Isothiocyanato-calix[4]phyrin-(1,1,1,1): a useful intermediate for the synthesis of derivatised anion sensors

A calix[4] phyrin-(1,1,1,1) substituted with a 4-isothiocyanatophenyl group has been synthesised and used to attach the macrocycle to a solid support. The NCS group can also be used to further functionalise the calix[4] phyrin-(1,1,1,1) by reaction with amines and amino acids. Stability constants for anion binding by the calix[4] phyrin-(1,1,1,1) are reported and these show a clear ability to differentiate F- and HSO4- from Cl-, Br-, I- which can be detected by both NMR and UV-visible spectroscopy.