Structural Phase Transition of Quinone-Containing PAH Derivatives on Au(111) at High Coverage

Delicate control over structural phase transition provides advanced approaches for the fabrication of the desired well-ordered nanoarchitectures on surfaces. The participation of intrinsic metal adatoms in pure organic systems can facilitate the structural phase transition by direct capture of surface metal adatoms and forming metal–organic bonds. However, most of the situations occur at low coverage; such structural phase transition at a higher molecular concentration is limited to some extent due to the poor migration ability. Thus, high-concentration phase transition needs to be explored, which might be significant for the design and exploitation of large-scale ordered metal–organic-related nanomaterials. Herein, we report the phase transition of pyrene-4,5,9,10-tetraone (PT) molecules at high coverage (∼1 monolayer (ML)) on Au(111) from hydrogen-bonded row-like nanostructures to metal–organic honeycomb networks by coordinating with surface Au adatoms as demonstrated by scanning tunneling microscopy (STM). Combined with density functional theory (DFT) calculations, we demonstrate that identical molecular density (or unit cells) of two nanostructures should be the key, which makes it possible to realize phase transition possibly by in situ rotation and coordinating with the gold adatoms. Also, the phase transition causes the modulation of electronic properties from semiconductive ones to metallic ones.