Design of switchable wettability sensor for paraquat based on clicking calix[4]arene.

A calix[4]arene acetylene (C4AE)-modified gold surface is successfully constructed in situ via click chemistry. The functionalized surface is used for selective recognition of paraquat by a wettability switch. Impedance measurements showed that the surface also expresses recognition for paraquat with a high sensitivity of 10 pM. The recognition mode, based on host-guest inclusion, is studied by computational calculations and the possible mechanism is analyzed.