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, 1 H & 19 F NMR and ESI-MS studies. Variable temperature NMR studies revealed the formation of HF 2 − . DFT and TD-DFT studies demonstrate strong binding interactions between the R and F − . A neutral electron-deficient, pentafluorophenyl hydrazone-functionalized upper rim derivative of calix[4]arene, R , showed naked eye detection of fluoride among 19 anions.