Renewable Reductants and Oxidants aimed at Energy Conversion
소속 :
연사 : Koji TANAKA
일시 : 2011-11-15 16:00 ~
장소 : 500동 목암홀
일 시 : 2011년 11월 15일, 4:00 PM
장 소 : 500동 목암홀
-Abstract-
Multi-electron redox reactions through stepwise one-electron transfer inevitably generate high-energy free radical intermediates, which often cause undesired reactions. Artificial photosynthetic systems that are able to transfer electrons to the reaction sites without accompanying high energy intermediates would lead to construct light-driven multi-electron redox reactions such as carbon dioxide reduction and water splitting.
Photo excitation (λ>420 nm) of [Ru(bpy)2(pbn)]2+ ([1]2+) (bpy = 2,2’-bipyridine; pbn = 2-(2-pyridyl)benzo[b]- 1,5-naphthyridine) in the presence of sacrificial reagents produced the two-electron reduced form, [Ru(bpy)2(pbnHH)]2+ ([1HH]2+), which regenerated [1]2+ by electro- and chemical- oxidation. Furthermore, [Ru(bpy)(pbn)2]2+ and [Ru(pbn)3]2+ underwent photo-induced four- and six-electron reductions to afford [Ru(bpy)(pbnHH)2]2+ and [Ru(pbnHH)3]2+, respectively, under similar reaction conditions. Thus, the reversible conversion between pbn and pbnHH ligated on Ru well simulates the NAD+/NADH redox reaction.
An ITO electrode modified with [Ru2(OH)2(q)2(btpyan)]2+ having two hydroxyl groups in a close distance effectively catalyzed four-electron oxidation of water to evolve O2 (TON = 33,500) under the electrolysis at +1.70 V in H2O (pH 4.0). Two dioxolene ligands of [Ru2(OH)2(q)2(btpyan)]2+ play the central role to remove four electrons from two hydroxyl groups. Indeed, the catalytic activity of [Ru2(OH)2(bpy)2(btpyan)]2+ toward water oxidation is much lower than that by [Ru2(btpyan)(q)2(OH)2]2+.
장 소 : 500동 목암홀
-Abstract-
Multi-electron redox reactions through stepwise one-electron transfer inevitably generate high-energy free radical intermediates, which often cause undesired reactions. Artificial photosynthetic systems that are able to transfer electrons to the reaction sites without accompanying high energy intermediates would lead to construct light-driven multi-electron redox reactions such as carbon dioxide reduction and water splitting.
Photo excitation (λ>420 nm) of [Ru(bpy)2(pbn)]2+ ([1]2+) (bpy = 2,2’-bipyridine; pbn = 2-(2-pyridyl)benzo[b]- 1,5-naphthyridine) in the presence of sacrificial reagents produced the two-electron reduced form, [Ru(bpy)2(pbnHH)]2+ ([1HH]2+), which regenerated [1]2+ by electro- and chemical- oxidation. Furthermore, [Ru(bpy)(pbn)2]2+ and [Ru(pbn)3]2+ underwent photo-induced four- and six-electron reductions to afford [Ru(bpy)(pbnHH)2]2+ and [Ru(pbnHH)3]2+, respectively, under similar reaction conditions. Thus, the reversible conversion between pbn and pbnHH ligated on Ru well simulates the NAD+/NADH redox reaction.
An ITO electrode modified with [Ru2(OH)2(q)2(btpyan)]2+ having two hydroxyl groups in a close distance effectively catalyzed four-electron oxidation of water to evolve O2 (TON = 33,500) under the electrolysis at +1.70 V in H2O (pH 4.0). Two dioxolene ligands of [Ru2(OH)2(q)2(btpyan)]2+ play the central role to remove four electrons from two hydroxyl groups. Indeed, the catalytic activity of [Ru2(OH)2(bpy)2(btpyan)]2+ toward water oxidation is much lower than that by [Ru2(btpyan)(q)2(OH)2]2+.
