Controlling electron transfer dynamics in donor-bridge-acceptor molecules by increasing unpaired spin density on the bridge

Erin T. Chernick, Qixi Mi, Amy M. Vega, Jenny V. Lockard, Mark A Ratner, Michael R Wasielewski

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

A t-butylphenylnitroxide (BPNO.) stable radical is attached to an electron donor-bridge-acceptor (D-B-A) system having well-defined distances between the components: MeOAn-6ANI-Ph(BPNO.)-NI, where MeOAn = p-methoxyaniline, 6ANI = 4-(N-piperidinyl)naphthalene-1,8-dicarboximide, Ph = phenyl, and NI = naphthalene-1,8:4,5-bis(dicarboximide). MeOAn-6ANI, BPNO ., and NI are attached to the 1, 3, and 5 positions of the Ph bridge, respectively. Time-resolved optical and EPR spectroscopy show that BPNO . influences the spin dynamics of the photogenerated triradical states 2,4(MeOAn+.-6ANI-Ph(BPNO.)-Nr -.), resulting in slower charge recombination within the triradical, as compared to the corresponding biradical lacking BPNO.. The observed spin-spin exchange interaction between the photogenerated radicals MeOAn+. and NI-. is not altered by the presence of BPNO.. However, the increased spin density on the bridge greatly increases radical pair (RP) intersystem crossing from the photogenerated singlet RP to the triplet RP. Rapid formation of the triplet RP makes it possible to observe a biexponential decay of the total RP population with components of τ = 740 ps (0.75) and 104 ns (0.25). Kinetic modeling shows that the faster decay rate is due to rapid establishment of an equilibrium between the triplet RP and the neutral triplet state resulting from charge recombination, whereas the slower rate monitors recombination of the singlet RP to ground state.

Original languageEnglish
Pages (from-to)6728-6737
Number of pages10
JournalJournal of Physical Chemistry B
Volume111
Issue number24
DOIs
Publication statusPublished - Jun 21 2007

Fingerprint

electron transfer
Naphthalene
Molecules
Electrons
Spin dynamics
molecules
Exchange interactions
Ground state
Paramagnetic resonance
Spectroscopy
naphthalene
Kinetics
spin exchange
spin dynamics
atomic energy levels
decay rates
monitors
ground state
kinetics
decay

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Controlling electron transfer dynamics in donor-bridge-acceptor molecules by increasing unpaired spin density on the bridge. / Chernick, Erin T.; Mi, Qixi; Vega, Amy M.; Lockard, Jenny V.; Ratner, Mark A; Wasielewski, Michael R.

In: Journal of Physical Chemistry B, Vol. 111, No. 24, 21.06.2007, p. 6728-6737.

Research output: Contribution to journalArticle

@article{a471aaf5156a4346a1726f6de65f26ed,
title = "Controlling electron transfer dynamics in donor-bridge-acceptor molecules by increasing unpaired spin density on the bridge",
abstract = "A t-butylphenylnitroxide (BPNO.) stable radical is attached to an electron donor-bridge-acceptor (D-B-A) system having well-defined distances between the components: MeOAn-6ANI-Ph(BPNO.)-NI, where MeOAn = p-methoxyaniline, 6ANI = 4-(N-piperidinyl)naphthalene-1,8-dicarboximide, Ph = phenyl, and NI = naphthalene-1,8:4,5-bis(dicarboximide). MeOAn-6ANI, BPNO ., and NI are attached to the 1, 3, and 5 positions of the Ph bridge, respectively. Time-resolved optical and EPR spectroscopy show that BPNO . influences the spin dynamics of the photogenerated triradical states 2,4(MeOAn+.-6ANI-Ph(BPNO.)-Nr -.), resulting in slower charge recombination within the triradical, as compared to the corresponding biradical lacking BPNO.. The observed spin-spin exchange interaction between the photogenerated radicals MeOAn+. and NI-. is not altered by the presence of BPNO.. However, the increased spin density on the bridge greatly increases radical pair (RP) intersystem crossing from the photogenerated singlet RP to the triplet RP. Rapid formation of the triplet RP makes it possible to observe a biexponential decay of the total RP population with components of τ = 740 ps (0.75) and 104 ns (0.25). Kinetic modeling shows that the faster decay rate is due to rapid establishment of an equilibrium between the triplet RP and the neutral triplet state resulting from charge recombination, whereas the slower rate monitors recombination of the singlet RP to ground state.",
author = "Chernick, {Erin T.} and Qixi Mi and Vega, {Amy M.} and Lockard, {Jenny V.} and Ratner, {Mark A} and Wasielewski, {Michael R}",
year = "2007",
month = "6",
day = "21",
doi = "10.1021/jp068741v",
language = "English",
volume = "111",
pages = "6728--6737",
journal = "Journal of Physical Chemistry B Materials",
issn = "1520-6106",
publisher = "American Chemical Society",
number = "24",

