Syntheses, Structures, and Photo luminescent Properties of Lanthanide Coordination Polymers Based on a Zwitterionic Aromatic Polycarboxylate Ligand

Three series of lanthanide coordination polymers, {[Ln(L)(H2O)(2)]center dot NO3 center dot 2H(2)O}(n) (Ln = La 1, Pr 2), {[Ln(2)(L)(2)(NO3) (H2O)(2)]center dot Cl center dot 6H(2)O}(n) (Ln = Nd 3), {[Ln(L)(H2O)(2)}center dot Cl center dot 3H(2)O}(n) (Ln = Sm 4, Eu 5, Gd 6, Tb 7, Dy 8, Ho 9, Er 10, Tm 11, Yb 12, and Lu 13) (H3L = 4-carboxy-1-(3,5-dicarboxy-benzyl)-pyridinium chloride), have been successfully synthesized under hydro(solvo)thermally conditions. Single-crystal Xray diffraction analyses revealed that compounds 1-3 all crystallize in triclinic space group P (1) over bar, but they display different three-dimensional structures with diverse dinudear subunits. In contrast, compounds 4-13 display the same layer structures in the triclinic space group P (1) over bar. The structural difference of these two classes of compounds is derived from the effect of lanthanide contraction. Powder X-ray diffraction (PXRD) and thermogravimetric analyses of compounds 1-13 have also been investigated and discussed in detail. The solid-state luminescent properties of compounds 4, 5, 7, and 8 were characterized, and the results revealed that they exhibit characteristic Sm(III), Eu(III), Tb(III), and Dy(III) emissions in the pink, red, green, and yellow light regions, respectively. More interestingly, the luminescence colors of the Tb(1-x)(L):xEu can easily be tuned from green to green-yellow, yellow, orange, and red-orange due to the energy transfer from Tb3+ to Eu3+ ions by adjusting the doping concentration of Eu3+ ions.