Controlling molecular photoisomerization mechanisms in confined space is key for the development of active materials, light-powered molecular machines and, in general, for mimicking the fidelity of nature in controlling molecular reactions under confinement. Molecular Pd-based cages were recently studied as hosts for light-switchable azobenzene-based guests that can switch in their interior when excited by light. The confinement of the Azobenzene-guest causes the slow down of trans-to-cis transition, or can even impede their isomerizatzion in their interior. The stability of the trans and cis host-guest complexes represent a fundamental descriptor for the characterization of these systems. Molecular dynamics-based simulations allow to characterize the mechanism and kinetics of isomerization inside the cages, providing a clear understanding of the molecular determinants controlling such systems. In particular, we used enhanced sampling methods allowing us to study the dynamics of rare isomerization events in the confined interior of the cages, where the process is constrained. Striking differences could be reproduced in the isomerization kinetics and in the stability of different Azobenzene derivatives, providing a complete molecular picture of the guest encapsulation and guest reactivity under confinement. Such a detailed study of the mechanism and dynamics of azobenzene isomerization in such confined conditions opens the way toward a rational design of controllable switchable systems that can be in principle controlled by controlling the flexibility and cavity of the cage.

Atomistic-scale modeling of azobenzene photoisomerization in the confined cavity of molecular cages

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.