Unraveling the role of ligand structure in modulating chiral europium complex luminescence

Circularly Polarized Luminescence (CPL) is a phenomenon where chiral luminescent materials emit light preferentially polarized in a specific direction. This property arises from the interaction of chiral ligands with lanthanide ions, inducing chirality into the luminescent center, with potential applications in information storage, optoelectronic devices, and bioimaging. This study reports the synthesis of a europium complex, [Eu(+tfc)₃(DPT)](H₂O)₂, incorporating a 3-(+)-trifluoroacetyl camphorate (tfc) chiral ligand and a triphenylene phosphine oxide ligand (DPT) adopting the well-established method. The compound is characterized using elemental analysis, ¹H and ³¹P NMR, FTIR, TGA, and XRD. The [Eu(+tfc)₃(DPT)](H₂O)₂ complex exhibits photoluminescence with an absolute quantum yield of 2.6 %, a lifetime of 0.323 ms, and a CPL dissymmetry factor of 0.038, alongside excellent thermal stability upto 320 °C. However, energy mismatch between the ligands and the europium ion results in non-radiative decay and reduced luminescence efficiency. This mismatch is attributed to the amorphous nature and rotational freedom of the ligands. The novel triphenylene phosphine oxide ligand enhances photophysical properties, highlighting the complex's potential for CPL-related applications, though further optimization is necessary.