Are Conical Intersections Responsible for the Ultrafast Processes of Adenine, Protonated Adenine, and the Corresponding Nucleosides?
Excited‐state potential energy surfaces of adenine, protonated adenine, and their N9‐methylated analogs are explored by means of a complete active space (CAS) and time‐dependent density functional theory (TD‐DFT) study to understand the dynamics associated with internal conversion. After photoexcita...
Saved in:
Published in | Chemphyschem Vol. 6; no. 7; pp. 1276 - 1281 |
---|---|
Main Authors | , |
Format | Journal Article |
Language | English |
Published |
Weinheim
WILEY-VCH Verlag
11.07.2005
WILEY‐VCH Verlag Wiley |
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | Excited‐state potential energy surfaces of adenine, protonated adenine, and their N9‐methylated analogs are explored by means of a complete active space (CAS) and time‐dependent density functional theory (TD‐DFT) study to understand the dynamics associated with internal conversion. After photoexcitation of the ground‐state molecules to the S1 state, the nuclear motions that are responsible for taking the wavepacket out of the Franck–Condon region are either an HN9/CN9 stretch or a ring‐puckering motion that leads to pyramidalization. These motions lead to accessible conical intersections with the ground‐state surface. The results are used to successfully interpret previous measurements on the photodissociation of adenosine 5′‐monophosphate nucleotide anions and cations, where the latter react in a highly nonstatistical manner.
A dynamic conversion: Ultrafast internal conversion from the first excited state to the ground state in adenine and its protonated form occurs by either activation of an NH stretch or via ring puckering that leads to pyramidalization. The potential energy surface topology directs the internal energy in a nonstatistical manner and the conical intersection is thereby responsible for the nonstatistical decomposition of adenosine monophosphate (see picture). |
---|---|
Bibliography: | ark:/67375/WNG-1BSTN6WL-J ArticleID:CPHC200400644 istex:44486A7D41F3A68AE45BFA0C0367DB4F0945BA05 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1439-4235 1439-7641 |
DOI: | 10.1002/cphc.200400644 |