Charge recombination in the photoinduced charge separated (CS) state of a rigidly linked donor/bridge/acceptor triad with a triarylamine (TAA) donor, a 1,3-diethynyl-2,5-dimethoxy benzene bridge (OMe), and a perylenediimide (PDI) unit as an acceptor, represents a spin chemical paradigm case of a rigid radical ion pair formed with singlet spin and recombining almost exclusively to the locally excited PDI triplet state (3PDI). The magnetic field dependence of the CS state decay and 3PDI formation kinetics are investigated from 0 to 1800 mT by nanosecond laser flash spectroscopy. The time-resolved magnetic field affected reaction yields spectra of the CS state population and 3PDI population exhibit a sharp and deep resonance at 18.9 mT, indicating level crossing of the S and T+ levels separated by an exchange interaction of J = 18.9/2 mT at zero field. The kinetics are biexponential around the resonance field and monoexponential outside that range. The monoexponential behavior can be simulated by a classical kinetic model assuming a single field dependent double Lorentzian function for the energy gap dependence of all spin conversion processes. The full field dependence of the kinetics has been simulated quantum theoretically. It has been shown that incoherent and coherent hyperfine coupling contribute to S/T+ spin conversion at all fields and that the biexponentiality of the kinetics at resonance is due to a partitioning of the overall kinetics into 2/3 of the singlet hyperfine states exhibiting strong isotropic coupling to T+ and 1/3 of the singlet hyperfine states that do not or only weakly couple isotropically to T+.
REFERENCES
1.
K.
Schulten
, H.
Staerk
, A.
Weller
, H. J.
Werner
, and B.
Nickel
, “Magnetic-field dependence of geminate recombination of radical ion-pairs in polar-solvents
,” Z. Phys. Chem.
101
, 371
–390
(1976
).2.
M. E.
Michel-Beyerle
, R.
Haberkorn
, W.
Bube
, E.
Steffens
, H.
Schröder
, H. J.
Neusser
, E. W.
Schlag
, and H.
Seidlitz
, “Magnetic field modulation of geminate recombination of radical ions inpolar solvent
,” Chem. Phys.
17
, 139
–145
(1976
).3.
T.
Miura
, A. M.
Scott
, and M. R.
Wasielewski
, “Electron spin dynamics as a controlling factor for spin-selective charge recombination in donor-bridge-acceptor molecules
,” J. Phys. Chem. C
114
, 20370
–20379
(2010
).4.
D.
Kuciauskas
, P. A.
Lidell
, A. L.
Moore
, T. A.
Moore
, and D.
Gust
, “Magnetic switching of charge separation lifetime in artificial photosynthetic reaction centers
,” J. Am. Chem. Soc.
120
, 10880
–10886
(1998
).5.
M.
Wegner
, H.
Fischer
, S.
Grosse
, H.-M.
Vieth
, A. M.
Oliver
, and M. N.
Paddon-Row
, “Field dependent CIDNP from photochemically generated radical ion pairs in rigid bichromophoric systems
,” Chem. Phys.
264
, 341
–353
(2001
).6.
J. W.
Verhoeven
, “On the role of spin correlation in the formation, decay, and detection of long-lived, intramolecular charge-transfer states
,” J. Photochem. Photobiol. C: Photochem. Rev.
7
, 40
–60
(2006
).7.
A. M.
Scott
, T.
Miura
, A. B.
Ricks
, Z. E. X.
Dance
, E. M.
Giacobbe
, M. T.
Colvin
, and M. R.
Wasielewski
, “Spin-selective charge transport pathways through P-Oligophyenylene-Linked donor-bridge-acceptor molecules
,” J. Am. Chem. Soc.
131
, 17655
–17666
(2009
).8.
T.
Miura
, “Studies on coherent and incoherent spin dynamics that control the magnetic field effect on photogenerated radical pairs
,” Mol. Phys.
(published online).9.
U. E.
Steiner
, J.
Schäfer
, N. N.
Lukzen
, and C.
Lambert
, “J-resonance lineshape of MARY spectrum from charge recombination in a linked donor/acceptor dyad
,” J. Phys. Chem. C
122
, 11701
–11708
(2018
).10.
J.
Schäfer
, M.
Holzapfel
, A.
Schmiedel
, U. E.
Steiner
, and C.
Lambert
, “Finetuning of electron transfer and spin chemistry parameters in triarylamine-bridge-naphthalene diimide dyads by bridge substituents
,” Phys. Chem. Chem. Phys.
20
, 27093
(2018
).11.
S.
Riese
, L.
Mungenast
, A.
Schmiedel
, M.
Holzapfel
, N. N.
Lukzen
, U. E.
Steiner
, and C.
Lambert
, “Nanoviscosity effect on the spin chemistry of an electron donor/Pt-Complex/Electron acceptor triad—Classical and quantum kinetics interpretation
,” Mol. Phys.
117
, 2632
(2019
).12.
J. H.
Klein
, D.
Schmidt
, U. E.
Steiner
, and C.
Lambert
, “Complete monitoring of coherent and incoherent spin flip domains in the recombination of charge-separated states of donor-iridium complex-acceptor triads
,” J. Am. Chem. Soc.
137
, 11011
–11021
(2015
).13.
I. H. M.
van Stokkum
, D. S.
Larsen
, and R.
van Grondelle
, “Global and target analysis of time-resolved spectra
,” Biochim. Biophys. Acta (BBA)
1657
, 82
–104
(2004
).14.
S.
Amthor
, B.
Noller
, and C.
