Color tuning and white light emission by codoping in isostructural homochiral lanthanide metal-organic frameworks.

Four lanthanide-based homochiral metal-organic frameworks (Ln-HMOFs), {[Ln(HL)(HO)]·2Cl·5HO} [Ln = Gd (1), Eu (2), Tb (3) and Dy (4)], have been synthesized through solvothermal reactions of chiral ligand ()-5-(((1-carboxyethyl)amino)methyl)isophthalic acid (HL) with corresponding LnCl·6HO. They are binodal (3,6)-connected frameworks with kgd nets based on binuclear cluster units and zwitterionic (HL) linkers. Considering the isostructuralism of these Ln-HMOFs as well as the blue emission of compound 1 and the strong typical Eu and Tb emissions of compounds 2 and 3, single-phase mixed-lanthanide HMOFs have been prepared by doping of Ln into the Ln-HMOFs to modulate light-emitting color. Interestingly, the bimetallic doped Eu/Tb-HMOFs [(Eu Tb )(HL)(HO)]·2Cl·5HO display a fluent change of light-emitting color among green, yellow, orange, orange-red, and red by adjusting the doping concentration of Eu ions into the Tb-HMOF. Very importantly, the trimetallic doped Eu/Gd/Tb-HMOF [(EuGdTb)(HL)(HO)]·2Cl·5HO emits white light upon excitation at 355 nm, whose emission can also be switched between different colors when excited with different ultraviolet light. Furthermore, the fluorescence response of Tb-HMOF to various usual metal ions, and especially fluorescent sensing behaviours to Fe, Cr and Al have been preliminarily investigated.