Identification of Molecular Flipping of an Asymmetric Tris(phthalocyaninato) Lutetium Triple-Decker Complex by Scanning Tunneling Microscopy/Spectroscopy

The assembling behavior and electronic properties of asymmetric tris(phthalocyaninato) lutetium tripledecker sandwich complex molecules (Lu₂Pc₃) on highly oriented pyrolytic graphite (HOPG) surfaces have been studied by scanning tunneling microscopy/spectroscopy (STM/STS) methods. Phase transitions were observed at different bias polarities, involving an ordered packing arrangement with fourfold symmetry at negative bias and an amorphous arrangement at positive bias. Molecular switching behaviour for individual Lu₂Pc₃ molecules was reported here according to the bias-polarity-induced flipping phenomena and the peak shift in dI/dV versus V curves at different voltage scanning directions. The sensitive response of the strong intrinsic molecular dipole to an external electric field is proposed to be responsible for molecular switching of Lu₂Pc₃ at the solid/liquid interface.