Complexation of metal cations (mono-, di- and trivalent) to cucurbiturils: Insights from a DFT/SMD study
Recently, supramolecular complexes based on synthetic macrocyclic host molecules have received much attention due to their broad applications as drug delivery carriers, biological and chemical sensors, light-emitting materials, bioimaging agents, etc. Cucurbit[n]urils are cavitands known for their high affinity for various guest molecules, although some aspects of their coordination chemistry remain enigmatic. They are still not tested as metalloenzyme models and not much is known about their metal-binding properties. Furthermore, there is no systematic study on the key factors controlling the processes of metal coordination to these systems. In the
computational study herein, DFT molecular modeling has been employed in order to investigate the interactions of biologically essential mono- (Na+), di- (Mg2+) and some trivalent (La3+, Lu3+) metal cations to cucurbit[n]urils and evaluate the major determinants shaping the process of recognition. The thermodynamic descriptors (Gibbs energies in the gas phase and in a water medium) of the corresponding complexation reactions have been estimated. The results obtained shed light on the mechanism of host–guest recognition and disclose which factors more specifically affect the metal binding process.