Development of the Redox Photocatalysts with Strong S-T Absorption

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K20367
• Project/Area Number (Other): 18H05355 (2018-2019)
• Research Category: Grant-in-Aid for Challenging Research (Pioneering)
• Allocation Type: Multi-year Fund (2020); Single-year Grants (2018-2019)
• Review Section: Medium-sized Section 34:Inorganic/coordination chemistry, analytical chemistry, and related fields
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Ishitani Osamu 東京工業大学, 理学院, 教授 (50272282)
• Co-Investigator(Kenkyū-buntansha): 玉置 悠祐 東京工業大学, 理学院, 助教 (10752389)
• Project Period (FY): 2018-06-29 – 2022-03-31
• Keywords: 光反応化学 / レドックス光増感錯体 / S-T吸収 / 光触媒反応

Outline of Final Research Achievements

In order to utilize solar light efficiently, absorption of longer-wavelength visible-light is highly important. In this study, therefore, we have focused on developing the redox photosensitizer expressing S-T absorption, that is originally forbidden direct transitions from ground state to the triplet excited states.
We have found that the heteroleptic ruthenium complexes having two different tridentate ligands function as a redox photosensitizer exhibiting S-T absorption. Based on the results using ligands with various electronic and steric characters, the ruthenium complexes having push-pull type configuration of tridentate ligands expressed strong S-T absorption and absorbed light shorter than 720 nm. The osmium complex with similar ligands absorbed entire wavelength range of visible light up to 800 nm and functioned as a redox photosensitizer.

Free Research Field

光反応化学

Academic Significance and Societal Importance of the Research Achievements

太陽光を有効に利用するには、長波長の光を活用することが不可欠である。従来の方法で光増感剤の吸収を長波長化すると、光増感剤に深刻な機能低下を引き起こしてしまう。本研究では、S-T吸収により光増感剤の機能を維持したまま、長波長の可視光を利用することに成功した。S-T吸収を発現できるルテニウム錯体の分子設計を明らかにできたことは、光化学の学術面で非常に意義深いものである。また可視光の全波長領域を利用できる光増感剤は、様々な光反応を可視光全域で駆動できる可能性がある。