Solvothermal syntheses, crystal structures and luminescence properties of three new lanthanide sulfate fluorides

Three novel lanthanide sulfate fluorides of formulae [C₄H ₁₆N₃]₆[Sm₄F₂(SO ₄)₁₄] 1 and LnFSO₄·H₂O (Ln = Tb 2; Nd 3) have been synthesized solvothermally and structurally characterized by single-crystal X-ray diffraction, IR, TGA, SEM, and ICP. Single crystal X-ray diffraction reveals that compound 1 crystallizes in the triclinic crystal system, with space group P-1 and cell dimensions: a = 11.1988(9), b = 11.4073(9), c = 16.2666(13) Å, α = 89.9010(10)°, β = 82.4060(10)°, γ = 67.7570(10)°, V = 1903.9(3) ų, Z = 1. Both compounds 2 and 3 crystallize in the monoclinic crystal system, with the space group P2(1)/n and cell dimensions: a = 5.0014(7), b = 7.3769(11), c = 11.6508(17) Å, β = 96.692(2)°, V = 426.93(11) ų, Z = 4 for 3; a = 4.9948(5), b = 7.3684(7), c = 11.6366(12) Å, β = 96.6720(10)°, V = 425.37(7) ų, Z = 4 for 3. The structure of 1 consists of a novel isolated large Z-type heteropolyanion [Sm₄F₂(SO₄)₁₄]^18- and full protonated organic amine cations. The chains are held together by hydrogen bond interactions involving the hydrogen of the amine and the framework oxygen. The compounds 2 and 3 are isostructural and their structures feature a three-dimensional network constructed from the left-handed and the right-handed helical channels which are connected by SO₄^2- groups using 6-membered rings and 4-membered rings.