ANBA and PABA crystallized with a single molecule per asymmetric unit and almost orthogonal dihedral angles between the anthracene plane and the aromatic substituents: 82.84(4)° for ANBA; 87.5 and 83.1(2)° for PABA (Figure ). PFPA crystallized with two molecules per asymmetric unit and the aromatic substituent is oriented at 77.2(1)° with respect to the anthracene plane. One O-H•••O hydrogen bond links together the two conformers present in the asymmetric unit and a non-classical intermolecular H bond (C-H•••F) was observed (Figure ). PABA-O2 showed loss of planarity in the central ring of the anthracene unit due to the formation of the O-O bond with the C atoms bound to the substituents that, instead, maintain their orientation (Figure ). Moreover, its crystalline and calculated structures overlap significantly, suggesting no major differences between the conformation of the EPO as a solid and in solution. In the case of naphthalene derivatives, the crystal structure of NABA was found to match previously published data (Figure ), displaying a dihedral angle of 46.8°. Interestingly, PNBA crystallized adopting six different conformers (Figure ). In accordance with DFT calculations and experimental data, the relative orientation of the substituents should be more favorable for anthracene derivatives, empowering the choice of the target candidates.