Site-Dependent Coordination Bonding in Self-Assembled Metal−Organic Networks

• Published in: The journal of physical chemistry letters Vol. 2; no. 2; pp. 55 - 61
• Main Authors: Henningsen, N, Rurali, R, Limbach, C, Drost, R, Pascual, J. I, Franke, K. J
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 20.01.2011
• Subjects: Surfaces, Interfaces, Catalysis; metal−organic networks; azobenzene; coordination bonding at surfaces; single-molecule spectroscopy; scanning tunneling microscopy; density functional thoery
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/jz1015907

The combination of organic linkers with metal atoms on top of inorganic substrates offers promising perspectives for functional electronic and magnetic nanoscale devices. Typically, coordination bonds between electron-rich end groups and transition-metal atoms lead to the self-assembly of metal−organic nanostructures, whose shape and electronic and magnetic properties crucially depend on the type of ligand. Here, we report on the site-selective bonding properties of Co atoms to the dichotomic dicyanoazobenzene molecule with its carbonitrile and diazo N-based moieties as possible ligands. Using low-temperature scanning tunneling microscopy (STM) and spectroscopy measurements, we resolve the formation of self-assembled metal−organic motifs. Cobalt atoms exhibit a clear spectroscopic fingerprint dependent on the different coordination site, which is further used to map their position, otherwise not clearly visible in the topographic STM images. Density functional theory corroborates the observed bonding patterns and evidences their coordinative nature.