Anion recognition by calix[4]arene-based p-nitrophenyl amides

Calix[4]arene derivatives immobilised in the cone conformation and bearing p-nitrophenyl moieties appended to the upper rim via the amide functions have been synthesised and applied as anion receptors. The 1H NMR and UV/Vis complexation studies towards selected anions proved that the complexation ability depends considerably on the substitution pattern of the calixarene core. Thus, the proximal diamide derivative has a complexation constant for H 2 PO 4 - by one order of magnitude higher than the distal analogue.