Mixed chloridometallate(ii) ionic liquids with tunable color and optical response for potential ammonia sensors

Abstract

Eight d-metal-containing N-butylpyridinium-based ionic liquids (ILs) were synthesized, characterized, and investigated for their optical properties.

Elucidating the Iron‐Based Ionic Liquid [C4py][FeCl4]: Structural Insights and Potential for Nonaqueous Redox Flow Batteries

“…In total, only four C‐H‐Cl hydrogen bonds, with an acceptor‐proton distance of up to 2.9 Å, are observed (see Figure S4, Supporting Information). As already seen in similar compounds, [ 13–15 ] anion‐π interactions between the cations and the anions significantly influence the molecular arrangement. Overall, nine of the 12 symmetry‐independent Cl atoms form anion‐π interactions with an aromatic‐Cl distance less than 4.5 Å (Figure S5, Supporting Information).…”

“…Interestingly, the compound has a much lower melting point than the parent compound N-butyl pyridinium chloride and one of the lowest melting points for a metal-containing ionic liquid structure. [13][14][15][16][17][18][19][20] The decrease in melting temperature is probably due to the anisotropic tetrahedral arrangement of the [FeCl 4 ] − moiety and due to the lack of anion-𝜋 interactions and hydrogen bonds in the long-range order of the material. TGA of the sample shows the compound is stable up to 250 °C without any degradation, as shown in Figure S13 (Supporting Information).…”

“…A unique advantage of this iron-based ionic liquid over traditional aqueous metal complexes is the absence of an added base and a potentially simplified system. [69] Moreover, [C 4 py][FeCl 4 ], like many other pyridine-based ionic liquids, [13][14][15]70] has an appreciable solubility in both aqueous (e.g., 0.5 m in H 2 O) and non-aqueous (e.g., 0.3 m in MeCN) solvents, allowing for analysis of its redox behavior in the context of aqueous or nonaqueous RFBs. Cyclic voltammetry (CV) was performed in the pure liquid state at elevated temperatures as well as for [C 4 py][FeCl 4 ] dissolved in water, and [C 4 py][FeCl 4 ] dissolved in MeCN, to fully probe its redox behavior.…”

“…[12] In this regard, ionic liquids based on organic-inorganic metal halides are also gaining interest in recent times due to their unique physical and chemical properties, which can be tailored by the choice of metal and ligand components. [13][14][15][16][17][18][19][20] Here we demonstrate a new iron-based organic-inorganic ionic liquid compound, N-butyl pyridinium tetrachlorido ferrate (III), which is synthesized through a single-step procedure in an ionic liquid medium. The material forms needle-shaped crystals.…”

“…[ 12 ] In this regard, ionic liquids based on organic–inorganic metal halides are also gaining interest in recent times due to their unique physical and chemical properties, which can be tailored by the choice of metal and ligand components. [ 13–20 ]…”