New di- and trimethoxyphenyl-substituted phosphorus-containing ligands, ( Z)-[2-(5-chloro-2-hydroxy-4-methylphenyl)-2-phenylvinyl]bis(3,4-di- and 3,4,5-trimethoxyphenyl)phosphine oxides, have been synthesized, and their adducts with europium(III) 2-thenoyltrifluoroacetonate have been obtained. High luminescence intensity of the synthesized complexes suggests prospects in using them for the design of various materials possessing unique photophysical properties.