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Issue 20, 2010
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Effect of substituents on the excited-state dynamics of the modified DNA bases 2,4-diaminopyrimidine and 2,6-diaminopurine

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Abstract

To explore the excited state dynamics of pyrimidine derivatives, we performed a combined experimental and theoretical study. We present resonant two-photon ionization (R2PI) and IR-UV double resonance spectra of 2,4-diaminopyrimidine and 2,6-diaminopurine seeded in a supersonic jet by laser desorption. For 2,4-diaminopyrimidine (S0 → S1 34 459 cm−1), we observed only the diamino tautomer with an excited state lifetime bracketed between experimental limits of 10 ps and 1 ns. For 2,6-diaminopurine, we observed two tautomers, the 9H- (S0 → S1 34 881 cm−1) and 7H- (S0 → S1 32 215 cm−1) diamino forms, with excited state lifetimes of 6.3 ± 0.4 ns and 8.7 ± 0.8 ns, respectively. We investigated the nature of the excited state of 2,4-diaminopyrimidine by means of multi-reference ab initio methods. The calculations of stationary points in the ground and excited states, minima on the S0/S1 crossing seam and connecting reaction paths show that several paths with negligible barriers exist, allowing ultrafast radiationless deactivation if excited at energies slightly higher than the band origin. The sub-nanosecond lifetime found experimentally is in good agreement with this finding.

Graphical abstract: Effect of substituents on the excited-state dynamics of the modified DNA bases 2,4-diaminopyrimidine and 2,6-diaminopurine

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Publication details

The article was received on 01 Sep 2009, accepted on 09 Feb 2010 and first published on 08 Apr 2010


Article type: Paper
DOI: 10.1039/B917852J
Citation: Phys. Chem. Chem. Phys., 2010,12, 5375-5388
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    Effect of substituents on the excited-state dynamics of the modified DNA bases 2,4-diaminopyrimidine and 2,6-diaminopurine

    Z. Gengeliczki, M. P. Callahan, N. Svadlenak, C. I. Pongor, B. Sztáray, L. Meerts, D. Nachtigallová, P. Hobza, M. Barbatti, H. Lischka and M. S. de Vries, Phys. Chem. Chem. Phys., 2010, 12, 5375
    DOI: 10.1039/B917852J

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