Electrochemical Activation of Self-Assembled Monolayers for the Binding of Effectors,Langmuir

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Electrochemical Activation of Self-Assembled Monolayers for the Binding of Effectors
Langmuir ( IF 3.7 ) Pub Date : 2020-11-24 , DOI: 10.1021/acs.langmuir.0c02426
Aleksandra Markovic ₁ , Leon Buschbeck ₁ , Izabella Brand ₁ , Carsten Dosche ₁ , Jens Christoffers ₁ , Gunther Wittstock ₁

Affiliation

A self-assembled monolayer (SAM) on gold was prepared from a diaminoterephthalate (DAT) derivative as functional molecule and 1-decanthiol as a backfiller. The DAT derivative is N-protected by a tert-butyloxycarbonyl (Boc) group and is anchored to the gold surface via a liponic acid as a stable anchor group. The terminal DAT moiety exhibits interesting effector properties such as fluorescence and electrochemical activity. Irreversible oxidation of the monolayer at 0.4 V (Hg|Hg₂SO₄) in 0.1 M HClO₄ triggers deprotection of the DAT group and subsequent chemical reactions, during which 10% of the DAT groups of the original SAM are transformed to a new surface-bound, quasi-reversible redox couple with a formal potential of 0.0 V (Hg|Hg₂SO₄) and a standard rate constant of 8 s^–1 in 0.1 M HClO₄. Immersion of the mixed SAM in 0.1 M HClO₄ at open circuit potential or oxidation in 0.1 M H₂SO₄ did not produce this surface-bound redox couple. The monolayers were thoroughly characterized by X-ray photoelectron spectroscopy (XPS) and polarization modulation infrared reflection absorption spectroscopy (PM IRRAS) after the different preparation steps indicating only minor changes in the overall composition of the monolayer, in particular, the preservation of the heteroatoms. The new redox couple is likely a diimine, in agreement with its ability to bind nucleophiles such as anilines by conjugate addition that could be followed by multicycle voltammetry and XPS. The DAT effector group is especially interesting because it can also report the binding reaction by changed electrochemical and fluorescence signals.

中文翻译：

自组装单层的电化学激活效应器的绑定。

由二氨基对苯二甲酸二氨基酯（DAT）衍生物作为功能分子和1-decanthiol作为回填剂制备金上的自组装单层（SAM）。DAT衍生物被叔丁氧羰基（Boc）基团进行N-保护，并通过脂酸作为稳定的锚定基团锚定在金表面。末端DAT部分显示出有趣的效应子特性，例如荧光和电化学活性。0.1 M HClO ₄中0.4 V（Hg | Hg ₂ SO ₄）下单层的不可逆氧化触发DAT基团的脱保护和随后的化学反应，在此过程中，原始SAM的DAT基团的10％被转化为新的表面结合的，准可逆的氧化还原对，其形式电位为0.0 V（Hg | Hg ₂ SO ₄），在0.1 M HClO _4中的标准速率常数为8 s ^–1。混合SAM在开路电势下浸入0.1 M HClO ₄或在0.1 MH ₂ SO _4中氧化没有产生这种表面结合的氧化还原对。在不同的制备步骤后，通过X射线光电子能谱（XPS）和偏振调制红外反射吸收光谱（PM IRRAS）彻底表征了单分子层，表明单分子层的整体组成仅发生了很小的变化，特别是杂原子的保存。新的氧化还原对可能是二亚胺，与其通过结合物加成物结合亲核试剂（如苯胺）的能力相一致，随后可以进行多周期伏安法和XPS。DAT效应子组特别有趣，因为它也可以通过改变的电化学和荧光信号报告结合反应。

更新日期：2020-12-08

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