Methods for the crystallization of nano-size crystals of molecular organic compounds while operating at a low supersaturation. The methods are based on controlling the domain size available during... Show moreMethods for the crystallization of nano-size crystals of molecular organic compounds while operating at a low supersaturation. The methods are based on controlling the domain size available during the crystallization process. In one exemplary method, microcontacted printed self-assembled monolayers (SAMs) with local domain area sizes ranging up to 2500 .mu.m.sup.2 and fabricated SAMs generated from electron beam lithography, are employed to control the size, orientation, phase, and morphology of the crystal. In another exemplary method, a continuous micro-crystallizer having a vessel diameter of 25 microns or less is used to ensure that that the maximum size of the crystals in at least one dimension, ad preferably two dimensions is constrained by the vessel itself. The methods allow control of supersaturation and growth conditions, as well as manageability over crystallinity and polymorphism, and each method's domain size has the potential for further reduction. Show less