T mainly corresponds to the C2 antisymmetric LUMO of naphthalene, while the symmetric orbital transforming to the HOMO of the closed form through the conrotatory mechanism appears at higher energy (LUMO+1 in Figure ). As a result, molecules based on this The symmetry of the LUMO around the C2 axis at the hexatriene moiety can be enforced by the appropriate choice of backbone substitution. In particular, the (local) symmetry at the fusing CC backbone of the substituent can be used to induce the necessary C2 symmetry of the LUMO and antisymmetry of the HOMO, providing the necessary driving force for efficient photocyclization. In the case of naphthalene, the LUMO presents antibonding p-interactions at the terminal zigzag CC bonds. Therefore, coupling the naphthalene unit at this position in T-