Elucidating the structures and binding of halide ions bound to cucurbit[6]uril, hemi-cucurbit[6]uril and bambus[6]uril using DFT calculations

Abstract

Understanding the binding and nature of the interactions present in host–guest complexes are central to supramolecular chemistry. In this paper, we tried to understand the nature of bonding between halides and three related host molecules using density functional theory. We have addressed a number of issues such as the role of solvation, the role of cations and the use of appropriate density functional calculations that are crucial for modeling host–guest complexes. Calculations show that the binding of halides in cucurbit-[6]-uril is assisted by a cation, whereas in hemi-cucurbit-[6]-uril, it is assisted by solvents. AIM calculations reveal the nature of non-bonded interactions present in these host–guest complexes and in particular brings out the two types of hydrogen bonding present in hm-CB-[6] and BU-[6] complexes.