A novel Zn-Ni heterotrinuclear Schiff base compound bearing acacen(2-) moieties was constructed through the selective assembly of a chemosensor Schiff base zinc compound with a Ni2+ ion. Its crystal structure not only clearly explains the binding mode between the chemosensor molecule and the detected metal ion but also represents the first trinuclear complex based on a symmetric acacen(2-) base Schiff base.