New 2,2′‐Bipyridine Derivatives and Their Luminescence Properties with Europium(III) and Terbium(III) Ions

Twenty differently substituted 2,2′,2″,2‴ ‐[(2,2′‐bipyridine‐6,6′‐diyl)bis(methylenenitrilo)]tetrakis(acetc acids) 75–94 were synthesized with the purpose of developing new markers to be used in bioaffinity assays based on the unique luminescence properties of Eu III and Tb III ions. The relative luminescence yields, excitation maxima, and emission decay constants were determined for the corresponding Eu III and Tb III chelates. The substituents at the bipyridine moiety had a significant effect on the luminescence properties: the best relative luminescence yields R were obtained for ligands with electron‐donating substituents ( e.g. Me, Ph), electron‐withdrawing substituents ( e.g. NO 2 , COOH) had a reverse effect. However, no clear correlation between the relative luminescence yields and the substituent parameters was found.