Spectroscopic scanning tunneling microscopy studies of single surface-supported free-base corroles

Abstract

Corroles are versatile chemically active agents in solution. Expanding their applications toward surface-supported systems requires a fundamental knowledge of corrole-surface interactions. We employed the tip of a low-temperature scanning tunneling microscope as local probe to investigate at the single-molecule level the electronic and geometric properties of surface-supported free-base corrole molecules. To provide a suitable reference for other corrole-based systems on surfaces, we chose the archetypal 5,10,15-tris(pentafluorophenyl)corrole [H 3(TpFPC)] as model system, weakly adsorbed on two surfaces with different interaction strengths. We demonstrate the nondissociative adsorption of H 3(TpFPC) on pristine Au(111) and on an intermediate organic layer that provides sufficient electronic decoupling to investigate geometric and frontier orbital electronic properties of almost undisturbed H 3(TpFPC) molecules at the submolecular level. We identify a deviating adsorption behavior of H 3(TpFPC) compared to structurally similar porphyrins, characterized by a chiral pair of molecule-substrate configurations. © 2011 American Chemical Society.