The double-decker flowers were formed by reacting the organic ligand (AdDB; Figure ) and two equivalents of Cu(CH3COO)2•H2O under solvothermal reaction conditions (DMF/CHCl3, 3:1 v/v) at 105 °C for 2 days, followed by controlled cooling to room temperature (16°C/h). The optical and scanning electron microscopy (SEM) images clearly show that most of the resulting crystals have a double-decker flower-like morphology with two size-asymmetric decks joined at the center (Figure ). Although the decks have different dimensions, they have a similar structure. Each deck has a multi-domain appearance consisting of 6 well-defined petals with curved lateral surfaces. Optical microscopy showed that the crystal size (l = 172 µm, w = 25 µm) varies widely (Figure ). Remarkable anisotropies were observed after analyzing the morphological details of single structures at selected reaction time intervals (Figure , S1-S4, t = 0h -48h). Optical microscopy of the samples at t = 0h shows two areas: needle-like rods and small clusters. Green hexagons among other morphologies were observed by optical microscopy after 4 hours (Figure , S1). SEM images of the same sample provide more details about these structures: (i) by imaging the structures from a lateral perspective, it is possible to observe dome-type morphologies; (ii) the hexagonal profile that appears with an optical microscope on closer inspection at higher magnification is actually an irregular dodecagon, as the "hexagon" tips are cut by short (about 1 µm) perpendicular facets; (iii) the size and shape (⌀ ≈ 11.6 µm) is comparable with those of the central domain (⌀ ≈ 18.1 µm) observed in the final double-decker flowers. After 6 h, all the above structures are no longer visible (Figure ). Green double-decker flowers are evident, six petals on each side. At t = 6h, the petals are formed from 4 to 6 lateral straight planes (Figure ). After 24 -48 h, the petals are markedly large and appear rounded in the final double-decker flowers (Figure ). Moreover, we observed that: (i) the two decks of a single crystal can have markedly different sizes (Figure indicating that a similar mechanism is operating. Scanning Electron Microscopy -Energy Dispersive X-ray Spectroscopy (SEM-EDS) indicates that the needle-like rods observed at t = 0h contain mainly carbon from the ligand (AdDB). Copper appears separately in small clusters of unreacted metal salt. No chlorine is seen at this stage (Figure ). Needle-like crystals have been previously observed by us and were characterized by Single Crystal X-ray Diffraction (SCXRD) as the AdDB ligand. SEM-EDS measurements of the hexagons (t = 4h) and of the double-decker flowers (t = 48h) reveal a metalligand composition (Figure ).