Dibenzothiophene-Containing Thiacarbaporphyrinoids

A new type of expanded dibenzothiophene-containing thiacarbaporphyrinoid containing one dibenzothiophene, two p-phenylene, one thiophene, and two pyrrole rings connected via four meso carbons and two direct bonds was synthesized over a sequence of six steps starting with commercially available dibenzothiophene. The X-ray structure obtained for one of the macrocycles revealed that the macrocycle was very nonplanar and the two p-phenylene rings and dibenzothiophene unit were deviated from the mean plane, whereas the thiophene ring attained inverted conformation and was facing toward outside the macrocyclic core. The X-ray structure also revealed that the dibenzothiophene unit of the macrocycle maintained its π-electron delocalization and did not extend the π-electron delocalization with the rest of the macrocycle, and the effective π-conjugation was present only in the lower part of the macrocyclic core, i.e., the thiatripyrrin moiety. The spectral and theoretical studies support the nonaromatic nature of the macrocycles. The macrocycles exhibit one strong absorption band at ∼430 nm and one broad absorption band in the 500-800 nm region, which were bathochromically shifted in diprotonated derivatives which absorb strongly in the visible-NIR region. The electrochemical studies indicated the electron-rich nature of the macrocycles and the theoretical studies corroborated the experimental observations.