Abstract
We have prepared a G-quadruplex (GQ-1) that incorporates an 8-(4′-aminophenylethynyl)guanine (GEAn) electron donor covalently attached to a 4-aminonaphthalene-1,8-imide (ANI) chromophore and a naphthalene-1,8:4,5-bis(dicarboximide) (NDI) electron acceptor (GEAn-ANI-NDI, 1). In the presence of KPF6 in tetrahydrofuran (THF), 1 self-assembles into a monodisperse, C4-symmetric GQ-1 with small spatial intraquadruplex overlap between the ANI-NDI units. Photoexcitation of monomeric 1 induces the two-step charge transfer GEAn-1∗ANI-NDI → GEAn+•-ANI-•-NDI → GEAn+•-ANI-NDI-• that occurs in τCS1 = 5 ps and τCS2 = 330 ps, respectively, while charge recombination in ca. 300 ns. Sharpening of the GEAn+• transient absorption and a shift of the ethynyl vibrational frequency in 1 were observed, concomitant with the stepwise electron transfer from ANI-• to NDI. Formation of GQ-1 from 1 in THF increases the secondary charge-shifting rate (τCS2 = 110 ps) and results in no change in ethynyl vibrational frequency. Charge recombination in GQ-1 is slowed by enhanced radical-pair intersystem crossing driven by the greater number of hyperfine couplings in the assembly. Moreover, time-resolved EPR spectroscopy shows that the spin-spin-exchange interaction (J) between the radicals of GEAn+•-ANI-NDI-• within GQ-1 is smaller than that of 1, suggesting that the spin (charge) density in GEAn+• is more dispersed in GQ-1. The spectroscopic results are consistent with hole sharing among the guanines within the G-quadruplex that is kinetically competitive with the formation of GEAn+•. This suggests that G-quadruplexes can serve as effective hole conduits in ordered donor-acceptor assemblies. (Graph Presented).
| Original language | English |
|---|---|
| Pages (from-to) | 3981-3990 |
| Number of pages | 10 |
| Journal | Journal of the American Chemical Society |
| Volume | 137 |
| Issue number | 11 |
| DOIs | |
| Publication status | Published - Mar 25 2015 |
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ASJC Scopus subject areas
- Chemistry(all)
- Catalysis
- Biochemistry
- Colloid and Surface Chemistry
Cite this
Photoinduced Hole Injection into a Self-Assembled π-Extended G-Quadruplex. / Wu, Yi Lin; Brown, Kristen E.; Gardner, Daniel M.; Dyar, Scott M.; Wasielewski, Michael R.
In: Journal of the American Chemical Society, Vol. 137, No. 11, 25.03.2015, p. 3981-3990.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Photoinduced Hole Injection into a Self-Assembled π-Extended G-Quadruplex
AU - Wu, Yi Lin
AU - Brown, Kristen E.
AU - Gardner, Daniel M.
AU - Dyar, Scott M.
AU - Wasielewski, Michael R
PY - 2015/3/25
Y1 - 2015/3/25
N2 - We have prepared a G-quadruplex (GQ-1) that incorporates an 8-(4′-aminophenylethynyl)guanine (GEAn) electron donor covalently attached to a 4-aminonaphthalene-1,8-imide (ANI) chromophore and a naphthalene-1,8:4,5-bis(dicarboximide) (NDI) electron acceptor (GEAn-ANI-NDI, 1). In the presence of KPF6 in tetrahydrofuran (THF), 1 self-assembles into a monodisperse, C4-symmetric GQ-1 with small spatial intraquadruplex overlap between the ANI-NDI units. Photoexcitation of monomeric 1 induces the two-step charge transfer GEAn-1∗ANI-NDI → GEAn+•-ANI-•-NDI → GEAn+•-ANI-NDI-• that occurs in τCS1 = 5 ps and τCS2 = 330 ps, respectively, while charge recombination in ca. 300 ns. Sharpening of the GEAn+• transient absorption and a shift of the ethynyl vibrational frequency in 1 were observed, concomitant with the stepwise electron transfer from ANI-• to NDI. Formation of GQ-1 from 1 in THF increases the secondary charge-shifting rate (τCS2 = 110 ps) and results in no change in ethynyl vibrational frequency. Charge recombination in GQ-1 is slowed by enhanced radical-pair intersystem crossing driven by the greater number of hyperfine couplings in the assembly. Moreover, time-resolved EPR spectroscopy shows that the spin-spin-exchange interaction (J) between the radicals of GEAn+•-ANI-NDI-• within GQ-1 is smaller than that of 1, suggesting that the spin (charge) density in GEAn+• is more dispersed in GQ-1. The spectroscopic results are consistent with hole sharing among the guanines within the G-quadruplex that is kinetically competitive with the formation of GEAn+•. This suggests that G-quadruplexes can serve as effective hole conduits in ordered donor-acceptor assemblies. (Graph Presented).
AB - We have prepared a G-quadruplex (GQ-1) that incorporates an 8-(4′-aminophenylethynyl)guanine (GEAn) electron donor covalently attached to a 4-aminonaphthalene-1,8-imide (ANI) chromophore and a naphthalene-1,8:4,5-bis(dicarboximide) (NDI) electron acceptor (GEAn-ANI-NDI, 1). In the presence of KPF6 in tetrahydrofuran (THF), 1 self-assembles into a monodisperse, C4-symmetric GQ-1 with small spatial intraquadruplex overlap between the ANI-NDI units. Photoexcitation of monomeric 1 induces the two-step charge transfer GEAn-1∗ANI-NDI → GEAn+•-ANI-•-NDI → GEAn+•-ANI-NDI-• that occurs in τCS1 = 5 ps and τCS2 = 330 ps, respectively, while charge recombination in ca. 300 ns. Sharpening of the GEAn+• transient absorption and a shift of the ethynyl vibrational frequency in 1 were observed, concomitant with the stepwise electron transfer from ANI-• to NDI. Formation of GQ-1 from 1 in THF increases the secondary charge-shifting rate (τCS2 = 110 ps) and results in no change in ethynyl vibrational frequency. Charge recombination in GQ-1 is slowed by enhanced radical-pair intersystem crossing driven by the greater number of hyperfine couplings in the assembly. Moreover, time-resolved EPR spectroscopy shows that the spin-spin-exchange interaction (J) between the radicals of GEAn+•-ANI-NDI-• within GQ-1 is smaller than that of 1, suggesting that the spin (charge) density in GEAn+• is more dispersed in GQ-1. The spectroscopic results are consistent with hole sharing among the guanines within the G-quadruplex that is kinetically competitive with the formation of GEAn+•. This suggests that G-quadruplexes can serve as effective hole conduits in ordered donor-acceptor assemblies. (Graph Presented).
UR - http://www.scopus.com/inward/record.url?scp=84926177540&partnerID=8YFLogxK
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U2 - 10.1021/jacs.5b00977
DO - 10.1021/jacs.5b00977
M3 - Article
C2 - 25737076
AN - SCOPUS:84926177540
VL - 137
SP - 3981
EP - 3990
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 11
ER -