Mechanically Driven Reactions with Graphene: A Tale of Two Reaction Coordinates; James D. Batteas, Texas A&M University

While the effects of light (photochemistry), electric charge (electrochemistry), and heat (thermochemistry) on chemical reactivity are well-understood, the way in which mechanical force alters reaction energies and pathways – mechanochemistry – is far less developed. As a controlling synthetic input however, force has the compelling and exciting potential to open up new avenues in chemical synthesis, and there are numerous examples of materials that cannot be synthesized by other means. Additionally, as mechanochemical reactions can frequently be carried out at lower temperatures and under solvent free conditions, they offer the potential for more sustainable approaches to chemical synthesis. Fundamentally, mechanically driven reactions occur at the buried interfaces between surfaces, where the compressive and shear forces imposed by the surfaces confine molecules between them and conspire to alter the reaction energy landscape, with the mechanics of these confined contacts, and the distribution of applied stresses being paramount in accelerating reaction and controlling selectivity. To explore these concerted effects, we have sought to simplify the problem, and have studied how the application of mechanical forces influence the reactions of 4-nitro-benzenediazonium tetrafluoroborate (4-NBD) and perfluorophenylazide (PFPA) with graphene to determine how the applied forces, and their direction, impact the chemical reactivity of these species with this well-defined surface.