Two Series of Luminescent Flexible Polycarboxylate Lanthanide Coordination Complexes with Double Layer and Rectangle Metallomacrocycle Structures

Two series of eight polycarboxylate lanthanide coordination complexes, namely, [Ln­(cpia)­(H2O)2]­·4H2O {Ln = Ce (1), Nd (2), and Sm (3)} and [Ln­(cpia)­(H2O)n]2­·2H2O {Ln = Eu (4), Gd (5), Tb (6), Er (7), and Lu (8), n = 5 in 47; n = 4 in 8} {H3cpia = N-[4-(carboxymethoxy)­phenyl]­iminodiacetic acid}, have been synthesized by self-assembly and characterized by IR, thermogravimetric analysis, and X-ray crystallography. Complexes 13 are isomorphic featuring two-dimensional double layer structures, while the isomorphic complexes 48 exhibit [2 + 2] rectangle metallomacrocycle structures. Further, photoluminescence (PL) spectra of complexes 2, 4, and 6 show the strong characteristic luminescence of Eu­(III), Tb­(III), and Nd­(III) ions, respectively, suggesting that cpia3– is able to efficiently sensitize the luminescence of lanthanide ions.