Left: 5,10,15,20-tetrakis(1-butyl-6-uracyl)porphyrin; the sphere represents Zn(II) (ZnTUrP) or free base (TUrP). Right: 5,10,15,20-tetrakis(1-pyrenyl)porphyrin (TPyrP). The uracyl and the pyrenyl groups are orthogonal to the porphyrin plane and the mixture of the four atropisomers (αααα, αααβ, ααββ and αβαβ, as synthesized) was used.