Photophysics of 2{prime}-deoxyuridine (dU) nucleosides covalently substituted with either 1-pyrenyl or 1-pyrenoyl. Observation of pyrene-to-nucleoside charge-transfer emission in 5-(1-pyrenyl)-dU
- Georgia State Univ., Atlanta, GA (United States)
- Washington State Univ., Pullman, WA (United States)
This paper reports syntheses electronic absorbance and emission spectra, and emission kinetics results for two types of pyrene-substituted uridine nucleosides as part of an ongoing study which is examining the photophysical and photochemical behaviors of these same nucleosides embedded in DNA oligomers and duplexes with varying base-sequence composition. The two labels are 1-pyrenyl itself and 1-carboxypyrenyl (1-pyrenoyl) which are each joined direcrly to the 5-position of 2`-deoxyuridine (dCT). These direct attachments significantly restrict the range of conformations available to the pyrene label when it is attached to a DNA oligomer or duplex. {pi},{pi}{sup *} emission is absent for 5-(1-pyrenyl)-dU, 1, in methanol (MeOH) but present in tetrahydrofuran (THF). The steady-state emission spectrum of 1 in MeOH shows that emission from the few long-lived {pi},{pi}{sup *} states is dominated at all wavelengths by the 0.9-ns lived CT emission. In contrast, only {pi},{pi}{sup *} emission is observed for 5-(1-pyrenoyl)-dU, 2, in both MeOH and THF with emission quantum yields of 0.002 and 0.028, respectively. The spectral and emission kinetics data for nucleosides 1 and 2 support the conclusions that each has multiple conformers in solution and that the relative orientation of the pyrene and uridine {pi}-systems plays a crucial role in determining the rates of both ET quenching of pyrene{sup *} and charge-recombination in the photoproduct. 98 refs., 2 figs., 3 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 115677
- Journal Information:
- Journal of the American Chemical Society, Vol. 117, Issue 36; Other Information: PBD: 13 Sep 1995
- Country of Publication:
- United States
- Language:
- English
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