Myers Carl P, Gilmartin Brian P, Williams Mary Elizabeth
Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Inorg Chem. 2008 Aug 4;47(15):6738-47. doi: 10.1021/ic800285s. Epub 2008 Jun 21.
Directed self-assembly using inorganic coordination chemistry is an attractive approach for making functional supramolecular structures. In this article, the synthesis and characterization of Ru(bpy) 3 (2+) compounds derivatized with aminoethylglycine (aeg) substituents containing pendant bipyridine (bpy) ligands is presented. The free bpy ligands in these complexes are available for metal chelation to form coordinative cross-links; addition of Cu (2+) or Zn (2+) assembles heterometallic structures containing two or three transition-metal complexes. Control over relative placement of metal complexes is accomplished using two strategies: two bipyridine-containing aeg strands tethered to Ru(bpy) 3 (2+) allow intramolecular coordination and result in a dimetallic hairpin motif. Ru(bpy) 3 (2+) modified with a single strand forms intermolecular cross-links forming the trimetallic complex. Each of these is characterized by a range of methods, and their photophysical properties are compared. These data, and comparison to an acetyl aeg- modified Ru(bpy) 3 (2+) complex, confirm that the metal ions cross-link bpy-containing aeg strands. Heterometallic complexes containing bound Cu (2+) cause a dramatic reduction in the Ru(bpy) 3 (2+) quantum yields and lifetimes. In contrast, the Ru(bpy) 3 (2+) hairpin with coordinated Zn (2+) has only a slight decrease in quantum yield but no change in lifetime, which could be a result of steric impacts on structure in the dimetallic species. Analogous effects are not observed in the trimetallic Ru-Zn-Ru structures in which this constraint is absent. Each of these heterometallic structures represents a facile and reconfigurable means to construct multimetallic structures by metal-coordination-based self-assembly of modular artificial peptide units.
利用无机配位化学进行定向自组装是制备功能性超分子结构的一种有吸引力的方法。本文介绍了用含有侧联联吡啶（bpy）配体的氨乙基甘氨酸（aeg）取代基衍生的Ru(bpy)₃(2+)化合物的合成与表征。这些配合物中的游离bpy配体可用于金属螯合以形成配位交联；添加Cu(2+)或Zn(2+)可组装包含两个或三个过渡金属配合物的异金属结构。通过两种策略实现对金属配合物相对位置的控制：连接到Ru(bpy)₃(2+)的两条含联吡啶的aeg链允许分子内配位并产生双金属发夹基序。用单链修饰的Ru(bpy)₃(2+)形成分子间交联，形成三金属配合物。通过一系列方法对它们进行了表征，并比较了它们的光物理性质。这些数据以及与乙酰aeg修饰的Ru(bpy)₃(2+)配合物的比较证实，金属离子使含bpy的aeg链交联。含有结合Cu(2+)的异金属配合物会使Ru(bpy)₃(2+)的量子产率和寿命大幅降低。相比之下，配位Zn(2+)的Ru(bpy)₃(2+)发夹量子产率仅略有下降，但寿命没有变化，这可能是由于双金属物种中空间位阻对结构的影响。在不存在这种限制的三金属Ru-Zn-Ru结构中未观察到类似效应。这些异金属结构中的每一种都代表了一种通过基于金属配位的模块化人工肽单元自组装来构建多金属结构的简便且可重构的方法。
