A “bimodal” or upper- and lower-rim functionalized “calix-crown-5” reported herein was unexpectedly formed preferentially in a cone conformation. This was confirmed both by NMR spectroscopy and by single-crystal X-ray crystallography. The thioacetate functionalities on the new calix-crown-5 enabled it to form stable SAMs on the Au surface of a microcantilever, and a sensitive cesium ion sensor.