Selective recognition of H 2 PO 4 - by a cholestane-imidazole-zinc ensemble

A new facile amphiphile cholestane-based zinc complex 4 containing a 3-aminopropylimidazole moiety at the 3α and 7α positions of cholestane was designed and synthesized. Recognition selectivity of the new receptor 4 with various anions was assessed by 1H NMR titration. Dihydrogen phosphate showed the highest binding affinity among all the tested anions (Ka=4.4×105M−1).