The reaction of single-component molecular crystal nanorods with a second species to form cocrystal nanorods is described. Single-component crystalline nanorods, composed of 9-methylanthracene (9-MA), are grown in a porous anodic aluminum oxide template. These templated rods are then exposed to a suspension of 1,2,4,5-tetracyanobenzene (TCNB) in water, which slowly diffuses into the 9-MA rods over the course of days. The two species form a 1:1 charge-transfer complex within the rods, which are transformed from crystalline 9-MA into cocrystalline 9-MA/TCNB. The cocrystal nanorods are characterized by electron microscopy, X-ray diffraction, and optical spectroscopy, confirming their highly crystalline structure and the formation of the charge-transfer complex. Attempts to grow cocrystal nanorods directly from a mixed solution were unsuccessful, as were attempts to recreate the single crystal-to-crystal reaction in macroscopic crystals. This work demonstrates how organic nanostructures can support structure-preserving chemical transformations that are impossible in larger crystals.

9,10-Dithioanthracene adsorbed on Cu(111) diffuses exclusively along the high-symmetry axis of the molecule-substrate system. Further reduction of the symmetry of the system by asymmetric methylation does not reduce the symmetry of the motion although it has a substantial effect on the diffusion rate (100-fold reduction) and renders the diffusion barrier asymmetric. This is in contrast to the behavior expected of a classical particle, and it provides a direct single-molecule-scale vista on the validity of The Principle of Microscopic Reversibility first formulated by Tolman in 1924, which despite its fundamental role has attracted little visualization.