π-Interactions as a tool for an easy deposition of meso-tetraferrocenylporphyrin on surfaces
作者:Andrea Vecchi、Valentina Grippo、Barbara Floris、Andrea Giacomo Marrani、Valeria Conte、Pierluca Galloni
DOI:10.1039/c3nj00519d
日期:——
A bottom-up approach was employed to prepare novel Self-Assembled Monolayers (SAMs) in which a naphthyl moiety acted as a âÏ-binderâ for unfunctionalised meso-tetraferrocenylporphyrin (H2TFcP). Four naphthalene derivatives with an appropriate functional group were synthesized and SAMs were prepared both on gold and ITO surfaces. Mixed H2TFcPânaphthalene films were thoroughly characterized using UV-Vis, XPS and electrochemical techniques. In particular, angle-dependent XPS experiments revealed an almost perpendicular orientation of the porphyrin on surfaces, suggesting that an intercalation occurred among naphthalene units. A large amount of porphyrin was deposited on both the surfaces (in the order of 10â10 mol à cmâ2), comparable to that afforded by more conventional covalent linkages. However, significant differences in homogeneity between SAMs on gold and ITO resulted in a diverse electrochemical behaviour. The electrochemical activity of the oxidised porphyrin was restored by prolonged exposure of the modified gold electrode (tens of seconds) to a negative potential, whereas no response was detected after the same treatment on ITO. This novel approach provides a general and versatile strategy to bind meso-substituted porphyrins on a pre-formed monolayer without the necessity for further functionalisations.
我们采用了一种自下而上的方法来制备新型自组装单层膜(SAMs),其中萘基是未官能化的中-四铁卟啉(H2TFcP)的 "粘合剂"。我们合成了四种具有适当官能团的萘衍生物,并在金和 ITO 表面制备了 SAM。使用紫外可见光、XPS 和电化学技术对混合 H2TFcPânaphthalene 薄膜进行了全面表征。其中,与角度相关的 XPS 实验显示,卟啉在表面的取向几乎是垂直的,这表明萘单元之间发生了插层。大量卟啉沉积在两个表面上(约为 10â10 mol à cmâ2),与更传统的共价连接所产生的卟啉量相当。然而,金和 ITO 上的 SAMs 在均匀性方面的显著差异导致了电化学行为的多样性。将修饰过的金电极长时间暴露在负电位下(数十秒),氧化卟啉的电化学活性就会恢复,而在 ITO 上进行相同处理后,则检测不到任何反应。这种新方法提供了一种通用的多用途策略,可将中取代卟啉结合到预先形成的单层上,而无需进一步的功能化处理。