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How to cite this paper: Tsalu, P.V., et al. (2016) In the meso-substituted case, the external and internal twists C β -C α -C meso -X and N-C α -Cmeso-X, re-P. V. Tsalu et al. 2 spectively are oppositely orientated. Similar effect is observed in meso-unsubstituted of C β -C α -C meso -H and N-C α -C meso -H. However, the external distortions are more significant than internal. Considering the same order, the limit of distortions is [97˚ and 132˚ (−48˚)] for external and [91˚ (−89˚) and 52˚] for internal. In the two cases, the substituents have opposite directions of distortions. The meso-substituted porphyrins have a high limit of twisting than usubstituted one, depending of the weight of substituents. The average of the bond angular deformations is 168˚, almost planar. However, the limit of angular deformation is 94˚.