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

摘要

The reaction of RE(NO)_3·6H_2O and formamide yielded the coordination polymers, [RE(HCOO)_4]-[NH _2CHNH_2]~+ (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 [NH_2CHNH_2]~+ cations. Complexes 2 and 4 display the characteristic down-conversion emissions corresponding to ~5D_0→~7F_J (J=1-4) transitions of Eu(III) ion and ~5D_4→~7F_J (J=6-3) transitions of Tb(III) ion, respectively. Longer lifetime values of 2.128±0.002 ms (~5D_0) for 2 and 2.132±0.002 ms (~5D_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 (~4H_(9/2)→~4I_(15/2), blue), 518-570 (~4S_(3/2), ~2H_(11/2)→ ~4I_(15/2), green), and 655 nm (~4F _(9/2)→~4I_(15/2), red).