Formation Mechanism of a Polyanonic Framework from Layer to Chain Explored by Adjusting Time, Temperature, and pH: Preparation and Characterization of Metal-Complex-Templated 1D Borate and 2D Nickel Borate.

The first column of two-dimensional (2D)-layered metal-complex-templated nickel borate was obtained by using a solvothermal synthesis method. The 2D nickel borate [Ni(en)3]·[Ni0.5B6O8(OH)4]·Cl (1; en = ethylenediamine) contains [Ni(en)3]2+, Cl-, and the first reported inorganic nickel borate layer [Ni0.5B6O8(OH)4]-, which is formed by the interconnection of Ni and O atoms in the B-O cluster. By increasing the reaction temperature during the synthesis process of compound 1, the one-dimensional (1D) chain nickel borate [Ni(en)3]2·[B7O10(OH)3]·Cl2 (2) was obtained, wherein the [B7O10(OH)3] cluster was connected through an O atom to form a 1D chain structure. By adjusting the molar ratio of the raw materials, that is, adjusting the pH of the reaction, the other 1D chain nickel borate Ni(en)3·Hen·[B9O13(OH)4]·H2O (3) was obtained, in which [B5O8(OH)2] and [B4O7(OH)2] clusters can be connected via a common O atom to form an infinite [B9O13(OH)4] polyanionic chain. Meanwhile, we successfully synthesized the isoform of compound 3 with the metal cadmium.