Photocurrent Generation Enhanced by Charge Delocalization over Stacked Perylenediimide Chromophores Assembled within DNA

Abstract

We now report the photocurrent generation and charge transfer dynamics of stacked perylenediimide (PDI) molecules within a π-stack array of DNA. The cofacially stacked PDI dimer and trimer were found to strongly enhance the photocurrent generation compared to an isolated PDI monomer. Femtosecond time-resolved transient absorption experiments revealed that the excitation of the stacked PDI dimer and trimer provided the broad transient absorption band, which was attributed to the charge delocalization of a negative charge over the PDI chromophores. The lifetime of the charge delocalization of the PDI dimer and trimer (nearly 1 ns) was much longer than that of the charge separated state of the PDI monomer. A comparison between the photocurrent measurements and time-resolved transient absorption measurements demonstrated that the cofacially stacked structure could possibly lead to the charge delocalization and increase the lifetime of the charge-separated state that is essential to enhancing the photocurrent generation.

Rapid Electron Transfer of Stacked Heterodimers of Perylene Diimide Derivatives in a DNA Duplex

“…In addition, after the decay of 1 PH*, PH .− was not observed, which was inconsistent with the observation for PH/Sp (Figure b). Based on the reduction potential of 1 PH* ( E red =2.0 V calculated from the reduction potential ( E red =0.34 V vs. a normal hydrogen electrode (NHE)), singlet excitation energy ( E s =2.3 eV), and oxidation potential of PN ( E ox =0.8 V vs. NHE), electron transfer from PN to 1 PH* is expected to occur with a driving force of about −1.2 eV . Therefore, the rapid decay of 1 PH* without the appearance of the transient absorption of PH .− indicates that the electron‐transfer reaction between 1 PH and PN, and back‐electron transfer in PH/PN, takes place within a few picoseconds; this originates from the favorable driving force and face‐to‐face arrangement of PH and PN (Figure c).…”

“…Based on the reduction potential of 1 PH* (E red = 2.0 Vc alculated from the reduction potential( E red = 0.34 Vv s. an ormalh ydrogen electrode (NHE)), singlet excitation energy (E s = 2.3 eV), and oxidation potentialo fP N( E ox = 0.8 Vv s. NHE), [55] electron transfer from PN to 1 PH* is expectedt oo ccur with ad riving force of about À1.2 eV. [29,34,42,56,57] Therefore, the rapid decay of 1 PH* withoutt he appearance of the transient absorption of PHC À indicatest hat the electron-transfer reaction between 1 PH and PN, and back-electron transfer in PH/PN, takes place within a few picoseconds;t his originates from the favorable driving force and face-to-face arrangement of PH and PN (Figure 3c). Complete fluorescenceq uenching observedb yt he PH/PN pair can be rationally supported by ultrafast electron-transfer quenching and the stable, stacked arrangement of PH and PN within the DNA structure.…”

“…Additionally, it has been demonstrated that the introduction of substituents to the perylene ring can modulate the electronic states, hydrophobicity, and intermolecular interactions . Due to excellent photochemical properties and electronic functionality, PDI‐modified nucleic acids have been reported . The photochemical properties of PDI can be easily modulated by introducing substituents into the perylene ring, which suggests that the PDI derivatives can be exploited as both fluorophore and quencher molecules .…”

“…[30] Due to excellent photochemical properties and electronic functionality,P DI-modified nucleic acids have been reported. [31][32][33][34][35][36][37][38][39][40][41][42] The photochemical properties of PDI can be easily modulated by introducing substituents into the perylene ring, which suggests that the PDI derivatives can be exploited as both fluorophore and quencher molecules. [43] Recently,w ed eveloped an effective way to incorporate PDI molecules into DNA by using enzymatically generated abasic sites, which allowed the placement of planarh ydrophobic molecules precisely in place of the nucleobases within aD NA p stack and the constructiono f stacked molecular arrays.…”

Interplay of monomers, dimers and J-aggregates of thiamonomethinecyanine dye with PEDOT and PSS in the dye–PEDOT:PSS composite system

“…On the other hand, the supramolecular dyepolymer assemblies have attracted widespread interest as components of molecular devices with potential applications in molecular electronics, artificial light harvesting, and medicine. The polymer template can render different effects onto dye assemblies, such as control of their H-and J-aggregation [7][8][9][10], induction of supramolecular chirality [11] which can be memorized even after the template helical polymer loses its optical activity or further inverts to the opposite helicity [12][13][14], tuning of energy transfer between donor and acceptor compounds intercalated into the template [15], as well as tuning of photocurrent generation and charge transfer dynamics of stacked guest molecules [16], etc.…”