التفاصيل البيبلوغرافية
| العنوان: |
Communication: The dark singlet state as a doorway state in the ultrafast and efficient intersystem crossing dynamics in 2-thiothymine and 2-thiouracil. |
| المؤلفون: |
Pollum, Marvin, Crespo-Hernández, Carlos E. |
| المصدر: |
Journal of Chemical Physics; 2/21/2014, Vol. 140 Issue 7, p071101-1-071101-5, 5p, 3 Graphs |
| مصطلحات موضوعية: |
SINGLET state (Quantum mechanics), ABSORPTION, DESORPTION, FEMTOCHEMISTRY, INTERSYSTEM crossing (Chemistry) |
| مستخلص: |
Femtosecond broadband transient absorption experiments are reported for 2-thiothymine and 2- thiouracil in aqueous buffer solution and in acetonitrile. It is shown that the S1(nπ") state acts as a doorway state in the ultrafast and efficient population of the T1(ππ") state upon 316 nm excitation. A sequential kinetic model is presented to explain the excited-state dynamics in 2-thiothymine and 2-thiouracil upon UVA excitation: S1(ππ") → S1(nπ") → T1(ππ"). The experimental results are also used to scrutinize the excited-state relaxation pathways recently predicted for 2-thiouracil at the CASPT2//CASSCF level of theory [G. Cui and W. Fang, J. Chem. Phys. 138, 044315 (2013)]. The efficient population of the T1(ππ") state for both 2-thiothymine and 2-thiouracil in a few hundreds of femtoseconds lends further support to the emerging idea that thiobase derivatives exhibit phototoxic properties that can be effectively harnessed in photo-chemotherapeutic applications. [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
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