Photoinduced electron transfer from a tetrathiafulvalene-calix[4]pyrrole to a porphyrin carboxylate within a supramolecular ensemble

Christina M. Davis, Yuki Kawashima, Kei Ohkubo, Jong Min Lim, Dongho Kim, Shunichi Fukuzumi, Jonathan L. Sessler

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

A supramolecular assembly is formed upon mixing millimolar concentrations of a tetrakis-tetrathiafulvalene calix[4]pyrrole (TTF-C4P) and a porphyrin tetraethylammonium carboxylate salt in benzonitrile (PhCN). The TTF-C4P binds to the carboxylate moiety of the porphyrin with a 1:1 stoichiometry and a binding constant of 6.3 × 10 4 M -1 in this solvent at 298 K. Laser photoexcitation of the supramolecular complex results in formation of the triplet charge-separated (CS) state composed of a radical cation of the TTF-C4P receptor and the radical anion of the porphyrin carboxylate. These processes and the resulting states were characterized by means of transient absorption and electron spin resonance (ESR) spectroscopies. The rate constants corresponding to the forward and backward intramolecular electron-transfer (ET) processes were determined to be 2.1 × 10 4 and 3.6 × 10 2 s -1 , respectively. The rate constants of intermolecular forward and backward electron transfer were also determined to be 4.4 × 10 8 and 9.8 × 10 8 M -1 s -1 , respectively. The electronic coupling constant (V), 1.2 × 10 -2 cm -1 , and the reorganization energy (λ), 0.76 eV, for back electron transfer were evaluated from the temperature dependence of the rate constants of intramolecular electron transfer. The small V value indicates little spinforbidden interaction between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) and substantiates the long-lived CS lifetime. These results were corroborated by density function theory (DFT) calculations, which provided support for the conclusion that the HOMO and LUMO, located on a TTF moiety of the TTF-C4P and the porphyrin core, respectively, have little interaction though space.

Original languageEnglish
Pages (from-to)13505-13513
Number of pages9
JournalJournal of Physical Chemistry C
Volume118
Issue number25
DOIs
Publication statusPublished - 2014 Jun 26

Fingerprint

Porphyrins
Molecular orbitals
pyrroles
porphyrins
carboxylates
electron transfer
molecular orbitals
Rate constants
Electrons
Electron spin resonance spectroscopy
Tetraethylammonium
Photoexcitation
Stoichiometry
Probability density function
Anions
Cations
photoexcitation
Negative ions
Salts
Positive ions

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

Cite this

Davis, Christina M. ; Kawashima, Yuki ; Ohkubo, Kei ; Lim, Jong Min ; Kim, Dongho ; Fukuzumi, Shunichi ; Sessler, Jonathan L. / Photoinduced electron transfer from a tetrathiafulvalene-calix[4]pyrrole to a porphyrin carboxylate within a supramolecular ensemble. In: Journal of Physical Chemistry C. 2014 ; Vol. 118, No. 25. pp. 13505-13513.
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abstract = "A supramolecular assembly is formed upon mixing millimolar concentrations of a tetrakis-tetrathiafulvalene calix[4]pyrrole (TTF-C4P) and a porphyrin tetraethylammonium carboxylate salt in benzonitrile (PhCN). The TTF-C4P binds to the carboxylate moiety of the porphyrin with a 1:1 stoichiometry and a binding constant of 6.3 × 10 4 M -1 in this solvent at 298 K. Laser photoexcitation of the supramolecular complex results in formation of the triplet charge-separated (CS) state composed of a radical cation of the TTF-C4P receptor and the radical anion of the porphyrin carboxylate. These processes and the resulting states were characterized by means of transient absorption and electron spin resonance (ESR) spectroscopies. The rate constants corresponding to the forward and backward intramolecular electron-transfer (ET) processes were determined to be 2.1 × 10 4 and 3.6 × 10 2 s -1 , respectively. The rate constants of intermolecular forward and backward electron transfer were also determined to be 4.4 × 10 8 and 9.8 × 10 8 M -1 s -1 , respectively. The electronic coupling constant (V), 1.2 × 10 -2 cm -1 , and the reorganization energy (λ), 0.76 eV, for back electron transfer were evaluated from the temperature dependence of the rate constants of intramolecular electron transfer. The small V value indicates little spinforbidden interaction between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) and substantiates the long-lived CS lifetime. These results were corroborated by density function theory (DFT) calculations, which provided support for the conclusion that the HOMO and LUMO, located on a TTF moiety of the TTF-C4P and the porphyrin core, respectively, have little interaction though space.",
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Photoinduced electron transfer from a tetrathiafulvalene-calix[4]pyrrole to a porphyrin carboxylate within a supramolecular ensemble. / Davis, Christina M.; Kawashima, Yuki; Ohkubo, Kei; Lim, Jong Min; Kim, Dongho; Fukuzumi, Shunichi; Sessler, Jonathan L.

