Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States.
ACS Nano. 2013 Aug 27;7(8):7193-9. doi: 10.1021/nn402599x. Epub 2013 Jul 23.
Graphene is an atomically thin, transparent, and conductive electrode material of interest for sensors and energy conversion and storage devices, among others. Fully realizing its potential will require robust and general methods to anchor active functionality onto its pristine basal plane. Such strategies should not utilize covalent bond formation, which disrupts the graphene's π-electron system, from which most of its desirable properties arise. We recently introduced a tripodal binding motif, which forms robust monolayers on graphene capable of immobilizing active proteins and preventing their denaturation. Here we describe structure-property relationships for a series of tripod binding groups with "feet" of different sizes. Each derivative adsorbs strongly (ΔGads ≈ -39 kJ mol(-1)) to graphene's basal plane, yet the resulting monolayers exhibit kinetic stabilities that vary over 2 orders of magnitude and molecular densities that vary by a factor of 2. This study identifies phenanthrene as a superior anchor relative to pyrene on the basis of its increased monolayer density and similar kinetic stability. We also demonstrate that varying the length of the methylene linkers between the feet and tripodal core does not affect binding substantially. These results represent the first demonstration of structure-property relationships in the assembly of molecular adsorbates on graphene and provide a paradigm for designing effective graphene binding motifs.
石墨烯是一种原子级薄、透明且导电的电极材料，对于传感器以及能量转换和存储设备等具有重要意义。要充分发挥其潜力，需要开发出稳健且通用的方法，将活性官能团锚定到其原始的基面。这些策略不应该利用会破坏石墨烯π电子体系的共价键形成，而石墨烯的大部分理想性质都源于此。我们最近提出了一种三脚架结合基序，它可以在石墨烯上形成稳定的单层，从而固定活性蛋白质并防止其变性。在这里，我们描述了一系列具有不同“支脚”尺寸的三脚架结合基团的结构-性能关系。每个衍生物都强烈（ΔGads ≈ -39 kJ mol(-1)）吸附在石墨烯的基面，但由此产生的单层的动力学稳定性差异超过 2 个数量级，分子密度差异超过 2 倍。该研究基于其增加的单层密度和相似的动力学稳定性，确定菲相对于芘是更好的石墨烯锚定基团。我们还证明了支脚和三脚架核心之间的亚甲基链接长度的变化不会显著影响结合。这些结果首次展示了在石墨烯上组装分子吸附剂的结构-性能关系，并为设计有效的石墨烯结合基序提供了范例。
