The efficient capture of carbon dioxide (CO₂) using polymer, supported ionic liquids (ILs) remains challenging due to limited understanding of atomic-scale interaction mechanisms. Here, a polystyrene (PS) oligomer supported by an amidinium chloride-based IL is proposed as a CO₂-absorbing material. Density functional theory (DFT) calculations were employed to investigate the structural, electronic, and intermolecular interaction energy characteristics of the PS oligomer, amidinium chloride ILs, CO₂, and their binary and ternary complexes. Molecular electrostatic potential maps (MEPs), reduced density gradient (RDG) plots with non-covalent interaction (NCI) snapshots, quantum theory of atoms in molecules critical point (CP) analysis, and electron localization function (ELF) analysis reveal pronounced hydrogen bonding and dispersion interactions between PS and IL that modulate the electronic environment of the IL anion, which is the primary CO₂ binding site. Interaction energy calculations show that the ternary PS–IL–CO₂ complex exhibits a significantly enhanced binding energy compared to the isolated IL–CO₂ complex, providing quantitative evidence for the cooperative role of the PS support. The results indicate enhanced CO₂ binding in the presence of PS supported by ILs, driven by cooperative electrostatic and dispersion interactions. These findings provide molecular-level insights into CO₂ capture mechanisms in polymer–IL hybrid systems.

Structural and spectroscopic properties of quinolizidine alkaloids lupinine and epilupinine stereoisomers were studied theoretically. The influence of the calculation method and structural change in the molecule on the results of geometry and other properties of compounds was considered. The equilibrium geometry, harmonic vibrational frequencies and infrared intensities were obtained by means of density functional theory (DFT/B3LYP) calculations with the split-valence medium-sized 6-31G(d) basis and Dunning’s correlation consistent basis set cc-pVDZ. From the optimized structure of the (+)-lupinine and (+)-epilupinine molecules, geometric parameters were compared with the literature X-ray experimental data. Structural and vibrational parameters for the (-)-lupinine and (-)-epilupinine molecules are predicted by theoretical calculations at B3LYP/6-31G(d) and B3LYP/cc-pVDZ levels of theory. Some physical characteristics for the title compounds, such as total electronic energy, zero-point energy, rotational constants and dipole moments were also defined by DFT methods. The thermodynamic functions of the title compounds were performed at the same theory levels. Stationary points are identified by the solution of the oscillatory problem.

The utilization and chemical transformation of carbon dioxide remains a pressing problem in modern chemistry. Numerous experimental and theoretical studies have focused on the interaction of CO₂ with amines. In this work, quantum chemical density functional theory (DFT) calculations of equilibrium geometries, energies, electronic and vibrational characteristics of CO₂-sensitive mono-, di-, tris-hydroxyamidines and their associates were carried out by the B3LYP/6-31G(d, p) method. The harmonic vibrational frequencies were scaled and compared with the experimental FTIR spectra for supporting wavenumber assignments. Natural bond orbital (NBO) analysis of the atomic charges and charge delocalization was employed to investigate the nature of hydrogen bonding in hydroxyamidine associates. We also used the intrinsically polarizable continuum model (IEFPCM), and the DFT-D3 method was applied to account for dispersion effects during associate formation. Using the 6-311+G(2d, p) basis set for tris-hydroxyamidine, and its adducts, a comparative analysis of the experimental and calculated ¹H NMR spectra was performed. Here, we considered non-trivial sites of carbon dioxide absorption and hydroxyamidine protonation, which, to our knowledge, have hardly been considered by other authors. Present DFT results agree rather well with the experimental data and support new insight into the formation of the PIL structure.

Quantum-chemical simulation of the ground state [the density function B3LYP/6-31G, B3LYP/6-31G(d), and B3LYP/6-31+G(d,p) and the perturbation theory MP2/6-31G(d) methods] and the transition states [the B3LYP/6-31G(d) method] of 4,4′-methoxypropylstilbene molecule has been performed. Using the Ellinger MM2 force field method, the potentials of internal rotation have been obtained for each rotational degree of freedom of the molecule. The B3LYP simulation has revealed the planarity of the conjugated system and the orthogonal position of the alkyl substituent, whereas the benzene rings have deviated by about 20° with respect to the double bond plane according to the MP2 data. Three transition states of the molecule corresponding to the saddle points of the first and the second orders have been revealed. The stationary points have been identified by means of vibrational analysis.

Background/Objectives: For the first time, water-soluble encapsulated forms of 20-hydroxyecdysone were synthesized as clathrate complexes with β-cyclodextrin. The derivatives included a ketoxime form (20-NOH), obtained by selective oximation of the C-6 carbonyl, and a triacetate form (3Ac-20E), obtained by regioselective acetylation of the C-2, C-3, and C-22 hydroxyl groups. Methods: The chemical structures of the obtained compounds were confirmed using spectroscopic methods, including ¹H and ¹³C NMR. The Z-configuration of the oxime in 20-NOH was established by the diagnostic upfield shift in the C-5 resonance (δ 36.0 ppm) relative to the parent compound (δ 51.4 ppm). Results: The antioxidant activity was evaluated using FRAP and DPPH assays. The β-cyclodextrin complexes were shown to exhibit significantly higher radical scavenging activity, with IC₅₀ values of 10 mg/mL). Conclusions: The obtained results indicate that β-cyclodextrin complexes significantly enhance the biological activity of 20E and highlight the potential of these compounds for pharmaceutical applications.