The crystals, Cu-AdDB, can be readily functionalized by immersion for several hours in a methanol solution containing a dye (sodium resorufin or methylene blue). The optical images of the colored crystals (Figure ), taken at a different focal plane, indicate the overall encapsulation of chromophores throughout the structure. MicroCT is used to visualize the inner structural features of the double-decker flowers (Figure ). The use of this method for analyzing micro-sized crystals is not often applied for such materials. A 3D reconstruction clearly showed a solid core connecting a pair of symmetrical flowers (Movie S1). Single-crystal X-ray diffraction measurements of five crystals confirm their single crystallinity. We analyzed two double-decker flowers, Cu-AdDB, and a larger structure found in a batch of Cu-AdDB as a minor product, observed by optical microscopy (Figure ). The single crystallinity is not obvious, considering the multidomain morphology. The three crystals were fully exposed to a relatively large X-ray beam of 100 μm. The diffraction patterns comprise distinct and separate reflections falling on the lattice planes (Ewald's sphere). No multiplicity or twinning is indicated, which we would have expected, based on the morphology. Another unique feature is the rare space group (P622) of our crystals. This achiral space group is one of the 65 Sohncke groups and allows a chiral arrangement of the molecular components. The three crystals were selected from two different batches. These crystals were found to be homochiral, although the starting materials were achiral; two crystals analyzed from the same batch had the opposite chirality. The near-zero values for the Flack parameters (F = 0.08 ± 0.12, 0.06 ± 0.07, -0.06 ± 0.04 and 0.09 ± 0.08) exclude the occurrence of inversion twinning. We have recently reported on crystallographically related structures having a concave "star"shaped morphology, and we ruled out the possibility of merohedral twinning as well. A cumulative intensity distribution plot also indicates the formation of non-centrosymmetric, single crystals (Figure ).