A general and versatile molecular design for host molecules working in water: a duplex-based potassium sensor consisting of three functional regions

A general and versatile molecular design for host molecules was proposed based on the structural motif of antibodies. A water-soluble potassium sensor was developed by this molecular design, which consists of three functional regions, benzo-15-crown-5 ether, DNA, and pyrene as guest-binding, dimerising, and signaling sites, respectively. The molecular sensor emitted the monomer fluorescence of the pyrene fluorophore predominantly when existing as a random structure, while it formed a duplex upon recognition of K+ to bring about monomer–excimer emission switching.