Uniform and directional growth of centimeter-sized single crystals of cyclodextrin-based metal organic frameworks

Abstract

Although macroscopically-sized MOF crystals have proven of interest for efficient chromatographic separations, information processing, or optoelectronic devices, growing really large crystals has proven problematic and the largest reported monocrystals are only ca. 0.025 cm³ in volume. Here, we report a sequential vapour-diffusion/reseeding procedure that yields monocrystals of γ-cyclodextrin (γ-CD) MOFs with volumes reaching 1 cm³. With such large monoliths at hand, it is possible to physically block their certain faces and thus guide further growth only in desired directions, ultimately producing crystals of low-symmetry shapes and – upon “doping” with different additives at different stages of growth – with spatially varying compositions.