An investigation on the physicochemical properties of the nanostructured [(4-X)PMAT][N(CN) 2 ] ion pairs as energetic and tunable aryl alkyl amino tetrazolium based ionic liquids

Pyrrolidinium-based (Pyr) ionic liquids are a very wide family of molecular species. Pyrrolidinium cations are electrochemically stable in a large potential interval and their molecular size hinders their transport properties. The corresponding ionic liquids with trifluoromethyl sulphonyl imide anions are excellent solvents for lithium/sodium salts and have been demonstrated as electrolytes in aprotic batteries with enhanced safety standards. In this study, the analysis of the physicochemical properties of a homologous series of pyrrolidinium-based ionic liquids with general formula Pyr1,xTFSI (x = 1–8) have been tackled by first principles calculations based on the density functional theory. The molecular structures of isolated ions and ion pairs have been predicted by electronic structure calculations at B3LYP level of theory in vacuum or in simulated solvents. Thermodynamic properties have been calculated to evaluate the ion pairs dissociation and oxidation/reduction stability. This is the first systematic computational analysis of this series of molecules with a specific focus on the impact of the length of the alkyl chain on the pyrrolidinium cation on the overall physicochemical properties of the ion pairs.

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Dynamics of Ion Locking in Doubly Polymerized Ionic Liquids

10.26434/chemrxiv.13239059.v1 ◽

2020 ◽

Author(s):

Swati Arora ◽

Julisa Rozon ◽

Jennifer Laaser

Keyword(s):

Dielectric Constant ◽

Ionic Liquid ◽

Ionic Liquids ◽

Ion Pairs ◽

Polymer Chains ◽

Ion Motion ◽

Charged Species ◽

Broadband Dielectric Spectroscopy ◽

Covalently Linked ◽

Insight Into

<div>In this work, we investigate the dynamics of ion motion in “doubly-polymerized” ionic liquids (DPILs) in which both charged species of an ionic liquid are covalently linked to the same polymer chains. Broadband dielectric spectroscopy is used to characterize these materials over a broad frequency and temperature range, and their behavior is compared to that of conventional “singly-polymerized” ionic liquids (SPILs) in which only one of the charged species is attached to the polymer chains. Polymerization of the DPIL decreases the bulk ionic conductivity by four orders of magnitude relative to both SPILs. The timescales for local ionic rearrangement are similarly found to be approximately four orders of magnitude slower in the DPILs than in the SPILs, and the DPILs also have a lower static dielectric constant. These results suggest that copolymerization of the ionic monomers affects ion motion on both the bulk and the local scales, with ion pairs serving to form strong physical crosslinks between the polymer chains. This study provides quantitative insight into the energetics and timescales of ion motion that drive the phenomenon of “ion locking” currently under investigation for new classes of organic electronics.</div>

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