A novel Schiff base oxime ligand (H₂L) can be used as a turn-on fluorescent sensor for selective detection of Zn²⁺.

Sensor H₂L vividly discriminates between Zn²⁺ and Cd²⁺.

Two tetranuclear complexes, [Zn₄(L)₄] and [Ni₄(L)₄] were synthesized and their crystal structures have been characterized.

Sensor H₂L is regular and consistent in its binding with transition metal ions with a good 4:4 stoichiometry.