Multiple Decay Mechanisms and 2D-UV Spectroscopic Fingerprints of Singlet Excited Solvated Adenine-Uracil Monophosphate.
The decay channels of singlet excited adenine uracil monophosphate (ApU) in water are studied with CASPT2//CASSCF:MM potential energy calculations and simulation of the 2D-UV spectroscopic fingerprints with the aim of elucidating the role of the different electronic states of the stacked conformer in the excited state dynamics. The adenine (1) La state can decay without a barrier to a conical intersection with the ground state. In contrast, the adenine (1) Lb and uracil S(U) states have minima that are separated from the intersections by sizeable barriers. Depending on the backbone conformation, the CT state can undergo inter-base hydrogen transfer and decay to the ground state through a conical intersection, or it can yield a long-lived minimum stabilized by a hydrogen bond between the two ribose rings. This suggests that the (1) Lb , S(U) and CT states of the stacked conformer may all contribute to the experimental lifetimes of 18 and 240 ps. We have also simulated the time evolution of the 2D-UV spectra and provide the specific fingerprint of each species in a recommended probe window between 25 000 and 38 000 cm(-1) in which decongested, clearly distinguishable spectra can be obtained. This is expected to allow the mechanistic scenarios to be discerned in the near future with the help of the corresponding experiments. Our results reveal the complexity of the photophysics of the relatively small ApU system, and the potential of 2D-UV spectroscopy to disentangle the photophysics of multichromophoric systems.
Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry, Beijing Institute of Technology, 100081, Beijing, P.R. China.
Quansong
Q
Li
Dipartimento di Chimica "G. Ciamician", Università di Bologna, Via Selmi 2, 40126, Bologna, Italy.
Angelo
A
Giussani
Dipartimento di Chimica "G. Ciamician", Università di Bologna, Via Selmi 2, 40126, Bologna, Italy.
Javier
J
Segarra-Martí
Dipartimento di Chimica "G. Ciamician", Università di Bologna, Via Selmi 2, 40126, Bologna, Italy.
Artur
A
Nenov
Univ Lyon, >Ens de Lyon, CNRS, Université Lyon 1, Laboratoire de Chimie UMR 5182, 69342, Lyon, France.
Ivan
0000-0002-1208-602X
I
Rivalta
Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, Campus de Montilvi, 17071, Girona, Spain.|Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010, Barcelona, Spain.
Alexander A
0000-0001-6620-4362
AA
Voityuk
Department of Chemistry, University of California, Irvine, California, 92697-2025, USA.
Shaul
S
Mukamel
Instituto de Ciencia Molecular, Universitat de València, P. O. Box 22085, 46071, Valencia, Spain.
Daniel
0000-0001-6495-2770
D
Roca-Sanjuán
Dipartimento di Chimica "G. Ciamician", Università di Bologna, Via Selmi 2, 40126, Bologna, Italy. marco.garavelli@unibo.it.|Univ Lyon, >Ens de Lyon, CNRS, Université Lyon 1, Laboratoire de Chimie UMR 5182, 69342, Lyon, France. marco.garavelli@unibo.it.
Marco
0000-0002-0796-289X
M
Garavelli
Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, Campus de Montilvi, 17071, Girona, Spain. lluis.blancafort@udg.edu.
Lluís
0000-0002-0003-5540
L
Blancafort
D000249:Adenosine Monophosphate / Q000737:chemistry*; D016172:DNA Fingerprinting / Q000379:methods; D008958:Models, Molecular; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D014542:Uridine Monophosphate / Q000737:chemistry*
D000249:Adenosine Monophosphate; D014542:Uridine Monophosphate
DNA; UV/Vis spectroscopy; ab initio calculations; molecular electronics; photophysics