Many applications of molecular layers deposited on metal surfaces, ranging from single-atom catalysis to on-surface magnetochemistry and biosensing, rely on the use of thermal cycles to regenerate the pristine properties of the system. Thus, understanding the microscopic origin behind the thermal stability of organic/metal interfaces is fundamental for engineering reliable organic-based devices. Here, we study nickel porphyrin molecules on a copper surface as an archetypal system containing a metal center whose oxidation state can be controlled through the interaction with the metal substrate. We demonstrate that the strong molecule-surface interaction, followed by charge transfer at the interface, plays a fundamental role in the thermal stability of the layer by rigidly anchoring the porphyrin to the substrate. Upon thermal treatment, the molecules undergo an irreversible transition at 420 K, which is associated with an increase of the charge transfer from the substrate, mostly localized on the phenyl substituents, and a downward tilting of the latters without any chemical modification
@article{arxiv.2006.10482,
title = {Molecular anchoring stabilizes low valence Ni(I)TPP on copper against thermally induced chemical changes},
author = {Henning Maximilian Sturmeit and Iulia Cojocariu and Matteo Jugovac and Albano Cossaro and Alberto Verdini and Luca Floreano and Alessandro Sala and Giovanni Comelli and Stefania Moro and Matus Stredansky and Manuel Corva and Erik Vesselli and Peter Puschnig and Claus Michael Schneider and Vitaliy Feyer and Giovanni Zamborlini and Mirko Cinchetti},
journal= {arXiv preprint arXiv:2006.10482},
year = {2020}
}