New porphyrin derivatives for phosphate anion sensing in both organic and aqueous media

New porphyrin-based anion receptors have been prepared from meso-tetrakis(pentafluorophenyl) porphyrin (TPPF20) and diamine derivatives. These receptors (compounds 1-3) interact preferentially with phosphate anions both in organic solutions and in basic aqueous media when coated on gold piezoelectric quartz crystals. A single crystal X-ray structure of the bis-HF complex of a imine derivative of 1 was obtained; it serves to highlight the main interactions between the anion and cation receptors in the solid state.