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

Abstract

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.

Conformational adaptation and manipulation of manganese tetra(4-pyridyl)porphyrin molecules on Cu(111)

“…Metal adatoms in metal-coordinated supramolecular structures are difficult to be resolved in STM images due to electronic effects. [35][36][37][38][39][40][41][42] Moreover, the close molecular proximity may not allow for the STM tip to approach sufficiently close to the adatoms. Therefore, only larger bonding motifs with two or more Cu atoms linking organic moieties were observed for ordered patterns on surfaces.…”

Photo-induced and thermal reactions in thin films of an azobenzene derivative on Bi(111)

“…On the Au(111) surface, the tunneling electrons of the STM stimulate a rotation of one of the phenyl rings around the C-N bond, but isomerization has not been observed, most likely due to the strong van der Waals interaction of the aromatic π system of the phenyl rings with the gold substrate or efficient quenching of excited states [12]. Together with cobalt adatoms, DMC forms metal-organic networks on Au(111) [28].…”

Switchable Self‐Assembly of a Bioinspired Alkyl Catechol at a Solid/Liquid Interface: Competitive Interfacial, Noncovalent, and Solvent Interactions

“…[8] Thanks to its intrinsic molecular resolution, STM can allow the direct observation, and therefore, the direct study and modelization of molecule/ molecule and molecule/surface interactions. [8a,c-e,i,k,m-q] Although, scarce examples of catechols on surfaces have been studied by STM [9] so far, none of these examples are at the liquid/solid interface to simulate a real situation.…”