Synthesis, characterization and Cu(2+) triggered selective fluorescence quenching of Bis-calix[4]arene tetra-triazole macrocycle.

Abstract A novel fluorescent bis-calix[4]arene macrocycle 9 incorporating metal-binding pockets was successfully prepared. The structure of macrocycle 9 and its precursors were characterized via EI-MS, MALDI-TOF-MS, ESI-MS, 1 H NMR, 13 CNMR, 2D NMR, and X-ray crystallography. The macrocycle 9 displayed selective fluorescence quenching after interacting with Cu 2+ in the presence competing metal cations including Mg 2+ , Ca 2+ , Ba 2+ , Ag + , Zn 2+ , Ti 4+ ,Cd 2+ , Hg 2+ , Pb 2+ , In 3+ , La 3+ , Cr 3+ , Ni 2+ , Sb 3+ , V 5+ , Fe 3+ , Co 2+ , Sn 2+ , Sn 2+ , and Tl + . The Cu 2+ limit of detection was found to be 40 nM much lower than its threshold level (∼20 μM) in drinking water permitted by the U.S Environmental Protection Agency (EPA). Furthermore, drinking water samples from Karachi University (Pakistan) spiked with Cu 2+ were analysed with the sensing system and the results showed an excellent agreement with the fluorescence quenching phenomenon of macrocycle 9 examined in deionized water. Importantly, the chemosensor 9 could be used to detect Cu 2+ in living cells