Design of Multichannel Osmium-Based Metalloreceptor for Anions and Cations by Taking Profit from Metal-Ligand Interaction and Construction of Molecular Keypad Lock and Memory Device

A polypyridylimidazole-based bifunctional Os-(II) complex of the type [(bpy)(2)Os(tpy-Hbzim-dipy)] (ClO4)(2) (1), where tpy-Hbzim-dipy = 4'44-(4,5-dipyridin-2-yl-1H-imidazol-2-yl)-phenyl]-2,2';6',2 ''-terpyridine and bpy = 2,2'-bipyridine, has been synthesized and structurally characterized for the construction of multifunctional logic devices. After coordination of an [Os(bpy)(2)](2+) unit to one of the two bidentate chelating sites, the complex offers a terpyridine motif for binding with cationic guests and an imidazole moiety for interacting with selective anionic species. Consequently, the anion- and cation-binding aspects of the metallorecptor were examined in solution and in the solid state by different spectroscopic and electrochemical methods. The complex behaves as a bifunctional sensor for F-, AcO-, CN-, Fe2+, and Cu2+ ions in acetonitrile, whereas it is a highly selective chromogenic chemosensor for only CN- and Fe2+ ions in water. Based on various output signals with a particular set of anionic and cationic inputs, the complex mimics the functions of two-input INHIBIT, OR, NOR, and XNOR logic gates, as well as threeinput NOR logic behavior. More importantly, the complicated functions of a keypad lock and memory device were also nicely demonstrated by the complex. Finally, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations also provide a rationale for properly understanding and interpreting the experimentally observed results.