Zinc(II) complex with teirpyridine derivative ligand as “on–off” type fluorescent probe for cobalt(II) and nickel(II) ions

A new terpyridine derivative ligand 4′-4-(1,2,4-triazol-1-yl)-phenyl-2,2′:6′,2″-terpyridine (L) was prepared and its metal complex [Zn(L)2](NO3)2·H2O (1) was obtained by reaction of L with zinc(II) nitrate hexahydrate. The structure of the complex was determined by X-ray crystallography. The fluorescent spectral measurements revealed that complex 1 is a selective fluorescent sensor for Co2 + and Ni2 + ions but not for metal ions such as Mg2 +, Pb2 +, Cu2 +, Fe2 +, In3 +, Zn2 +, Cd2 + and Fe3 +. Furthermore, EDTA (ethylene diamine tetraacetic acid) can selectively turn on the quenched fluorescence of complex 1 induced by Co2 + (“on–off–on” type sensor) but cannot turn on the one induced by Ni2 + (“on–off” type sensor).