Structural and Functional Modulation of Five 4‑Cyanopyridinium Iodoargentates Built Up from Cubane-like Ag₄I₄ Nodes

Five iodoargentate hybrids, {[MC]­[Ag₂I₃]}_<i>n</i> (<b>1</b>), {[EC]­[Ag₂I₃]}_<i>n</i> (<b>2</b>), {[PC]₂[Ag₄I₆]}_<i>n</i> (<b>3</b>), {[BC]₂[Ag₄I₆]}_<i>n</i> (<b>4</b>), and {[IPC]₂[Ag₄I₆]}_<i>n</i> (<b>5</b>) (MC⁺ = <i>N</i>-methyl-4-cyanopyridinium, EC⁺ = <i>N</i>-ethyl-4-cyanopyridinium, PC⁺ = <i>N</i>-propyl-4-cyanopyridinium, BC⁺ = <i>N</i>-butyl-4-cyanopyridinium, and IPC⁺ = <i>N</i>-isopentyl-4-cyanopyridinium), have been solvothermally synthesized. Built up from μ-I bridging cubane-like Ag₄I₄ nodes, <b>1</b> and <b>2</b> present similar two-dimensional grid-like layers with the MC⁺ and EC⁺ cations located at the apertures of inorganic layers and interlayer space, while <b>3</b>,<b> 4</b>, and <b>5</b> possess three-dimensional open frameworks with the PC⁺, BC⁺, and IPC⁺ cations intercalated in the channels. <b>1</b>–<b>5</b> exhibit reducing band gaps with respect to the bulk β-AgI and interesting low temperature reversible thermochromism, which can be ascribed to the temperature effects directly on the population of intermolecular charge transfer. Variations in structure and property reveal delicate modulating effect of <i>N</i>-alkyl-4-cyanopyridinium cations and flexibility of iodoargentate frameworks

Two Thermochromic Layered Iodoargentate Hybrids Directed by 4- and 3‑Cyanopyridinium Cations

Two layered iodoargentates, [HCP]­[Ag₂I₃] (HCP⁺ = NH-4-cyanopyridinium) (<b>1</b>) and [MCP]­[Ag₄I₅] (MCP⁺ = <i>N</i>-methyl-3-cyanopyridinium) (<b>2</b>) have been solvothermally synthesized. For <b>1</b>, the inorganic layer is built up by 4-connected Ag₄I₈ unit with cubane-type Ag₄I₄ core via sharing peripheral μ₂-I in <i>ab</i> plane, while the HCP⁺ cations are located at the apertures and interlayer space. For <b>2</b>, the inorganic layer is constructed from [Ag₆I₆]_<i>n</i> and [AgI₃]_<i>n</i>^2<i>n</i>– chains via alternative corner- and edge-sharing modes along the <i>b</i>-axis, while the MCP⁺ cations lie between neighboring layers. Compounds <b>1</b> and <b>2</b> exhibit reducing band gaps relative to the bulk β-AgI and remarkable thermochromism, which are ascribed to the intermolecular charge transfer (CT) and affected by electron affinity of pyridinium cations

Bipyridyltriazolium Chlorobismuthate with Thermo-/Photochromic and Photoluminescent Switching Behaviors Based on ET and CT^†

Matched with 3,5-bis­(pyridine-2-yl)-1,2,4-triazole (2-bpt), a new electron donor–acceptor-based chlorobismuthate­(III) hybrid, [2-bpt]₂[Bi₂Cl₁₀(H₂O)]·5H₂O was prepared solvothermally and characterized. The title compound (hydrated form) and its dehydrated form exhibit photo- and thermo-induced intermolecular electron transfer (ET), which correspond to dual ET photo/thermochromism for hydrated form, charge transfer thermochromism during dehydration, and simultaneously photoluminescent responses, respectively