Dynamics of analyte binding onto a metallophthalocyanine: NO∕FePc

Tuning the Catalytic Activity of a Quantum Nutcracker for Hydrogen Dissociation

A quantum nutcracker, a recently proposed catalytic system for hydrogen dissociation, consists of two inert components: an organic molecule such as a transition metal phthalocyanine and an inert surface such as Cu or Au. The reaction takes place at the interface between the two components, which are weakly bonded by Van der Waals (VdW) forces. Here, we explore a method used to tune the reaction barrier in a quantum nutcracker system for hydrogen dissociation. By employing density-functional-theory calculations, we find that the H2 entry barrier, which is the rate-limiting barrier, is reduced by replacing the phthalocyanine by porphyrin derivatives such as octaethylporphyrin (OEP) and tetraphenylporphyrin (TPP). The system remains active if a dissociated H atom is adsorbed on the transition metal ion. Metallic two-dimensional materials such as NbS2 and CoS2 are good candidates for the quantum nutcracker. The present design of a quantum nutcracker for hydrogen dissociation provides new opportunities with which to induce catalytic activity in VdW-bonded systems.

Organic Multilayer Films Studied by Scanning Tunneling Microscopy

This Minireview focuses exclusively on work with scanning tunneling microscopy to study the self-assembled multilayer films (SAMTs) of organic molecules. The π-conjugated organic molecules form different structures within different monolayers on various substrates. The interplay between molecule-substrate and intermolecular interactions plays a key role in determining the stacking mode of organic multilayer films. Different substrates strongly influence the organic-film growth and electronic properties of the organic molecules. Geometric and electronic structures of SAMTs are important factors that may determine device performance. In addition to the inorganic interface, this Minireview addresses the organic-organic interface. Homo- and hetero-SAMTs of organic molecules are also considered. The subtle interplay between structural and electronic characteristics, on one hand, and functionality and reactivity, on the other hand, are highlighted.

Ammonia adsorption on iron phthalocyanine on Au(111): influence on adsorbate-substrate coupling and molecular spin

The adsorption of ammonia on Au(111)-supported monolayers of iron phthalocyanine has been investigated by x-ray photoelectron spectroscopy, x-ray absorption spectroscopy, and density functional theory calculations. The ammonia-induced changes of the x-ray photoemission lines show that a dative bond is formed between ammonia and the iron center of the phthalocyanine molecules, and that the local spin on the iron atom is quenched. This is confirmed by density functional theory, which also shows that the bond between the iron center of the metalorganic complex and the Au(111) substrate is weakened upon adsorption of ammonia. The experimental results further show that additional adsorption sites exist for ammonia on the iron phthalocyanine monolayer.