MOLLIQ-04501; No of Pages 6
Journal of Molecular Liquids
Short Communication
Theoretical evaluation on solubility of synthesized task specific ionic
liquids in water
Surya V.J. Yuvaraj a,d, , Oleg S. Subbotin b,d,f, Rodion V. Belosludov c, Vladimir R. Belosludov b,d,f, Kiyoshi Kanie d,
⁎
Kenji Funaki d, Atsushi Muramatsu d, Takashi Nakamura d, Hiroshi Mizuseki e, Yoshiyuki Kawazoe a,f
a
New Industry Creation Hatchery Center, Tohoku University, 6-6-4 Aoba, Aramaki, Sendai 980-8579, Japan
Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090, Russia
Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea
Institute of Thermophysics, SB RAS, Novosibirsk 630090, Russia
b
c
d
e
f
a r t i c l e i n f o
a b s t r a c t
Article history:
Task specific ionic liquids (TSILs) are synthesized and utilized for extraction of different metal atoms from
their complexes. Since physico-chemical properties of ionic liquids (ILs) are modified by water (H2O) mol-
ecules, less hydrophilic ILs are suitable for the liquid–liquid metal extraction process. Recently, we have
synthesized amino acid functionalized imidazolium based TSILs for extraction of rare earth metals. The syn-
thesized ILs have a common functionalized cation [C20H28N3O3]+ and different anions namely, bromide-
[Br]− and bis(trifluoromethylsulfonyl)imide-[NTF2]−. In this study, various first principles (Hatree–Fock
and density functional theory) and molecular mechanics calculations are done to understand intermolecu-
lar interactions between H2O and the synthesized TSILs. The results of gas phase cluster calculations project
the difference in solubility of these two TSILs in H2O.
Received 5 August 2014
Received in revised form 10 October 2014
Accepted 19 October 2014
Available online xxxx
Keywords:
Task specific ionic liquids
Solubility
Anions
Quantum chemistry
First principles method
Molecular mechanics
© 2014 Elsevier B.V. All rights reserved.
1. Introduction
example, symmetric ILs are less viscous than asymmetric ones [7].
Other attractive property of some ILs is their high stability up to several
Ionic liquids are a class of organic salts with low melting tempera-
ture below 100 °C and they are composed of cations and anions. Most
of the cations are imidazolium, pyridinium, phosphonium or ammoni-
um derivatives and the anions are typically halides such as F−, Cl− or
Br−, large fluorinated organic compounds and so on. Scientific reports
on ionic liquids (ILs) have made their debut more than a century ago.
However, intensive research has begun from the end of twentieth cen-
tury when second generation of ILs has been created. Since then many
ILs are being synthesized and characterized by both experimental and
theoretical methods worldwide [1–23]. The relatively lower vapor pres-
sure of ILs allows using them without causing damages to the environ-
ment. Hence, ILs are considered to be perspective compounds for green
chemistry in many applications such as electrochemistry [1,2], for
chemical synthesis as solvents [1,3], for catalysis [1,3], for rare elements
extraction [1,4,5], for energy storage applications [1], for organic com-
pound and gases separation [6] and so on. The properties of ILs are de-
pendent on the size and nature of both the cations and anions. For
hundred degrees that allows them to lead chemical reactions at very
high temperatures. In recent years, apart from the conventional ILs, a
new kind of designer solvents called task specific ionic liquids (TSILs)
are synthesized and utilized for specific applications where convention-
al ILs fail to accomplish the required tasks. ILs are modified by covalently
functionalizing them with different chemical groups to obtain TSILs to
achieve the targeted application [8,9].
Since ILs are easily affected by moisture, the goals of many scientific
investigations on ILs are mainly focused on construction of hydrophobic
ILs with minimal viscosity and with the pre-determined useful proper-
ties. Water (H2O) is recognized as the usual impurity in ILs such that it
can significantly influence on the structure and transport properties of
ILs [10–13]. Also, the presence of trace of water in ILs changes their
physicochemical properties significantly [14] and may also affect reac-
tion rates and selectivity [15]. It is reported that the hydrophobicity de-
pends on the anions and length of the alkyl chains in cations [16]. In
particular, ILs with hydrophilic anions such as halides (i.e. F−, Cl− and
Br−) are known to be miscible with water [17] and ILs with hydropho-
bic anion, such as NTF−2 and PF6− are immiscible with water. The H2O
molecules interact strongly with anions of ILs via ion–dipole interac-
tions, which can be accompanied by the formation of hydration shells
⁎
Corresponding author at: New Industry Creation Hatchery Center (NICHe), Tohoku
University, 6-6-4 Aoba, Aramaki, Sendai 980-8579, Japan.
0167-7322/© 2014 Elsevier B.V. All rights reserved.
Please cite this article as: S.V.J. Yuvaraj, et al., Theoretical evaluation on solubility of synthesized task specific ionic liquids in water, J. Mol. Liq.