A comprehensive effort in photodynamical ab initio simulations of the ultrafast deactivation pathways for the DNA/RNA nucleobases adenine, guanine, cytosine, thymine and uracil is reported. The ultrafast decay of these bases is directly related to their photostability, an extremely important property protecting the genetic code against destructive effects of the UV irradiation emitted by the sun. The purine bases adenine and guanine represent the most simple photodeactivation mechanism with the dynamics leading along a diabatic * path directly and without barrier to the conical intersection seam with the ground state. The photodynamics of the pyrimidine bases is much richer and includes also n* states with varying importance, depending on the actual nucleobase considered.

DOI: 10.1073/pnas.1014982107

Representative conical intersection structures responsible for the photostability of the DNA/RNA nucleobases.

Project Part:

P05 Embedded Cluster Approach and Non-Adiabatic Processes in Physics and Chemistry / Hans Lischka

External Link:

PNAS - Proceedings of the National Academy of Sciences of the United States of America

External Link:

University of Vienna / Öffentlichkeitsarbeit und Veranstaltungsmanagement