Department of Chemistry and Chemical Biology, Cornell University, Baker Laboratory, Ithaca, New York 14853-1301, United States.
J Am Chem Soc. 2011 Nov 9;133(44):17614-7. doi: 10.1021/ja208239v. Epub 2011 Oct 17.
Single-layer graphene is a newly available conductive material ideally suited for forming well-defined interfaces with electroactive compounds. Aromatic moieties typically interact with the graphene surface to maximize van der Waals interactions, predisposing most compounds to lie flat on its basal plane. Here we describe a tripodal motif that binds multivalently to graphene through three pyrene moieties and projects easily varied functionality away from the surface. The thermodynamic and kinetic binding parameters of a tripod bearing a redox-active Co(II) bis-terpyridyl complex were investigated electrochemically. The complex binds strongly to graphene and forms monolayers with a molecular footprint of 2.3 nm(2) and a ΔG(ads) = -38.8 ± 0.2 kJ mol(-1). Its monolayers are stable in fresh electrolyte for more than 12 h and desorb from graphene 1000 times more slowly than model compounds bearing a single aromatic binding group. Differences in the heterogeneous rate constants of electron transfer between the two compounds suggest that the tripod projects its redox couple away from the graphene surface.
单层石墨烯是一种新出现的导电材料，非常适合与电活性化合物形成明确的界面。芳基部分通常与石墨烯表面相互作用，以最大化范德华相互作用，使大多数化合物倾向于平躺于其基面。在这里，我们描述了一种三脚架基序，它通过三个芘部分多价结合到石墨烯上，并将易于变化的官能团从表面突出。通过电化学研究了带有氧化还原活性 Co(II) 双吡啶基配合物的三脚架的热力学和动力学结合参数。该配合物与石墨烯强烈结合，并形成具有 2.3nm(2)分子足迹和 ΔG(ads)=-38.8±0.2kJmol(-1)的单层。其单层在新鲜电解质中稳定超过 12 小时，并且从石墨烯上解吸的速度比带有单个芳基结合基团的模型化合物慢 1000 倍。两种化合物之间电子转移的非均相速率常数的差异表明，三脚架将其氧化还原偶对从石墨烯表面突出。
