Exploring Optically Fueled Dissipative Self-Assembly of a Redox-Active Perylene Diimide Scaffold

Abstract

Dissipative self-assembly is ubiquitous in nature and underlie many complex structures and functions in natural systems, primarily enabled by the consumption of chemical fuels. However, dissipative self-assembly fueled by light have also been parallelly developed. Photoswitchable molecules have been widely investigated as prototypical molecular systems for light driven dissipative self-assembly. Elucidation of optically fueled dissipative self-assembly by a photo-responsive yet non-photoswitchable molecule however remains elusive. This contribution thus demonstrates the first ever report of an optically fueled dissipative self-assembly arising from a redox active perylene diimide scaffold (DIPFPDI). Photo-reduction of neutral DIPFPDI in a poor solvent DMF affords its radical anion and batches of optical re-fueling leads to an increased concentration of radical anion, inducing the construction of an H-type aggregate. Nevertheless, when the influx of visible light is adjourned, the radical anions are converted to their neutral precursors and thus the self-assembled state is no longer sustained. Signature of H-type aggregation is deduced from steady-state UV-Vis, fluorescence as well as time-resolved fluorescence spectroscopy. Theoretical insights reveal that dimerization is more feasible in the charged states because of greater delocalization of the excess charge in the charged states.