The formation of the two title compounds, Na3[Sm(DPA)3]·14H2O tris­odium tris­(pyridine-2,6-di­carboxyl­ato-κ3 O 2,N,O 6)samarate(III) tetra­deca­hydrate, Na3[Sm(C7H3NO4)3]·14H2O, and catena-poly[[[di­aqua­(6-carb­oxy­pyridine-2-carb­oxyl­ato-κ3 O 2,N,O 6)samarium(III)]-μ-pyridine-2,6-di­carboxyl­ato-κ4 O 2,N,O 6:O 2] tetra­hydrate], {[Sm(C7H3NO4)(C7H4NO4)(H2O)2]·4H2O} n , depends on the pH value adjusted with NaOH solution. In both crystal structures, the coordination spheres of the SmIII cations were found to be best described by a tricapped trigonal prism (TTP), with a more regular O6N3 donor set for Na3[Sm(DPA)3]·14H2O than that of O7N2 for [Sm(DPA)(HDPA)(H2O)2]·4H2O. The supra­molecular features of both crystal structures are dominated by O - H⋯O hydrogen bonds between water mol­ecules and the O atoms of the dipicolinato ligands. Samples were made from solutions at pH = 2, pH = 5, pH = 7, and pH = 10, and the crystals present in each sample were ground to a powder. The powder samples were analyzed with powder X-ray diffraction and luminescence spectroscopy. The splitting of the bands in the luminescence spectra recorded on powders at 77 K was observed to vary with the pH.