A second-generation hyperbranched polyester with the terminal carbamoyl phosphonate groups has been synthesized. The structure of the resulting polyester has been studied by IR, ¹H NMR, ³¹P NMR, and electron spectroscopy. It has been found that 25% of the terminal OH groups of polyester polyol were subjected to functionalization. Using the TGA method, the thermal stability temperature of the resulting polyester was evaluated to be 138°C. We have synthesized a complex of the resulting polyester with the Pd(II) ions, and the complex structure has been studied by IR and electron spectroscopy. The composition of the ligand–Pd(II) complex has been evaluated to be 1 : 6. We have found by the TGA method that this complex is thermally stable up to 207°C. The temperature of reduction of the Pd(II) ions by molecular hydrogen to Pd(0) has been assessed as –20.6°C. Electron microscopy has been used to demonstrate the spherical morphology of hyperbranched polyester polycarbamoyl phosphonate with Pd(0) atoms, with the predominant fraction being 1.5 μm. It has been shown that the use of hyperbranched polyester polycarbamoyl phosphonate as a catalyst provides the activation energy of 55.8 kJ/mol for hydrogenation of α-methylstyrene to cumene with the effective rate constant of 1.950×10^–2 L/(g_cat s) at 45°C and atmospheric pressure. The results indicate the prospects of using hyperbranched polyester polycarbamoyl phosphonate as a matrix to obtain catalysts for the hydrogenation of unsaturated compounds.

Metal complexes of hyperbranched polymers have attracted attention as potential catalysts due to their unique, tunable structure. Hyperbranched polyester polybenzoylcarbamate was synthesized by the reaction of second-generation hyperbranched polyester polyol with benzoyl isocyanate. The structure was studied by ¹H, ¹³C NMR, and IR spectroscopies. The degree of functionalization as determined by ¹H NMR spectroscopy was 25%. Reaction of palladium chloride with the synthesized ligand yielded a complex of hyperbranched polyester polybenzoylcarbamate was obtained for the first time. The participation of oxygen atom C = O of benzoyl fragments in coordination with Pd(II) ions was established by IR spectroscopy. The thermostability temperature of the synthesized ligand and complex was studied by thermogravimetric analysis and was found to be 124 °C. The mass content of palladium in complex is 14%, with the ratio of ligand: Pd = 1:2.7. The average particle size of complex as determined by electron microscopy is 1,8 ± 0,07 μm, and the complex forms cluster structures. Pd(II) ions in the complex were reduced to palladium nanoparticles in toluene hydrogen stream, followed by the study of hydrogenation of α-methylstyrene to isopropylbenzene under mild conditions, the activation energy was 61.2 kJ∙mol⁻¹, and the selectivity reached 100%. Graphical Abstract

At present, multifunctional adsorbents capable of not only effectively binding metal ions but also maintaining stability under aggressive conditions (e.g., in an acidic medium) are of great interest. In this work, Cu(II) and Co(II) complexes based on hyperbranched polyester polyphthalate are obtained and characterized for the first time. Complexation is confirmed by IR and electron spectroscopy methods, which revealed the monodentate nature of the coordination of carboxylate groups and the formation of covalent bonds with metals. The coordination units of the complexes have a six-coordinated octahedral geometry with tetragonal distortion, and the ligand:metal molar ratio is 4:1. Calculation of the stability constants showed high stability of the complexes with logarithms of the constants of 18.11 for Cu(II) and 17.23 for Co(II). The TGA method established that the onset temperature of destruction of the copper and cobalt complexes is 210 and 252°C. The ligand demonstrated high sorption capacity for Cu(II) and Co(II) ions—47.88 and 28.21 g/kg, respectively, while desorption was not observed even at low pH (1), which indicates the strength of the complex bonds. These results indicate the possibility of using the macroligand as a sorbent in an acidic environment, for example, in the purification of industrial wastewater and mine waters.