Manipulating the Electronic and Magnetic Properties of Coordinated Nickel Atoms in Metal–Organic Frameworks by Hydrogenation

Abstract

In the pursuit of manipulating the properties of single atoms, the surface-supported metal–organic frameworks (MOFs) provide us opportunities to individually address the electronic and magnetic properties of coordinated metal atoms by scanning tunneling microscopy. Recently, we have synthesized Ni-TPyP (TPyP = 5,10,15,20-tetra-(4-pyridyl) porphyrin) networks with dinuclear Ni centers on a Au(111) surface, in which the top-Ni atoms are sitting above the molecular plane. Here, we investigate the top-Ni atoms and their hydrogenated derivatives by low-temperature scanning tunneling microscopy and spectroscopy, and show that the electronic and magnetic states of top-Ni atoms can be manipulated by hydrogen adsorption. Specifically, by fitting the spin-flip spectra in vertical magnetic field, we find the spin state of top-Ni atoms is tuned from S = 1/2 to S = 1 by attaching one H atom and S = 3/2 by attaching two H atoms. Our work demonstrates atomic-scale control over the electronic and magnetic properties of coordinated metal atoms in a surface-supported MOF.

High-Throughput Preparation of Supramolecular Nanostructures on Metal Surfaces

“…Supramolecular chemistry has been a subject of intense study for developing functional materials with various applications. , Molecular self-assembly at solid surfaces offers a promising strategy and unparalleled route for the large-scale construction of low-dimensional nanostructures, which have gained considerable attention in the past few decades. , The organized surface molecular nanostructures are driven by molecule–molecule and/or molecule–metal recognitions through dynamic noncovalent interactions including hydrogen and halogen bonding, van der Waals forces, and dipole–dipole and metal–organic coordinated interactions. − A spectrum of interesting, and in some cases peculiar, supramolecular nanostructures were successfully constructed on surfaces. ,− Another noteworthy factor to the popularity of surface-supported supramolecular chemistry lies in the expansion of the surface science community, particularly thanks to the advances of scanning probe microscopy (SPM), which enables the submolecular characterization of the surface-supported species. − …”

Spin-engineered Cu–Ni metallic aerogels for enhanced ethylamine electrosynthesis from acetonitrile

“…As for Cu 3 Ni 1 NPs, although the delocalization spin state of the Ni atom would promote the adsorption of acetonitrile molecules to a certain extent, the dissociative imine intermediates would continue to react with ethylamine to produce diethylamine, resulting in a lower selectivity of the primary amines over the Cu 3 Ni 1 NPs. 47 It is worth noting that, attributed to the crosslinked network structure, rich active sites, and higher spin state of the Cu 3 Ni 1 MAs, the Cu 3 Ni 1 MAs exhibited not only faster electron transfer, but also a stronger adsorption of acetonitrile molecules and the imine intermediate. Through the adsorption of the dissociative imine intermediates, the imine intermediate could be hydrogenated to produce ethylamine, so as to improve the yield.…”

Revealing the Evolution of Hybridized Electronic States with the Coordination Number in Surface-Supported Metal–Organic Frameworks

“…In metal–organic complexes, the properties of metal atoms are closely related to their local coordination environments. − Coordination number, the number of σ-bonds between ligands and the central metal atom, plays a vital role in determining the electronic, magnetic, optical and catalytic properties of metal–organic complexes. − The relationship between the electronic structure and the coordination number in metal–organic complexes has been investigated using various spectroscopic methods, such as magnetic circular dichroism (MCD), , near-edge X-ray absorption fine structure (NEXAFS), and electroparamagnetic resonance (EPR) spectroscopy . While the spectroscopic studies were performed on an ensemble of atoms, scanning tunneling microscopy (STM) directly resolves the local coordination environments of the central metal atom and detects the hybridized electronic states of the complex in real space. − In previous STM studies on metal–organic complexes, the hybridized electronic states have been tuned by the choice of metal atoms, the choice of organic ligand, and the number of metal atoms coordinated to an aromatic molecule .…”