Excited-state energy transfer and ground-state hole/electron hopping in p-phenylene-linked porphyrin dimers

Sung Ik Yang, Robin K. Lammi, Jyoti Seth, Jennifer A. Riggs, Toru Arai, Dongho Kim, David F. Bocian, Dewey Holten, Jonathan S. Lindsey

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Abstract

The ground- and excited-state properties of a series of p-phenylene-linked porphyrin dimers have been examined using a variety of static and time-resolved spectroscopic techniques. The dimers consist of a zinc porphyrin and a free base (Fb) porphyrin (ZnFbΦ), two zinc porphyrins (Zn2Φ), or two Fb porphyrins (Fb2Φ). In each array, the porphyrins are joined by the p-phenylene linker at one meso position, with the nonlinking meso positions bearing mesityl groups. Three analogous dimers in which the mesityl groups are replaced with pentafluorophenyl groups (F30ZnFbΦ, F30Zn2Φ and F30Fb2Φ) were also synthesized and characterized. The excited-state energy-transfer rate from the photoexcited Zn porphyrin to the Fb porphyrin is (3.5 ps)-1 for ZnFbΦ and (10 ps)-1 for F30ZnFbΦ. The quantum yields of excited-state energy transfer are ≥99% for both complexes. The energy-transfer rates in the p-phenylene-linked dimers are considerably faster than those observed for the analogous dimers containing a diphenylethyne linker ((24 ps)-1, ZnFbU; (240 ps)-1, F30ZnFbU). At these distances, both through bond and through space contributions to the electronic coupling are important. The faster energy-transfer rates in the p-phenylene- versus diarylethyne-linked dimers are attributed to enhanced electronic coupling between the porphyrins in the former dimers arising primarily from the shorter inter-porphyrin separation. The electronic coupling in the p-phenylene-linked dimers is sufficient to support ultrafast energy transfer in both ZnFbΦ and F30ZnFbΦ, but is not so large as to significantly perturb the redox or inherent lowest excited-state photophysical properties of the porphyrin constituents. Electronic perturbations resulting from fluorination have little effect on the energy-transfer rates in the p-phenylene-linked dimers, but the rates of room-temperature ground-state hole/electron hopping processes in the corresponding monocation radicals of the bis-Zn-analogues of the p-phenylene-linked dimers (≥(0.05 μ)-1, [Zn2Φ]+; ≤(2.5 μs)-11, [F30Zn2Φ]+) are significantly influenced by the fluorination-induced changes in the electronic structure. Collectively, these characteristics make these constructs attractive candidates for incorporation into extended multi-porphyrin arrays for a variety of molecular photonics applications.

Original languageEnglish
Pages (from-to)9426-9436
Number of pages11
JournalJournal of Physical Chemistry B
Volume102
Issue number47
Publication statusPublished - 1998 Nov 19

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Porphyrins
Excited states
porphyrins
Dimers
Energy transfer
Ground state
energy transfer
dimers
ground state
Electrons
excitation
Fluorination
fluorination
electronics
Bearings (structural)
Zinc
zinc
Quantum yield
Photonics
Electronic structure

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

Yang, S. I., Lammi, R. K., Seth, J., Riggs, J. A., Arai, T., Kim, D., ... Lindsey, J. S. (1998). Excited-state energy transfer and ground-state hole/electron hopping in p-phenylene-linked porphyrin dimers. Journal of Physical Chemistry B, 102(47), 9426-9436.
Yang, Sung Ik ; Lammi, Robin K. ; Seth, Jyoti ; Riggs, Jennifer A. ; Arai, Toru ; Kim, Dongho ; Bocian, David F. ; Holten, Dewey ; Lindsey, Jonathan S. / Excited-state energy transfer and ground-state hole/electron hopping in p-phenylene-linked porphyrin dimers. In: Journal of Physical Chemistry B. 1998 ; Vol. 102, No. 47. pp. 9426-9436.
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title = "Excited-state energy transfer and ground-state hole/electron hopping in p-phenylene-linked porphyrin dimers",
abstract = "The ground- and excited-state properties of a series of p-phenylene-linked porphyrin dimers have been examined using a variety of static and time-resolved spectroscopic techniques. The dimers consist of a zinc porphyrin and a free base (Fb) porphyrin (ZnFbΦ), two zinc porphyrins (Zn2Φ), or two Fb porphyrins (Fb2Φ). In each array, the porphyrins are joined by the p-phenylene linker at one meso position, with the nonlinking meso positions bearing mesityl groups. Three analogous dimers in which the mesityl groups are replaced with pentafluorophenyl groups (F30ZnFbΦ, F30Zn2Φ and F30Fb2Φ) were also synthesized and characterized. The excited-state energy-transfer rate from the photoexcited Zn porphyrin to the Fb porphyrin is (3.5 ps)-1 for ZnFbΦ and (10 ps)-1 for F30ZnFbΦ. The quantum yields of excited-state energy transfer are ≥99{\%} for both complexes. The energy-transfer rates in the p-phenylene-linked dimers are considerably faster than those observed for the analogous dimers containing a diphenylethyne linker ((24 ps)-1, ZnFbU; (240 ps)-1, F30ZnFbU). At these distances, both through bond and through space contributions to the electronic coupling are important. The faster energy-transfer rates in the p-phenylene- versus diarylethyne-linked dimers are attributed to enhanced electronic coupling between the porphyrins in the former dimers arising primarily from the shorter inter-porphyrin separation. The electronic coupling in the p-phenylene-linked dimers is sufficient to support ultrafast energy transfer in both ZnFbΦ and F30ZnFbΦ, but is not so large as to significantly perturb the redox or inherent lowest excited-state photophysical properties of the porphyrin constituents. Electronic perturbations resulting from fluorination have little effect on the energy-transfer rates in the p-phenylene-linked dimers, but the rates of room-temperature ground-state hole/electron hopping processes in the corresponding monocation radicals of the bis-Zn-analogues of the p-phenylene-linked dimers (≥(0.05 μ)-1, [Zn2Φ]+; ≤(2.5 μs)-11, [F30Zn2Φ]+) are significantly influenced by the fluorination-induced changes in the electronic structure. Collectively, these characteristics make these constructs attractive candidates for incorporation into extended multi-porphyrin arrays for a variety of molecular photonics applications.",
author = "Yang, {Sung Ik} and Lammi, {Robin K.} and Jyoti Seth and Riggs, {Jennifer A.} and Toru Arai and Dongho Kim and Bocian, {David F.} and Dewey Holten and Lindsey, {Jonathan S.}",
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Yang, SI, Lammi, RK, Seth, J, Riggs, JA, Arai, T, Kim, D, Bocian, DF, Holten, D & Lindsey, JS 1998, 'Excited-state energy transfer and ground-state hole/electron hopping in p-phenylene-linked porphyrin dimers', Journal of Physical Chemistry B, vol. 102, no. 47, pp. 9426-9436.

