Effects of pH on the differential absorbance spectra, d-d transition bands and structural properties of copper complexes with humic substances and model compounds.

Interactions between metal cations, notably Cu(II), and humic substances (HS) affect their mobility, bioavailability, and toxicity. This necessitates a molecular-level determination of the nature of HS functional groups binding Cu(II) (Cu-HS) and effects of pH on them. This study investigates the pH effects on the spectroscopic and structural properties of the complexes of Cu(II) with HS and representative model compounds using differential absorbance spectroscopy (DAS), examination of the properties of the d-d transition band characteristic for Cu(II) ions, and quantum chemical (QC) calculations.

DFT and ONIOM Simulation of 1,3-Butadiene Polymerization Catalyzed by Neodymium-Based Ziegler-Natta System.

Using modern methods of quantum chemistry, a theoretical substantiation of the high -stereospecificity of 1,3-butadiene polymerization catalyzed by the neodymium-based Ziegler-Natta system was carried out. For DFT and ONIOM simulation, the most -stereospecific active site of the catalytic system was used. By analyzing the total energy, as well as the enthalpy and Gibbs free energy of the simulated catalytically active centers, it was found that the coordination of 1,3-butadiene in the -form was more favorable than in the -form by 11 kJ/mol.

Modulating the Inclusive and Coordinating Ability of Thiacalix[4]arene and Its Antenna Effect on Yb-Luminescence via Upper-Rim Substitution.

The present work introduces the series of thiacalix[4]arenes (HL) bearing different upper-rim substituents (R = H, Br, NO) for rational design of ligands providing an antenna-effect on the NIR Yb-centered luminescence of their Yb complexes. The unusual inclusive self-assembly of HL (Br) through Brπ interactions is revealed through single-crystal XRD analysis. Thermodynamically favorable formation of dimeric complexes [2Yb:2HL] leads to efficient sensitizing of the Yb luminescence for HL (Br, NO), while poor sensitizing is observed for ligand HL (H).

Role of PSS-based assemblies in stabilization of Eu and Sm luminescent complexes and their thermoresponsive luminescence.

The present work introduces self-assembled polystyrenesulfonate (PSS) molecules as soft nanocapsules for incorporation of Eu-Sm complexes by the solvent exchange procedure. The high levels of Eu- and Sm-luminescence of the complexes derives from the ligand-to-metal energy transfer, in turn, resulted from the complex formation of Euand Sm ions with the three recently synthesized cyclophanic 1,3-diketones. The structural features of the ligands are optimized for the high thermal sensitivity of Eu- luminescence in DMF solutions.