Modeling and Thermodynamic Values of Complex Equilibrium of Cobalt(II) with Diethylenetriaminepentaacetic Acid in Aqueous Solution

The paper reports the study of the complex formation of cobalt (II) with diethylenetriaminepentaacetic acid (DTPA, H5L) based on spectrophotometric (SF) and potentiometric data (pH). Complexes of different compositions were found, and equilibrium constants, as well as the stability constants of these complexes, were determined. Accumulation of complexes in proportion is calculated based on the acidity of the medium. The experimental data have been carried out by using mathematical models to assess the solution's possible existence with a wide spectrum of complex particles and to point out those which are quite sufficient to copy the experimental data. In addition, thermodynamic parameters (ΔG°, ΔH°, and ΔS°) for the studying complexes were calculated according to the values of stability constant (KST) at 25 °C obtained from the temperature dependence of stability constant by using van’t Hoff equation.

Reply to the ‘Comment on “Investigation of Zr(iv) and 89Zr(iv) complexation with hydroxamates: progress towards designing a better chelator than desferrioxamine B for immuno-PET imaging”’ by A. Bianchi and M. Savastano, Chem. Commun., 2020, 56, D0CC01189D

The relevance of simplified models used for potentiometric data interpretation is discussed in the context of radiolabelling chemistry (herein the complexation of a radiometal, 89Zr, by a ligand L).

Monocationic porphyrin dyads with fullerene as the electron-accepting material

Dyad compounds in which a fullerene [Formula: see text] was covalently linked to a monocationic porphyrin at a N,N[Formula: see text]-bridge substituent, were synthesized by condensation reaction. The low solubility of a dyad containing tetraphenylporphyrin (TPP) derivative was improved by using octaethylporphyrin (OEP) derivatives and introduction of an alkyl substituent to the porphyrin derivatives. The energy levels of the frontier orbitals, estimated experimentally using potentiometric data and the optical energy band gaps obtained by the UV-vis spectra, were sufficiently low to be comparable to acceptor materials. They varied depending on the peripheral substituents on the porphyrin unit. DSC analysis of the drop-cast films of the P3HT/dyad blends showed that the film containing the OEP dyad, annealed at a higher temperature, had more amorphous fractions than the films containing the TPP dyad.

Computer analysis of potentiometric data of complexes formation in the solution

The determination of equilibrium constants is an important process for many branches of chemistry. In this review we provide the readers with a discussion on computer methods which have been applied for elaboration of potentiometric experimental data generated during complexes formation in solution. The review describes both: general basis of modeling tools and examples of the use of calculated stability constants.

Study of Metal-1,10-Phenanthroline Complex Equilibria by Potentiometric Measurements

The interaction of Sc(III), Y(III), and La(III) ions with 1,10-phenanthroline (Phen) has been investigated, using the potentiometric method at 25 and M KNO3. Collected potentiometric data were processed by the “BEST” software program to establish the complexation model for each system. SPE software program was used to evaluate the concentration distributions of the species formed in solution. The stability constants for the binary complexes increased as the ionic radii of the metal cations decreased.