Synthesises, Structures And Luminescent Properties Of Series Of Ag-Ln Coordination Polymers

Six novel Ag-Ln (Ln= Eu, Yb, Er, Ho, Sm, Nd) heterometallic coordination polymers and one binuclear silver complex have been synthesized by hydrothermal method. The crystal structures are determined by X-ray diffraction and their formulas are presented as following except complex (6): (1) {EuAg₅[C₆H₄(COO)₂]₄ }_n (2){YbAg₅[C₆H₄(COO)₂]₄ }_n (3) {ErAg₅[C₆H₄(COO)₂]₄ }_n (4){HoAg₅[C₆H₄(COO)₂]₄ }_n(5) {Sm_0.5Ag_0.5[C₆H₄(COO)₂]₄ }_n (6){Nd-Ag-[C₅H₃N(COO)₂]} undifined (7) Ag₂(C₇H₅O₃)₂Complexes (1), (2), (3) and (4) are coordination polymers with 2D infinite framework. Their luminescences in the visible spectral and the near-infrared (NIR) regions are mainly studied. Complex (1) can display intense red luminescence. Complex (5) can display luminescence in the range of orange color. Complexes (3), (4), and (6) can exhibit faint emission in visible region, but they have intense emission in the NIR region. The NIR luminescence of complex (2) isn't measured, because we measure the NIR-Luminescent at Beijing University, so we can't measure it in time. It may exhibit emission in the NIR region. Through the photophysical comparative study of the Ag-Ln heterometallic coordination polymers, we found that the introduction of Ag^â… ion can not only increase the structural diversity, but also can change the intermolecular energy level of the f-block (f-L part) and sensitize the emission of lanthanide ions, bacause there may have partly overlapped between the 4d orbit of Ag^â… ion and the 4f orbit of lanthanide ion. For one thing, we can find that the structures of the polymers change a lot when the Ag^â… ion is imported. For another, It can affect the emission of the lanthanide ions obviously: (i) it can't sensitize the emission of the lanthanide ions efficiently; (ii) it can affect the emission of the lanthanide ions (such as Ho, Er, and Nd) in the NIR region. The phenomenon of shift, split or widen can be seen in the NIR spectra. Just because the interactions between the 4d orbit of Ag^â… ion and the 4f orbit of the lanthanide ion, the intermolcular energy levels of lanthanide ion have been affected. We can testify the split, widen and shift of the bands in emission spectra through the contrast between the same position in the absorption spectra and the emission spectra, and we have explained them well. In addition, their IR, UV-VIS-NIR spectra which are important to further analyses and contrast the luminescent property are measured and investigated. Through different combinations of Ag-Ln, a variety of d-f polymers with novel structure can be synthesized, and it has important significance on the topology study of series of d-f complexes.