Gas-Phase Cytosine and Cytosine-N 1 -Derivatives Have 0.1–1 ns Lifetimes Near the S 1 State Minimum

Blaser, Susan; Trachsel, Maria Angela; Lobsiger, Simon; Wiedmer, Timo; Frey, Hans-Martin; Leutwyler, Samuel (2016). Gas-Phase Cytosine and Cytosine-N 1 -Derivatives Have 0.1–1 ns Lifetimes Near the S 1 State Minimum. The journal of physical chemistry letters, 7(5), pp. 752-757. American Chemical Society 10.1021/acs.jpclett.6b00017

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Ultraviolet radiative damage to DNA is inefficient because of the ultrafast S1 ⇝ S0 internal conversion of its nucleobases. Using picosecond pump–ionization delay measurements, we find that the S1(1ππ*) state vibrationless lifetime of gas-phase keto-amino cytosine (Cyt) is τ = 730 ps or ∼700 times longer than that measured by femtosecond pump–probe ionization at higher vibrational excess energy, Eexc. N1-Alkylation increases the S1 lifetime up to τ = 1030 ps for N1-ethyl-Cyt but decreases it to 100 ps for N1-isopropyl-Cyt. Increasing the vibrational energy to Eexc = 300–550 cm–1 decreases the lifetimes to 20–30 ps. The nonradiative dynamics of S1 cytosine is not solely a property of the amino-pyrimidinone chromophore but is strongly influenced by the N1-substituent. Correlated excited-state calculations predict that the gap between the S2(1nOπ*) and S1(1ππ*) states decreases along the series of N1-derivatives, thereby influencing the S1 state lifetime.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry
13 Central Units > Services of the Rector's Office > Forum für Universität und Gesellschaft
08 Faculty of Science > Other Institutions > Teaching Staff, Faculty of Science

UniBE Contributor:

Blaser, Susan; Trachsel, Maria Angela; Lobsiger, Simon; Wiedmer, Timo; Frey, Hans-Martin and Leutwyler, Samuel

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry
500 Science
600 Technology > 620 Engineering

ISSN:

1948-7185

Publisher:

American Chemical Society

Language:

English

Submitter:

Beatrice Niederhauser

Date Deposited:

15 Dec 2016 15:05

Last Modified:

07 Dec 2018 13:14

Publisher DOI:

10.1021/acs.jpclett.6b00017

BORIS DOI:

10.7892/boris.90038

URI:

https://boris.unibe.ch/id/eprint/90038

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