Surface & Interface Modeling
for Emerging Nanomaterials and Devices

Designing optoelectronic properties by on-surface synthesis: formation and electronic structure of an iron-terpyridine macromolecular complex

Agustin Schiffrin||,~,†,§,‡, Martina Capsoni||,‡, Gelareh Farahi||, Chen-Guang Wang^, Cornelius Krull†, Marina Castelli†, Tanya S. Roussy||, Katherine A. Cochrane#, Yuefeng Yin§,±,†, Nikhil Medhekar§,±, Adam Q. Shaw||, Wei Ji^,* and Sarah A. Burke||,#,~

||Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z1
~Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z4
†School of Physics & Astronomy, Monash University, Clayton, Victoria 3800, Australia
§ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, Victoria 3800, Australia
#Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z1
^Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro nano Devices, Renmin University of China, Beijing 100872, People’s Republic of China
±Department of Materials Science and Engineering, Monash University, Clayton, Victoria 3800, Australia

DOI:10.1021/acsnano.8b01026    Publication Date: June 18, 2018


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 intra-ligand 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, providing evidence of a linear tri-Fe linkage between facing, coplanar tpy groups. Scanning Tunneling Spectroscopy reveals 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 photo induced 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 synthesis methods, and is mediated by the bottom-up on-surface approach used here, offering new pathways to engineer the optoelectronic properties and reactivity of metal-organic nanostructures.


View: ACS NANO  12, 6545−6553 (2018)    

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