Photodissociation of 1,2-dioxetane: An excited state nonadiabatic dynamics study

Abstract

Dioxetanes are a class of high energy molecules that show unique ability to dissociate thermally onto excited state products. Quite recently, it attracts much attention due to their role in what is known as “dark secondary metabolite”. The present work, presents a comprehensive investigation of the photochemical and photophysical properties of 1,2-dioxetane. Several post HF-methods were utilized. The behavior of the excited states of 1,2-dioxetane, was explored by simulating the ultra-violet photoabsorption spectrum and nonadiabatic dynamics of 1,2-dioxetane. Simulation of the photoabsorption spectrum was performed within the nuclear ensemble approximation, sampling a Wigner distribution with 500 points; whereas, the surface hopping approach was utilized to simulate the dynamics. Dynamic simulations have been started in two different spectral windows centered at 7.5 and 9.0 eV, corresponding to populations of states S6 and S7, respectively. The time domain for such simulations is 100 fs. The dynamics in the spectral window centered about 7.5 eV show 24% probability to originate from excited state 6 (nO-σ*CO) suggesting the dissociation of the C–O bonds. Whereas, dynamics in the spectral windows centered about 9.0 eV, show 67% probability to originate from state 7 (nO-σ*OO) predicting an O–O dissociation.