Synthesis of a novel doubly strapped zinc porphyrin and its recognition property for anions

A novel doubly strapped zinc porphyrin (2) was synthesized, characterized and studied as anion receptor. It showed a very high affinity and selectivity for image, F− and AcO− over other anions by combining Lewis acidic binding site (Zn2+) with NHs of the urea groups. In contrast, free base porphyrin (1) and ZnTPP did not show detectable affinities for all the anions examined.