Europium Doped Atomically Precise Bismuth Oxido Nanoclusters as Molecular Building Blocks for Photoluminescent Hybrid Materials

Abstract

ABSTRACT Structural and optical characterization of Eu 3+ doped atomically precise bismuth oxido nanoclusters (BiO‐NCs) of about 2 nm in size is reported. The BiO‐NC [Bi 38 O 45 (NO 3 ) 24 (dmso) 28 ]:Eu ( C‐1 D :Eu ) is transformed into soluble methacrylate ( − OMc) coordinated [Bi 38 O 45 (OMc) 24 (dmso) 4 ]:Eu·4dmso·4H 2 O ( C‐2 D :Eu ) and [Bi 38 O 45 (OMc) 24 (EtOH) 10 ]:Eu·4EtOH ( C‐2 E :Eu ) by ligand exchange and without changing the amount of Eu 3+ doping ( ω ≈ 1%). Based on SC XRD analysis of C‐1 D :Eu and C‐2 E :Eu partial substitution of the bismuth atoms with preference in the inner {Bi 6 O 9 } core of the {Bi 38 O 45 } cluster is suggested. Temperature dependent photoluminescence studies show bismuth‐ and europium‐based dual emission at low temperatures, whereas only the latter is preserved at room temperature. As a result of the low‐symmetry environment of Eu 3+ a remarkable intensity of the 5 D 0 → 7 F 0 (electric dipole) transition is observed, accompanied by lifetimes of about 2 ms and quantum yields ranging from 53% ( C‐2 D :Eu) to 65 % ( C‐1 D :Eu) . The solubility of C‐2 E :Eu enables its use for the synthesis of organic–inorganic hybrid materials. Thus, transparent hybrid materials were prepared by radical copolymerization of methyl methacrylate, 2‐hydroxyethyl methacrylate and C‐2 E :Eu , showing distinct photoluminescence characteristics even with a low Eu 3+ content of 2.7·10 −5 mol%.