Identification of a Stable ZnII -Oxyl Species Produced in an MFI Zeolite and Its Reversible Reactivity with O2 at Room Temperature

Akira Oda; Takahiro Ohkubo; Takashi Yumura; Hisayoshi Kobayashi; Yasushige Kuroda

doi:10.1002/anie.201702570

Identification of a Stable Zn^II -Oxyl Species Produced in an MFI Zeolite and Its Reversible Reactivity with O₂ at Room Temperature

Angew Chem Int Ed Engl. 2017 Aug 7;56(33):9715-9718. doi: 10.1002/anie.201702570. Epub 2017 Jul 17.

Authors

Akira Oda^{1

2}, Takahiro Ohkubo³, Takashi Yumura⁴, Hisayoshi Kobayashi⁴, Yasushige Kuroda³

Affiliations

¹ Precursory Research for Embryonic Science and Technology Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
² Okayama University, 3-1-1 Tsushima, Kita-ku, Okayama, 700-8530, Japan.
³ Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima, Kita-ku, Okayama, 700-8530, Japan.
⁴ Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matugasaki, Sakyo-ku, Kyoto, 606-8585, Japan.

PMID: 28608610
DOI: 10.1002/anie.201702570

Abstract

Although a terminal oxyl species bound to certain metal ions is believed to be the intermediate for various oxidation reactions, such as O-O bond generation in photosystem II (PSII), such systems have not been characterized. Herein, we report a stable Zn^II -oxyl species induced by an MFI-type zeolite lattice and its reversible reactivity with O₂ at room temperature. Its intriguing characteristics were confirmed by in situ spectroscopic studies in combination with quantum-chemical calculations, namely analyses of the vibronic Franck-Condon progressions and the ESR signal features of both Zn^II -oxyl and Zn^II -ozonide species formed during this reversible process. Molecular orbital analyses revealed that the reversible reaction between a Zn^II -oxyl species and an O₂ molecule proceeds via a radical O-O coupling-decoupling mechanism; the unpaired electron of the oxyl species plays a pivotal role in the O-O bond generation process.

Keywords: MFI zeolites; oxyl species; ozonides; vibronic transitions; zinc.

Publication types

Research Support, Non-U.S. Gov't