“…The aromaticity of various porphyrinoids has been actively investigated. − Porphyrinoids are excellent scaffolds for achieving effective macrocyclic π-conjugation, thus enabling aromaticity in Möbius π-systems, , large macrocycles, and macrocycles that contain metallocene units. − Among various porphyrinoids, the macrocyclic aromaticity and antiaromaticity of 10-heterocorroles are sensitive to the heteroatoms incorporated at the 10-position, thus highlighting the important role that the heteroatoms play in the cyclic conjugation (Figure ). − While a lone pair on either nitrogen (X = N), , oxygen (X = O), , sulfur (X = S), , phosphorus (X = P), or selenium (X = Se) in conjunction with the 16π-conjugation of the bis(dipyrrin) unit leads to macrocyclic 18π-conjugated aromatic systems, 10-boracorrole (X = B) exhibits a unique form of global antiaromaticity due to the vacant p orbital on the boron atom, which affords a 16π-conjugated system. 10-Silacorrole (X = Si) shows no global antiaromaticity because the sp 3 -hybridized silicon atom disrupts the macrocyclic π-conjugation.…”