Theoretical investigation of the complexation, structural, and electronic properties of complexes between oseltamivir drug and cucurbit[n = 6–9]urils

• Published in: Structural chemistry 2022-06, Vol.33 (3), p.757-768
• Main Authors: Rakrai, Wandee, Tabtimsai, Chanukorn, Kaewtong, Chatthai, Wanno, Banchob
• Format: Article
• Language: English
• Subjects: Analysis; Aqueous solutions; Atomic properties; Charge transfer; Chemical bonds; Chemistry; Chemistry and Materials Science; Complexation; Computer Applications in Chemistry; Density functional theory; Density functionals; Dipole interactions; Energy gap; Hydrogen; Hydrogen atoms; Hydrogen bonding; Hydrogen bonds; Investigations; Mathematical analysis; Molecular orbitals; Original Research; Oseltamivir phosphate; Oxygen atoms; Physical Chemistry; Supramolecular compounds; Theoretical and Computational Chemistry
• ISSN: 1040-0400; 1572-9001
• DOI: 10.1007/s11224-022-01888-1

The structural geometries of cucurbit[ n ]uril CB[n] with n  = 6–9 and their complexes with oseltamivir (OST) drug were obtained using the density functional theory computations. The stationary points of the most stable complexes were confirmed using vibrational frequency calculation. The complexation energies and electronic properties of CB[ n ]/OST complexes were investigated. The calculated results indicate that the intermolecular interactions in all the studied complexes occur via a large number of dipole–dipole interactions, especially hydrogen bonds between oxygen atoms of CB[ n ] and hydrogen atoms of amine of oseltamivir drug. The negative complexation energies of CB[ n ]/OST complexes in both gas and water phases indicate that the host–guest complexes are exothermic process and the complexes are more stable than its bare CB[ n ]. In addition, the CB[7]/OST complex is more stable than that of all studied CB[ n ]/OST complexes. The frequency calculation results of the most stable complexes for each of CBs indicate that complexations occur via a spontaneous process. The NBO analysis of complexes shows the transferring of partial charge from CB[ n ]s to oseltamivir which correspond to their MEP contours. The HOMO and the LUMO orbitals are localized on the oseltamivir in CB[ n ]/OST complexes. After drug complexation, the electronic properties also display that the energy gaps of CB[ n ] are significantly changed. All of the complexation properties point out that CB[ n ]s can act as a host for appropriately oseltamivir guest, even in aqueous solution.