Luminescent Lanthanide Complex Sensor for Acac and Cd2.

In this work, phenylmalonic acid (H2 pmal) and phenanthroline (phen) are selected to react with Ln(NO3 )3 ·6H2 O (Ln = Tb, Eu) to form two lanthanide coordination complex [Ln2 (PAA)4 (phen)2 (NO3 )2 ] (Ln = Tb, Tb complex; Eu, Eu complex), PAA = deprotonated phenylacetic acid, phen = 1,10-phenanthroline). Two lanthanide complexes are stable in neutral, acid (pH = 4) and base (pH = 10) water solutions. Especially, Tb complex is a bifunctional sensor for acac and Cd2+ , through luminescence "turn on" and "turn off," respectively. Importantly, the limit of detections (LODs) for acac and Cd2+ are 90 nm and 0.5 μm, respectively. Furthermore, the sensing mechanisms are discussed in detail.