Department of Chemistry, 112 Fleming Building, University of Houston , Houston, Texas 77204-5003, United States.
J Am Chem Soc. 2014 Apr 2;136(13):4881-4. doi: 10.1021/ja501257d. Epub 2014 Mar 20.
An approximately planar tetradentate polypyridine ligand, 8-(1″,10″-phenanthrol-2″-yl)-2-(pyrid-2'-yl)quinoline (ppq), has been prepared by two sequential Friedländer condensations. The ligand readily accommodates Co(II) bearing two axial chlorides, and the resulting complex is reasonably soluble in water. In DMF the complex shows three well-behaved redox waves in the window of 0 to -1.4 V (vs SHE). However in pH 7 buffer the third wave is obscured by a catalytic current at -0.95 V, indicating hydrogen production that appears to involve a proton-coupled electron-transfer event. The complex [Co(ppq)Cl2] (6) in pH 4 aqueous solution, together with [Ru(bpy)3]Cl2 and ascorbic acid as a sacrificial electron donor, in the presence of blue light (λmax = 469 nm) produces hydrogen with an initial TOF = 586 h(-1).
一种近似平面的四齿多吡啶配体 8-(1″,10″-菲咯啉-2″-基)-2-(吡啶-2′-基)喹啉(ppq)通过两次 Friedländer 缩合反应制备而成。该配体容易容纳两个轴向氯化物的 Co(II)，得到的配合物在水中具有相当的溶解性。在 DMF 中，该配合物在 0 到-1.4 V（相对于 SHE）的窗口中显示出三个行为良好的氧化还原波。然而，在 pH 7 缓冲液中，第三波被-0.95 V 处的催化电流所掩盖，表明在该电位下发生了析氢反应，该反应似乎涉及质子耦合电子转移事件。在 pH 4 水溶液中，[Co(ppq)Cl2]（6）与[Ru(bpy)3]Cl2和抗坏血酸作为牺牲电子供体，在蓝光（λmax = 469nm）的存在下，初始 TOF = 586 h-1 时产生氢气。
