Three heterometallic dinuclear compounds, [(MDyIII)-Dy-II(L)(Pc)(ROH)]center dot ROH (R = CH3, M = Ni (1), Zn (2); R = C2H5, M = Zn (3)), were stepwise synthesized based on phthalocyanine (H2Pc) and one tripodal Schiff-base ligand 1,1,1-tris[(salicylideneamino)methyl] ethane (H3L). All of them have been studied structurally and magnetically. The six-coordinate M-II ion and the seven-coordinate Dy-III ion are bridged by two phenolic oxygen atoms to form an M-II-Ln(III) heterodinuclear unit. Magnetic measurements indicate that the ferromagnetic Ni-II-Dy-III interaction is operative in compound 1 and all three compounds exhibit the field-induced slow relaxation of magnetizations. In particular, compounds 2 and 3 have the improved magnetic performance. Ab initio calculations indicate that the weak Ni-II-Dy-III interaction decreases the energy barrier, while the replacement of the paramagnetic Ni-II ion by the diamagnetic Zn-II in compound 2 and 3 not only controls the magnetic interaction but also alters the local magnetic axes of Dy-III ions to optimize the magnetic relaxation behavior.