Pentacene-Bridge Interactions in an Axially Chiral Binaphthyl Pentacene Dimer.

Molecular chirality can be exploited as a sensitive reporter of the nature of intra- and interchromophore interactions in π-conjugated systems. In this report, we designed an intramolecular singlet fission (iSF)-based pentacene dimer with an axially chiral binaphthyl bridge (2,2'-(2,2'-dimethoxy-[1,1'-binaphthalene]-3,3'-diyl) -octyl-di-isopropyl silylethynyl dipentacene, ) to utilize its chiroptical response as a marker of iSF chromophore-bridge-chromophore (SFC-β-SFC) interactions. The axial chirality of the bridge enforces significant one-handed excitonic coupling of the pentacene monomer units; as such, exhibits significant chiroptical response in the ground and excited states. We analyzed the chiroptical response of using the exciton coupling method and quadratic response density functional theory calculations to reveal that higher energy singlet transitions in involve significant delocalization of the electronic density on the bridging binaphthyl group. Our results highlight the promising application of chiroptical techniques to investigate the nature of SFC-β-SFC interactions that impact singlet fission dynamics.