Three new aluminoborates: from 1D tube to 3D framework

Abstract

Three new aluminoborates (ABOs) KCs[Al{B₅O₉(OH)}{BO(OH)₂} (1), K_0.5Cs[Al{B₅O₁₀}_1/2{BO₂(OH)}] (2), and Cs_1.5[Al{B₅O₁₀}_1/2{BO₂(OH)}] (3) have been made under solvothermal conditions. 1 features a 1D tube constructed by the alternation of [B₅O₉(OH)]⁴⁻ clusters and AlO₄ units, onto which the [BO(OH)₂]⁻ triangles are grafted. To further construct higher dimensional structures based on the structure 1, solvents were adjusted for high basicity, resulting in the formations of the 3D ABO frameworks 2 and 3. 2 and 3 are isostructural and built from [B₅O₁₀]⁵⁻ clusters, AlO₄ tetrahedra and [BO₂(OH)]²⁻ triangles, in which [B₅O₁₀]⁵⁻ clusters are bridged by AlO₄ tetrahedra to produce a 2D ABO layer with 14-membered ring (MR) windows, and the [BO₂(OH)]²⁻ triangles act as the linkers to bridge the adjacent ABO layers to form 3D ABO frameworks containing eight types of channels. UV-vis diffuse reflectance spectra indicate that 1, 2, and 3 have potential applications in deep ultraviolet (DUV) regions.