For a wide range of 1,10-phenanthroline-2,9-dicarboxylic acid diamides (DAPhen), differing in the structure of the amide substituent and the presence of chlorine atoms in the 4,7-positions of the phenanthroline core, the extraction properties for lanthanides(III) and americium(III) were studied. Protonation and binding constants to Eu(III) were determined by using UV-vis titration. The values of binding constants and protonation constants are higher for nonsubstituted diamides than for 4,7-chlorinated diamides, which is in good agreement with the solvent extraction data. The structures of more than 20 complexes with lanthanide nitrates in the solid state have been determined using X-ray diffraction analysis. Unusual DAPhen ligand complexes with lanthanum and neodymium nitrates were obtained. For the first time, the possibility of entering a water molecule into the internal coordination sphere of neodymium in a complex with the DAPhen ligand was shown, resulting in the coordination number of neodymium increasing to 11. An unusual complex with a bridge structure was obtained for lanthanum nitrate in which the lanthanum ions have different coordination numbers of 10 and 12.

Management of high-level waste is essential for the further sustainable development of nuclear energy. Solvent extraction is one of the technologically acceptable methods for carrying out such processing. The search for new selective extractants is an urgent task that requires systematic research into the structure-properties relationship. 1,10-phenanthroline-2,9-diamides (DAPhen) is a promising ligand class for processing such solutions. Identification of the binding and separation mechanism is the most important fundamental question for any separation system. In this work, we systematically studied of the mechanism of extraction and complex formation by this class of compounds on the example of 4,7-substituted aliphatic 1,10-phenanthroline-2,9-diamides. For systematic comparison, we conducted liquid-liquid extraction studies of f-elements and nitric acid, determination of binding constants (UV–vis and luminescence titration), and structural studies of complexes. Using these methods, it was shown how electron-withdrawing substituents (-Cl) and electron-donating (-OBu) significantly affect the Brønsted and Lewis basicity, the stoichiometry of the complexes formed and the trends in the extraction of f-elements. Moreover, XRD study of an array of complex compounds allowed us to establish the structural features that determine the efficiency and selectivity of liquid-liquid extraction.

The reactions of trifluoromethylated 2-bromoenones and N,N'-dialkyl-1,2-diamines have been studied. Depending on the structures of the starting compounds, the formation of 2-trifluoroacetylpiperazine or 3-trifluoromethylpiperazine-2-ones was observed. The mechanism of the reaction is discussed in terms of multistep processes involving sequential substitution of bromine in the starting α-bromoenones and intramolecular cyclization of the captodative aminoenones as key intermediates to form the target heterocycles. The results of theoretical calculations are in perfect agreement with the experimental data. The unique role of the trifluoromethyl group in this reaction is demonstrated.