyheterotopic molecular coreceptor consisted of the replacement of chlorine atoms with an optically active (S)-(1-benzylpyrrolidin-2-yl) methanamine. The structure was confirmed by using elemental analysis, mass spectrometry, and NMR spectroscopy. This work covers results concerning the complexing properties of the new ligand towards Ag+, Cu2+, Co2+, Ni2+, and Zn2+ ions. The formation of non-covalent complexes of 1:1 stoichiometry with the Cu2+, Co2+, Ni2+, and Zn2+ ions have been confirmed by mass spectrometry. Due to the previous work and application possibilities, a large emphasis was put on the investigation of the complexation ability of lariat ether with silver (I) cation to determine stability constants by direct potentiometric method. In this case, the formation of four different forms of complexes AgL, Ag2L, Ag3L, and Ag4L has been proved. The observed unusual binding through the nitrogen atoms from the exocyclic substituents may provide the structural unit to build a new coordination polymers.