Highly optically-diluted lanthanide coordination polymers with unexpected strong luminescence

Abstract

A series of lanthanide coordination polymers with general chemical formula [Ln 2 (dcpa) 3 (H 2 O)] ∞ (Ln = La-Er except Pm plus Y; H 2 dcpa = 4,5-dichloro-phthalic acid), has been obtained by micro-waves assisted synthesis. Isostructural hetero-lanthanides molecular alloys in which the emissive ions are highly diluted by non-emitting ions have also been prepared. These compounds exhibit unexpectedly high luminescence intensities. Based on photo-physics measurements and theoretical calculations this strong luminescence was attributed to unusually low non-radiative vibrational de-excitation. Intermetallic Tb 3+ → Eu 3+ energy transfers have also been estimated in the frame of Forster's mechanism. This study opens the way to the design of series of compounds, with strong and highly tunable luminescence in the visible domain, which is of interest for materials traceability.