Interactions in inclusion complex of β-cyclodextrin/l-Metheonine: DFT computational studies

In the present work, the host–guest complexation between l-Metheonine/β-Cyclodextrin was investigated using the DFT/B97-D3/6-31G (d) level of the theory. The results obtained clearly indicate that the Orientation B (the carboxylic group of l-Metheonine points toward the primary hydroxyl of β-CD) is energetically favored than that one of the Orientation A (the carboxylic group of l-Metheonine points toward the secondary hydroxyl of β-CD). The energy decomposition analysis, thermodynamic parameters, HOMO, LUMO, the global reactivity descriptors and non covalent interactions-reduced density gradient analysis of the two complexes were calculated and interpreted. The QAIM theory has been used to examine the properties of the bond critical points. Finally, the 1H nuclear magnetic resonance (NMR) chemical shift of the complexes was studied using the Gauge-Including Atomic Orbital (GIAO) method and compared with experimental values. The structures of inclusion complexes of l-Metheonine@β-CD.