Theoretical Investigation on Inclusion Complex of (s)-2-Isopropyl-1-(o-nitrophenyl) Sulfonyl) Aziridine with β-Cyclodextrin

The present work aims to study the theoretical chemistry applied to organic systems such as host/guest inclusion complexes. In literature, different molecular modeling computational methods have been used to study the complexation of the host β-cyclodextrin molecule (β-CD) with the guest (S)-2-Isopropyl-1-(o-nitrophenyl) sulfonyl) aziridine molecule (AZ). Among such methods are semiempirical (PM3) and Density Functional Theory (DFT) calculations in gas and aqueous phases. The present paper focuses on complexation, interaction, deformation energies determination, besides geometries, electronic structure, and chemical reactivity to describe the changes of AZ during encapsulation in two phases and at two orientations. Long-range corrected hybrid functional (WB97X-D/6-31G (d) basis) was used and the results clearly indicate that the formed complex is energetically preferred in both phases. The orientation in which the guest molecule pointed toward the secondary hydroxyls of β-CD showed good compatibility with the experimental results. The Natural Population Analysis (NPA) charges obtained from NBO analysis were used in order to find out the possible coordination modes of the AZ compound with β-CD. Natural bond orbital analysis (NBO) and Non-covalent interaction (NCI) analysis were performed on the β- CD/AZ complex to understand the different interactions. The 1H nuclear magnetic resonance (NMR) of the complex was studied using the Gauge-Including Atomic Orbital (GIAO).