Mechanism of Photoinduced Dihydroazulene Ring-Opening Reaction

TY - JOUR

T1 - Mechanism of Photoinduced Dihydroazulene Ring-Opening Reaction

AU - Abedi, Mostafa

AU - Papai, Matyas

AU - Mikkelsen, Kurt V.

AU - Henriksen, Niels E.

AU - Moller, Klaus B.

PY - 2019/6/25

Y1 - 2019/6/25

N2 - The photoinduced ring-opening reaction is a key process in the functioning of dihydroazulene/vinylheptafulvene (DHA/VHF) photoswitches. Over the years, the mechanism of this reaction has been extensively debated. Herein, by means of nonadiabatic trajectory dynamics simulations and quantum chemistry calculations, we present the first detailed and comprehensive investigation on the mechanism of the photoinduced ring-opening reaction of DHA. The results show the crucial role of the excited-state ring planarization process for the bond breaking. Our dynamics simulations show that the DHA ring opening is an ultrafast reaction that does not follow exponential kinetics but exhibits ballistic dynamics. Upon photoexcitation, the planarization occurs within 300-500 fs. This leads to the ring-opening reaction and concurrent decay of the molecule to the ground state within 100 fs through an S1 → S0 internal conversion process toward forming the VHF isomer. These results are consistent with previous ultrafast time-resolved experiments and lead to a thorough understanding of the DHA/VHF photoconversion.

AB - The photoinduced ring-opening reaction is a key process in the functioning of dihydroazulene/vinylheptafulvene (DHA/VHF) photoswitches. Over the years, the mechanism of this reaction has been extensively debated. Herein, by means of nonadiabatic trajectory dynamics simulations and quantum chemistry calculations, we present the first detailed and comprehensive investigation on the mechanism of the photoinduced ring-opening reaction of DHA. The results show the crucial role of the excited-state ring planarization process for the bond breaking. Our dynamics simulations show that the DHA ring opening is an ultrafast reaction that does not follow exponential kinetics but exhibits ballistic dynamics. Upon photoexcitation, the planarization occurs within 300-500 fs. This leads to the ring-opening reaction and concurrent decay of the molecule to the ground state within 100 fs through an S1 → S0 internal conversion process toward forming the VHF isomer. These results are consistent with previous ultrafast time-resolved experiments and lead to a thorough understanding of the DHA/VHF photoconversion.

U2 - 10.1021/acs.jpclett.9b01522

DO - 10.1021/acs.jpclett.9b01522

M3 - Letter

C2 - 31264882

SN - 1948-7185

VL - 10

SP - 3944

EP - 3949

JO - Journal of Physical Chemistry Letters

JF - Journal of Physical Chemistry Letters

IS - 14

ER -