Cyanide-bridged bimetallic multidimensional structures derived from organotin(IV) and dicyanoaurate building blocks: ion exchange, luminescence, and gas sorption properties

The recent success of using methyltin(IV) cations in constructing multidimensional structures containing the Au–CN–Sn link with interesting physical properties will be surveyed. The methyltin(IV)-dicyanoaurates, Me3Sn[Au(CN)2] (1) and Me2Sn[Au(CN)2]2 (2) containing the Au–CN–Sn link can be easily prepared by aqueous reaction of Me3SnCl or Me2SnCl2 with stoichiometric amounts of an aqueous solution of K[Au(CN)2]. The room temperature solid-state emission spectrum of 1 excited at 254 nm shows two intense emission bands at 442 and 670 nm, and a shoulder at 390 nm. When excited at 320 nm, the crystalline sample shows two intense emission bands at 442 and 720 nm, and a shoulder at 380 nm. After 2 min of grinding, only the blue emission band at 442 nm is observed. In contrast, the emission spectrum of 2 shows only one emission maximum at 422 nm. The porosity of 1 and 2 was probed by gas sorption measurements performed at 77 K. 1 exhibited no detectable microporosity as revealed by the inspection of the N2, H2, as well as, O2 isotherms. The gas adsorption studies reveal that only a small amount of N2 and H2 (3.82 and 4.66 cm3 g 1, respectively) is adsorbed by the framework of 2 at 77 K. However, a CO uptake of 11.20 cm3 g 1 can be reached at 1 atm. The framework of 2 can take up significant amounts of O2 (23.27 cm3 g 1). In addition to intriguing photoluminescence and gas sorption behavior, these complexes also exhibit ion exchange properties in the presence of bivalent transition metal cations, such as cobalt(II), nickel(II), copper(II), and zinc(II).