SYNTHESIS, BASICITY AND COMPLEXING PROPER TIES TOWARD ZN(II) OF A NEWACYCLIC RECEPTOR OF PYRAZOLE AND PROTON-IONIZABLE PYRIDINE

The synthesis of bis (2'-pyridylmethyl) N-1-H pyrazole 3,5-dicarboxyla te 1 [L] is reported. The formation of its sodium pyrazolate salt 1' [ L(-)] has been studied by C-13 NMR, and the deprotonation pK(a) value of the pyrazole ring of 1 and those corresponding to the protonation o f their pyridine rings have been measured using potentiometric methods in H2O-MeOH (v/v 9:1) Starting from 1 [L] or 1'[L(-)], the formation of mono-and dinuclear complexes 2 Zn[L] and 3[Zn-2[L(-)](3+) respectiv ely has been studied.