Efficient pure white light emission based on a three-component La:Eu,Tb-doped luminescent lanthanide metal–organic framework

Abstract

A series of novel similar lanthanide metal–organic frameworks, namely, [Ln₂L1₂L2_(4−x−y)L3_xL4_y]·nH₂O (LnMOF-1–13) (LnMOF-1: Ln = La, x = 0.7, y = 1.3, n = 4.7; LnMOF-2: Ln = Ce, x = 0.7, y = 1.3, n = 4.7; LnMOF-3: Ln = Pr, x = 1, y = 1, n = 5; LnMOF-4: Ln = Sm, x = 1, y = 1, n = 2.5; LnMOF-5: Ln = Eu, x = 1, y = 1, n = 3; LnMOF-6: Ln = Tb, x = 0, y = 2, n = 2; LnMOF-7: Ln = Dy, x = 1, y = 1, n = 3; LnMOF-8: Ln = Er, x = 0, y = 1, n = 3; LnMOF-9: Ln = Nd, x = 1.4, y = 1.4, n = 3.6; LnMOF-10: Ln = Gd, x = 1, y = 1, n = 3; LnMOF-11: Ln = Ho, x = 1.6, y = 0, n = 3; LnMOF-12: Ln = La_0.44Eu_0.10Tb_0.46, x = 1, y = 1, n = 7; LnMOF-13: Ln = La_0.66Eu_0.11Tb_0.23, x = 1, y = 1, n = 7; L1 = 5-((4-formylphenoxy)methyl)isophthalic acid anion, L2 = C₃H₇ON, L3 = H₂O, L4 = HCOOH), have been prepared using a solvothermal method and characterized by single crystal and powder X-ray diffraction, IR spectroscopy, elemental analysis and thermogravimetric analysis. All structures are similar and possess a 3D binodal (3,6)-connected net with the point symbol (4²·6)₂(4⁴·6²·8⁷·10²). Furthermore, the luminescence measurements indicate that compounds LnMOF-5 and LnMOF-6 display intense characteristic red and yellowish-green emission with quantum yields of 23.30% & 28.25%, respectively. And the three-component La:Eu,Tb-doped compounds exhibit white emission under UV irradiation, especially the compound LnMOF-12 which exhibits the Commission International de l'Eclairage (CIE) chromaticity coordinate (0.332, 0.333) with pure white light emission (Φ = 11.22% at 345 nm). Additionally, the magnetic properties of LnMOF-10 are also investigated.