The mononuclear complex [Dy(H₃L)(H₂O)(NO₃)](NO₃)₂ (Dy) and the heterotrinuclear compound [Zn₂Dy(L)(NO₃)₃(OH)]·3H₂O (Zn₂Dy·3H₂O) can be obtained with the same H₃L compartmental ligand. The single X-ray crystal structure of the both complexes shows a DyO₉ core but with different geometries: a muffin-like disposition in Dy and a spherical capped square antiprism in Zn₂Dy. The luminiscent characterisation of the metal compounds in methanol solution at 298 K shows a notable increase in the fluorescent emission of the heterotrinuclear complex respect to the mononuclear one, indicating that the presence of zinc improves significantly the fluorescent character of Zn₂Dy·3H₂O respect to Dy. Accordingly, Zn₂Dy·3H₂O could be a potential fluorescent probe for imaging applications.