Deciphering Electronic Structures of the Crystal-Solvent Interface to Unveil the Formation Mechanism of Polymorphic Molecular Crystals

It is well known that crystals of an organic molecule may be different in their internal packing motifs. The polymorphic crystal structures can be developed typically by the crystallization in different solvents. Our goal of this one-year project is to understand the fundamental mechanism of polymorphic formation with respect to solid-solvent interactions on the crystal-solvent interface. Our hypothesis is that there must be a match of electronic structures along the interface between the crystal surface of a specific polymorph and adsorbed solvent molecules. We believe this key-lock match is a result of reconciliation of the internal energy of a polymorphic structure and the crystal-solvent interactions. As a result, the match gives rise to the unique packing of internal structures. To test our hypothesis, we will calculate and analyze electronic structures of the crystal-solvent interface of selected polymorphic drug crystals including acetaminophen with high-performance quantum mechanical methods. p:\faculty grants and programs\new investigators program\04-05\applctn\forms.doc--1/21/04