Synthesis and Studies of Meso‐Triaryl Trithiapentaphyrin(2.2.1.1.1)s

Three examples of meso ‐triaryl trithiapentaphyrin(2.2.1.1.1)s 1 – 3 (Figure 1) that contains three thiophenes and two pyrrole rings connected via seven meso ‐carbons were synthesized by condensing newly synthesized benzo‐fused trithiatripyrrane diol and appropriate meso ‐aryl dipyrromethane under mild acid catalysed conditions in 5–8 % yields. In these macrocycles, two of the meso ‐positions were fused with the benzene rings and the DFT optimized structural analysis revealed that the macrocycles adopt saddled conformation with the two thiophene rings oriented towards outside the macrocyclic core. HR‐MS and detailed 1D & 2D NMR studies were used in deducing the molecular structures of the macrocycles and NMR studies support their nonaromatic nature. The macrocycles exhibit one strong sharp absorption band at ~430 nm and a broad band in the region of 550–850 nm which were further red‐shifted to NIR region in their protonated derivatives. The macrocycles exhibit two reversible oxidations and one reduction and the redox data revealed that the macrocycles were easier to oxidize and were electron‐rich.