Annihilation luminescent Eu-MOF as a near-infrared electrochemiluminescence probe for trace detection of trenbolone

A Eu-MOF (Eu2[Ru(dcbpy)3]3) with novel mechanism of annihilation electroluminescence (ECL) was designed via synthesizing a MOF coordinated with photoactive metalloligand and lanthanide metal ion. Firstly, the redox of [Ru(H2dcbpy)3]·Cl2 ligand produced Ru(dcbpy)33+ and Ru(dcbpy)32+, then Eu2[Ru(dcbpy)3]3•+ was produced under the catalysis of Ru(dcbpy)33+ and Ru(dcbpy)32+. Secondly, Eu2[Ru(dcbpy)3]3 gained electrons to produce Eu2[Ru(dcbpy)3]3•-, thus realizing annihilation luminescence without any extra coreactant. Thirdly, the antenna effect of [Ru(H2dcbpy)3]·Cl2 ligand on Eu3+ greatly improved the luminescence efficiency of Eu2[Ru(dcbpy)3]3 by strong energy transfer. In addition, the introduction of Eu3+ endowed the ECL sensor characteristics of second near-infrared (NIR-II) luminescence. These allowed the ECL sensor to work normally in harsh conditions, accomplished non-destructive testing of samples, and made the ECL sensor with high and stable signals. Hence, the Eu2[Ru(dcbpy)3]3 can be used as a NIR probe to achieve efficient and sensitive detection of trenbolone with low limit of detection (LOD) of 4.83 fg/mL. Therefore, it is a considerable design strategy to realize ultrasensitive detection of environmental pollutants.