Synthesis, Structure, Spectral, Redox, and Theoretical Studies of Sterically Crowded Decaaryl Triphyrin(2.1.1)s

First examples of sterically crowded β- and meso-arylated decaaryl triphyrin(2.1.1)s were synthesized by reacting β-hexabromo meso-tetraaryl triphyrin(2.1.1) with five different aryl boronic acids in THF/toluene/H₂O (1 : 1 : 1) in the presence of catalytic amount of Pd(PPh₃)₄/Na₂CO₃ at 80 °C for 12-24 h. The X-ray structure obtained for one of the decaaryl triphyrin(2.1.1)s revealed that the macrocycle exhibited saddle type of distortion due to steric crowding by bulky aryl substituents introduced at the six β-carbons of meso-tetraaryl triphyrin(2.1.1) unlike almost planar structure observed for β-unsubstituted meso-tetraaryl triphyrin(2.1.1). The absorption bands of decaaryl triphyrin(2.1.1)s were broadened and bathochromically shifted compared to meso-tetraaryl triphyrin(2.1.1) and the redox potentials were dependent on the kind of aryl substituents present at the β-pyrrole carbons in decaaryl triphyrin(2.1.1)s. DFT and TD-DFT studies helped in understanding the alteration in the structure, spectral, and redox properties in decaaryl triphyrin(2.1.1)s compared to meso-tetraaryl triphyrin(2.1.1).