Enhancement of Photodriven Charge Separation by Conformational and Intermolecular Adaptations of an Anthracene–Perylenediimide–Anthracene Triad to an Aqueous Environment

Abstract

Photoinduced electron-transfer dynamics of an electron donor–acceptor–donor triad, consisting of anthracenes and perylenediimide (An2PDI), were investigated in different media by using time-resolved laser spectroscopic techniques. The aromatic components are attached by flexible linkers containing hydrophilic quaternary ammonium joints in the triad. In MeOH, in which An2PDI dissolves completely, no electron-transfer products were observed in the transient absorption measurements after the excitation of anthracenes and PDI because of the rapid back-electron transfer. The charge-separation rate of the triad in MeOH was estimated as 1.2 × 1010 s–1 from the quenching of the singlet-excited state of PDI. In contrast, the formation of electron-transfer products was evident in water, and the electron-transfer rate was 200 times faster than the rate in MeOH in the course of the excitations of the selected components of An2PDI (2.5 × 1012 s–1). It is concluded from the time-resolved data that the conformational disposition of the hydrophilic joints due to hydrophilic–lipophilic interactions and the facile π-stacking of hydrophobic PDI cores in water results in the contraction and the relative rigidity of the electron-transfer distance and the intermolecular stabilization of electron-transfer species within the polymeric self-assemblies of An2PDI, enabling an efficient photodriven electron-transfer process to occur.

Energy and Electron Transfer of One-Dimensional Nanomaterials of Perylenediimides

“…62 The charge recombination in the aggregates of 20 was also determined to be fast in water (30 ps) even though the occurrence of electron migration in the PDI stacks was proved by the femtosecond transient absorption spectra. 63 The charge-separation rate was comparable to those of the aggregates of 22 and 23 and oligomers of 24 (vide supra). It is suggested that the extensive charge migration along the stacks of donor and acceptor can be achieved by limiting the number of donors against the PDI stacks.…”

“…63 Alkyl linkers containing hydrophilic quaternary ammonium joints connected the aromatic components of the triad. Triad 20 forms solubilized polymeric self-assemblies in one dimension in water as understood from the steady-state anisotropy measurements.…”

“…It is suggested that the extensive charge migration along the stacks of donor and acceptor can be achieved by limiting the number of donors against the PDI stacks. 63 By this way, fast recombination between adjacent donor and acceptor can be prohibited. The distance between PDIs and the terminal electron donors is important to hinder the fast charge recombination in the monomers and aggregates.…”

Broadband Light Harvesting and Fast Charge Separation in Ordered Self-Assemblies of Electron Donor–Acceptor-Functionalized Graphene Oxide Layers for Effective Solar Energy Conversion

“…Energy transfer among the dye units seems less likely due to close distance and the highly polar aqueous environment favoring the electron-transfer processes. [43][44][45][46] Consequently, there was no signal to be assigned for energy transfer from Por and/or PDI to ZnPc in the transient absorption spectra. 45,46 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36...…”

The impact of trans/cis photoisomerization on photoinduced electron transport between 4,4′-stilbenedicarboxylic acid and columnar perylenediimide aggregates in water

“…Many organic compounds with covalently linked donor and acceptor moiety have been designed and synthesized for the purpose of revealing the origin of PET process [7][8][9]. At the same time, mimicking the natural PET with non-covalently systems based on varies of supramolecular interactions has also gained much attention in the past several decades [10,11].…”