| Project/Area Number |
16350029
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Inorganic chemistry
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| Research Institution | Kanazawa University |
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Principal Investigator |
ISOBE Kiyoshi Kanazawa University, Graduate School of Natural Science and Technology, Professor (70101285)
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| Co-Investigator(Kenkyū-buntansha) |
HAYASHI Yoshihito Kanazawa University, Graduate School of Natural Science and Technology, Associate Professor (10231531)
NAKAI Hidetaka Kanazawa University, Graduate School of Natural Science and Technology, Assistant Professor (70377399)
西岡 孝訓 大阪市立大学, 大学院理学研究科, 講師 (10275240)
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| Project Period (FY) |
2004 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥16,010,000 (Direct Cost: ¥15,800,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 2005: ¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2004: ¥9,000,000 (Direct Cost: ¥9,000,000)
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| Keywords | Active S-S Bond / Crystalline-state Reaction / Photoresponsive Function / Photochromism / Variable Temperature Solid State ^2H NMR Spectroscopy / Chiral Crystalzation / Absolute Asymmetric Synthesis / 光誘起相転移 / 光応答錯体 / 結晶相フォトクコミック反応 / 温度可変固体^2H NMR測定 / ジチオナイト錯体 / 有機金属錯体 / 絶対不斉光異性化反応 / 結晶相異性化反応 / ホトクロミズム / ロジウム錯体 / 反応空間 / ジチオナイト配位子 / 結晶相フォトクロミズム / ロジウム二核錯体 / シクロペンタジェニル環 / 反応活性ジスルフィド錯体 / 光異性化 / 結晶相平衡 / オキシジスルフィド錯体 |
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| Research Abstract |
In the crystalline state, the rhodium dinuclear complex[(RhCp^*)_2(μ-CH_2)_2(μ-O_2SSO_2)] (1) with a photoresponsive dithionite group (μ-O_2SSO_2) and two pentamethylcyclopentadienyl ligands (Cp^*=η^5-C_5Me_5) undergoes a 100% reversible unimolecular type T inverse photochromism upon interconversion to [(RhCp^*)_2(μ-CH_2)_2(μ-O_2SOSO)] (2). The photochromism can be followed directly by using stepwise crystal structure analysis.
In this study, we found that the photoreaction of 1 was triggered by absorption of the 510 nm light (charge transfer band from σ(S-S)to σ^*(S-S)and σ^*(Rh-Rh)orbitals assigned by DFT calculation) and included two important processes:kinetically controlled oxygen-atom transfer to produce four stereoisomers of 2 and thermodynamically controlled isomerization between the four stereoisomers of 2 to afford the most stable isomer. Although the formation rate of the four stereoisomer products was kinetically controlled and the population of the four stereoisomers produc
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ed in the system was thermodynamically controlled, both processes were regulated by the steric hindrance between the μ-O_2SSO_2 or μ-O_2SOSO ligand and the reaction cavity formed by the Cp^* ligands. The cooperation of both processes achieved an intriguing stereospecific oxygen-atom rearrangement to produce only one stereoisomer of 2 at the final stage of the photoreaction at room temperature.
We also determined the effect of the oxygen-atom rearrangement on the rotational motion of the two crystallographibally independent Cp^* ligands (parallel and perpendicular arrangement). Using variable-temperature ^13C CP/MAS NMR and quadrupolar echo solid-state ^2H NMR spectroscopies, before photoirradiation, the activation energies for the rotation of the parallel and perpendicular Cp^* ligands in 1 were determined to be 30±3 and 10±1 kJ/mol, respectively, and after photoirradiation, in 2, they were much lower than those in 1 (20±2 and 8±1 kJ/mol, respectively). The large decrease in the activation energy for the parallel Cp^* in 2 is attributed to the relaxation of molecular stress via a stereospecific oxygen-atom rearrangement, which suggests that the rotational motion of the Cp^* ligands is coupled to the photochromism.
Furthermore, we have found an absolute asymmetric photoisomerization of a new achiral photochromic dithionite complex having n-propyl moieties [(RhCp^<Pro>)_2(μ-CH_2)(μ-O_2SSO_2)] (Cp^<Pro>=η^5-C_5Me_4n-Propyl) in chiral crystals. This complex is crystallized in the space group of P2_12_12_1 and gives both crystals containing the helical isomers of P and M.
We performed a crystalline-state photoreaction by using these chiral crystals in similar way to [(RhCp^*)_2(μ-CH_2)(μ-O_2SSO_2)] and obtained [RhCp^<Pro>)_2(μ-CH_2)(μ-OSOSO_2)] almost quantitatively. The obtained μ-OSOSO_2 complex has an e.e value of 95%. Less
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