Photoluminescence and magnetic analysis of a family of lanthanide(III) complexes based on diclofenac

A family of ten novel isostructural Ln(III) complexes based on the nonsteroidal anti-inflammatory drug diclofenac, with the general formula [Ln(2)(dicl)(6)(MeOH)(2)(H2O)(2)] [Ln(III) = Pr (1), Nd (2), Sm(3), Eu (4), Tb (5), Dy (6), Ho (7), Er (8), Tm (9), Yb (10)], has been prepared. These complexes consist of centrosymmetric dimers in which each metallic centre is coordinated to three diclofenac ligands as well as water and methanol molecules. Alternating current magnetic measurements of complex 6 show a slight SMM behaviour. The evaluation of solid-state photophysical properties reveals that the diclofenac ligand is able to sensitize the luminescence emission of compounds 2, 3, 4, 5, and 6 both in the visible and near-infrared (NIR) regions at 10 K. Measurements of the decay curves show persistent fluorescence, with lifetimes of nearly 1.5 ms, and temperature stable lifetimes in the case of complex 5. Moreover, the NIR emission of compound 2 may open the way to applications in the field of fluoroimmunoassays and in vivo detection, given the bioactive nature of the diclofenac molecule.