A computational study of competing conformational selection and induced fit in an abiotic system.

Host-guest complexations can be described by two competing mechanisms, conformational selection (CS) and induced fit (IF). In this work, we used a combination of nudged elastic band (NEB), adaptive steered molecular dynamics (ASMD), and density functional theory (DFT, with a correction for dispersion) to study the dynamics of the pathways (IF/CS) by which two conformers of basket B(+) and B(-) interconvert and trap CX 4 guests (X = Cl and Br). While the results from NEB/DFT studies disclosed host-guest noncovalent contacts reducing the basket's conformational dynamics, ASMD methodology suggested an associative mechanism for the guest complexation. With theory in excellent agreement with experiments, NEB and ASMD emerge as the methods of choice for studying dynamics of supramolecular systems.