Photoinitiated electron transfer in zinc porphyrin-perylenediimide cruciforms and their self-assembled oligomers

Sarah M. Mickley Conron, Leah E. Shoer, Amanda L. Smeigh, Annie Butler Ricks, Michael R Wasielewski

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Two X-shaped, cruciform electron donor2-acceptor- acceptor′2 (D2-A-A′2) molecules, 1 and 2, in which D = zinc 5-phenyl-10,15,20-tripentylporphyrin (ZnTPnP) or zinc 5,10,15,20-tetraphenylporphyrin (ZnTPP), respectively, A = pyromellitimide (PI), and A′ = perylene-3,4:9,10-bis(dicarboximide) (PDI), were prepared to study self-assembly motifs that promote photoinitiated charge separation followed by electron and hole transport through π-stacked donors and acceptors. PDI secondary electron acceptors were chosen because of their propensity to form self-ordered, π-stacked assemblies in solution, while the ZnTPnP and ZnTPP donors were selected to test the effect of peripheral substituent steric interactions on the π-stacking characteristics of the cruciforms. Small- and wide-angle X-ray scattering measurements in toluene solution reveal that 1 assembles into a π-stacked structure having an average of 5 ± 1 molecules, when [1] ≅ 10-5 M, while 2 remains monomeric. Photoexcitation of the π-stacked structure of 1 results in formation of ZnTPnP•+-PI-PDI•- in τCS1 = 0.3 ps, which is nearly 100-fold faster than the formation of ZnTPnP•+-PI•- in a model system lacking the PDI acceptor. The data are consistent with a self-assembled structure for 1 in which the majority of the intermolecular interactions have the ZnTPnP donor of one monomer cofacially π-stacked with the PDI acceptor of a neighboring monomer in a crisscrossed fashion. In contrast, 2 remains monomeric in toluene, so that photoexcitation of ZnTPP results in the charge separation reaction sequence: 1*ZnTPP-PI-PDI → ZnTPP•+-PI •--PDI → ZnTPP•+-PI-PDI•-, where τCS1 = 33 ps and τCS2 = 239 ps. The perpendicular orientation of ZnTPnP and ZnTPP relative to PDI in 1 and 2 is designed to decrease the porphyrin-PDI distance without greatly decreasing the overall number of bonds linking them. This serves to decrease the Coulomb energy penalty required to produce D•+-PI-PDI•- relative to the corresponding linear D-PI-PDI array, while retaining the weak electronic coupling necessary to achieve long-lived charge separation, as evidenced by τCR = 24 ns for ZnTPP•+-PI-PDI •-.

Original languageEnglish
Pages (from-to)2195-2204
Number of pages10
JournalJournal of Physical Chemistry B
Volume117
Issue number7
DOIs
Publication statusPublished - Feb 21 2013

Fingerprint

Porphyrins
oligomers
Oligomers
porphyrins
Zinc
electron transfer
zinc
Electrons
polarization (charge separation)
Photoexcitation
Toluene
perylenediimide
zinc hematoporphyrin
photoexcitation
toluene
monomers
Monomers
Perylene
Molecules
electrons

ASJC Scopus subject areas

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

Cite this

Photoinitiated electron transfer in zinc porphyrin-perylenediimide cruciforms and their self-assembled oligomers. / Mickley Conron, Sarah M.; Shoer, Leah E.; Smeigh, Amanda L.; Ricks, Annie Butler; Wasielewski, Michael R.

In: Journal of Physical Chemistry B, Vol. 117, No. 7, 21.02.2013, p. 2195-2204.

