Light harvesting vesicular donor–acceptor scaffold limits the rate of charge recombination in the presence of an electron donor

Abstract

We report the synthesis and excited state properties of a single component light harvesting donor–acceptor dyad (R/S)-NP(OH)₂ containing an α,β-dihydroxypropyl side-chain that can undergo molecule–bilayer–vesicle–gel–crystal transition. By virtue of steric hindrance offered by orthogonal naphthalimide and 2,6-diisopropylphenyl substituents, very weak H-type excitonic interactions between the perylenimide units resulted in high fluorescence quantum yield in the dyad-based metastable vesicular gel having a near-quantitative excitation energy transfer from naphthalimide to perylenimide. Femtosecond transient absorption measurements of the dyad (R/S)-NP(OH)₂ : indole co-gel show that the vesicular scaffold promoted extension of the survival time of charge separated states (∼1.4 ns) when compared to ultrafast charge recombination (∼6 ps) in dyad (R/S)-NP(OH)₂ : indole solution.