# Guest Binding Mechanism of Polycyclic Aromatic Hydrocarbons by Au(I) Metallo-Tweezers Revealed by Computation

## TL;DR

This study uses computation to reveal how polycyclic aromatic hydrocarbons bind to gold-based molecular tweezers, uncovering a dynamic process involving cavity reshaping and guest molecule positioning.

## Contribution

The study reveals a novel dynamic binding mechanism involving spontaneous rotations of the host's polyaromatic panels to accommodate guest molecules.

## Key findings

- Calculated binding Gibbs energies align well with experimental results, validating computational approaches.
- The host's polyaromatic panels undergo spontaneous rotations to modulate cavity shape for guest binding.
- A complete rotation around carbon-Au bonds positions the guest molecule in the cavity core.

## Abstract

Revealing the mechanisms
of supramolecular host–guest
binding
holds crucial elements for exploring the full potential of supramolecular
structures and can lead to further designs and optimizations. Here,
we present a computational study of how polycyclic aromatic hydrocarbons
(PAHs) bind to a tweezer-shaped molecular receptor (Au­(I) metallo-tweezers)
in organic solvents. First, the structure and dynamics of the gold
tweezers in solution are characterized with and without the guest
molecule bound in the cavity. Second, the guest-binding process is
investigated by means of metadynamics simulations. We found that the
calculated binding Gibbs energies are in very good agreement with
the experimental results, showing the viability of these approaches
in the field. Importantly, the study reveals an unanticipated dynamic
process that involves spontaneous rotations of the polyaromatic panels
of the host, which modulate the size and shape of the cavity until
an effective face-to-face arrangement with the planar guest occurs.
Once such an interaction occurs, a complete rotation around the carbon-Au
bonds finally locates the planar guest molecule in the core of the
cavity. This mechanism highlights the variety of dynamic processes
that the rich chemical space of supramolecular chemistry can offer.