Research output: Contribution to journalArticle

Mickley Conron, Sarah M. ; Shoer, Leah E. ; Smeigh, Amanda L. ; Ricks, Annie Butler ; Wasielewski, Michael R. / Photoinitiated electron transfer in zinc porphyrin-perylenediimide cruciforms and their self-assembled oligomers. In: Journal of Physical Chemistry B. 2013 ; Vol. 117, No. 7. pp. 2195-2204.
@article{bade85bff0154da1818c791604d4bb04,
title = "Photoinitiated electron transfer in zinc porphyrin-perylenediimide cruciforms and their self-assembled oligomers",
abstract = "Two X-shaped, cruciform electron donor2-acceptor- acceptor′2 (D2-A-A′2) molecules, 1 and 2, in which D = zinc 5-phenyl-10,15,20-tripentylporphyrin (ZnTPnP) or zinc 5,10,15,20-tetraphenylporphyrin (ZnTPP), respectively, A = pyromellitimide (PI), and A′ = perylene-3,4:9,10-bis(dicarboximide) (PDI), were prepared to study self-assembly motifs that promote photoinitiated charge separation followed by electron and hole transport through π-stacked donors and acceptors. PDI secondary electron acceptors were chosen because of their propensity to form self-ordered, π-stacked assemblies in solution, while the ZnTPnP and ZnTPP donors were selected to test the effect of peripheral substituent steric interactions on the π-stacking characteristics of the cruciforms. Small- and wide-angle X-ray scattering measurements in toluene solution reveal that 1 assembles into a π-stacked structure having an average of 5 ± 1 molecules, when [1] ≅ 10-5 M, while 2 remains monomeric. Photoexcitation of the π-stacked structure of 1 results in formation of ZnTPnP•+-PI-PDI•- in τCS1 = 0.3 ps, which is nearly 100-fold faster than the formation of ZnTPnP•+-PI•- in a model system lacking the PDI acceptor. The data are consistent with a self-assembled structure for 1 in which the majority of the intermolecular interactions have the ZnTPnP donor of one monomer cofacially π-stacked with the PDI acceptor of a neighboring monomer in a crisscrossed fashion. In contrast, 2 remains monomeric in toluene, so that photoexcitation of ZnTPP results in the charge separation reaction sequence: 1*ZnTPP-PI-PDI → ZnTPP•+-PI •--PDI → ZnTPP•+-PI-PDI•-, where τCS1 = 33 ps and τCS2 = 239 ps. The perpendicular orientation of ZnTPnP and ZnTPP relative to PDI in 1 and 2 is designed to decrease the porphyrin-PDI distance without greatly decreasing the overall number of bonds linking them. This serves to decrease the Coulomb energy penalty required to produce D•+-PI-PDI•- relative to the corresponding linear D-PI-PDI array, while retaining the weak electronic coupling necessary to achieve long-lived charge separation, as evidenced by τCR = 24 ns for ZnTPP•+-PI-PDI •-.",
author = "{Mickley Conron}, {Sarah M.} and Shoer, {Leah E.} and Smeigh, {Amanda L.} and Ricks, {Annie Butler} and Wasielewski, {Michael R}",
year = "2013",
month = "2",
day = "21",
doi = "10.1021/jp311067q",
language = "English",
volume = "117",
pages = "2195--2204",
journal = "Journal of Physical Chemistry B Materials",
issn = "1520-6106",
publisher = "American Chemical Society",
number = "7",

}

TY - JOUR

T1 - Photoinitiated electron transfer in zinc porphyrin-perylenediimide cruciforms and their self-assembled oligomers

AU - Mickley Conron, Sarah M.

AU - Shoer, Leah E.

AU - Smeigh, Amanda L.

