High-conductance surface-anchoring of a mechanically flexible platform-based porphyrin complex

The conductances of molecular modeljunctions comprising a triazatriangulenium platform with or without an ethynyl spacer and an upright Zn-porphyrin are probed with a low-temperature scanning probe microscope. The platform alone is found to be highly conductive. The ethynyl-linked Zn-porphyrin moiety reduces the conductance by three orders of magnitude and leads to an unexpected, non-monotonous variation of the force thatwas measured simultaneously at the tip of the microscope. Density functional theory calculations show that this variation results from an induced tilting of the porphyrin.