Aluminoborates with Open Frameworks: Syntheses, Structures, and Properties

Five aluminoborates Al[B5O10]·H2dab·2H2O (1), [Al(B4O9)(BO)]·H2en (2), [Al(B4O9)(BO)]·H2dap (3), K2Al[B5O10]·4H2O (4), and (NH4)2Al[B5O10]·4H2O (5) have been synthesized under hydrothermal conditions and characterized by means of elemental analysis, IR, TG analysis, MAS NMR, UV−vis and fluorescence spectroscopy, powder X-ray diffraction, single-crystal X-ray diffraction, and NLO determination. The structure 1 comprises of AlO4 tetrahedra and B5O10 clusters and contains 12-, 11-, and 8-MR 3D-intersecting channels with a CrB4 topological net. Structures 2 and 3 are both constructed from the same AlB5O13 clusters and exhibit a six-connected framework with 41263 topology. Structures 4 and 5 are isomorphous and are composed of AlO4 tetrahedra and B5O10 clusters that possess odd 11-MR channels and 8-MR helical channels. Structures 2−5 crystallized in an acentric structure and presented good SHG properties. UV−vis spectral investigation indicates that they are wide-band-gap semiconductors. The electronic structure calculations for the compounds also have been performed.