The geometry-optimized structures of S2O2Iphs (1a-1c) were obtained at the cam-B3LYP/6-311G(d,p) theory level, and are shown in Figure -c exhibiting saddle-type distorted structures. Figure -g shows the skeletal deviations of the macrocycle atoms from the mean plane defined by the 24 core atoms. The analysis revealed decreasing planarity (1a > 1b > 1c) with the thiophene rings showing larger deviations from the mean plane than the furan rings in all compounds. The mean plane deviation (mpd), which serves as an index of planarity, followed the order 1a (0.223) < 1b (0.303) < 1c (0.354). The tilt angles between the meso-substituents and the mean plane of the isophlorin macrocycles decreased (1a (63.0°) > 1b (52.1°) > 1c (51.7°)) correlating with the steric bulkiness of the substituents and mpd values.