Dynamics and thermal stability of surface-confined metal-organic chains

Understanding the dynamics and thermal stability of metallosupramolecular chains on surfaces is of relevance for the development of molecular connectors in nanoelectronics or other fields. Here we present a combined study using temperature-controlled STM and Monte Carlo simulations to explore the behavior of metal-organic porphyrin chains on Cu(111) based on two-fold pyridyl-Cu-pyridyl coordination motifs. We monitor their behavior in the 180-360 K range, revealing three thermal regimes: i) flexibility up to 240 K, ii) diffusion of chain fragments and partial dissociation into a fluid phase for T > 240 K, and iii) full dissolution with temperatures exceeding similar to 320 K. The experimentally estimated reaction enthalpy of the metal-organic bonding is similar to 0.6 eV. Monte Carlo simulations reproduce qualitatively our STM observations and reveal the preference for linear and extended supramolecular chains with reduced substrate temperatures. (C) 2015 Elsevier B.V. All rights reserved.