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)3·6H2O 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 5D0→7FJ (J=1–4) transitions of Eu(III) ion and 5D4→7FJ (J=6−3) transitions of Tb(III) ion, respectively. Longer lifetime values of 2.128±0.002 ms (5D0) for 2 and 2.132±0.002 ms (5D4) 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 (4H9/2→4I15/2, blue), 518–570 (4S3/2, 2H11/2→4I15/2, green), and 655 nm (4F9/2→4I15/2, red).

Graphical AbstractThe complexes [RE(HCOO)4]−[NH2CHNH2]+ possess 3D porous frameworks. Eu(III) and Tb(III) complexes show characteristic emission of Ln(III) ions. The up-conversion emission of the Y:Yb,Er and Gd:Yb,Er codoped complexes was observed.Figure optionsDownload as PowerPoint slideHighlights
► The reaction of RE(NO)3·6H2O and formamide produced complexes [RE(HCOO)4]−[NH2CHNH2]+.
► The complexes possess 3D frameworks with the 1D channels occupied by [NH2CHNH2]+ cations.
► Eu(III)/Tb(III) complexes display the characteristic down-conversion emission of Ln(III) ions.
► The Y:Yb,Er and Gd:Yb,Er doped complexes exhibit the up-conversion emission.