1,3-Bis(pyren-1-yliminomethyl)calix[4]arene As a Selective Fluorescent Turn-on Sensor for Mercury(ii) Ion

A novel calixarene-based diimine, 1,3-bis(pyren-1-yliminomethyl)calix[4]arene (5), serves as a turn-on-type fluorescent sensor, which selectively detects Hg2+ in THF/H2O (99:1, v/v) in the presence of various other metal ions. Such selectivity is not seen with half salen 1 derived from salicylaldehyde and 1-aminopyrene. H-1 NMR analysis reveals that it is a chemodosimetric sensor based on its hydrolysis mediated by Hg2+ to release 1-aminopyrene molecules as fluorescent chromophores.