Platinum(II) Terpyridyl Acetylide Complexes on Platinized TiO2: Toward the Photogeneration of H2 in Aqueous Media

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• 作者：Paul Jarosz ; Pingwu Du ; Jacob Schneider ; Soo-Hyun Lee ; David McCamant ; Richard Eisenberg
• 刊名：Inorganic Chemistry
• 出版年：2009
• 出版时间：October 19, 2009
• 年：2009
• 卷：48
• 期：20
• 页码：9653-9663
• 全文大小：996K
• 年卷期：v.48,no.20(October 19, 2009)
• ISSN：1520-510X

文摘

New platinum(II) terpyridyl acetylide complexes having the ability to bind to TiO₂ have been synthesized and assayed in their ability to sensitize platinized titanium dioxide for the photogeneration of H₂ using visible light (λ > 410 nm). Specifically, the complexes [Pt(tpy-phen-COOH)(C≡C−C₆H₅)]Cl (1), where tpy-phen-COOH = 4′-(4-carboxyphenyl)-[2,2′;6′,2′′]terpyridine and C≡C−C₆H₅ = phenylacetylide, and [Pt(tpy-COOH)(C≡C−C₆H₅)]Cl (2), where tpy-COOH = 4′-carboxy-2,2′;6′,2′′-terpyridine, were prepared to investigate the effectiveness of attachment and proximity to the TiO₂ surface on hydrogen yield. Both complexes 1 and 2 sensitize the photogeneration of hydrogen, but produce fewer turnovers than the unbound chromophore, [Pt(ttpy)(C≡C−C₆H₅)]PF₆ (5). On the basis of these observations and electrochemical data, a major limitation to the effectiveness of these chromophores is their instability upon oxidation. To attempt to remedy this problem, two donor-chromophore (D-C) dyads, [Pt(tpy-phen-COOH)(C≡C−C₆H₄CH₂−PTZ)]PF₆ (3), where C≡C−C₆H₄CH₂−PTZ = N-(4-ethynylbenzyl)-phenothiazine and [Pt(tpy-COOH)(C≡C−C₆H₄CH₂−PTZ)]Cl (4) were prepared to function as TiO₂-attached sensitizers. Transient absorption measurements have shown that the PTZ moiety reductively quenches the Pt center in several picoseconds. While the resultant PTZ⁺ radical cation is capable of oxidizing rapidly the triethanolamine sacrificial electron donor, dyads 3 and 4 attached to platinized TiO₂ do not function to generate hydrogen upon irradiation, in contrast with results seen for 1 and 2.