title: Heptanuclear CoII5CoIII2Cluster as Efficient Water Oxidation Catalyst.
abstract: Inspired by the transition-metal-oxo cubical Mn4CaO5in photosystem II, we herein report a disc-like heptanuclear mixed-valent cobalt cluster, [CoII5CoIII2(mdea)4(N3)2(CH3CN)6(OH)2(H2O)2·4ClO4] (1, H2mdea = N-methyldiethanolamine), for photocatalytic oxygen evolution. The topology of the Co7core resembles a small piece of cobaltate protected by terminal H2O, N3-, CH3CN, and multidentate N-methyldiethanolamine at the periphery. Under the optimal photocatalytic conditions, 1 exhibits water oxidation activity with a turnover number (TON) of 210 and a turnover frequency (TOFinitial) of 0.23 s-1. Importantly, electrospray mass spectrometry (ESI-MS) was used to not only identify the possible main active species in the water oxidation reaction but also monitor the evolutions of oxidation states of cobalt during the photocatalytic reactions. These results shed light on the design concept of new water oxidation catalysts and mechanism-related issues such as the key active intermediate and oxidation state evolution in the oxygen evolution process. The magnetic properties of 1 were also discussed in detail.
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University , Jinan 250100, P. R. China.
authors.forename: Jia-Heng
authors.initials: JH
authors.lastname: Xu
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University , Jinan 250100, P. R. China.
authors.forename: Ling-Yu
authors.initials: LY
authors.lastname: Guo
authors.affiliation: State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, P. R. China.
authors.forename: Hai-Feng
authors.initials: HF
authors.lastname: Su
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University , Jinan 250100, P. R. China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Gao
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University , Jinan 250100, P. R. China.
authors.forename: Xiao-Fan
authors.initials: XF
authors.lastname: Wu
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University , Jinan 250100, P. R. China.
authors.forename: Wen-Guang
authors.initials: WG
authors.lastname: Wang
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University , Jinan 250100, P. R. China.
authors.forename: Chen-Ho
authors.initials: CH
authors.lastname: Tung
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University , Jinan 250100, P. R. China.
authors.forename: Di
authors.identifier: http://orcid.org/0000-0001-5966-1207
authors.initials: D
authors.lastname: Sun