In: Journal of Physical Chemistry C, Vol. 118, No. 25, 26.06.2014, p. 13505-13513.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Photoinduced electron transfer from a tetrathiafulvalene-calix[4]pyrrole to a porphyrin carboxylate within a supramolecular ensemble

AU - Davis, Christina M.

AU - Kawashima, Yuki

AU - Ohkubo, Kei

AU - Lim, Jong Min

AU - Kim, Dongho

AU - Fukuzumi, Shunichi

AU - Sessler, Jonathan L.

PY - 2014/6/26

Y1 - 2014/6/26

N2 - A supramolecular assembly is formed upon mixing millimolar concentrations of a tetrakis-tetrathiafulvalene calix[4]pyrrole (TTF-C4P) and a porphyrin tetraethylammonium carboxylate salt in benzonitrile (PhCN). The TTF-C4P binds to the carboxylate moiety of the porphyrin with a 1:1 stoichiometry and a binding constant of 6.3 × 10 4 M -1 in this solvent at 298 K. Laser photoexcitation of the supramolecular complex results in formation of the triplet charge-separated (CS) state composed of a radical cation of the TTF-C4P receptor and the radical anion of the porphyrin carboxylate. These processes and the resulting states were characterized by means of transient absorption and electron spin resonance (ESR) spectroscopies. The rate constants corresponding to the forward and backward intramolecular electron-transfer (ET) processes were determined to be 2.1 × 10 4 and 3.6 × 10 2 s -1 , respectively. The rate constants of intermolecular forward and backward electron transfer were also determined to be 4.4 × 10 8 and 9.8 × 10 8 M -1 s -1 , respectively. The electronic coupling constant (V), 1.2 × 10 -2 cm -1 , and the reorganization energy (λ), 0.76 eV, for back electron transfer were evaluated from the temperature dependence of the rate constants of intramolecular electron transfer. The small V value indicates little spinforbidden interaction between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) and substantiates the long-lived CS lifetime. These results were corroborated by density function theory (DFT) calculations, which provided support for the conclusion that the HOMO and LUMO, located on a TTF moiety of the TTF-C4P and the porphyrin core, respectively, have little interaction though space.

AB - A supramolecular assembly is formed upon mixing millimolar concentrations of a tetrakis-tetrathiafulvalene calix[4]pyrrole (TTF-C4P) and a porphyrin tetraethylammonium carboxylate salt in benzonitrile (PhCN). The TTF-C4P binds to the carboxylate moiety of the porphyrin with a 1:1 stoichiometry and a binding constant of 6.3 × 10 4 M -1 in this solvent at 298 K. Laser photoexcitation of the supramolecular complex results in formation of the triplet charge-separated (CS) state composed of a radical cation of the TTF-C4P receptor and the radical anion of the porphyrin carboxylate. These processes and the resulting states were characterized by means of transient absorption and electron spin resonance (ESR) spectroscopies. The rate constants corresponding to the forward and backward intramolecular electron-transfer (ET) processes were determined to be 2.1 × 10 4 and 3.6 × 10 2 s -1 , respectively. The rate constants of intermolecular forward and backward electron transfer were also determined to be 4.4 × 10 8 and 9.8 × 10 8 M -1 s -1 , respectively. The electronic coupling constant (V), 1.2 × 10 -2 cm -1 , and the reorganization energy (λ), 0.76 eV, for back electron transfer were evaluated from the temperature dependence of the rate constants of intramolecular electron transfer. The small V value indicates little spinforbidden interaction between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) and substantiates the long-lived CS lifetime. These results were corroborated by density function theory (DFT) calculations, which provided support for the conclusion that the HOMO and LUMO, located on a TTF moiety of the TTF-C4P and the porphyrin core, respectively, have little interaction though space.

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