Lambert
, “UV/Vis/NIR spectral properties of triarylaminesand their corresponding radical cations
,” Chem. Phys.
316
, 141
–152
(2005
).15.
C.
Huang
, M. M.
Sartin
, N.
Siegel
, M.
Cozzuol
, Y.
Zhang
, J. M.
Hales
, S.
Barlow
, J. W.
Perry
, and S. R.
Marder
, “Photo-induced charge transfer and nonlinear absorption in dyads composed of a two-photon-absorbing donor and a perylene diimide acceptor
,” J. Mater. Chem.
21
, 16119
–16128
(2011
).16.
D. J.
Gosztola
, M. P.
Niemczyk
, W. A.
Svec
, A. S.
Lukas
, and M. R.
Wasielewski
, “Excited doublet states of electrochemically generated aromatic imide and diimide radical anions
,” J. Phys. Chem. A
104
, 6545
–6551
(2000
).17.
W. E.
Ford
and P. V.
Kamat
, “Photochemistry of 3,4,9,10-perylenetetracarboxylic dianhydryde dyes. 3. Singlet and triplet excited-state properties of the bis(2,5-di-tert-Butylphenyl)Imide derivative
,” J. Phys. Chem.
91
, 6373
–6380
(1987
).18.
E. A.
Weiss
, M. J.
Ahrens
, L. E.
Sinks
, M. A.
Ratner
, and M. R.
Wasielewski
, “Solvent control of CPIN-dependent charge recombination mechanisms within donor-conjugated cridge-acceptor molecule
,” J. Am. Chem. Soc.
126
, 9510
–9511
(2004
).19.
A.
Weller
, H.
Staerk
, and R.
Treichel
, “Magnetic-field effects on geminate radical-pair recombination
,” Faraday Discuss.
78
, 271
–278
(1984
).20.
T. P.
Fay
and D. E.
Manolopoulos
, “Radical pair intersystem crossing: Quantum dynamics or incoherent kinetics?
,” J. Chem. Phys.
150
, 151102
(2019
).21.
A positive J value was found in the case of the triad with naphthalene bisdiimide instead of perylene bisdiimide in the present case, cf.,
I.
Zhukov
, N.
Fishman
, A.
Kiryutin
, N.
Lukzen
, M.
Panov
, U.
Steiner
, H.-M.
Vieth
, J.
Schäfer
, C.
Lambert
, and A.
Yurkovskaya
, “Positive electronic exchange interaction and predominance of minor triplet channel in CIDNP formation in short lived charge separated states of D-X-A dyads
,” J. Chem. Phys.
(unpublished).22.
MATHEMATICA, Version 11.2, Wolfram Research, Inc., Champaign, IL,
2017
.23.
N. N.
Lukzen
, J. H.
Klein
, C.
Lambert
, and U. E.
Steiner
, “The quantum dynamical basis of a classical kinetic scheme describing coherent and incoherent regimes of radical pair recombination
,” Z. Phys. Chem.
231
, 197
–223
(2017
).24.
D. R.
Kattnig
, B.
Mladenova
, G.
Grampp
, C.
Kaiser
, A.
Heckmann
, and C.
Lambert
, “Electron paramagnetic resonance spectroscopy of bis(triarylamine) paracyclophanes as model compounds for the intermolecular charge-transfer in solid state materials for optoelectronic applications
,” J. Chem. Phys. C
113
, 2983
–2995
(2009
).25.
S.-G.
Chen
, H. M.
Branz
, S. S.
Eaton
, P. C.
Taylor
, R. A.
Cormier
, and B. A.
Gregg
, “Substitutional N-type doping of an organic semiconductor investigated by electron paramagnetic resonance spectroscopy
,” J. Phys. Chem. B
108
, 17329
–17336
(2004
).26.
V. A.
Ryabinin
, V. F.
Starichenko
, G. N.
Vorozhtsov
, and S. M.
Shein
, “Radical-anions of derivatives of binaphthyl- and perylene-tetracarboxylic acids
,” J. Struct. Chem.
19
, 821
–823
(1978
).27.
28.
M. V.
Fedin
, P. A.
Purtov
, and E. G.
Bagryanskaya
, “Spin relaxation of radicals in low and zero magnetic field
,” J. Chem. Phys.
118
, 192
–201
(2003
).29.
N. I.
Avdievich
and M. D. E.
Forbes
, “Dynamic effects in spin-correlated radical pair theory: J-modulation and a new look at the phenomenon of alternating line widths in the EPRS spectra of flexibel biradicals
,” J. Phys. Chem.
99
, 9660
–9667
(1995
).30.
K.
Maeda
, T.
Miura
, and T.
Arai
, “A practical simulation and a novel insight to the magnetic field effect on a radical pair in a micelle
,” Mol. Phys.
104
, 1779
–1788
(2006
).31.
T.
Miura
, K.
Maeda
, and T.
Arai
, “The spin mixing process of a radical pair in low magnetic field observed by transient absorption detected nanosecond pulsed magnetic field effect
,” J. Phys. Chem. A
110
, 4151
–4156
(2006
).32.
M. D. E.
Forbes
, “State mixing, electron spin relaxation, and chain dynamics in transient flexible 1,N-biradicals
,” Electron Paramag. Reson.
23
, 58
–78
(2013
).33.
J.
Schäfer
, “Synthesis and photophysical investigation of donor-acceptor-substituted meta- and para-benzene derivatives
,” Ph.D. dissertation (University of Würzburg
, Würzburg
, 2017
).© 2019 Author(s).
2019
Author(s)
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