Crystal chemistry of compounds with lanthanide based microporous heteropolyhedral frameworks: Synthesis, crystal structures, and luminescence properties of novel potassium cerium and erbium silicates

摘要: Abstract Single crystals of compounds based on novel microporous heteropolyhedral frameworks containing Ce and Er were synthesized hydrothermally their structures determined. The triclinic unit cell parameters K7[Ce3(Si12O32)]⋅2H2O K7[Er3(Si12O32)]⋅2H2O, respectively, are as follows: a = 6.9833(2), 6.8334(3) A, b = 11.4171(3), 11.4474(3) c = 11.6988(4), 11.4792(3) α = 87.632(2), 88.501(2)°, β = 87.546(3), 89.086(3)°, γ = 78.732(2), 79.711(3)°; V = 913.40(5), 883.16(5) A3, space group P-1. Structural models refined to R = 6.52 4.74%, respectively. crystal similar reported with the general formula K7+x[Ln3(Si12O32)]Ox⋅nH2O (Si12O32) layers silicate tetrahedra that one tetrahedron wide linked by LnO6 octahedra Ln2O10 dimers into a framework. contain two systems parallel channels potassium cations water molecules. Topological analysis indicates formed condensation sequence tiles [46][34.43.63]2[34.48.68.82]. Bond valence sums show partial oxidation Ce3+ Ce4+, previously observed XANES. Luminescence spectra for K7[Er3(Si12O32)]⋅2H2O indicate emission bands related transitions from 2H11/2 4S3/2 exited states 4I15/2 ground state. A short review all lanthanide compounds, most which have frameworks, is provided in twenty-four chemical families isostructural grouped according type anion.