On the Interplay Between Force, Temperature, and Electric Fields in the Rupture Process of Mechanophores

The use of oriented external electric fields (OEEFs) shows promise as an alternative method for catalyzing chemical reactions. The ability to target a specific bond by aligning it with a bond-weakening electric field may be beneficial in mechanochemical reactions, which use mechanical force to selectively rupture specific bonds. Previous computational studies have focused primarily on a static description of molecules in OEEFs, while the crucial influence of thermal oscillations on the stability of the molecules has been neglected. Here, we performed ab initio molecular dynamics (AIMD) simulations based on density functional theory (DFT) to investigate the behaviour of a model mechanophore under the simultaneous influence of thermal and electric field effects. We examine and compare the changes to the bond and its thermal oscillations in strong OEEFs at various temperatures, without and with mechanical stretching forces applied to the molecule. We show that the change in bond length caused by an electric field is largely independent of the temperature, both without and with applied mechanical force. The amplitude of the thermal oscillation increases with increasing field strength and with increasing temperature, but at low temperatures, the application of mechanical force leads to an additional increase in amplitude. Our research shows that methods for applying mechanical force and OEEFs can be safely combined and included in an AIMD simulation at both low and high temperatures, allowing researchers to computationally investigate mechanochemical reactions in realistic application scenarios.