Single Open Sites on FeII Ions Stabilized by Coupled Metal Ions in CN-Deficient Prussian Blue Analogues for High Catalytic Activity in the Hydrolysis of Organophosphates

Mari Yamane; Hiroyasu Tabe; Masami Kawakami; Hisashi Tanaka; Tohru Kawamoto; Yusuke Yamada

doi:10.1021/acs.inorgchem.0c02528

Single Open Sites on Fe^II Ions Stabilized by Coupled Metal Ions in CN-Deficient Prussian Blue Analogues for High Catalytic Activity in the Hydrolysis of Organophosphates

Inorg Chem. 2020 Nov 2;59(21):16000-16009. doi: 10.1021/acs.inorgchem.0c02528. Epub 2020 Oct 19.

Authors

Mari Yamane¹, Hiroyasu Tabe^{1

2}, Masami Kawakami³, Hisashi Tanaka³, Tohru Kawamoto³, Yusuke Yamada^{1

2}

Affiliations

¹ Department of Applied Chemistry and Bioengineering, Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka 558-8585, Japan.
² Research Center of Artificial Photosynthesis (ReCAP), Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka 558-8585, Japan.
³ Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8565, Japan.

PMID: 33076661
DOI: 10.1021/acs.inorgchem.0c02528

Abstract

CN-deficient Prussian blue analogues (PBAs), [M^N(H₂O)_x]_y[Fe^II(CN)₅(NH₃)] (M^N = Cu^II, Co^II, or Ga^III), were synthesized and examined as a new class of heterogeneous catalysts for hydrolytic decomposition of organophosphates often used as pesticides. The active species of the CN-deficient PBAs were mainly C-bound Fe^II ions with only single open sites generated by liberation of the NH₃ ligand during the catalytic reactions. [Cu^II(H₂O)_8/3]_3/2[Fe^II(CN)₅(NH₃)] showed higher catalytic activity than [Co^II(H₂O)_8/3]_3/2[Fe^II(CN)₅(NH₃)] and [Ga^III(H₂O)][Fe^II(CN)₅(NH₃)], although N-bound Cu^II species has been reported as less active than Co^II and Ga^III species in conventional PBAs. IR measurements of a series of the CN-deficient PBAs after the catalytic reactions clarified that a part of the NH₃ ligands remained on [Co^II(H₂O)_8/3]_3/2[Fe^II(CN)₅(NH₃)] and that hydrogen phosphate formed as a product strongly adsorbed on the Fe^II ions of [Ga^III(H₂O)][Fe^II(CN)₅(NH₃)]. Hydrogen phosphate also adsorbed, but weakly, on the Fe^II ions of [Cu^II(H₂O)_8/3]_3/2[Fe^II(CN)₅(NH₃)]. These results suggest that heterogeneous catalysis of the Fe^II ions with single open sites were tuned by the M^N ions through metal-metal interaction.