Fig. 4: Single crystal packing model.

Crystal packing of DPA[3] (a) and DPA[4] (b) and intermolecular interaction of DPA[3] (edge to face π–π stacking, c) and DPA[4] (offset π–π stacking, d).
Crystal packing of DPA[3] (a) and DPA[4] (b) and intermolecular interaction of DPA[3] (edge to face π–π stacking, c) and DPA[4] (offset π–π stacking, d).