A piperazine N,N'-bis naphthyl thiourea derivative was designed and synthesized. The interactions of this compound with different dicarboxylate anion were characterized by UV- vis and 1^H NMR spectroscopy. Results indicated that the complex formation through the hydrogen bond interactions between anion and the title compound induced variation of absorption spectrum. The stability constants were determined in this work, It was found that the selectivity ofdicarboxylate is dependent strongly on the chain length of anion. The complex model is also proposed according to the results obtained.

Key words: SULFOCARBAMIDES, ACCEPTOR, ANION, IDENTIFICATION, CARBOXYLATES