3D Rare earth porous coordination frameworks with formamide generated in situ syntheses: Crystal structure and down- and up-conversion luminescence

The reaction of RE(NO)(3)center dot 6H(2)O and formamide yielded the coordination polymers, [RE(HCOO)(4)](-) [NH2CHNH2](+) (RE = Y 1, Eu 2, Gd 3, Tb 4, Dy 5, Er 6, and Yb 7). They possess 3D porous frameworks with the 1D rhombic channels occupied by [NH2CHNH2](+) cations. Complexes 2 and 4 display the characteristic down-conversion emissions corresponding to D-5(0) -> F-7(J) (J=1-4) transitions of Eu(III) ion and D-5(4) -> F-7(J) (J=6-3) transitions of Tb(III) ion, respectively. Longer lifetime values of 2.128 +/- 0.002 ms (D-5(0)) for 2 and 2.132 +/- 0.002 ms (D-5(4)) for 4 have been observed. The up-conversion spectra of the Y:Yb,Er and Gd:Yb,Er codoped complexes exhibit three emission bands around 410 (H-4(9/2) -> I-4(15/2), blue), 518-570 (S-4(3/2), H-2(11/2) -> 4I(15/2), green), and 655 nm (F-4(9/2) -> I-4(15/2), red). (C) 2013 Elsevier Inc. All rights reserved.