To further investigate the effect of meso-substituents on planarity, we performed geometry optimizations of 1d and its meso-free analog 1e. Unlike 1a-1c, 1d and 1e exhibited perfectly planar structures with zero mpd. This demonstrates that aryl substituents at the meso-positions reduce the planarity of isophlorins thus decreasing their antiaromaticity. The degree of planarity depends on substituent bulkiness, with the sterically demanding 2,6dichlorophenyl groups in 1d adopting an orthogonal orientation relative to the isophlorin macrocycle, thus minimizing their effect on planarity. For the unsubstituted isophlorin (1e), both our calculations and those of Valiev et al. showed a completely planar structure without imaginary frequencies.