Incorporation of transition metals into single molecule devices has been expected to provide appealing transport properties and spintronic capabilities. In order to probe these effects on robust molecular junctions with coordination complexes containing metal atoms, we need to establish the integrity of metal-ligand bonding in the context of the molecular junction on gold electrodes, most commonly used for such measurements. Here, we use heterobimetallic lantern complexes as a model system to study the interplay of gold-linker donor-acceptor chemistry between the molecule and the electrode, and the intramolecular metal-ligand bonding of lantern complexes. We probe the binding and conductance of single hetero- and homo-bimetallic complexes on gold using the Scanning Tunneling Microscope Break Junction method. Aspects of the lantern framework are synthetically varied to systematically establish how different components of the complex interact with gold electrodes. Our results suggest that gold-linker interactions can outcompete intramolecular donor-acceptor metal-ligand bonding, and that Lewis acid-base principles used in synthesis also determine the binding affinity of linkers to gold, affecting the stability of our complexes in the junction. We propose design principles for forming robust coordination complex junctions to enable the study of electronic and spin properties of transition metals at the single molecule level.

Establishing design rules for robust coordination complexes on gold using single molecule conductance measurements

ACS Spring Meeting 2021

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