TY - JOUR
T1 - Effect of substituents on the excited-state dynamics of the modified DNA bases 2,4-diaminopyrimidine and 2,6-diaminopurine
AU - Gengeliczki, Zsolt
AU - Callahan, Michael P.
AU - Svadlenak, Nathan
AU - Pongor, Csaba István
AU - Sztáray, Bálint
AU - Meerts, Leo
AU - Nachtigallová, Dana
AU - Hobza, Pavel
AU - Barbatti, Mario
AU - Lischka, Hans
AU - de Vries, Mattanjah S.
PY - 2010
Y1 - 2010
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=77952350234&partnerID=8YFLogxK
U2 - 10.1039/b917852j
DO - 10.1039/b917852j
M3 - Article
C2 - 20379571
AN - SCOPUS:77952350234
SN - 1463-9076
VL - 12
SP - 5375
EP - 5388
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 20
ER -