Noble Metal Substrate Identity Effects on the Self-Assembly, Dynamics, and Dehydrocyclization Reaction of Octaethylporphyrin Molecules

Schultz, Jeremy F.; Jiang, Nan

Noble Metal Substrate Identity Effects on the Self-Assembly, Dynamics, and Dehydrocyclization Reaction of Octaethylporphyrin Molecules

2021

Schultz, Jeremy F. | Jiang, Nan

Conjugated organic molecules are attractive candidates to realize platforms on surfaces, where self-assembly and molecule–substrate interactions can be used to impart tailored characteristics at the interface or enable single-molecule studies of chemistry. Scanning tunneling microscopy (STM) enables the interrogation of these surfaces at the atomic scale, providing a method to image and develop the understanding of fundamental interactions. This includes the ability to identify individual products of any chemical reactions that may be an end result of sufficiently strong molecule–substrate interactions. Here, ultrahigh vacuum STM was used to study the self-assembly and surface-catalyzed reactions of octaethylporphyrin on noble metal substrates: Cu(100), Ag(100), Au(100), and Ag(110). The substrate identity and facet were found to substantially determine the nature of molecule–substrate interactions. As a result, the temperature necessary to drive the dehydrocyclization of peripheral ethyl groups, resulting in the formation of tetrabenzoporphyrin molecules, was found to differ significantly between substrates. STM provided the ability to probe and manipulate molecules on the surface, revealing single-molecule behavior and therefore a fundamental view of molecule–substrate interactions and a surface-catalyzed reaction.

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