2,6-Bis(diethylamide)-4-oxo(3-thiopropane)pyridine (BDP) and 2,6-bis(methyl ester)-4-oxo(3-thiopropane)pyridine (BMP) were synthesized. These compounds chelated him ions and sensitized their emission. The 3:1 complexes of BDP displayed efficiencies of 18% and 12% for Eu-III and Tb-III, respectively. The analogous complexes of BMP had efficiencies of 23% and 18% for Eu-III and Tb-III, respectively. Both BDP and BMP were used to cap ZnS nanoparticles (NPs) in a one -pot synthesis, and then Ln(III) ions were added, resulting in systems with metal ions at the surface of the capped NPs. Photoexcitation of the Eu-III and Tb-III systems through NPs capped with these two ligands, with the carboxylato derivative of BMP [dicarboxylato4-oxo(3-thiopropane)pyridine] and the nonchromophore 3-mercaptopropionate, resulted in sensitized Ln(III)-centered emission. The Eu-III-containing systems displayed higher efficiencies in the range 0.04-0.23% than the corresponding TBIII-containing systems with efficiencies in the range 0.01-0.15%. The NPs capped with BDP were the exception; in this case, efficiencies of 0.36% and 0.79% for Eu-III and Tb-III, respectively, were observed.