title: Controlling molecular crystal polymorphism with self-assembled monolayer templates.
abstract: The control of crystal polymorphism is a long-standing issue in solid-state chemistry, which has many practical implications for a variety of commercial applications. At least four different crystalline forms of 1,3-bis(m-nitrophenyl) urea (MNPU), a classic molecular crystal system, are known to crystallize from solution in various concomitant combinations. Herein we demonstrate that the introduction of gold-thiol self-assembled monolayers (SAMs) of substituted 4'-X-mercaptobiphenyls (X = H, I, and Br) into the crystallization solution can serve as an effective means to selectively template the nucleation and growth of alpha-, beta-, and gamma-MNPU phases, respectively. Polymorph control in the presence of SAM surfaces persists under a variety of solution conditions and consistently results in crystalline materials with high phase purity. The observed selectivity is rationalized on the basis of long-range two-dimensional geometric lattice matching and local complementary chemical interactions at the SAM/crystal interfaces.
authors.affiliation: Department of Chemistry, Georgetown University, 37th and "O" Streets NW, Washington, DC 20057-1227, USA.
authors.forename: Rupa
authors.initials: R
authors.lastname: Hiremath
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Basile
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Varney
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Swift