Ultrafast, Light-Induced Electron Transfer in a Perylene Diimide Chromophore-Donor Assembly on TiO₂

Abstract

Surface-bound, perylenediimide (PDI)-based molecular assemblies have been synthesized on nanocrystalline TiO2 by reaction of a dianhydride with a surface-bound aniline and succinimide bonding. In a second step, the Fe(II) polypyridyl complex [Fe(II)(tpy-PhNH2)2](2+) was added to the outside of the film, also by succinimide bonding. Ultrafast transient absorption measurements in 0.1 M HClO4 reveal that electron injection into TiO2 by (1)PDI* does not occur, but rather leads to the ultrafast formation of the redox-separated pair PDI(•+),PDI(•-), which decays with complex kinetics (τ1 = 0.8 ps, τ2 = 15 ps, and τ3 = 1500 ps). With the added Fe(II) polypyridyl complex, rapid (<25 ps) oxidation of Fe(II) by the PDI(•+),PDI(•-) redox pair occurs to give Fe(III),PDI(•-) persisting for >400 μs in the film environment.

Photodriven hydrogen evolution by molecular catalysts using Al2O3-protected perylene-3,4-dicarboximide on NiO electrodes

“…S7A † ). The subsequent decay of 1 * PMI along a number of pathways including excimer formation 65 is approximated using a species-associated model in which 1 * PMI (species A) decays to species B, which decays to species C, which decays to the ground state (GS). While the spectra for “species B” and “species C” contain contributions from the several species formed along these decay pathways, excimer can be identified by a loss of stimulated emission and red-shift and broadening of the absorptive signal in species C (Fig.…”

Computational Modeling of Exciton Localization in Self-Assembled Perylene Helices: Effects of Thermal Motion and Aggregate Size

“…40 Moreover in water oxidation devices, as shown in Ref. 33 , surface sensitization by hydrophobic aggregates, adsorbed on the surface by electrostatic and dispersion interactions, does not trigger the hydrolytic cleavage 41 generally observed for conventional (carboxylic or phosphonic) 42,43 anchoring groups. On the other hand, however, to have an efficient electron/hole injection by these photoexcited aggregates into the semiconductor/catalyst, the nature (localized Frenkel-type or charge transfer (CT)-like) and delocalization (i.e.…”

Amino acid appended perylene bisimides: self-assembly, immobilization on nanocrystalline TiO2, and electrochromic properties

“…1 The combination of ease of functionalisation with the retention of the outstanding optical properties of the perylene core have led to a huge increase in interest in the use of PBIs spanning many fields of chemistry which exploit optical and/or electrical characteristics, 3 and PBIs have been reported for use in organic photovoltaics, 4 sensing, 5 luminescent materials, 6 n-type photoconductivity, 7,8 microwave conductivity, 9 dye-sensitised solar cells (DSSCs), 10 photocatalysis 2 and photoelectrochemistry (PEC). 11 PBIs are well-known to self-assemble, primarily through π-π interactions. These aggregates can range from molecular dimers to superstructures on the micron length scale.…”

“…PBIs have been immobilised onto various metal oxides (In:SnO2, WO3, Al2O3, NiO, TiO2) for use in fundamental photophysical studies and dyesensitised PEC cells, typically using phosphonate linkers. 11,17,18,19 There is also at least one example of PBI-based n-type electrochromics, through polymerisation of thin (38 nm) PBI films onto In:SnO2. 20 In this study, we utilise nanoparticulate TiO2 substrates to immobilise various aggregated forms of PBI-A ( Fig.…”