Three novel Zn(II) complexes, [Zn 4 L 1 Cl 4 ]·3H 2 O (1), [Zn 4 L 2 Cl 4 ]·2DMF (2) and [Zn 4 L 3 Cl 4 ]·H 2 O (3), have been synthesized and structurally characterized. In these complexes, interesting 32-membered dodecadentate macrocyclic ligands were generated in situ by ‘2+2’ type condensation reactions between a tetraamine and various dialdehydes. All the complexes are isostructurally tetranuclear Zn(II) complexes, containing endogenous alkoxo and phenoxo bridges. Applications of the macrocyclic ligands as Zn 2+ sensors have been investigated. Take H 4 L 1 for example, it exhibits a 4-fold fluorescence enhancement upon the addition of 2equiv. of Zn 2+ in MeOH.