Excess polarizability reveals excitan localization/delocalization controlled by linking positions on porphyrin rings in butadiyne-bridged porphyrin dimers

Chunxing She, Shanmugam Easwaramoorthi, Pyosang Kim, Satoru Hiroto, Ichiro Hisaki, Hiroshi Shinokubo, Atsuhiro Osuka, Dongho Kim, Joseph T. Hupp

Research output: Contribution to journalArticle

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Abstract

We report direct measurements of the excess polarizability volumes of butadiyne-bridged zinc porphyrin dimers at singly β-to-β (1Zn) and doubly β-to-β (2Zn) positions using the transient dc photoconductivity (TDCP) technique. The excess polarizability volumes of the singlet exciton for 1Zn and 2Zn are 110 and 270 Å3, respectively, while those of the triplet exciton are ∼100 Å3 for both dimers. Our measurements suggest that the singlet exciton is mainly localized on one porphyrin subunit for 1Zn, similar to the case for the porphyrin monomer. While the exciton is fully delocalized on two porphyrin subunits in the case of meso-to-meso linked dimer (3Zn), the extent of exciton localization/ delocalization for doubly β-to-β linked dimer lies between those of singly β-to-β and meso-to-meso linked dimers. Electronic structure calculations show that the dramatically different extents of exciton localization/delocalization are the results of frontier orbital coefficients being small at β positions but large at meso positions. Two butadiyne linkages between the porphyrins at β positions (2Zn) clearly facilitate electronic communication between the two porphyrin subunits by virtue of stabilization of cumulenic charge resonance structures through enforced planarity.

Original languageEnglish
Pages (from-to)3384-3390
Number of pages7
JournalJournal of Physical Chemistry A
Volume114
Issue number10
DOIs
Publication statusPublished - 2010 Mar 18

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Porphyrins
porphyrins
Dimers
dimers
excitons
rings
Photoconductivity
linkages
photoconductivity
Electronic structure
LDS 751
Stabilization
monomers
zinc
stabilization
Monomers
communication
electronic structure
orbitals
Communication

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

Cite this

She, Chunxing ; Easwaramoorthi, Shanmugam ; Kim, Pyosang ; Hiroto, Satoru ; Hisaki, Ichiro ; Shinokubo, Hiroshi ; Osuka, Atsuhiro ; Kim, Dongho ; Hupp, Joseph T. / Excess polarizability reveals excitan localization/delocalization controlled by linking positions on porphyrin rings in butadiyne-bridged porphyrin dimers. In: Journal of Physical Chemistry A. 2010 ; Vol. 114, No. 10. pp. 3384-3390.
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abstract = "We report direct measurements of the excess polarizability volumes of butadiyne-bridged zinc porphyrin dimers at singly β-to-β (1Zn) and doubly β-to-β (2Zn) positions using the transient dc photoconductivity (TDCP) technique. The excess polarizability volumes of the singlet exciton for 1Zn and 2Zn are 110 and 270 {\AA}3, respectively, while those of the triplet exciton are ∼100 {\AA}3 for both dimers. Our measurements suggest that the singlet exciton is mainly localized on one porphyrin subunit for 1Zn, similar to the case for the porphyrin monomer. While the exciton is fully delocalized on two porphyrin subunits in the case of meso-to-meso linked dimer (3Zn), the extent of exciton localization/ delocalization for doubly β-to-β linked dimer lies between those of singly β-to-β and meso-to-meso linked dimers. Electronic structure calculations show that the dramatically different extents of exciton localization/delocalization are the results of frontier orbital coefficients being small at β positions but large at meso positions. Two butadiyne linkages between the porphyrins at β positions (2Zn) clearly facilitate electronic communication between the two porphyrin subunits by virtue of stabilization of cumulenic charge resonance structures through enforced planarity.",
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Excess polarizability reveals excitan localization/delocalization controlled by linking positions on porphyrin rings in butadiyne-bridged porphyrin dimers. / She, Chunxing; Easwaramoorthi, Shanmugam; Kim, Pyosang; Hiroto, Satoru; Hisaki, Ichiro; Shinokubo, Hiroshi; Osuka, Atsuhiro; Kim, Dongho; Hupp, Joseph T.

In: Journal of Physical Chemistry A, Vol. 114, No. 10, 18.03.2010, p. 3384-3390.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Excess polarizability reveals excitan localization/delocalization controlled by linking positions on porphyrin rings in butadiyne-bridged porphyrin dimers

AU - She, Chunxing

AU - Easwaramoorthi, Shanmugam

AU - Kim, Pyosang

AU - Hiroto, Satoru

AU - Hisaki, Ichiro

AU - Shinokubo, Hiroshi

AU - Osuka, Atsuhiro

AU - Kim, Dongho

AU - Hupp, Joseph T.

PY - 2010/3/18

Y1 - 2010/3/18

N2 - We report direct measurements of the excess polarizability volumes of butadiyne-bridged zinc porphyrin dimers at singly β-to-β (1Zn) and doubly β-to-β (2Zn) positions using the transient dc photoconductivity (TDCP) technique. The excess polarizability volumes of the singlet exciton for 1Zn and 2Zn are 110 and 270 Å3, respectively, while those of the triplet exciton are ∼100 Å3 for both dimers. Our measurements suggest that the singlet exciton is mainly localized on one porphyrin subunit for 1Zn, similar to the case for the porphyrin monomer. While the exciton is fully delocalized on two porphyrin subunits in the case of meso-to-meso linked dimer (3Zn), the extent of exciton localization/ delocalization for doubly β-to-β linked dimer lies between those of singly β-to-β and meso-to-meso linked dimers. Electronic structure calculations show that the dramatically different extents of exciton localization/delocalization are the results of frontier orbital coefficients being small at β positions but large at meso positions. Two butadiyne linkages between the porphyrins at β positions (2Zn) clearly facilitate electronic communication between the two porphyrin subunits by virtue of stabilization of cumulenic charge resonance structures through enforced planarity.

AB - We report direct measurements of the excess polarizability volumes of butadiyne-bridged zinc porphyrin dimers at singly β-to-β (1Zn) and doubly β-to-β (2Zn) positions using the transient dc photoconductivity (TDCP) technique. The excess polarizability volumes of the singlet exciton for 1Zn and 2Zn are 110 and 270 Å3, respectively, while those of the triplet exciton are ∼100 Å3 for both dimers. Our measurements suggest that the singlet exciton is mainly localized on one porphyrin subunit for 1Zn, similar to the case for the porphyrin monomer. While the exciton is fully delocalized on two porphyrin subunits in the case of meso-to-meso linked dimer (3Zn), the extent of exciton localization/ delocalization for doubly β-to-β linked dimer lies between those of singly β-to-β and meso-to-meso linked dimers. Electronic structure calculations show that the dramatically different extents of exciton localization/delocalization are the results of frontier orbital coefficients being small at β positions but large at meso positions. Two butadiyne linkages between the porphyrins at β positions (2Zn) clearly facilitate electronic communication between the two porphyrin subunits by virtue of stabilization of cumulenic charge resonance structures through enforced planarity.

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JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

SN - 1089-5639

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