DOI: https://doi.org/10.29363/nanoge.dynamic.2023.018
Publication date: 15th February 2023
The incorporation of molecular machines into the structure of porous frameworks facilitates the exciting potential for enhanced molecular transport, nano actuation and other out-of-equilibrium host-guest phenomena [1]. Recently, a diamine-based light-driven molecular motor has been incorporated into a series of imine-based polymers and covalent organic frameworks (COF) [2]. In this work, we extend advanced simulations to understand the structural and dynamic properties of this molecular motor building unit and its derived self-assembled solids.
Models of a crystalline 2D COF with stacked hexagonal layers were produced to match experimental reports. This COF contains ~20 mol-% molecular motors and features significant pore space with an experimentally determined pore volume of up to 0.45 cm3 g−1. We examined the ground state potential energy surface and how this is affected by the framework environment, given the molecular structure and bulkiness of the diamine motor. Our simulations demonstrate that intermolecular interactions from adjacent layers may not necessarily hamper or restrict motor movement and could even lead to fast rotor dynamics.
There are increasing reports of dynamic host-guest properties caused by the responsive dynamics of framework-embedded molecular motors. The simulation approach and in-depth structural characterization demonstrated here provide important access to the dynamics of these exciting materials. These findings are crucial to probe design criteria for the operation of molecular motors in porous solids to produce novel transport phenomena.