Using oriented external electric fields to manipulate rupture forces of mechanophores.

Oriented external electric fields (OEEFs) can facilitate chemical reactions by selectively weakening bonds. This makes them a topic of interest in mechanochemistry, where mechanical force is used to rupture specific bonds in molecules. Using electronic structure calculations based on density functional theory (DFT), we investigate the effect of OEEFs on the mechanical force required to activate mechanophores. We demonstrate that OEEFs can greatly lower the rupture force of mechanophores, and that the degree of this effect highly depends on the angle relative to the mechanical force at which the field is being applied. The greatest lowering of the rupture force does not always occur at the point of perfect alignment between OEEF and the vector of mechanical force. Using natural bond orbital analysis, we show that mechanical force amplifies the effect that an OEEF has on the scissile bond of a mechanophore. By combining methods to simulate molecules in OEEFs with methods applying mechanical force, we present an effective tool for analyzing mechanophores in OEEFs and show that computationally determining optimal OEEFs for mechanophore activation can assist in the development of future experimental studies.