Research Projects

Helical chirality in porphyrinoid chemistry is a less explored area due to its intriguing properties associated with photophysical features. Expanded porphyrinoids with a minimum of eight cyclic units reduce bond angle strain by undergoing two half twists (T20), exhibiting intrinsic helical chirality. Vogel and coworkers synthesized a figure of eight Octaphyrin-(1.0.1.0.1.0.1.0) in 1995, but the enantiomers could not be separated. In 1999, the same group separated the figure of eight enantiomers from chiral High-Performance Liquid-Chromatography (cHPLC) on a preparative scale and showed mirror image cotton effects. The low racemization energy barrier in structurally flexible macrocycles hampers optical resolution, and there is a need to synthesize conformationally/configurationally stable twisted porphyrinoids. Studies into circular dichroism (CD) properties are yet to be explored for essential applications. This proposal aims to target the correlation between CPL and CD intensities and the structure-chiroptical property relationships of rigid π-systems, including various conformationally rigid, configurationally stable, and flexible macrocycles. The incorporation of various PAHs (pyrene, anthracene, flourene, spirobifluorene, carbazole) with various coupling strategies enables fine tuning of optical absorptive features of resulting twisted and configurationally stable macrocycles.