A Comparative Theoretical Study of Picric Acid and Its Cocrystals

A novel cocrystal of picric acid/acetophenone was prepared by solvent evaporation method and the crystal structure was characterized by single crystal X-ray diffraction. Analysis of the crystal structure shows that the hydrogen bonding, van der Waals and π-π stacking are the main driving forces for the cocrystal formation. Density functional theory (DFT) calculation was performed to better understand the formation mechanism and properties of the cocrystal. The results suggest that π-π stacking is more important than hydrogen bonding considering their interaction energies. Furthermore, Mulliken charge analysis shows picric acid becomes less sensitive after cocrystallization with other compounds because of the electron transfer.