Schiffrin Agustin, Capsoni Martina, Farahi Gelareh, Wang Chen-Guang, Krull Cornelius, Castelli Marina, Roussy Tanya, Cochrane Katherine A, Yin Yuefeng, Medhekar Nikhil V, Fuhrer Michael, Shaw Adam Q, Ji Wei, Burke Sarah A
Department of Physics and Astronomy , University of British Columbia , Vancouver , British Columbia , Canada , V6T 1Z1.
School of Physics & Astronomy , Monash University , Clayton , Victoria 3800 , Australia.
ACS Nano. 2018 Jul 24;12(7):6545-6553. doi: 10.1021/acsnano.8b01026. Epub 2018 Jun 18.
Supramolecular chemistry protocols applied on surfaces offer compelling avenues for atomic-scale control over organic-inorganic interface structures. In this approach, adsorbate-surface interactions and two-dimensional confinement can lead to morphologies and properties that differ dramatically from those achieved via conventional synthetic approaches. Here, we describe the bottom-up, on-surface synthesis of one-dimensional coordination nanostructures based on an iron (Fe)-terpyridine (tpy) interaction borrowed from functional metal-organic complexes used in photovoltaic and catalytic applications. Thermally activated diffusion of sequentially deposited ligands and metal atoms and intraligand conformational changes lead to Fe-tpy coordination and formation of these nanochains. We used low-temperature scanning tunneling microscopy and density functional theory to elucidate the atomic-scale morphology of the system, suggesting a linear tri-Fe linkage between facing, coplanar tpy groups. Scanning tunneling spectroscopy reveals the highest occupied orbitals, with dominant contributions from states located at the Fe node, and ligand states that mostly contribute to the lowest unoccupied orbitals. This electronic structure yields potential for hosting photoinduced metal-to-ligand charge transfer in the visible/near-infrared. The formation of this unusual tpy/tri-Fe/tpy coordination motif has not been observed for wet chemistry synthetic methods and is mediated by the bottom-up on-surface approach used here, offering pathways to engineer the optoelectronic properties and reactivity of metal-organic nanostructures.
应用于表面的超分子化学协议为有机-无机界面结构的原子尺度控制提供了引人注目的途径。在这种方法中，吸附质与表面的相互作用以及二维限制可导致形态和性质与通过传统合成方法所实现的有显著差异。在此，我们描述了基于从用于光伏和催化应用的功能性金属有机配合物借鉴而来的铁（Fe）-三联吡啶（tpy）相互作用，在表面自下而上合成一维配位纳米结构。依次沉积的配体和金属原子的热激活扩散以及配体内构象变化导致Fe-tpy配位并形成这些纳米链。我们使用低温扫描隧道显微镜和密度泛函理论来阐明该系统的原子尺度形态，表明在相对的共面tpy基团之间存在线性三铁键合。扫描隧道光谱揭示了最高占据轨道，主要由位于铁节点的态贡献，以及主要对最低未占据轨道有贡献的配体态。这种电子结构为在可见/近红外区域实现光诱导的金属到配体的电荷转移提供了潜力。这种不寻常的tpy/三铁/tpy配位基序的形成在湿化学合成方法中未被观察到，而是由本文所采用的自下而上的表面方法介导，为设计金属有机纳米结构的光电性质和反应性提供了途径。
