Series of open-framework aluminoborates containing [B₅O₁₀] clusters

Three new open-framework aluminoborates (ABOs), Rb₂AlB₅O₁₀·4H₂O (1), [C₅N₂H₁₆]AlB₅O₁₀ (2, C₅N₂H₁₆ = N-ethyl-1,3-diaminopropane) and [H₂dap][(CH₃)₂NH]AlB₅O₁₀ (3, dap = 1,2-diaminopropane) have been made under solvothermal conditions and characterized by elemental analysis, IR, TGA, UV-vis, powder XRD, single-crystal XRD, fluorescence spectra and NLO determination, respectively. These three ABOs display two structural types: 1 and 2 are isostructural and crystallize in acentric space groups C222₁ and P2₁2₁2₁ respectively, showing intersecting helical channels and good NLO properties; while, 3 crystallizes in the centrosymmetric space group Pbca and has CrB₄ topology, exhibiting intersecting 8-, 11- and 14-ring channels. UV-vis spectral investigation indicates that they are wide-band-gap semiconductors.