Excited-state energy transfer and ground-state hole/electron hopping in p-phenylene-linked porphyrin dimers. / Yang, Sung Ik; Lammi, Robin K.; Seth, Jyoti; Riggs, Jennifer A.; Arai, Toru; Kim, Dongho; Bocian, David F.; Holten, Dewey; Lindsey, Jonathan S.

In: Journal of Physical Chemistry B, Vol. 102, No. 47, 19.11.1998, p. 9426-9436.

Research output: Contribution to journalArticle

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T1 - Excited-state energy transfer and ground-state hole/electron hopping in p-phenylene-linked porphyrin dimers

AU - Yang, Sung Ik

AU - Lammi, Robin K.

AU - Seth, Jyoti

AU - Riggs, Jennifer A.

AU - Arai, Toru

AU - Kim, Dongho

AU - Bocian, David F.

AU - Holten, Dewey

AU - Lindsey, Jonathan S.

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N2 - The ground- and excited-state properties of a series of p-phenylene-linked porphyrin dimers have been examined using a variety of static and time-resolved spectroscopic techniques. The dimers consist of a zinc porphyrin and a free base (Fb) porphyrin (ZnFbΦ), two zinc porphyrins (Zn2Φ), or two Fb porphyrins (Fb2Φ). In each array, the porphyrins are joined by the p-phenylene linker at one meso position, with the nonlinking meso positions bearing mesityl groups. Three analogous dimers in which the mesityl groups are replaced with pentafluorophenyl groups (F30ZnFbΦ, F30Zn2Φ and F30Fb2Φ) were also synthesized and characterized. The excited-state energy-transfer rate from the photoexcited Zn porphyrin to the Fb porphyrin is (3.5 ps)-1 for ZnFbΦ and (10 ps)-1 for F30ZnFbΦ. The quantum yields of excited-state energy transfer are ≥99% for both complexes. The energy-transfer rates in the p-phenylene-linked dimers are considerably faster than those observed for the analogous dimers containing a diphenylethyne linker ((24 ps)-1, ZnFbU; (240 ps)-1, F30ZnFbU). At these distances, both through bond and through space contributions to the electronic coupling are important. The faster energy-transfer rates in the p-phenylene- versus diarylethyne-linked dimers are attributed to enhanced electronic coupling between the porphyrins in the former dimers arising primarily from the shorter inter-porphyrin separation. The electronic coupling in the p-phenylene-linked dimers is sufficient to support ultrafast energy transfer in both ZnFbΦ and F30ZnFbΦ, but is not so large as to significantly perturb the redox or inherent lowest excited-state photophysical properties of the porphyrin constituents. Electronic perturbations resulting from fluorination have little effect on the energy-transfer rates in the p-phenylene-linked dimers, but the rates of room-temperature ground-state hole/electron hopping processes in the corresponding monocation radicals of the bis-Zn-analogues of the p-phenylene-linked dimers (≥(0.05 μ)-1, [Zn2Φ]+; ≤(2.5 μs)-11, [F30Zn2Φ]+) are significantly influenced by the fluorination-induced changes in the electronic structure. Collectively, these characteristics make these constructs attractive candidates for incorporation into extended multi-porphyrin arrays for a variety of molecular photonics applications.

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