Dedicated to Prof. Francis C. Spano.
Abstract
Dissipative self-assembly is ubiquitous in nature and underlies many complex structures
and functions in natural systems. These processes are primarily enabled by the consumption
of chemical fuels. However, dissipative self-assembly processes fueled by light have
also been parallelly developed, known as optically fueled dissipative self-assembly.
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 moiety 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 such as DMF affords
its radical anion and repeated irradiation leads to an increased concentration of
radical anion, inducing the construction of an H-type aggregate. Nevertheless, dissolved
molecular oxygen can efficiently deactivate the radical anions to their neutral precursors
and thus the self-assembled state is no longer sustained. The 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. We believe that these findings will infuse new energy into the field
of optically fueled dissipative self-assembly of redox-active chromophores.
Key words radical anions - aggregation - perylene - non-covalent forces - fuel-driven
