Four new Ni^II, Co^II, Zn^II, and Cu^II complexes with the promising anti-tuberculosis drug (E/Z)-N′-((5-Hydroxy-3,4-bis(hydroxymethyl)-6-methylpyridin-2-yl)methylene)-isonicotino-hydrazide (LH) were synthesized and characterized by structural methods: single-crystal X-ray diffraction, vibrational spectroscopy, and mass spectrometry. The Ni^II, Co^II, and Zn^II metal ions form only amorphous phases with various morphologies according to mass spectrometry and IR spectroscopy. The Cu^II forms a crystalline 1D coordination polymer with the relative formula $\left\{\left[\mathrm{Cu}L\mathrm{Cl}\right]·0.5{\mathrm{H}}_2\mathrm{O}\right\}_{\infty }^1$. Even though the LH ligand in the crystalline state includes a mixture of E-/Z-isomers, only the tautomeric iminol E-/Z-form is coordinated by Cu^II in the crystal. The copper(II) complex crystallizes in the monoclinic P2₁/n space group with the corresponding cell parameters a = 16.3539(11) Å, b = 12.2647(6) Å, and c = 17.4916(10) Å; α = 90°, β = 108.431(7)°, and γ = 90°. DFT calculations showed that the Z-isomer of the LH ligand in solution has the lowest formation energy due to intramolecular hydrogen bonds. According to the quantum chemical calculations, the coordination environment of the Cu^II atom during the transfer of the molecule into the solution remains the same as in the crystal, except for the polymeric bond, namely, distorted trigonal bipyramidal. Some of the complexes investigated can be used as effective sensors in biosystems.

A new polymorphic modification of lanthanum sulfate was obtained by thermal dehydration of the respective nonahydrate. According to powder X-ray diffraction, it was established that β-La₂(SO₄)₃ crystallized in the C2/c space group of the monoclinic system with the KTh₂(PO₄)₃ structure type (a = 17.6923(9), b = 6.9102(4), c = 8.3990(5) Å, β = 100.321(3)°, and V = 1010.22(9) ų). Temperature dependency studies of the unit cell parameters indicated almost zero expansion along the a direction in the temperature range of 300–450 K. Presumably, this occurred due to stretching of the [LaO₉]_n chains along the c direction, which occurred without a significant alteration in the layer thickness over the a direction. A systematic study of the formation and destruction processes of the lanthanum sulfates under heating was carried out. In particular, the decisive impact of the chemical composition and formation energy of compounds on the thermodynamic and kinetic parameters of the processes was established. DFT calculations showed β-La₂(SO₄)₃ to be a dielectric material with a bandgap of more than 6.4 eV. The processing of β-La₂(SO₄)₃ with the Kubelka–Munk function exhibited low values below 6.4 eV, which indicated a fundamental absorption edge above this energy that was consistent with LDA calculations. The Raman and infrared measurements of β-La₂(SO₄)₃ were in accordance with the calculated spectra, indicating that the obtained crystal parameters represented a reliable structure.

Quaternary ammonium salts (QASs), acylhydrazones and catechols are well known for their antimicrobial, antioxidant and antitumor properties. Complexation of acylhydrazones and catechols with Cu(II) ions potentially leads to obtaining compounds with promising biological properties. In this paper, we present a synthesis of two binuclear copper(II) complexes based on redox-active QASs with acylhydrazone and catechol fragments and a study of their structure in the solid state. The copper(II) complex with a tributylammonium fragment crystallizes in the triclinic space group with the following lattice parameters: a = 10.1459(5) Å, b = 15.1239(7) Å, c = 16.3279(5) Å, α = 110.231(4)°, β = 104.689(4)°,γ = 101.637(4)°. The structure exhibits binuclear nature, showing the distance Cu–Cu of 3.507 Å, and Jahn-Teller distortions with large elongation along the axial positions. The thermal stability of the ligands was found to be higher than that of the corresponding complexes up to 66–77 °C. EPR spectroscopy proved the dissociation of the complexes in the methanol solution into the monomeric forms. Complexation with Cu(II) cation shifted oxidation peaks of the ligands towards the lower potentials. The target compounds may be applied to create selective systems for metal ion separation, and may also possess potential antimicrobial, antioxidant, and antitumor properties.