AU - Ricks, Annie Butler

AU - Wasielewski, Michael R

PY - 2013/2/21

Y1 - 2013/2/21

N2 - Two X-shaped, cruciform electron donor2-acceptor- acceptor′2 (D2-A-A′2) molecules, 1 and 2, in which D = zinc 5-phenyl-10,15,20-tripentylporphyrin (ZnTPnP) or zinc 5,10,15,20-tetraphenylporphyrin (ZnTPP), respectively, A = pyromellitimide (PI), and A′ = perylene-3,4:9,10-bis(dicarboximide) (PDI), were prepared to study self-assembly motifs that promote photoinitiated charge separation followed by electron and hole transport through π-stacked donors and acceptors. PDI secondary electron acceptors were chosen because of their propensity to form self-ordered, π-stacked assemblies in solution, while the ZnTPnP and ZnTPP donors were selected to test the effect of peripheral substituent steric interactions on the π-stacking characteristics of the cruciforms. Small- and wide-angle X-ray scattering measurements in toluene solution reveal that 1 assembles into a π-stacked structure having an average of 5 ± 1 molecules, when [1] ≅ 10-5 M, while 2 remains monomeric. Photoexcitation of the π-stacked structure of 1 results in formation of ZnTPnP•+-PI-PDI•- in τCS1 = 0.3 ps, which is nearly 100-fold faster than the formation of ZnTPnP•+-PI•- in a model system lacking the PDI acceptor. The data are consistent with a self-assembled structure for 1 in which the majority of the intermolecular interactions have the ZnTPnP donor of one monomer cofacially π-stacked with the PDI acceptor of a neighboring monomer in a crisscrossed fashion. In contrast, 2 remains monomeric in toluene, so that photoexcitation of ZnTPP results in the charge separation reaction sequence: 1*ZnTPP-PI-PDI → ZnTPP•+-PI •--PDI → ZnTPP•+-PI-PDI•-, where τCS1 = 33 ps and τCS2 = 239 ps. The perpendicular orientation of ZnTPnP and ZnTPP relative to PDI in 1 and 2 is designed to decrease the porphyrin-PDI distance without greatly decreasing the overall number of bonds linking them. This serves to decrease the Coulomb energy penalty required to produce D•+-PI-PDI•- relative to the corresponding linear D-PI-PDI array, while retaining the weak electronic coupling necessary to achieve long-lived charge separation, as evidenced by τCR = 24 ns for ZnTPP•+-PI-PDI •-.

AB - Two X-shaped, cruciform electron donor2-acceptor- acceptor′2 (D2-A-A′2) molecules, 1 and 2, in which D = zinc 5-phenyl-10,15,20-tripentylporphyrin (ZnTPnP) or zinc 5,10,15,20-tetraphenylporphyrin (ZnTPP), respectively, A = pyromellitimide (PI), and A′ = perylene-3,4:9,10-bis(dicarboximide) (PDI), were prepared to study self-assembly motifs that promote photoinitiated charge separation followed by electron and hole transport through π-stacked donors and acceptors. PDI secondary electron acceptors were chosen because of their propensity to form self-ordered, π-stacked assemblies in solution, while the ZnTPnP and ZnTPP donors were selected to test the effect of peripheral substituent steric interactions on the π-stacking characteristics of the cruciforms. Small- and wide-angle X-ray scattering measurements in toluene solution reveal that 1 assembles into a π-stacked structure having an average of 5 ± 1 molecules, when [1] ≅ 10-5 M, while 2 remains monomeric. Photoexcitation of the π-stacked structure of 1 results in formation of ZnTPnP•+-PI-PDI•- in τCS1 = 0.3 ps, which is nearly 100-fold faster than the formation of ZnTPnP•+-PI•- in a model system lacking the PDI acceptor. The data are consistent with a self-assembled structure for 1 in which the majority of the intermolecular interactions have the ZnTPnP donor of one monomer cofacially π-stacked with the PDI acceptor of a neighboring monomer in a crisscrossed fashion. In contrast, 2 remains monomeric in toluene, so that photoexcitation of ZnTPP results in the charge separation reaction sequence: 1*ZnTPP-PI-PDI → ZnTPP•+-PI •--PDI → ZnTPP•+-PI-PDI•-, where τCS1 = 33 ps and τCS2 = 239 ps. The perpendicular orientation of ZnTPnP and ZnTPP relative to PDI in 1 and 2 is designed to decrease the porphyrin-PDI distance without greatly decreasing the overall number of bonds linking them. This serves to decrease the Coulomb energy penalty required to produce D•+-PI-PDI•- relative to the corresponding linear D-PI-PDI array, while retaining the weak electronic coupling necessary to achieve long-lived charge separation, as evidenced by τCR = 24 ns for ZnTPP•+-PI-PDI •-.

UR - http://www.scopus.com/inward/record.url?scp=84874170098&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84874170098&partnerID=8YFLogxK

U2 - 10.1021/jp311067q

DO - 10.1021/jp311067q

M3 - Article

VL - 117

SP - 2195

EP - 2204

JO - Journal of Physical Chemistry B Materials

JF - Journal of Physical Chemistry B Materials

SN - 1520-6106

IS - 7

ER -