A Series of Lanthanide Coordination Polymers Based on Designed Bifunctional 1,4-Bis(imidazol-1-yl)terephthalic Acid Ligand: Structural Diversities, Luminescence, and Magnetic Properties

On the basis of the designed bifunctional 1,4-bis(imidazol-1-yl)terephthalic acid (H(2)BTA) ligand, a series of three-dimensional lanthanide coordination polymers, namely, [La-2(BTA)(1.5)(ox)(1.5)(H2O)(3]n), (1), [Nd(BTA)(ox)(0.5)(H2O)](n) (2), {[Ln(HBTA)(ox)(H2O)]center dot xH(2)O} (Ln = Pr for 3 (x = 0), Sm for 4 (x = 0), Dy for 5 (x = 1.5), and Eu for 6 (x = 1)), and [Ln(BTA)(SO4)(0.5)(H2O)], (Ln = Eu for 7, and Tb for 8) were obtained with the help of oxalate or sulfate ions. On the basis of the binuclear La2 secondary building unit (SBUs), the framework of 1 displays an unprecedented (3,3,4,9)-connected net with the point symbol of (4(11).5(5).6(14).7(5).8)(2)(4(2).5)(2)(4(3))(2)(4(4).6(2)). While in complex 2, the binuclear Nd2 SBUs are connected by the BTA(2-) ligands to generate an interestingly (4,10)-connected (412.516.612.7s) (46)2 net. Complexes 3-6 are isomorphism and show a 2-fold interpenetrated 4-connected (6(6))-dia net. Complexes 7 and 8 are isomorphism and show a novel (4,5)-connected (4(4).6(2))(4(4).6(6)) net. Photoluminescence investigations show that 2 is a good near-infrared luminescent material, and 4 is a rarely reported single component white light emitting material. Complexes 6 and 7 show typically red emission, while complex 8 shows typically green emission, which can be used as a red or green emitting phosphor. Moreover, the luminescent lifetimes and quantum yields of the titled complexes were investigated. The magnetic susceptibility data of 2 indicated there are antiferromagnetic interactions between the Nd-III ions.