Dual-mode recognition of transition metal ions by bis-triazoles chained pyrenes

Fluorescent chemosensors 7−10, with variable methylene chain length as spacers between the two triazole methyl ether units, have been synthesized under 'Click' condition, where the bistriazoles are used as the metal ion binding sites and the pyrenes as the fluorophores. Compound 10, having the longest methylene chain among 7−10, shows monomer and excimer fluorescence quenching in acetonitrile toward Ni2+, Pb2+, Cu2+, Hg2+, and Cr3+ ions, however, it shows an enhanced monomer but a decreased excimer emission when complexed with Cd2+ and Zn2+ ions.