Synthesis of Double-Armed Lariat Ethers with Pyrene Moieties at Each End of Two Sidearms and Their Fluorescence Properties in the Presence of Alkali Metal and Alkaline Earth Metal Cations
suppression of both the crown ring and one of the two sidearms based on complexation with the metal cation. The selectivity for alkalineearth metal cations was highly dependent on the fitness of the host cavity and the guest size. Although most of the fluorophores did not respond to alkali metal cations, only trans-7a containing an 18-crown-6 ring showed K+ selectivity.