Fig. 2: Chiral hexagonal trapezohedral crystals.
From: Direct chiroptical correlation of dissymmetric crystal morphologies
Optical micrographs showing (A, B) Two crystals with opposite handedness, and C a racemic mixture, (scale bar: 50 μm).D Polar bipyramids: X-ray tomographs of enantiomorphs indicating that the top pyramid is shorter (h ≠ k, pink vertical) compared with the bottom (h = k, green vertical) (scale bar: 20 μm). E–G Optical microscopy of enantiomorphous bipyramids prepared by layering using different amounts of methanol. The degree of the morphological dissymmetry increases with decreasing the amount of methanol (v/v): 0%: 4.4° (±0.3), 5%: 2.5° (±0.5), 10%: 0.6° (±0.3) (scale bar: 25 μm). Optical images of the L-“twisted” crystals are shown in Fig. S6. H Images of crystals between crossed polarizers showing multiorder interference colors as a function of thickness. I Molecular structure of the dye. J Confocal fluorescence micrographs of crystals after adsorption with sodium resorufin (λεxc = 561 nm, λem = 583–650 nm). K, L Linear dichroism of crystals under polarized light after adsorption with sodium resorufin, (scale bar: 50 μm). M Scanning electron micrographs (SEM) of crystals obtained after solvothermal reaction and N) after aging for 20 h at room temperature. These crystals show an additional form {122} producing a concavity. The bipyramidal edge curves, highlighted by a rainbow of line segments, widen the angle at the apex (scale bar: 20 μm).
