Amplified chiroptic response in a multi-helical penta-perylene structure

Abstract

We report the synthesis of a 29-ring, multi-helical penta-perylene (diNPDH) that displays ECD across most of the visible spectrum and a g-factor ∼4x that of its mono-helicene parent. This electron deficient multi-helical penta-perylene exhibits an amplified, broadband chiroptical response across the visible spectrum. This unique structure was prepared by the fusion of perylene and perylenediimide (PDI). This heavily contorted nano-carbon molecule can be viewed as either a penta-perylene, a twice annulated double [6]helicene, a dimer of π-extended [7]helicenoids or as a centrally-annulated, cross-conjugated [7]twistacene. The chirality of the structure is induced by the helical units, and the electrochemistry is dominated by the PDI units. The molecule exists in three distinct, conformationally stable stereoisomers, all of which are accessible. This unique structure is electroactive and readily accepts eight electrons, one per imide.