Synthesis, Structure And Characterization Of Open-framework Lanthanide Sulfate

Open-framework rare earth sulfates as a family of microporous material have attracted much attention as evidenced by the vast number of reseach paper published in the last decades owing to zeotypical structure with properties involving in ion-exchange, gas-separation and catalysis and potential applications in the non-linear opitical materials and magnetic materials. According to the higher coordination numbers (from 7- to 12-fold), a variety of coordination geometries have been observed associated with transition metal to meet requirement of industry.In this study, eight novel rare earth sulfates have been synthesized under hydro/solvothermal conditions in the presence of organic amines. Furthermore, XRD, ICP, elemental analysis, IR and TG are utilized to characterize structures, respectively.1. 1D H2DETA·[Ho(H2O)2·HSO4·(SO4)2](3-1) crystallizes in the monoclinic space group P21/c with data of unit cell:a=6.5904(13)A, b=14.783(3)A, c=16.599(3)A,β=93.47(3)°, V=1614.2(6)A3, Dc=2.454g/cm3,μ(Mo Ka)=5.37mm-1, Z=4, R1=0.0265 for 1815 reflections with Fo>2(Fo). Ho ions of (3-1) are coordinated by eight oxygen atoms from two bidentate sulfuric anions, two monodentate sulfuric anions and two water molecules. The strand-like structure of (3-1) is formed by alternatively arranging HoO8 polyhedra and SO4 tetrahedra.2.2D layer H2DETA·[Ln(H2O)·HSO4·(SO4)2] (Ln=Nd, La, Ce, Sm)(4-1-4-4) templated by H2DETA. The compounds is monoclinic with space group P21 and unit cell: a=6.6518(13)A, b=10.373(2)A, c=11.091(2)A,β=93.61(3)°, V=763.7(3)A3, Dc=2.421g/cm3,μ(Mo Kα)=3.885mm-1, Z=2, R1=0.0195 for 3312 reflections with Fo>2(Fo). Ln ions are coordinated by nine oxygen atoms from three bidentate sulfuric anions, two monodentate sulfuric anions and one water molecule. The compounds has the layer structure with 8MR net defined as four LnO9 polyhedra and four SO4 tetrahedra. S(2)O4 tetrahedra are only grafted onto the Ln via edge sharing.3.2D layer (H2DABCO)2·[Ln2(H2O)4·(SO4)4]·(SO4)·5H2O (DABCO=C6H14N2) (Ln= Sm, Pr, Er)(5-1-5-3) templated by H2DABCO. The compounds is crystallized in orthorhombic Pbcn space group with data of unit cell:a=25.572(5)A, b=10.085(3)A, c=13.085(2)A, V=3368.6(13)A3, Dc=2.312g/cm3,μ(Mo Ka)=3.877mm-1, Z=4, R1=0.037 for 3546 reflections with Fo>2(Fo). The isolated S (3) O4 compensates the charge of framework. S(1)O4 and S(2)O4 bridge the adjacent Ln cations along (010) and (001) directions to the infinite zigzag layer.