The antiaromatic character of S2O2Iphs decreased in the order 1e > 1d > 1a > 1b > 1c, directly correlating with the structural changes driven by the substituent bulk. Unsubstituted (1e) and orthogonally substituted (1d) isophlorins maintained completely planar macrocycles with strong antiaromaticity. As the tilt angle decreased from 1a to 1c due to decreasing steric hindrance, the extent of π-conjugation between the substituents and the macrocycle increased, leading to weaker antiaromaticity. Our findings highlight the dual requirements for stable antiaromatic systems: electron-withdrawing groups are necessary to lower the HOMO energies and prevent oxidation, whereas their steric bulk influences the degree of antiaromaticity preservation.