Structural isomers of di--benzidithiaoctaphyrins.

The and structural isomers of di--benzidithiaoctaphyrins were synthesized by adopting two different synthetic routes using readily available precursors under acid-catalyzed conditions, and the isomers were separated using basic alumina column chromatography. 1D and 2D NMR spectroscopy were used to deduce the molecular structures of the macrocycles, which also helps to differentiate the isomer from the isomer. DFT studies revealed that both the and isomers adopt figure of eight conformations but exhibit clear differences in their structural features, and the isomer is more distorted than the isomer. Experimental and theoretical studies revealed that both the and isomers are nonaromatic stable macrocycles and show subtle differences in their structure, spectral and redox properties. The and isomers of di--benzidithiaoctaphyrin exhibit nonaromatic absorption features in the visible-NIR region, and electrochemical studies revealed their electron-rich nature. TD-DFT studies are in agreement with the experimental observations.