An Overall Comprehension of Anti‐Aromatic Porphyrinoids Using 3D‐Graphical Chemical Shielding Description

A systematic investigation to rank the anti‐aromatic porphyrinoids is performed. Based on density functional theory calculations, four rules are summarized to obtain the highest anti‐aromatic porphyrinoids: 1) the replacement from meso‐C to meso‐(─C≡C─), 2) the replacement from pyrrole unit to inner‐N to inner‐O, 3) the replacement from two opposite meso‐C/N atoms to two pyrrole units, and 4) the replacement from one pyrrole ring to a carbonyl benzene ring. It is worth noting that the long chain with alternating single/double bonds is not beneficial or harmful to the anti‐aromaticity.