Rapid naked eye sensing of fluoride by calix[4]arene upper rim tetra functionalized pentafluorophenyl hydrazone

A neutral electron-deficient, pentafluorophenyl hydrazone-functionalized calix[4]arene, R, showed naked eye detection of fluoride among 19 anions. The formation of R + F- was evidenced by UV-vis, H-1 & F-19 NMR and ESI-MS studies. Variable temperature NMR studies revealed the formation of HF2-. DFT and TD-DFT studies demonstrate strong binding interactions between the R and F-.

Automated summary

A neutral electron-deficient, pentafluorophenyl hydrazone-functionalized calix[4]arene, R, was able to visually detect fluoride out of 19 anions. The formation of R + F- was confirmed by UV-vis, H-1 & F-19 NMR, and ESI-MS studies. Variable temperature NMR studies revealed the formation of HF2-. DFT and TD-DFT studies demonstrated strong binding interactions between R and F-.