Cathodo- and X-ray excited luminescence of Europium Tri- and Tetracarboxybenzoates and Phenanthroline

Abstract

Two europium(III) coordination compounds based on tri- and tetracarboxybenzene ligands (H3btc and H4btec) and 1,10-phenanthroline were synthesized and thoroughly characterized. Both complexes display characteristic Eu3+ photoluminescence with high quantum yields (22% and 41%). Cathodoluminescence studies revealed bright and stable emission up to 9 kV, with the btec-based complex exhibiting higher intensity and greater resistance to electron-beam-induced degradation. Most notably, thin films of the btec complex demonstrate robust X-ray-induced luminescence (XRL) under 40–90 kV excitation. XRL intensity increases linearly with both voltage and current, and remains spectrally stable over prolonged exposure, with minimal performance loss. These results highlight the role of ligand structure and complex stability in high-energy-excited luminescence and suggest promising applications of Eu3+-polycarboxylate frameworks in X-ray sensing and imaging devices.