Synthesis, Structures, Tunable White-light Emission Of Multifunctional Metal-organic Coordination Polymers Based On Flexible Multicarboxylate Ligands

Recently, metal–organic frameworks (MOFs) have attracted much attention due to their funny structural diversities and possible applications in optical, magnetism, storage and catalysis. Design and synthesis of functional metal-organic frameworks has become a new crossover in chemistry, materials chemistry, physical sciences and so on. White-light emitting materials deserve particular attention due of their promising applications, such as photodynamic therapy, backlight sources, biomedical imaging and other photonic devices. The lanthanide metal-organic frameworks (LnMOFs) displaying interesting optical properties can be used in designing white-light emitting materials. With judiciously chosen suitable ligands and lanthanide ions to build coordination polymers with unique fluorescent properties, we can obtain white-light emitting materials.In this article, our work includes two parts as follows:1. A series of novel lanthanide metal–organic frameworks {[Ln2(L1)2]·(H2O)3·(Me2NH2)2}n (Ln=La(1), Ce(2), Pr(3), Nd(4), Sm(5), Eu(6), Gd(7), Tb(8), Ho(9), Er(10)) were synthesized by reactions of H4L1(H4L1=5-(3,5-dicarboxybenzyloxy)isophthalic acid) and lanthanide centers. Their structures and properties have been characterized. This series of complexes are isomorphous, exhibiting a3D anionic porous chiral framework.The luminescent properties of Eu and Tb compounds have been investigated in detail. The Eu and Tb compounds emit strong red and green light. Additionly, Eu3+and Tb3+ions have the same charge and similar ionic radii, we can successfully obtain the functional luminescent MOF materials by doping isostructural Eu3+into Tb compounds and changing the doped Eu3+concentration to tune the emission color. We also successfully obtained white-light emitting materials through the doping of Eu3+and Tb3+ions in the La compounds.2. A porous metal–organic framework, {[Zn2(L2)·H2O]·3H2O·3DMAc·NH2(CH3)2}n (11)(Zn(II)-MOF) was obtained by the reactions of ZnCl2and H5L2(H5L2=3,5-bis(1-methoxy-3,5-benzene dicarboxylic acid)benzoic acid). It has large1D nano-tubular channels along b-axis and a rare5-connected vbk topology. The MOF was shown to readily and quickly adsorb toluidine blue dye molecules. In addition, white light emitting materials were obtained based on the porous Zn(II)–MOF by a cation exchanged approach.