Betulin is an important triterpenoid substance isolated from birch bark, which, together with its sulfates, exhibits important bioactive properties. We report on a newly developed method of betulin sulfation with sulfamic acid in pyridine in the presence of an Amberlyst^®15 solid acid catalyst. It has been shown that this catalyst remains stable when being repeatedly (up to four cycles) used and ensures obtaining of sulfated betulin with a sulfur content of ~10%. The introduction of the sulfate group into the betulin molecule has been proven by Fourier-transform infrared, ultraviolet-visible, and nuclear magnetic resonance spectroscopy. The Fourier-transform infrared (FTIR) spectra contain absorption bands at 1249 and 835–841 cm⁻¹; in the UV spectra, the peak intensity decreases; and, in the nuclear magnetic resonance (NMR) spectra, of betulin disulfate, carbons С3 and С28 are completely shifted to the weak-field region (to 88.21 and 67.32 ppm, respectively) with respect to betulin. Using the potentiometric titration method, the product of acidity constants K₁ and K₂ of a solution of the betulin disulfate H⁺ form has been found to be 3.86 × 10^–6 ± 0.004. It has been demonstrated by the thermal analysis that betulin and the betulin disulfate sodium salt are stable at temperatures of up to 240 and 220 °C, respectively. The density functional theory method has been used to obtain data on the most stable conformations, molecular electrostatic potential, frontier molecular orbitals, and mulliken atomic charges of betulin and betulin disulfate and to calculate the spectral characteristics of initial and ulfated betulin, which agree well with the experimental data.

Uranyl tris-(carbohydrazide) nitrate [UO₂((N₂H₃)₂CO)₃](NO₃)₂ was prepared by the reaction of water solution of dioxouranium(VI) nitrate UO₂(NO₃)₂(H₂O)₆ with ethanol solution of carbohydrazide (N₂H₃)₂CO in a molar ratio of 1 to 3 in an neutral medium. The substance was characterized by elemental, thermal analysis and IR and ¹⁵N MAS CP NMR spectroscopy. Ab initio crystal structure determination was carried out using X-ray powder diffraction techniques. The compound crystallizes in monoclinic lattice with unit cell parameters: a = 15.193(1) Å, b = 12.005(1) Å, c = 10.842(1) Å, β = 109.15(1)^○, V = 1868.11 ų, Z = 4, SG = Cc. The type of carbohydrazide coordination was additionally confirmed by ¹⁵N MAS CP NMR and IR spectroscopy. In the complex ion [UO₂((N₂H₃)₂CO)₃]²⁺ three carbohydrazide ligands coordinate to UO₂ ²⁺ through oxygen and nitrogen forming three five-membered chelate rings. The carbohydrazide rings are tuned to the equatorial plane of complex. The crystal structure consists of zig-zag chains of [UO₂((N₂H₃)₂CO)₃]²⁺ cations stretched along c-axis. The cations in the chain are linked by the hydrogen bonds between the cations themselves. The anions are located in the pores between chains and participate in hydrogen bonding between adjacent chains and additionally link the chain sections. The length of the chain section is 5.768 Å and the angle between sections is 140^○. The substance [UO₂((N₂H₃)₂CO)₃](NO₃)₂ is thermally stable up to 215 ℃ and then decomposes with an explosion.

This paper deals with complex formation of Bi(III) with 3-mercaptopropionic acid (H₂MPA, H₂L) in aqueous perchloric solutions. An extensive investigation on stoichiometry, stability and geometry of complex species in aqueous solutions and of solid H[Bi(MPA)₂]·H₂O complexes has been carried out by UV-Vis, ¹H-NMR, Raman, ICP-AES and EXAFS spectroscopic methods combined with ab initio research. All complex species have cyclic S,O-chelate structures. An ab initio simulation on the thermodynamics of complexation of Bi(III) by H₂MPA has been carried out aiming to choose an appropriate quantum chemical methodology. The most accurate results have been achieved with M06 density functional, a SMD solvation model and the Def2-TZVPP basis set with discrepancies of stability constants within ± 1.0 logarithmic units.