Imidazole and oxazole containing fluorescent dyad: Cu2+ induced fluorescence quenching and cyanide sensing 'On-Off-On' via copper displacement approach

摘要

A new simple organic molecule 4 containing imidazole and oxazole moiety has been synthesized and utilized for Cu2+ and cyanide sensing via displacement approach and fluorescence On-Off-On mechanism with rapid response in either of two sequential sensing events. The photophysical behavior of probe 4 toward different metal ions and anions has been examined through the absorption and fluorescence spectroscopy in HEPES buffer. Probe 4 shows high selectivity for Cu2+ with fluorescence quenching (similar to 93%; switch-Off). The in situ generated ensemble, 4+Cu2+ upon interaction with different anions shows high selectivity for CN-in which the fluorescence intensity revived (switched-On) due to the formation [Cu(CN)(x)](1-x) species in the medium. Further, the naked eye sensitive "On-Off-On" sensing behavior of 4 has been utilized for construction of a sequential logic circuit at the molecular level. The FT-IR, H-1 NMR and ESI-MS spectroscopy and DFT support the proposed mechanism of interaction.