Self-assemble monolayers of metallosalophenes on gold

Salophene complexes of transition metals exhibit a reversible electrochemistry. We have synthesized salophene complexes with sulfur-containing substituents aimed at the formation of self-assembled monolayers on a gold surface. Such monolayers have interesting cation complexating properties. The monolayers were fully characterized by wettability studies, grazing-angle Fourier transform infrared spectroscopy (FT-IRS), X-ray photoelectron spectroscopy (XPS), time-of-flight secondary-ion mass spectrometry (TOF-SIMS), and electrochemical capacitance measurements. These measurements indicate liquid-like monolayers. Cation complexation could be monitored indirectly by electrochemical impedance spectroscopy measurements, showing responses for Na+ and K+. This complexation behavior of the metallosalophene monolayers could not be studied directly by electrochemistry of the metallosalophene either due to electrochemical instability of the monolayer or a smeared redox response.