Excitation Wavelength Dependent O2 Release from Copper(II)–Superoxide Compounds: Laser Flash-Photolysis Experiments and Theoretical Studies

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• 作者：Claudio Saracini ; Dimitrios G. Liakos ; Jhon E. Zapata Rivera ; Frank Neese ; Gerald J. Meyer ; Kenneth D. Karlin
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：January 29, 2014
• 年：2014
• 卷：136
• 期：4
• 页码：1260-1263
• 全文大小：274K
• ISSN：1520-5126

文摘

Irradiation of the copper(II)鈥搒uperoxide synthetic complexes [(TMG₃tren)Cu^II(O₂)]⁺ (1) and [(PV-TMPA)Cu^II(O₂)]⁺ (2) with visible light resulted in direct photogeneration of O₂ gas at low temperature (from 鈭?0 掳C to 鈭?0 掳C for 1 and from 鈭?25 to 鈭?35 掳C for 2) in 2-methyltetrahydrofuran (MeTHF) solvent. The yield of O₂ release was wavelength dependent: 位_exc = 436 nm, = 0.29 (for 1), = 0.11 (for 2), and 位_exc = 683 nm, = 0.035 (for 1), = 0.078 (for 2), which was followed by fast O₂-recombination with [(TMG₃tren)Cu^I]⁺ (3) and [(PV-TMPA)Cu^I]⁺ (4). Enthalpic barriers for O₂ rebinding to the copper(I) center (10 kJ mol^鈥?) and for O₂ dissociation from the superoxide compound 1 (45 kJ mol^鈥?) were determined. TD-DFT studies, carried out for 1, support the experimental results confirming the dissociative character of the excited states formed upon blue- or red-light laser excitation.