Two new tetrathiafulvalene based receptors in which the favorable redox properties of the tetrathiafulvalene unit are coupled to either a benzo-crown (X = O) or a dithiabenzo-crown (X = S) ether binding site were designed and synthesized as receptors for K(+) and Ag(+). The receptors display a good (K(+), X = O) to strong (Ag(+), X = S) affinity toward the cation and a high discrimination against other metal cations.