Specific Ion Solvation and Pairing Effects in Glycerol Carbonate

Abstract

Identifying the driving forces behind the solvation of inorganic salts by nonaqueous solvents is an important step in the development of green solvents. Here we focus on one promising solvent: glycerol carbonate (GC). Using ab initio molecular dynamics simulations, we build upon our previous work by detailing glycerol carbonate’s interactions with a series of anions, a lithium ion, and the LiF ion pair. Through these investigations, we highlight the changes in solvation behavior as the anion size increases, the competition of binding shown by lithium for the oxygens of GC, and the behavior of the LiF ion pair in a GC solution. These results indicate the importance of the cation’s identity in ion-pairing structure and dynamics and lend insight into the key factors behind the specific ion effects seen in GC.

Understanding specific ion effects and the Hofmeister series

“…The understanding of mixed salt SIE systems, relevant for biological and industrial applications (Section 5), has also developed recently, specifically regarding the additivity (or lack-there-of) of co-dissolved anions. 160,249,250 Direct investigations of SIE in nonaqueous environments (Section 6) constitute a new frontier for the field, 24,27,[39][40][41][42][43][44][45]128,169,244,[251][252][253][254][255][257][258][259][260][261][262][263][264][265] and in doing so are generalising our understanding of SIEs and their underlying mechanisms. Similarly, a new category of SIE observed in concentrated electrolytes (Section 7) has been shown to facilitate re-entrant behaviour in polyelectrolyte [279][280][281] and colloidal systems.…”

“…This has led to the prevalent assumption that the SIEs observed originate from the properties of water itself, or that the existence of the Hofmeister series is dependent upon water. Recent reports by Mazzini and Craig, 41–44 Liu et al , 40,251–255 Gregory et al , 45,128,256 Smiatek et al 169,244,257–263 and others 24,27,39,264,265 demonstrate however that SIEs and the Hofmeister series also exist in nonaqueous solvents. The origins of SIEs therefore cannot be solely attributed to an ion's ability to induce order in an aqueous environment; their origins must be more general in nature ( i.e.…”