{"id":13267,"date":"2024-06-06T15:03:27","date_gmt":"2024-06-06T08:03:27","guid":{"rendered":"https:\/\/chemistry.sc.mahidol.ac.th\/?page_id=13267"},"modified":"2024-06-06T15:06:12","modified_gmt":"2024-06-06T08:06:12","slug":"mechanisms-of-hydrogen-evolution-by-six-coordinate-cobalt-complexes-a-density-functional-study-on-the-role-of-a-redox-active-pyridinyl-substituted-diaminotriazine-benzamidine-ligand-as-a-proton-relay","status":"publish","type":"page","link":"https:\/\/chemistry.sc.mahidol.ac.th\/mechanisms-of-hydrogen-evolution-by-six-coordinate-cobalt-complexes-a-density-functional-study-on-the-role-of-a-redox-active-pyridinyl-substituted-diaminotriazine-benzamidine-ligand-as-a-proton-relay\/","title":{"rendered":"Mechanisms of hydrogen evolution by six-coordinate cobalt complexes: a density functional study on the role of a redox-active pyridinyl-substituted diaminotriazine benzamidine ligand as a proton relay"},"content":{"rendered":"\t\t
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Kittimeth Thammanatpong\u2020, and Panida Surawatanawong*,\u2020,\u2021<\/p>

\u2020Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
\u2021Center of Sustainable Energy and Green Materials, Mahidol University, Salaya, Nakhon Pathom 73170, Thailand
*E-mail :panida.sur@mahidol.ac.th<\/p>

The hydrogen evolution reaction is an important process for energy storage. The six-coordinate cobalt complex [CoIII(L1\u2212)(LH)]2+ (LH = N-(4-amino-6-(pyridin-2-yl)-1,3,5-triazin-2-yl)benzamidine) was found to catalyze photocatalytic hydrogen evolution. In this work, we performed density functional calculations to obtain the reduction potentials and the proton-transfer free energy of possible intermediates to determine the preferred pathways for proton reduction. The mechanism involves the metal-based reduction of Co(III) to Co(II) before the protonation at the amidinate N on the pyridinyl-substituted diaminotriazine benzamidinate ligand L1\u2212 to form [CoII(LH)(LH)]2+. Essentially, the subsequent electron transfer is not metal-based reduction, but rather ligand-based reduction to form [CoII(LH)(LH\u02d91\u2212)]1+. Through a proton-coupled electron transfer process, the cobalt hydride [CoIIH(LH)(LH2\u02d9)]1+ is formed as the key intermediate for hydrogen evolution. As the cobalt hydride complex is coordinatively saturated, a structural change is required when the hydride on Co is coupled with the proton on pyridine. Notably, the redox-active nature of the ligand results in the low acidity of the protonated pyridine moiety of LH2\u02d9, which impedes its function as a proton relay. Our findings suggest that separating the proton relay fragment from the electron reservoir fragment of the redox-active ligand is preferred for fully utilizing both features in catalytic H2 evolution.<\/p>

Reference:<\/strong> Thammanatpong, K.; Surawatanawong, P., Mechanisms of hydrogen evolution by six-coordinate cobalt complexes: a density functional study on the role of a redox-active pyridinyl-substituted diaminotriazine benzamidine ligand as a proton relay. Dalton Transactions 2024, 53 (13), 6006-6019. https:\/\/doi.org\/10.1039\/D3DT03960A<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Kittimeth Thammanatpong\u2020, and Panida Surawatanawong*,\u2020,\u2021 \u2020Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand\u2021Center of Sustainable Energy and Green Materials, Mahidol University, Salaya, Nakhon Pathom 73170, Thailand*E-mail :panida.sur@mahidol.ac.th The hydrogen evolution reaction is an important process for energy storage. The six-coordinate cobalt complex [CoIII(L1\u2212)(LH)]2+ (LH […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-13267","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/chemistry.sc.mahidol.ac.th\/wp-json\/wp\/v2\/pages\/13267","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/chemistry.sc.mahidol.ac.th\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/chemistry.sc.mahidol.ac.th\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/chemistry.sc.mahidol.ac.th\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/chemistry.sc.mahidol.ac.th\/wp-json\/wp\/v2\/comments?post=13267"}],"version-history":[{"count":4,"href":"https:\/\/chemistry.sc.mahidol.ac.th\/wp-json\/wp\/v2\/pages\/13267\/revisions"}],"predecessor-version":[{"id":13272,"href":"https:\/\/chemistry.sc.mahidol.ac.th\/wp-json\/wp\/v2\/pages\/13267\/revisions\/13272"}],"wp:attachment":[{"href":"https:\/\/chemistry.sc.mahidol.ac.th\/wp-json\/wp\/v2\/media?parent=13267"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}