Two metal complexes 1 ([Cu(L1)]²⁺) and 2([Cu(L2)]²⁺) based on Schiff base were synthesized and studied as anion-binding receptors in polar solvent such as V(H₂O):V(Ethanol)=98:2 mixture. The results indicated that the metal complex 1 with a C_3v symmetric cavity could act as efficient and selective reagents for PO₄^3-. The UV-vis spectroscopic titration experiments indicated the formation of 1:1 stable complexes between 1 and PO₄^3-. In addition, complex 1 has also a little response to HPO₄^2-, but there are no any responses to other anions such as non-tetrahedron type anions and tetrahedron type anions. The binding manner and possible structure formed between the complex 1 and PO₄^3- were proposed. The experimental results and some consideration concerned to improve the selectivity of sensor on design were discussed preliminarily.

Key words: metal complex, anion detection, molecular recognition, phosphate anion