β‐Heptasubstituted Porphyrins: Synthesis, Structural, Spectral, and Electrochemical Properties

A new series of β‐heptasubstituted porphyrins MTPP(NO 2 )(Me) 6 (M = 2H, Co II , Ni II , Cu II , and Zn II ) was synthesized and characterized by various spectroscopic techniques. The single‐crystal X‐ray structure analysis of CoTPP(NO 2 )(Me) 6 revealed the significant saddle distortion of the macrocyclic core from the porphyrin mean plane (Δ C β = 0.928 Å). These porphyrins exhibit significant redshifted electronic spectral features (Δ λ max = 40–62 nm) as compared with MTPP due to the combined effect of the nonplanar conformation of the macrocyclic core and mixed β‐substituents. H 2 TPP(NO 2 )(Me) 6 has shown a high dipole moment (7.12 D) as compared with H 2 TPP (0.052 D) due to cross‐polarized push–pull substituents. The redox tunability was achieved by appending the electron‐donating methyl and electron‐withdrawing NO 2 group at the β‐positions of the porphyrin skeleton.