Torsionally broken symmetry assists infrared excitation of biomimetic charge-coupled nuclear motions in the electronic ground state

Gourab Chatterjee , Ajay Jha , Alejandro Blanco-Gonzalez , Vandana Tiwari , Madushanka Manathunga , Hong-Guang Duan , Friedjof Tellkamp , Valentyn Prokhorenko , Nicolas Ferré (1) , Jyotishman Dasgupta , Massimo Olivucci , R. Miller

1 ICR - Institut de Chimie Radicalaire

The concerted interplay between reactive nuclear and electronic motions in molecules actuates chemistry. Here, we demonstrate that out-of-plane torsional deformation and vibrational excitation of stretching motions in the electronic ground state modulate the charge-density distribution in a donor-bridge-acceptor molecule in solution. The vibrationally-induced change, visualised by transient absorption spectroscopy with a mid-infrared pump and a visible probe, is mechanistically resolved by ab initio molecular dynamics simulations. Mapping the potential energy landscape attributes the observed charge-coupled coherent nuclear motions to the population of the initial segment of a double-bond isomerization channel, also seen in biological molecules. Our results illustrate the pivotal role of pre-twisted molecular geometries in enhancing the transfer of vibrational energy to specific molecular modes, prior to thermal redistribution. This motivates the search for synthetic strategies towards achieving potentially new infrared-mediated chemistry.

Domaines: Chimie théorique et/ou physique

Gourab Chatterjee, Ajay Jha, Alejandro Blanco-Gonzalez, Vandana Tiwari, Madushanka Manathunga, et al.. Torsionally broken symmetry assists infrared excitation of biomimetic charge-coupled nuclear motions in the electronic ground state. Chemical Science, 2022, 13 (32), pp.9392-9400. ⟨10.1039/d2sc02133a⟩. ⟨hal-03818171⟩