Solvothermal synthesis and luminescent properties of two organically-templated chain-structure fluorides, [C4H14N2][MF5] (M = In, Sc)

The solvothermal syntheses and crystal structures of organically templated indium fluoride, [C4H14N2][InF5] 1, and its scandium analogue, [C4H14N2][ScF5] 2, are reported. Compound 1 represents the first indium fluoride with extended inorganic connectivity prepared using an organic airline, 1,4-diaminobutane (DAB), as a structure-directing agent. 1 is orthorhombic, space group Ibam, with cell parameters a = 9.324(2) angstrom, b = 11.391(2) angstrom, c = 8.401(2), and Z = 4 (for isostructural 2: a = 9.353(3) angstrom, b = 11.433 (1) angstrom, c = 8.226 (4) angstrom). The structure of I consists of infinite trans vertex sharing (InF5)(infinity) chains running parallel to the c-axis, which are linked via H-bonded organic moieties. The photoluminescence properties of the doped compounds, of nominal composition [C4H14N2][In(1-x)Ln(x)F(5)] (Ln=Tb and/or Eu), have been explored. For x = 0.05 Eu3+, 1 exhibits a dominant orange emission at 592.5 nm from the D-5(0) -> F-7(1) magnetic dipole transition within Eu3+ For x = 0.08 Tb3+, 1 shows strong down conversion fluorescence corresponding to D-5(4) -> F-7(5) (green at 543 5 nm). In addition, a Tb3+/Eu3+ co-doped sample exhibits a combination of green (Tb3+) and orange (Eu3+) luminescence. with Tb3+ enhancing the emission of Eu3+ in this host. The dependence of luminescence intensity on dopant concentration for 1 has been analyzed. The scandium and fluorine local environments in 2 have been characterized by F-19 and Sc-45 solid-state magic-angle spinning (MAS) NMR, which confirms a single scandium site together with discrete bridging and planar fluorine sites.