Activationless Multiple-Site Concerted Proton-Electron Tunneling

作者：Bowring Miriam A^*; Bradshaw Liam R; Parada Giovanny A; Pollock Timothy P; Fernandez Teran Ricardo J; Kolmar Scott S; Mercado Brandon Q; Schlenker Cody W; Gamelin Daniel R; Mayer James M^*

来源：Journal of the American Chemical Society, 2018, 140(24): 7449-7452.

DOI：10.1021/jacs.8b04455

The transfer of protons and electrons is key to energy conversion and storage, from photosynthesis to fuel cells. Increased understanding and control of these processes are needed. A new anthracene-phenol-pyridine molecular triad was designed to undergo fast photo-induced multiple-site concerted proton-electron transfer (MS-CPET), with the phenol moiety transferring an electron to the photoexcited anthracene and a proton to the pyridine. Fluorescence quenching and transient absorption experiments in solutions and glasses show rapid MS-CPET (3.2 X 10(10) s(-1) at 298 K). From 5.5 to 90 K, the reaction rate and kinetic isotope effect (KIE) are independent of temperature, with zero Arrhenius activation energy. From 145 to 350 K, there are only slight changes with temperature. This MS-CPET reaction thus occurs by tunneling of both the proton and electron, in different directions. Since the reaction proceeds without significant thermal activation energy, the rate constant indicates the magnitude of the electron/proton double tunneling probability.

• 出版日期2018-6-20