| Project/Area Number |
23K21120
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| Project/Area Number (Other) |
21H01949 (2021-2023)
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Multi-year Fund (2024)
Single-year Grants (2021-2023) |
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| Section | 一般 |
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| Review Section |
Basic Section 34010:Inorganic/coordination chemistry-related
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| Research Institution | Nagoya University |
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Principal Investigator |
CRUDDEN Cathleen 名古屋大学, トランスフォーマティブ生命分子研究所, 客員教授 (10721029)
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| Project Period (FY) |
2021-04-01 – 2025-03-31
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| Project Status |
Granted (Fiscal Year 2024)
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| Budget Amount *help |
¥17,550,000 (Direct Cost: ¥13,500,000、Indirect Cost: ¥4,050,000)
Fiscal Year 2024: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
Fiscal Year 2023: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
Fiscal Year 2022: ¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000)
Fiscal Year 2021: ¥7,930,000 (Direct Cost: ¥6,100,000、Indirect Cost: ¥1,830,000)
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| Keywords | nanocluster / gold / N-heterocyclic carbene / catalysis / chirality / chiral / C-H oxidation |
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| Outline of Research at the Start |
In this proposal we will design highly active and highly selective Au nanocluster catalysts for the stereospecific oxidation of C-H bonds in complex organic molecules. Catalyst activation methods that do not result in complete degradation of the ligand sphere are critical, as are catalysts that are stable under the oxidative reaction conditions. We will take advantage of the ability to have adjacent metal atoms of the same or different oxidation states to aid in the activation, something that catalysts based on individual metal atoms lack.
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| Outline of Annual Research Achievements |
In FY 2022, we successfully synthesized gold nanoclusters stabilized by N-heterocyclic carbene (NHC) ligands in collaboration with the Tsukuda and Hakkinen group. We demonstrated that the use of chiral, BIANP-inspired NHCs to prepare chiral Au10 nanoclusters with a unique elongated central Au10 core. ESI-MS and single-crystal X-ray crystallography confirmed the molecular formula to be [Au10(bisNHC)4Br2]2+. The chiral Au10 nanocluster adopts a linear edge-shared tetrahedral geometry with a prolate shape. The UV-vis spectrum this cluster in CH2Cl2 displayed four prominent absorption bands at 291, 325, and 546 nm, which is a significant departure from the spectra of bis-NHC dinuclear Au(I) complexes. CD spectra demonstrate chirality transfer from the chiral bisNHC ligand to the inner Au10 nanocluster core. The reaction monitoring by ESI-MS and UV-vis spectroscopy indicated the formation of [Au9(bisNHC)4Br]2+ as a key intermediate.
In addition, we achieved the synthesis of a toroidal Au10 cluster stabilized by NHC bearing bulky 2,4,6-trimethylbenzyl units. The [Au10(NHC)6Br3]Br cluster readily undergoes conversion to form a biicosahedral Au25 cluster, while the corresponding Cl cluster showed no conversion. This facyt may be explained both by the steric environment imposed by the bulky mesityl-substituted NHC ligand, as well as steric and electronic factors introduced by the smaller chloride ligands.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
We have been able to make new examples of gold nanoclusters containing NHC ligands. These nanoclusters are the first example of isolable Au10-NHC clusters with chirality, which promise to be an important starting point for the development of new types of ligands for magic number clusters. In addition, we have clarified for the first time that the Au10 nanocluster is an important intermediate of Au25 nanocluster. This is a very important finding for understanding the formation process of gold clusters.
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| Strategy for Future Research Activity |
Future work will entail the synthesis of new series of gold nanoclusters by using designed NHC ligands to control size and shape of gold core. Focusing on the bulkiness of ligands, we aim to control the size of stable nanoclusters. Additionally, building on our synthetic method, the synthesis of new heterobimetallic clusters stabilized by NHC ligands will be examined. For application to catalysis, homogeneous electrochemical investigation of NHC-gold nanoclusters will be established.
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