CNR-IOM DEMOCRITOS, Theory@Elettra Group, Istituto Officina dei Materiali, c/o Sincrotrone Trieste-SS14, Km 163, 5 Basovizza, I-34012 Trieste, Italy.
Nano Lett. 2011 Dec 14;11(12):5414-20. doi: 10.1021/nl2031713. Epub 2011 Oct 28.
The high chemical reactivity of unsaturated metal sites is a key factor for the development of novel devices with applications in sensor engineering and catalysis. It is also central in the research for sustainable energy concepts, e.g., the efficient production and conversion of chemical fuels. Here, we study the process of oxygen dissociation by a surface-supported metal-organic network that displays close structural and functional analogies with the cofactors of non-heme enzymes. We synthesize a two-dimensional array of chemically active di-iron sites on a Cu(001) surface where molecular oxygen readily dissociates at room temperature. We provide an atomic-level structural and electronic characterization before and after reaction by combining scanning tunneling microscopy, X-ray absorption spectroscopy, and density functional theory. The latter identifies a novel mechanism for O2 dissociation controlled by the cooperative catalytic action of two Fe2+ ions. The high structural flexibility of the organic ligands, the mobility of the metal centers, and the hydrogen bonding formation are shown to be essential for the functionality of these active centers allowing to mimick biologically relevant reactions in a confined environment.
不饱和金属位点的高化学反应活性是开发具有传感器工程和催化应用的新型器件的关键因素。它也是可持续能源概念研究的核心，例如，化学燃料的高效生产和转化。在这里，我们研究了表面支撑的金属有机网络中氧的离解过程，该网络与非血红素酶的辅因子具有密切的结构和功能相似性。我们在 Cu(001)表面合成了二维阵列的化学活性二铁位点，在室温下，氧气很容易在此处离解。我们通过结合扫描隧道显微镜、X 射线吸收光谱和密度泛函理论，在反应前后提供了原子级的结构和电子特性。后者确定了一种由两个 Fe2+离子协同催化作用控制的新型 O2 离解机制。有机配体的高结构灵活性、金属中心的迁移率以及氢键的形成对于这些活性中心的功能至关重要，使它们能够在受限环境中模拟生物相关反应。
