Fig. 1. Ligands in the porphyrin rings under study. (a) H, (b) F, (c) OH, (d) NH2, (e) CH3, and (f) BH2. Rings with F, OH and BH2 ligands generally exhibit the typical flat configuration of metalloporphyrins with H ligands, whereas NH2 and CH3 ligands introduce large distortions. In all cases, the MN4 complex made of four nitrogen atoms and a transition metal atom (M) is in a square planar arrangement. Porphyrins with –H ligands and ORR/OER adsorbates are also shown: (g) *O; (h) *OH; (i) *OOH.
