Highly varied reaction cavities within a single molecular crystal

Abstract

Due to the challenges associated with the systematic study of reaction cavities, the role of reaction cavities on the reactivity of molecular solids has often been built upon presumption. The incomplete understanding has thus led to numerous instances where modeling has proved ineffective. In response, this work systematically assessed five highly varied cavities of tetracene crystals, which could be generated at the different facets of the crystal. The relative kinetics for the cavities were measured via energy dispersive X-ray spectroscopy for the reaction of tetracene with vapors of maleic anhydride, and the effects were understood via molecular dynamic simulations. Steric effects on the reactivity were consistent with the postulated models for molecular cavities, though they required fine levels of structural detail to explain the experimental trends. The stabilization effects ranged from confinement to prepositioning of the reactant to accelerate a reaction, with the latter result not dissimilar to the active sites in enzymes. The measured stabilization effects highlight the need for the field of solid-phase chemistry to incorporate these in models and suggest the potential for a greater degree of control over reactivity in the solid phase than has been previously reported.