Synthesis of a di(2-picolyl)amino-β-diketone dual-functional ligand that can coordinate to europium(III) for responding to copper(II) and sulfide ions

• Published in: Chinese chemical letters 2015-12, Vol.26 (12), p.1485-1489
• Main Authors: Liu, Yan, Shi, Qiu-Ling, Yuan, Jing-Li
• Format: Article
• Language: English
• Subjects: Copper(II) ion; Europium complex; Luminescent probe; Sulfide ion; Time-resolved luminescence detection
• ISSN: 1001-8417; 1878-5964
• DOI: 10.1016/j.cclet.2015.10.021

A dual-functional ligand that can coordinate to Eu3+, DPA–BPPBCB, has been synthesized for responding to Cu2+ and S2− ions in aqueous media. Lanthanide complex-based luminescent probes/chemosensors have shown great utilities in various biological and environmental assays with time-resolved detection mode to eliminate background noises. In this work, by conjugating di(2-picolyl)amine (DPA) with a tetradentate β-diketone 1,2-bis[4′-(1′′,1′′,1′′,2′′,2′′-pentafluoro-3′′,5′′-pentanedion-5′′-yl)benzyl]-4-chlorosulfo-benzene (BPPBCB), a novel dual-functional ligand that can coordinate to Eu3+ for responding to Cu2+ and S2− ions in aqueous media, DPA–BPPBCB, has been designed and synthesized. The β-diketone moiety of DPA–BPPBCB can form a strongly luminescent complex with Eu3+. Upon reaction with Cu2+, accompanied by the formation of heterobimetallic complex Cu2+–DPA–BPPBCB–Eu3+, the Eu3+ luminescence was quenched. While in the presence of S2−, owing to the high affinity of S2− to Cu2+, stable CuS was formed, which resulted in the release of Cu2+ from Cu2+–DPA–BPPBCB–Eu3+, to restore the luminescence of the Eu3+ complex. This unique “on-off-on” luminescence response of the Eu3+ complex enabled Cu2+ and S2− ions in aqueous media to be detected with time-resolved luminescence detection mode.