Two samarium(III) complexes showing different luminescent intensity, namely Sm(HL¹)₂·NO₃·2H₂O (1) and [SmL²(C₂H₅OH)₂·NO₃]₂ (2), were constructed via the solvothermal in situ lanthanide metal–ligand reactions of 2-ethoxy-6-((pyridin-2-ylmethylimino)-methyl)phenol (HL) from pyridin-2-ylmethanamine and 3-ethoxy-2-hydroxybenzaldehyde with Sm³⁺ ion at different temperatures, in which H₂L¹ resulted from C–C coupling dimerization of HL, while H₂L² from C–C coupling of HL and pyridin-2-ylmethanamine.