The steric bulkiness of substituents significantly influences the tilt angle relative to the isophlorin plane. Smaller tilt angles enhance π-electron perturbation between the isophlorin and aryl substituents, potentially reducing antiaromaticity through contributions from nonaromatic resonance structures. Molecular orbital (MO) analysis revealed that 1c, with its smaller tilt angle, exhibited delocalized molecular orbitals extending across the molecule with more extensive π-conjugation toward the meso-substituents (Figures and). In contrast, compounds with larger tilt angles showed more localized π-conjugation. This computationally predicted extension of π-conjugation in 1c is further corroborated by the observed bathochromic shifts and spectral broadening in its absorption spectrum. The MO energy diagrams of 1a-f (Figure ) show that the HOMO energies of 1d-f were substantially higher than those of the isolated compounds 1a-c. This explains the instability of 1d-f toward oxidation and highlights the importance of electron-withdrawing substituents in stabilizing isophlorins.