Growing crystalline chalcogenidoarsenates in surfactants: From zero-dimensional cluster to three-dimensional framework

Although surfactants have been widely used to tailor the size, shape, and surface properties of nanocrystals and control the pore size and phases of mesoporous frameworks, the use of surfactants as reaction media to grow chalcogenide crystals is unprecedented. In addition, compared with ionic liquids, surfactants are much cheaper and can have multifunctional properties such as acidic, basic, neutral, cationic, anionic, or even block. These features suggest that surfactants could be promising reaction platforms for the development of novel chalcogenide crystals. In this work, we used chalcogenidoarsenates as a model system to demonstrate our strategy. By using three different surfactants as reaction media, we obtained a series of novel thioarsenates ranging from a zero-dimensional (0D) cluster to a three-dimensional (3D) framework, namely, [NH₄]₈[Mn ₂As₄S₁₆] (1), [Mn(NH₃) ₆][Mn₂As₂S₈(N₂H ₄)₂] (2), [enH][Cu₃As₂S₅] (3), and [NH₄][MnAs₃S₆] (4). The band gaps (estimated from the steep absorption edges) were found to be 2.31 eV for 1 (0D), 2.46 eV for 2 (1D), 1.91 eV for 3 (2D), and 2.08 eV for 4 (3D). The magnetic study of 4 indicated weak antiferromagnetic behavior. Our strategy of growing crystalline materials in surfactants could offer exciting opportunities for preparing novel crystalline materials with diverse structures and interesting properties.