表面吸附对菲咯啉金属-配体结合的影响,The Journal of Physical Chemistry C

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表面吸附对菲咯啉金属-配体结合的影响
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2021-09-17 , DOI: 10.1021/acs.jpcc.1c04509
Johnson Dalmieda ₁ , Ana Zubiarrain-Laserna ₁ , Dipankar Saha ₁ , Ponnambalam Ravi Selvaganapathy ₂ , Peter Kruse ₁

Affiliation

菲咯啉是一类已知可与许多不同金属阳离子结合形成复合物的配体。菲咯啉的芳香主链还允许通过 π-π 堆叠优先吸附在几层石墨烯 (FLG) 薄膜上。在这里，我们研究了吸附和由此产生的空间限制对四种不同菲咯啉衍生物的结合能力的影响：菲咯啉、新铜碱、红菲咯啉和浴铜灵。在溶液中，测试的多种金属阳离子与这些配体形成络合物，但只有 Cu ²⁺和 Ag ⁺显示与吸附在 FLG 上的配体结合的证据，如通过薄膜的化学电阻响应所测量的。每个配体上存在的取代基以不同的方式影响响应的大小。拉曼和 X 射线光电子能谱 (XPS) 被用于更详细地研究两种不同的系统：铁与菲咯啉，在溶液（铁蛋白）中显示响应，但在 FLG 表面（声称的单配体复合物）上没有响应，铜与新铜碱，它在溶液（双[新铜嘌呤]铜（I））和 FLG 表面（单配体复合物）中都有响应。拉曼和 XPS 数据表明铜通过表面结合的配体络合。理论计算表明，铜-新铜嘌呤单络合物比铁-菲咯啉单络合物具有更高的吸附能和对石墨烯表面的结合能。表面结合的新铜碱将铜 (II) 还原为铜 (I) 进一步导致来自传感器的更强的电荷转移响应。这项研究的结果提供了对金属阳离子固态传感机制的见解，用于基于表面吸附诱导的空间和电化学限制的水质检测。

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Impact of Surface Adsorption on Metal–Ligand Binding of Phenanthrolines

Phenanthrolines are a class of ligands known to bind with many different metal cations to form complexes. The aromatic backbone of phenanthroline also allows for preferential adsorption on few-layer graphene (FLG) films via π–π stacking. Here we investigate the effects of adsorption and the resulting steric restrictions on the binding ability of four different phenanthroline derivatives: phenanthroline, neocuproine, bathophenanthroline, and bathocuproine. In solution, a wide range of metal cations tested formed complexes with these ligands, but only Cu²⁺ and Ag⁺ showed evidence of binding to ligands adsorbed onto FLG, as measured by the chemiresistive response of the films. The substituents present on each ligand affected the magnitude of the response in different ways. Raman and X-ray photoelectron spectroscopy (XPS) were used to study two different systems in more detail: iron with phenanthroline, which shows a response in solution (ferroin) but not on the FLG surface (purported monoligand complex), and copper with neocuproine, which responds both in solution (bis[neocuproine]copper(I)) and on the FLG surface (monoligand complex). Raman and XPS data indicate complexing of copper by surface-bound ligands. Theoretical calculations show that the copper–neocuproine monocomplex has a higher adsorption energy and binding energy to a graphene surface than the iron–phenanthroline monocomplex. The reduction of copper(II) to copper(I) by the surface-bound neocuproine further results in a stronger charge transfer response from the sensor. The results of this study provide insights into the mechanisms of solid-state sensing of metal cations for water quality detection based on steric and electrochemical restrictions induced by surface adsorption.

更新日期：2021-09-30

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