Foldamer with a spiral perylene bisimide staircase aggregate structure

Abstract

Although the precise control of dye–dye interactions is known to be of fundamental importance to achieve desired functional properties in π-conjugated materials, there are only sporadic examples where precise structural control of dye–dye interactions could be achieved by the attachment of the chromophores to an oligomeric or polymeric backbone. In this edge article, we introduce an oligophenylene ethynylene/perylene bisimide (PBI) dye system which is conceived by the foldamer concept. The molecular design enables folding of the π-conjugated oligomer to give a geometrically well-defined π-stack of intrastrand PBI molecules. The synthesis of the foldamer and its characterization by MALDI-TOF mass spectrometry are described, and the average size is estimated by gel permeation chromatography (GPC) and diffusion ordered NMR spectroscopy (DOSY). The folding dynamics are demonstrated by ultraviolet/visible absorption and fluorescence emission spectroscopic studies as the folded and unfolded states possess distinct optical properties. Quantum dynamic considerations revealed a good agreement of the calculated aggregate absorption spectrum with those obtained experimentally.