Abstract
Self-assembled monolayers (SAMs) of thiol-derivatized tetraphenylporphyrin on gold are able to bind anions reversibly from aqueous solutions. Electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) are employed to investigate the binding of anions by porphyrin SAMs and proved to be efficient and convenient techniques for detecting anions in aqueous solutions using the redox couple Fe(CN)(6)(3-/4-) as reporter ion. SAMs of porphyrins are shown to selectively bind dihydrogenphosphate over various other anions, including Cl-, Br-, NO2-, or NO3-. Gold electrodes modified with porphyrins can detect H2PO4- even in the presence of a 10-fold excess of other anions studied.