doi:10.1016/j.optmat.2026.118113engMaurin-Pasturel, GuillaumePiñol, RafaelCases, RafaelBrites, Carlos D.S.Saraiva, Leonardo F.Carneiro Neto, Albano N.Ara, IreneFalvello, LarrySanjuán, MarisaCarlos, Luís D.Millán, AngelEnhanced luminescence of (Eu3+/Sm3+)(diketone)3(N-Base) complexes enabled by ancillary ligandsART-2026-149152Lanthanide β-diketonate complexes are prominent luminescent materials due to their intense, spectrally pure emissions and their broad utility in sensing, display technologies, and photonics. Their efficiency, however, depends critically on the effectiveness of ligand-to-metal energy transfer and the suppression of non-radiative deactivation. Introducing ancillary N-donor ligands enhances these processes by improving energy-transfer efficiency and reducing vibrational quenching. We report a family of Eu3+ and Sm3+ complexes of general formula LnL3L*, where L is a β-diketonate (4,4,4- trifluoro-1-phenyl-1,3-butanedionate, btfa− , or 2-thenoyltrifluoroacetate, tta− ) and L* a bidentate (1,10-phenanthroline) or tridentate (terpyridine derivatives) N-donor ligand. The complexes were synthesized and characterized by single-crystal and powder X-ray diffraction, Raman, and IR spectroscopies. Photophysical measurements, supported by computational analysis, reveal clear structure–property correlations. All complexes exhibit markedly enhanced emission relative to the parent LnL3⋅2H2O species (Ln = Eu and Sm). The highest luminescence intensities were obtained with 4′(4-methyl)-2,2′:6′,2″-terpyridine, followed by 1,10-phenanthroline, 2,2′:6′,2″-terpyridine, and 2,6-bis(5-(p-methoxyphenyl)-1H-pyrazol-3-yl)pyridine. Overall, these results highlight the critical role of ancillary N-donor ligands in tuning lanthanide photophysics, thereby enabling enhanced emission efficiency and tailored optical properties for advanced luminescent technologies.2026http://zaguan.unizar.es/record/17106410.1016/j.optmat.2026.118113http://zaguan.unizar.es/record/171064oai:zaguan.unizar.es:171064info:eu-repo/grantAgreement/ES/DGA/E11-17Rinfo:eu-repo/grantAgreement/ES/DGA/E17-23Rinfo:eu-repo/grantAgreement/ES/DGA/LMP220_21info:eu-repo/grantAgreement/ES/MICINN/PID2021-124354NB-I00info:eu-repo/grantAgreement/ES/MICIU/RYC2024-048927-IOptical Materials 176 (2026), 118113 [11 pp.]by-nc-ndhttps://creativecommons.org/licenses/by-nc-nd/4.0/deed.esinfo:eu-repo/semantics/embargoedAccess