Preferred Formation of Minority Concomitant Polymorphs in 2D Self-Assembly under Lateral Nanoconfinement.

Control over polymorph formation in the crystallization of organic molecules remains a huge scientific challenge. Now, preferential formation is presented of one polymorph, formed by chiral molecules, in controlled two-dimensional (2D) nanoconfinement conditions at a liquid-solid interface. So-called nanocorrals to control concomitant polymorph formation were created in situ via a nanoshaving protocol at the interface between 1-phenyloctane and covalently modified highly-oriented pyrolytic graphite (HOPG). The preferentially formed polymorphs, which were less stable in the large-scale monolayers, could be selected simply by varying the orientation of the square nanocorrals with respect to the HOPG lattice.