Proton-coupled energy transfer in molecular triads

Rimgard, Belinda Pettersson; Tao, Zhen; Parada, Giovanny A.; Cotter, Laura F.; Hammes‐Schiffer, Sharon; Mayer, James M.; Hammarström, Leif

doi:10.1126/science.abq5173

Cited by 17 publications

(13 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, the reorganization energy also defines the minimum free energy necessary to access the Marcus inverted region for homogeneous systems and further extends the impact of this analysis to other catalytically relevant reactions. , A comparison of the reorganization energies reveals that λ PCET expt is significantly larger than λ ET expt (Table ). A review of the literature shows that this is not always the case. , To better understand the physical origins of the different reorganization energies, λ PCET expt > λ ET expt , the inner-sphere and outer-sphere contributions to the total reorganization energies were computed using DFT in conjunction with other approaches discussed below and more extensively in the Supporting Information.…”

Section: Discussionmentioning

confidence: 99%

“…13,64 A comparison of the reorganization energies reveals that λ PCET expt is significantly larger than λ ET expt (Table 1). 65 A review of the literature shows that this is not always the case. 66,67 To better understand the physical origins of the different reorganization energies, λ PCET expt > λ ET expt , the inner-sphere and outer-sphere contributions to the total reorganization energies were computed using DFT in conjunction with other approaches discussed below and more extensively in the Supporting Information.…”

Section: ■ Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Reorganization Energies for Interfacial Proton-Coupled Electron Transfer to a Water Oxidation Catalyst

et al. 2022

Self Cite

View full text Add to dashboard Cite

The reorganization energy (λ) for interfacial electron transfer (ET) and proton-coupled ET (PCET) from a conductive metal oxide (In 2 O 3 :Sn, ITO) to a surface-bound water oxidation catalyst was extracted from kinetic data measured as a function of the thermodynamic driving force. Visible light excitation resulted in rapid excited-state injection (k inj > 10 8 s −1 ) to the ITO, which photo-initiated the two interfacial reactions of interest. The rate constants for both reactions increased with the driving force, −ΔG°, to a saturating limit, k max , with rate constants consistently larger for ET than for PCET. Marcus−Gerischer analysis of the kinetic data provided the reorganization energy for interfacial PCET (0.90 ± 0.02 eV) and ET (0.40 ± 0.02 eV), respectively. The magnitude of k max for PCET was found to decrease with pH, behavior that was absent for ET. Both the decrease in k max and the larger reorganization energy for an unwanted competing PCET reaction from the ITO to the oxidized catalyst showcases a significant kinetic advantage for driving solar water oxidation at high pH. Computational analysis revealed a larger innersphere reorganization energy contribution for PCET than for ET arising from a more significant change in the Ru−O bond length for the PCET reaction. Extending the Marcus−Gerischer theory to PCET by including the excited electron−proton vibronic states and the proton donor−acceptor motion provided an apparent reorganization energy of 1.01 eV. This study demonstrates that the Marcus−Gerischer theory initially developed for ET can be reliably extended to PCET for quantifying and interpreting reorganization energies observed experimentally.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: ■ Discussionmentioning

confidence: 99%

Reorganization Energies for Interfacial Proton-Coupled Electron Transfer to a Water Oxidation Catalyst

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…A new concept of proton-coupled singlet-singlet energy transfer (PCEnT), which couples an electronic transition to nuclear motions, has recently been discovered in a series of anthracene-phenol-pyridine triads. 7 The authors envisioned this mechanism as a potentially important process for some biologically significant molecules. In this work, we propose that the PCEnT mechanism can also take place in the triplet excited state (PCTEnT), and we demonstrate it on systems consisting of a porphyrin antenna and a covalently bound flavonol moiety as an acceptor.…”

Section: Discussionmentioning

confidence: 99%

“…6 The same laboratories very recently reported a unique mechanism in anthracene-phenol-pyridine triads, in which energy transfer is coupled to a nuclear motion, termed proton-coupled energy transfer (PCEnT). 7 In this process, the formation of a locally excited state on anthracene is followed by singlet-singlet energy transfer to the phenol-pyridine chromophore. Despite the lack of spectral overlap of the donor emission and acceptor absorption spectra required for the Förster resonance (dipole-dipole) mechanism, [8][9] the process was made possible by coupling proton transfer in the phenol-pyridine unit with energy transfer that lowered its excited-state energy.…”

Section: Introductionmentioning

confidence: 99%

Proton-Coupled Triplet-Triplet Energy Transfer: Carbon Monoxide Photorelease from Porphyrin-Flavonol Hybrids

Ramundo

Janos

Muchová

et al. 2022

Preprint

View full text Add to dashboard Cite

A new photochemical mechanism, termed proton-coupled energy transfer (PCEnT), was recently discovered in anthracene-phenol-pyridine triads (Pettersson Rimgard et al., Science 2022, 377, 742). It couples an electronic transition to nuclear motions allowing Förster (dipole-dipole) energy transfer even though there is no overlap of the donor emission and acceptor absorption spectra. Here, we extend this concept to triplet-triplet energy transfer (TEnT) from light-harvesting porphyrin to a covalently bound flavonol group. While direct TEnT to the flavonol acceptor would be highly endergonic, it becomes feasible thanks to the flavonol energy stabilization upon intramolecular proton transfer in the triplet state. We describe the overall mechanism as proton-coupled TEnT (PCTEnT) – a one-photon process that enables the activation of a UV-absorbing chromophore by visible light. Several porphyrin-flavonol hybrids containing 4 flavonol units attached to the porphyrin meso positions were designed as photoactivatable carbon monoxide (CO)-releasing molecules (photoCORMs). The photoreaction mechanism was studied by steady-state and transient absorption spectroscopy techniques and complementary quantum-chemical calculations. While intrinsically toxic, CO is an endogenous signaling molecule with therapeutic potential that regulates various physiological processes, and photoCORMs offer precise spatial and temporal control of CO administration. We evaluated the viability of the human hepatoblastoma HepG2 cells in the presence of the studied hybrids and tested the effects associated with the intracellular release of CO and the production of singlet oxygen. We demonstrate that the PCTEnT process could be used to devise new photoactivatable molecular devices with potential biological applications.

show abstract

“…Generally, PCET reactions are particularly prevalent in PET systems, as the excited state population leads to a significant charge rearrangement and hence the breakage of hydrogen bonds. [96][97][98][99] Knowing that the charge rearrangement of TET is subtle in the MV systems, the breakage of hydrogen bond may not occur and the TET reaction proceeds via a PUET mechanism. Our work in this regard is based on the dimolybdenum hydrogen-bonded MV complexes, with amide-amide hydrogen bond interaction.…”

Section: Quantitative Analysis Of Electronic Coupling and Electron Tr...mentioning

confidence: 99%

Electronic coupling and electron transfer in hydrogen-bonded mixed-valence compounds

Shi

Cheng

2023

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

show abstract

Proton-coupled energy transfer in molecular triads

Cited by 17 publications

References 47 publications

Reorganization Energies for Interfacial Proton-Coupled Electron Transfer to a Water Oxidation Catalyst

Reorganization Energies for Interfacial Proton-Coupled Electron Transfer to a Water Oxidation Catalyst

Proton-Coupled Triplet-Triplet Energy Transfer: Carbon Monoxide Photorelease from Porphyrin-Flavonol Hybrids

Electronic coupling and electron transfer in hydrogen-bonded mixed-valence compounds

Contact Info

Product

Resources

About