Synthesis and Properties of Butterfly-Shaped Fluorenyl-Vinyl Diketopyrrolopyrrole Derivatives

This study presents a novel stepwise synthetic strategy involving an intramolecular Scholl reaction, successfully achieving the synthesis of butterfly-shaped fluorenyl-vinyl DPP (R-Flu) derivatives. These compounds showed a wider absorption range from 400 to 700 nm, featuring dominant absorption peaks at 569 nm, resulting from the enhanced intramolecular charge transfer (ICT) through the spiral chiral structure. The molecular configurations were further confirmed by X-ray crystallographic analysis, revealing X-type stacking by PP/MM isomers with an ultra close π–π distance of approximately 3.3 Å. The optical and electrochemical properties of the compounds were systematically characterized, providing a foundation for the design of new DPP-based functional materials.