Using two Schiff-base ligands containing an electron-withdrawing group (NO₂), we obtained two mononuclear and two trinuclear complexes with the general formula [Dy(hni)(NO₃)(DMF)₂]·DMF (1·DMF), [Dy(hni)₂(H₂O)₂]·NO₃·EtOH (2·NO₃·EtOH), [Dy₃(hnc)₃(DMF)₆] (3) and [Gd₃(hnc)₃(DMF)₆] (4) (H-hni: 2-(hydroxyl-3-methoxy-5-nitrophenyl)methylene(isonictino)hydrazine and H₃-hnc: 1,5-bis(2-hydroxy-3-methoxy-5-nitrobenzylidene)carbonohydrazide). Four complexes were confirmed by infrared spectroscopy and single-crystal X-ray diffraction. The crystal structure of complex 3 reveals that the modified Schiff-base ligand provides two different tridentate coordination pockets (ONN and ONO) to encapsulate Dy^III with a unique N–N pathway. The magnetic properties of all four complexes have been investigated using dc and ac susceptibility measurements. The frequency-dependent ac susceptibility is indicative of single-molecule magnetic behavior without and/or with an optimum dc field with a relaxation barrier U_eff = 34 K (400 Oe), 19 K (0 Oe) and 80 K (0 Oe) for complexes 1, 2 and 3, respectively.