Controlling the crystal morphology of one-dimensional tunnel structures: induced crystallization of alkane/urea inclusion compounds as hexagonal flat plates

We propose a general strategy for controlling the crystal morphology of tunnel inclusion compounds in order to induce crystal growth as flat plates rather than long needles. The strategy employs additive molecules designed to selectively inhibit crystal growth along the tunnel direction. The successful application of this strategy is illustrated by the induced crystallization of alkane/urea inclusion compounds as hexagonal flat-plate crystals using 5-octadecyloxyisophthalic acid as the selective crystal growth inhibitor (in the absence of inhibitor, alkane/urea crystals grow spontaneously as long hexagonal needles).