On-surface Synthesis of a Semiconducting 2D Metal–Organic Framework Cu3(C6O6) Exhibiting Dispersive Electronic Bands

A 2D metal–organic framework (2D-MOF) was formed on a Cu(111) substrate using benzenehexol molecules. By means of a combination of scanning tunneling microscopy and spectroscopy, X-ray photoelectron spectroscopy and density-functional theory, the structure of the 2D-MOF is determined to be Cu₃(C₆O₆), which is stabilized by O–Cu–O bonding motifs. We find that upon adsorption on Cu(111), the 2D-MOF features a semiconductor band structure with a direct band gap of 1.5 eV. The O–Cu–O bonds offer efficient charge delocalization, which gives rise to a highly dispersive conduction band with an effective mass of 0.45 m_e at the band bottom, implying a high electron mobility in this material.     

Surface‐Assisted Cyclodehydrogenation; Break the Symmetry,Enhance the Selectivity

Selectivity in chemical reactions is a major objective in industrial processes to minimize spurious byproducts and to save scarce resources. In homogeneous catalysis the most important factor which determines selectivity is structural symmetry. However, a transfer of the symmetry concept to heterogeneous catalysis still requires a detailed comprehension of the underlying processes. Here, we investigate a ring‐closing reaction in surface‐confined meso‐substituted porphyrin molecules by scanning tunneling microscopy, temperature‐programmed desorption, and computational modeling. The identification of reaction intermediates enables us to analyze the reaction pathway and to conclude that the symmetry of the porphyrin core is of pivotal importance regarding product yields.