Structure and Stability of Metalloporphyrin Networks on Au(111)

Abstract

We use density functional theory (DFT) calculations to analyze the properties of FeTPyP self-assembled monolayers (SAMs) and FeTPyP+Fecmetal-organic coordination networks (MOCNs) on Au(111). Through a rigorous step-by-step approach, we determine the relative importance of the multiple competing interactions that determine the optimum structure and stability of both networks. For FeTPyP/Au(111) SAMs, we see a complex energy landscape, with molecules preferring to stay at molecule-molecule distances dop∼13.7 and 14.3 Å. Molecule-surface interactions are more prominent in less dense packing (dop∼14.3 Å), and intermolecular interactions favor the compact structure (dop∼13.7 Å). In the case of the FeTPyP-Fec/Au(111) MOCN, the strong Fec-Npybond between the peripheral iron atom Fecand nitrogen atoms of neighboring pyridyl groups (Npy) is what causes the network development and that the preferred molecule-molecule distance remains at dop∼13.7 Å. Our findings demonstrate the necessity of theoretical treatments that take into account all relevant interactions in order to adequately describe the primary characteristics of surface-supported SAMs and MOCNs.