Quantum dynamics study of the excited-state double-proton transfer in 2,2'-bipyridyl-3,3'-diol.
Density functional theory and quantum dynamics simulations have been used to study the double-proton transfer reaction in 2,2'-bipyridyl-3,3'-diol in the first singlet excited electronic state. This process is experimentally known to be branched: It consists of a fast, concerted reaction mechanism (tau approximately 100 fs) and a stepwise reaction mechanism [with a fast initial step (tau approximately 100 fs) and a slower final step (tau approximately 10 ps)]. Quantum dynamics simulations on a two-dimensional model reveal that the concerted reaction occurs despite the nonexistence of a concerted reaction path, but they fail to explain the relative slowness of the stepwise mechanism. A qualitative simulation using a three-dimensional model suggests that internal vibrational relaxation (IVR) might be the reason why the second stage of the stepwise mechanism is so slow.
Gelabert
Ricard
R
Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona (Spain).
Moreno
Miquel
M
Lluch
José M
JM
D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives* / Q000737:chemistry; D003198:Computer Simulation; D004563:Electrochemistry; D015394:Molecular Structure; D011522:Protons; D011789:Quantum Theory; D013816:Thermodynamics; D014732:Vibration
C499984:(2,2'-bipyridyl)-3,3'-diol; D011522:Protons; D015082:2,2'-Dipyridyl