Metal–organic framework solid solutions of rare earth ions Tb3+, Eu3+ and Y3+ with pyridine-2, 4, 6-tricarboxylate ligand emitting high quantum yield white light

Tuning white light emission using single-component tetrachroic Dy3+ metallacrowns: the role of chromophoric building blocks

White light production is of major importance for ambient lighting and technological displays. White light can be obtained by several types of materials and their combinations, but single component emitters remain rare and desirable towards thinner devices that are, therefore, easier to control and that require fewer manufacturing steps. We have designed a series of dysprosium(iii)-based luminescent metallacrowns (MCs) to achieve this goal. The synthesized MCs possess three main structural types LnGa4(L')4(L'')4 (type A), Ln2Ga8(L')8(L''')4 (type B) and LnGa8(L')8(OH)4 (type C) (H3L', HL'' and H2L''' derivatives of salicylhydroxamic, benzoic and isophthalic acids, respectively). The advantage of these MCs is that, within each structural type, the nature of the organic building blocks does not affect the symmetry around Dy3+. By detailed studies of the photophysical properties of these Dy3+-based MCs, we have demonstrated that CIE coordinates can be tuned from warm to neutral to cold white by (i) defining the symmetry about Dy3+, and (ii) choosing appropriate chromophoric building blocks. These organic building blocks, without altering the coordination geometry around Dy3+, influence the total emission profile through changing the probability of different energy transfer processes including the 3T1 ← Dy3+* energy back transfer and/or by generating ligand-centered fluorescence in the blue range. This work opens new perspectives for the creation of white light emitting devices using single component tetrachroic molecular compounds.