Displacement of the two FMOs away from the pro-cyclic carbons would invalidate the WH rules, i.e., the orbital diagram in Figure does not apply, and hinder the photoinduced molecular cyclization (affecting the quantum yield). In these compounds, the π*-type orbital located on the cyclopentene unit appears at higher energies, either the LUMO+2 or LUMO+4, and hardly mixes with the orbitals from the side groups (Figure ). Interestingly, when the thiophene unit and the phenyl ring are fused in TfPh in contrast to TPh, where they are linked by a single bond, the LUMO preserves the π*-type character at the cyclopentene unit, which is expected to facilitate the electrocyclic ring closure. Although N-substitution in the two thiophenes of DTE in TNPh-CP-TNPh stabilizes the π*-type orbital of the cyclopentene unit (Figure ), such stabilization is not enough to compensate for the side chain conjugation, and the LUMO also localizes on the side groups.