X-Ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) ha
ve been used to study the interactions between self-assembled monolayers (S
AMs) of crown ether adsorbates and metal ions. Both analytical techniques c
onfirmed the selectivities of the 12-crown-4 and 15-crown-5 SAMs that had p
reviously been determined by electrochemical impedance spectroscopy. AFM ha
s also been used to characterize microcontact-printed crown ether monolayer
s. The electrochemical patterning of monolayers on gold allowed the design
of a dual sensor for the electrochemical detection of cations. However, due
to cross-contamination of both monolayers during the patterning process a
significant selectivity reduction of the layers was observed. Nevertheless,
the remaining Na+ selectivity of the 12-crown-4 SAM and the K+ selectivity
of the 15-crown-5 SAM allowed the unambiguous discrimination between both
metal ions.