Host-guest complex of N-(2-chloroethyl), N-nitroso, N′, N′ -dicyclohexylsulfamid with β-cyclodextrin: Fluorescence, QTAIM analysis and structure-chemical reactivity

Current Status of Quantum Chemical Studies of Cyclodextrin Host-Guest Complexes

This article aims to review the application of various quantum chemical methods (semi-empirical, density functional theory (DFT), second order Møller-Plesset perturbation theory (MP2)) in the studies of cyclodextrin host-guest complexes. The details of applied approaches such as functionals, basis sets, dispersion corrections or solvent treatment methods are analyzed, pointing to the best possible options for such theoretical studies. Apart from reviewing the ways that the computations are usually performed, the reasons for such studies are presented and discussed. The successful applications of theoretical calculations are not limited to the determination of stable conformations but also include the prediction of thermodynamic properties as well as UV-Vis, IR, and NMR spectra. It has been shown that quantum chemical calculations, when applied to the studies of CD complexes, can provide results unobtainable by any other methods, both experimental and computational.

Encapsulation of thiabendazole in hydroxypropyl-β-cyclodextrin nanofibers via polymer-free electrospinning and its characterization

BACKGROUND

Thiabendazole (TBZ) is a poorly water-soluble benzimidazole fungicide. However, the water solubility of TBZ can be significantly enhanced by inclusion complexation with cyclodextrins. In this study, a thiabendazole/hydroxypropyl-β-cyclodextrin (TBZ/HPβCD) complex was synthesized and electrospinning was performed to produce a TBZ/HPβCD nanofibrous (TBZ/HPβCD-NF) complex that improved water solubility and antifungal activity.

RESULTS

The formation of TBZ/HPβCD-NF was characterized by Fourier transform infrared spectroscopy, X-ray diffraction and nuclear magnetic resonance. The morphology of TBZ/HPβCD-NF was studied by scanning electron microscopy. A phase solubility experiment showed that HPβCD exerted a great solubilization effect on TBZ, and TBZ/HPβCD-NF had better antifungal activity compared to that of TBZ alone.

CONCLUSIONS

In summary, the solid fungicidal nanodispersion prepared in the present study is a new type of formulation that can enhance the water solubility of TBZ. This formulation, which demonstrated potential as a new fast dissolving formulation type with increased efficacy, is expected to be conducive to the sustainable development of agriculture. © 2020 Society of Chemical Industry.

Evaluation of the molecular inclusion process of β-hexachlorocyclohexane in cyclodextrins

The present work aimed to study the guest-host complexes of β-hexachlorocyclohexane (β-HCH), a pesticide with high environmental stability that can cause severe health problems, with the most common cyclodextrins (α-, β-, and γ-CDs). The formation reactions of these molecular inclusion complexes were addressed in this research. The multiple minima hypersurface methodology, quantum calculations based on density functional theory and a topological exploration of the electron density based on the quantum theory of atoms in molecules approach were used to characterize the interaction spaces of the pollutant with the three CDs. Additionally, charge distribution, charge transfer and dual descriptor analyses were employed to elucidate the driving forces involved in the formation of these molecular inclusion complexes. Three types of fundamental interactions were observed: total occlusion, partial occlusion and external interaction (non-occlusion). Finally, experiments were performed to confirm the formation of the studied complexes. The most stable complexes were obtained when γ-CD was the host molecule. The interactions between the pesticide and CDs have fundamentally dispersive natures, as was confirmed experimentally by spectroscopic results. All the obtained results suggest the possibility of using CDs for the purification and treatment of water polluted with β-HCH.