Europium(III) Macrocyclic Chelates Appended with Tyrosine‐based Chromophores and Di‐(2‐picolyl)amine‐based Receptors: Turn‐On Luminescent Chemosensors Selective to Zinc(II) Ions

Zinc ions play an important role in many biological processes in the human body. To selectively detect Zn2+, two EuDO3A‐based complexes (DO3A=1,4,7,10‐tetraazacyclododecane‐1,4,7‐tricarboxylic acid) appended with tyrosine as a chromophore and di‐(2‐picolyl)amine (DPA) as the Zn2+ recognition moiety were developed as suitable luminescent sensors. Their luminescence intensity is affected by the photoinduced electron transfer mechanism. Upon addition of Zn2+, both probes display an up to sevenfold enhancement in Eu3+ emission. Competition experiments demonstrated their specificity toward Zn2+ over other metal ions, while also revealing the nonspecificity of the derivatives lacking the DPA‐moiety, thus confirming the essential role of the DPA for the recognition of Zn2+. The induced emission changes of Eu3+ allow for precise quantitative analysis of Zn2+, establishing these lanthanide‐based complexes as viable chemosensors for biological applications. Highly selective: Two EuDO3A‐based complexes, appended with tyrosine as a chromophore and DPA as a Zn2+ recognition moiety were developed as suitable luminescent sensors. Both probes exhibit strong luminescence enhancement in response to zinc over other studied metal ions.