DFT studies of cation binding by β-cyclodextrin

Abstract

Interactions of the b-cyclodextrin (b-CD) ligand with Na ? , Cu ? , Mg 2? , Zn 2? , and Al 3? cations were investigated using density functional theory modeling. The objective of this study was to give insight into the mechanism of cation complexation. Two groups of conformers were found. The first group preserved the initial orientation of glucopyranose residues inside the b-CD ligand. The mutual orientation of glucopyranose residues was strongly affected by the cation in the second group of conformers. The system interaction energy was decomposed into electrostatic (ES), Pauli and orbital contributions using the Ziegler-Rauk energy partitioning scheme. The total electrostatic energy, i.e., the sum of ES energy and polarization energy, is the dominating term in the interaction energy. In vacuum, the complexes formed with Al 3? were found to be more stable than with di-and monocations. The vacuum stability sequence was changed in aqueous solution.

Probing the common alkali metal affinity of native and variously methylated β-cyclodextrins by combining electrospray-tandem mass spectrometry and molecular modeling

“…44 Full geometry optimizations were performed with the hybrid B3LYP density functional method 45 using the 6-31G* basis set, which represents good compromise between the accuracy and computational cost. 41. Zero-point, thermal and entropic corrections at a pressure of 1 atm and a temperature of 298 K were added to the electronic energies to calculate the Gibbs free energies in the gas phase.…”

“…39 Computational methods that are able to predict ligand selectivity in a variety of condensed-phase environments have demonstrated to be valuable tools for the molecular recognition mechanism correlation. 41 Taking into account that the distance between the opposite oxygen atoms is twofold shorter within the smaller rim as compared with the bigger rim, the authors considered the coordination of cations to the smaller rim. 40 Molecular modeling applied to b-CD/metals cannot be easily achieved by high-level ab initio techniques due to the system's size.…”

“…Such methods require accurate models of the relevant noncovalent interactions and suitable experimental data to benchmark the calculations. 41,42 In the study herein, we investigated the relative affinity of common alkali metals with native and variously methylated b-CDs (Scheme 1). However, Hartree-Fock and density functional theory (DFT) based methods have been applied for complexes involving b-CD with Na + , Mg 2+ , Al 3+ , Cu + and Zn 2+ .…”

Theoretical study on β-cyclodextrin inclusion complexes with propiconazole and protonated propiconazole

“…The PM3 method has proved to be a powerful tool in the conformational study of supramolecular systems, such as CD inclusion compounds and provides better performance compared to the AM1 method for molecular geometry optimization, due to its improved description of hydrogen bonds and steric effects [8–10]. Advanced methods, such as Hartree–Fock (HF) and density functional theory (DFT), were also applied in cyclodextrin chemistry to explain experimental data [11–12]. Very often, ab initio methods are used in tandem with the semi-empirical PM3 method [13–17].…”

Charge sensitivity approach to mutual polarization of reactants: molecular mechanics perspective

“…BCD has several conformers; more information about their structures can be found in [45–49]. The conformer with a counterclockwise orientation of hydrogen bonds in both rims was chosen.…”