}

TY - JOUR

T1 - Controlling electron transfer dynamics in donor-bridge-acceptor molecules by increasing unpaired spin density on the bridge

AU - Chernick, Erin T.

AU - Mi, Qixi

AU - Vega, Amy M.

AU - Lockard, Jenny V.

AU - Ratner, Mark A

AU - Wasielewski, Michael R

PY - 2007/6/21

Y1 - 2007/6/21

N2 - A t-butylphenylnitroxide (BPNO.) stable radical is attached to an electron donor-bridge-acceptor (D-B-A) system having well-defined distances between the components: MeOAn-6ANI-Ph(BPNO.)-NI, where MeOAn = p-methoxyaniline, 6ANI = 4-(N-piperidinyl)naphthalene-1,8-dicarboximide, Ph = phenyl, and NI = naphthalene-1,8:4,5-bis(dicarboximide). MeOAn-6ANI, BPNO ., and NI are attached to the 1, 3, and 5 positions of the Ph bridge, respectively. Time-resolved optical and EPR spectroscopy show that BPNO . influences the spin dynamics of the photogenerated triradical states 2,4(MeOAn+.-6ANI-Ph(BPNO.)-Nr -.), resulting in slower charge recombination within the triradical, as compared to the corresponding biradical lacking BPNO.. The observed spin-spin exchange interaction between the photogenerated radicals MeOAn+. and NI-. is not altered by the presence of BPNO.. However, the increased spin density on the bridge greatly increases radical pair (RP) intersystem crossing from the photogenerated singlet RP to the triplet RP. Rapid formation of the triplet RP makes it possible to observe a biexponential decay of the total RP population with components of τ = 740 ps (0.75) and 104 ns (0.25). Kinetic modeling shows that the faster decay rate is due to rapid establishment of an equilibrium between the triplet RP and the neutral triplet state resulting from charge recombination, whereas the slower rate monitors recombination of the singlet RP to ground state.

AB - A t-butylphenylnitroxide (BPNO.) stable radical is attached to an electron donor-bridge-acceptor (D-B-A) system having well-defined distances between the components: MeOAn-6ANI-Ph(BPNO.)-NI, where MeOAn = p-methoxyaniline, 6ANI = 4-(N-piperidinyl)naphthalene-1,8-dicarboximide, Ph = phenyl, and NI = naphthalene-1,8:4,5-bis(dicarboximide). MeOAn-6ANI, BPNO ., and NI are attached to the 1, 3, and 5 positions of the Ph bridge, respectively. Time-resolved optical and EPR spectroscopy show that BPNO . influences the spin dynamics of the photogenerated triradical states 2,4(MeOAn+.-6ANI-Ph(BPNO.)-Nr -.), resulting in slower charge recombination within the triradical, as compared to the corresponding biradical lacking BPNO.. The observed spin-spin exchange interaction between the photogenerated radicals MeOAn+. and NI-. is not altered by the presence of BPNO.. However, the increased spin density on the bridge greatly increases radical pair (RP) intersystem crossing from the photogenerated singlet RP to the triplet RP. Rapid formation of the triplet RP makes it possible to observe a biexponential decay of the total RP population with components of τ = 740 ps (0.75) and 104 ns (0.25). Kinetic modeling shows that the faster decay rate is due to rapid establishment of an equilibrium between the triplet RP and the neutral triplet state resulting from charge recombination, whereas the slower rate monitors recombination of the singlet RP to ground state.

UR - http://www.scopus.com/inward/record.url?scp=34547492814&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34547492814&partnerID=8YFLogxK

U2 - 10.1021/jp068741v

DO - 10.1021/jp068741v

M3 - Article

C2 - 17309293

AN - SCOPUS:34547492814

VL - 111

SP - 6728

EP - 6737

JO - Journal of Physical Chemistry B Materials

JF - Journal of Physical Chemistry B Materials

SN - 1520-6106

IS - 24

ER -