Charge-transfer and spin dynamics in dna hairpin conjugates with perylenediimide as a base-pair surrogate

Tarek A. Zeidan, Raanan Carmieli, Richard F. Kelley, Thea M. Wilson, Frederick D. Lewis, Michael R Wasielewski

Research output: Contribution to journalArticle

67 Citations (Scopus)

Abstract

A perylenediimide chromophore (P) was incorporated into DNA hairpins as a base-pair surrogate to prevent the self-aggregation of P that is typical when it is used as the hairpin linker. The photoinduced charge-transfer and spin dynamics of these hairpins were studied using femtosecond transient absorption spectroscopy and time-resolved EPR spectroscopy (TREPR). P is a photooxidant that is sufficiently powerful to quantitatively inject holes into adjacent adenine (A) and guanine (G) nucleobases. The charge-transfer dynamics observed following hole injection from P into the A-tract of the DNA hairpins is consistent with formation of a polaron involving an estimated 3-4 A bases. Trapping of the (A3-4)+• polaron by a G base at the opposite end of the A-tract from P is competitive with charge recombination of the polaron and P-• only at short P-G distances. In a hairpin having 3 A-T base pairs between P and G (4G), the radical ion pair that results from trapping of the hole by G is spin-correlated and displays TREPR spectra at 295 and 85 K that are consistent with its formation from 1*P by the radical-pair intersystem crossing mechanism. Charge recombination is spin-selective and produces 3*P, which at 85 K exhibits a spin-polarized TREPR spectrum that is diagnostic of its origin from the spin-correlated radical ion pair. Interestingly, in a hairpin having no G bases (OG), TREPR spectra at 85 K revealed a spin-correlated radical pair with a dipolar interaction identical to that of 4G, implying that the A-base in the fourth A-T base pair away from the P chromophore serves as a hole trap. Our data suggest that hole injection and transport in these hairpins is completely dominated by polaron generation and movement to a trap site rather than by superexchange. On the other hand, the barrier for charge injection from G +• back onto the A-T base pairs is strongly activated, so charge recombination from G (or even A trap sites at 85 K) most likely proceeds by a superexchange mechanism.

Original languageEnglish
Pages (from-to)13945-13955
Number of pages11
JournalJournal of the American Chemical Society
Volume130
Issue number42
DOIs
Publication statusPublished - Oct 22 2008

Fingerprint

Spin dynamics
Gene Conversion
Base Pairing
Paramagnetic resonance
Charge transfer
Spectrum Analysis
Spectroscopy
Genetic Recombination
Chromophores
DNA
Ions
Hole traps
Charge injection
Guanine
Adenine
Absorption spectroscopy
Agglomeration
perylenediimide
Injections

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Charge-transfer and spin dynamics in dna hairpin conjugates with perylenediimide as a base-pair surrogate. / Zeidan, Tarek A.; Carmieli, Raanan; Kelley, Richard F.; Wilson, Thea M.; Lewis, Frederick D.; Wasielewski, Michael R.

In: Journal of the American Chemical Society, Vol. 130, No. 42, 22.10.2008, p. 13945-13955.

Research output: Contribution to journalArticle

Zeidan, Tarek A. ; Carmieli, Raanan ; Kelley, Richard F. ; Wilson, Thea M. ; Lewis, Frederick D. ; Wasielewski, Michael R. / Charge-transfer and spin dynamics in dna hairpin conjugates with perylenediimide as a base-pair surrogate. In: Journal of the American Chemical Society. 2008 ; Vol. 130, No. 42. pp. 13945-13955.
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