1,2-Disubstituted ethanes adopt gauche and anti conformations whose stability is governed by steric, electrostatic, and hyperconjugative effects. These conformations differ in energy and molecular properties such as dipole moments, which influence lipophilicity, solubility, and other physicochemical characteristics. Accurate prediction of dipole moments is therefore important for understanding these properties. Here, a quantitative structure–property relationship (QSPR) approach based on multivariate image analysis (MIA) descriptors was employed to predict dipole moments from quantum-chemically optimized geometries. The conformational behavior of 1,2-disubstituted ethanes bearing F, Cl, Br, CN, and NO₂ substituents was revisited using density functional theory, and MIA-QSPR models were developed for their gauche and anti conformers. Predictions of conformer populations and absolute and relative energies showed limited performance, whereas dipole moments were predicted robustly, with r² = 0.74, q² = 0.64, and r²pred = 0.83. These results demonstrate the potential of MIA-QSPR for rapid dipole-moment prediction.
In this work, a newly developed computational package named GMSGC is reported for the efficient and accurate identification of global-minimum structures of giant clusters, with a specific focus on fullerene-like gadolinium-oxygen (GdnOm) clusters spanning the size range of 50 to 25650 gadolinium atoms. The GMSGC package integrates multiple advanced algorithms, including symmetric structure generation, random perturbation, duplicate structure recognition, standard and improved basin-hopping, genetic algorithm, and particle swarm optimization, to enhance the efficiency and reliability of global optimization. Computational investigations at relativistic DFT levels are performed, enabling systematic exploration of the structural characteristics, self-assembly mechanisms, topological rules, and size-dependent properties of giant rare-earth oxide clusters. The giant icosahedral fullerene-like M60n2 clusters (n = 1–12) exhibit strict adherence to the isolated pentagon rule (IPR), possessing pseudo-Ih symmetry with twelve pentagonal faces and a variable number of hexagonal faces. This work not only provides a powerful tool for global-minimum structure searching of giant clusters but also unveils the fundamental self-assembly and topological principles governing giant fullerene-like rare-earth oxide clusters, laying a solid foundation for future studies on the structure–property relationships and practical applications of large-scale rare-earth nanoclusters.
The development of innovative technologies for processing fibrous materials used in the production of biomedical textiles requires the integration of the results of fundamental knowledge on the physical–chemical properties of textile auxiliaries into technological applications. One of the promising biopolymers in textile technologies is sericin, which has attracted considerable attention due to its biocompatibility, biodegradability, and suitability for microcapsulation of biological active substances. The functional properties of sericin can be improved through modification with crown esters, which are capable of selectively binding organic and inorganic cations in a variety of media. The rational design of such systems requires detailed knowledge of the thermodynamic parameters governing complex formation, as well as the associated structural changes occurring upon interactions between sericin and crown ether. However, these aspects of the sericin-crown ether system remain largely unexplored and are currently not represented in the scientific literature. The objective of this research was to obtain physical–chemical characteristics of interactions between sericin and 18-crown-6 ether (18C6) in water–ethanol solutions. To achieve this, molecular docking, molecular dynamics simulations, isothermal titration calorimetry, scanning electron microscopy and dynamic light scattering were employed. For the first time, the formation of molecular complexes between 18C6 and amino acid residues within the structural framework of sericin was demonstrated. The thermodynamic parameters of the [Sericin 18C6] complexation process in water and in water–ethanol mixtures (lgK0, ΔrH0, ΔrG0 and TΔrS0) were determined and compared with those reported for complexes formed between 18C6 and individual amino acids. In addition, microcapsules composed of sericin and anionic polyelectrolyte stabilizer Acremonium LK-2 were successfully synthesized, characterized, and subsequently immobilized onto textile substrates.
Analysis of the known crystal structures containing aqua complexes of lanthanoids [Ln(H2O)n]3+ (n = 8,9) shows that essentially all lanthanoids can form both nonaaqua and octaaqua complexes. On going along the lanthanoid row the nonaaqua complexes are found less frequently, while octaaqua complexes more often, with europium and gadolinium being the border elements – their aqua complexes with nine and eight water molecules are found with approximately equal frequency. Aqua complexes [Ln(H2O)8]3+ most often have the square antiprism (SAP) structure, but other polyhedra are also met: trigonal dodecahedron (DDH), bicapped trigonal prism (BTP) and even cube. The tricapped trigonal prism (TTP) is typical of nonaaqua complexes, the capped square antiprism (cSAP) is less common, and the polyhedra intermediate between these two ones also occur. In the TTP polyhedra, the Ln-Ocap bonds are on average slightly longer than Ln-Oprism ones, but in each individual crystal structure the ratio of the lengths of these bonds is governed by the intermolecular interactions in which this aqua complex is involved. According to the quantum chemical calculations at the ZORA/DFT/B3LYP level accounting for the continuum effect (SMD), SAP and TTP configurations correspond to the global energy minima for coordination numbers 8 and 9, respectively. However, the energies of DDH, BTP and cSAP polyhedra are only slightly higher (by 1–9 kJ mol− 1) than those of SAP and TTP, respectively. The obtained results prove that the aqua complexes of Ln3+ ions have fluxional structures, easily changing their configurations and coordination numbers.
Confinement can change hydrogen-bond geometry and so alter the energetics of proton transfer, but the effect of fullerene cage size on the formic acid dimer has not been established. Using ωB97X-D/6-311G(d, p), we examined the dimer inside five fullerene cages: C₆₀, C₇₀, C₈₀, C₉₀, and C₁₀₀. Inside C₆₀, C₇₀, and C₈₀ the dimer is bent, loses its symmetry, and has a large deformation energy. Inside C₉₀ and C₁₀₀ the dimer retains a symmetric, planar ring, the deformation energy is small, and a transition state for the concerted transfer can be located. The encapsulation energy is large and positive for the three small cages and close to zero for the two large ones; after correction for basis set superposition error, the latter values become positive, so no net binding is claimed. For the two cages that retain the intact dimer, the proton-transfer barrier is lower than the gas-phase value in C₉₀ and higher in C₁₀₀ (6.50 and 12.64 versus 7.93 kcal mol⁻¹). This order holds for the electronic, zero-point-corrected, and Gibbs barriers and follows the reactant O···O distance, which is shorter in C₉₀ and longer in C₁₀₀ than in the gas phase. The tunnelling crossover temperatures lie between 275 and 302 K. Within a one-dimensional Wigner treatment, the corrected transition-state-theory rates retain the kinetic order C₉₀ > gas phase > C₁₀₀ at 298.15 K. For the cages studied here, confinement can therefore either lower or raise the double-proton-transfer barrier, depending on the hydrogen-bond geometry the cage imposes.
