1-(4-Alkyloxybenzyl)-3-methyl-1H-imidazol-3-ium organic backbone: A versatile smectogenic moiety

Article abstract of DOI:10.3762/bjoc.5.62

The merger of ionic liquid and liquid crystal fields, obtained by using the imidazolium ring as a common element, has allowed us to tailor a new set of materials which associate specific functionalities. These functionalities are consequences of the origi

Full text of DOI:10.3762/bjoc.5.62

1-(4-Alkyloxybenzyl)-3-methyl-1H-imidazol-3-ium
organic backbone: A versatile smectogenic moiety
William Dobbs*, Laurent Douce* and Benoît Heinrich
Full Research Paper
Open Access
Address:
Beilstein Journal of Organic Chemistry 2009, 5, No. 62.
Institut de Physique et Chimie des Matériaux de Strasbourg, UMR
7504, CNRS-Université de Strasbourg, BP 43, 23 rue du Loess,
F-67034 Strasbourg Cedex 2, France
doi:10.3762/bjoc.5.62
Received: 24 July 2009
Accepted: 08 October 2009
Published: 06 November 2009
Email:
William Dobbs* - dobbs@ipcms.u-strasbg.fr; Laurent Douce* -
douce@ipcms.u-strasbg.fr
Guest Editor: S. Laschat
* Corresponding author
© 2009 Dobbs et al; licensee Beilstein-Institut.
License and terms: see end of document.
Keywords:
crystal liquid; imidazolium salts; ionic liquid; supramolecular
arrangement
Abstract
The merger of ionic liquid and liquid crystal fields, obtained by using the imidazolium ring as a common element, has allowed us to
tailor a new set of materials which associate specific functionalities. These functionalities are consequences of the original proper-
ties of the component, ionic liquids, liquid crystals and their association in a single compound. The study of this interesting associa-
tion led us to elaborate environment-flexible cationic architectures from which mesomorphic properties emerge. Moreover, we have
also explored the influence of different anions on the mesomorphic properties.
Introduction
Uniting the properties of ionic derivatives with those of liquid phosphonium, ammonium, pyridinium, imidazolium) can be
crystals, with their many forms of labile macroscopic ordering, used for the design of ionic liquids, none of these cations are as
raises interesting prospects [1]. By themselves ionic liquids are popular as the imidazolium ion.
organic salts (i.e. totally composed of cations and anions) that
are – unlike traditional salts – liquid at or near ambient tempera- In particular, the modification of the N,N′ substituents in
tures. The combination of properties is truly unique: ionic imidazolium systems is a facile mean of creating various
liquids are non-volatile and non-flammable, have high chem- amphotropic liquid crystals. Such imidazolium liquid crystals
ical and radiochemical stabilities, tunable electric conductiv- have especially great potential as ordered reaction media that
ities, exceptional dissolution properties [2-4]. By varying the can impart selectivity in reactions by organising reactants, as
cations and anions the physico-chemical properties of ionic scaffolds for the synthesis of nanostructured particles [12-14],
liquids can be tuned and specifically optimised for a wide range in dye-sensitized solar cells [15,16] or also in bio-related
of applications [5-11]. Although many organic cations (e.g. science [17,18].
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Beilstein Journal of Organic Chemistry 2009, 5, No. 62.
In conclusion, this combination represents a fascinating class of
new multifunctional materials [19] in which the organic modi-
fications afforded to the imidazolium central part and the ions’
environment (e.g. ion assemblies) closely govern their melting
points and their use [20].
The present article concerns a synthetic route to imidazolium
salts, which have been modified to present thermotropic liquid
crystal behaviour. In association with different anions and in
relation to the chain length incorporated in the methylim-
idazolium cations, we were able to tune the different transition
temperatures and thus obtain stable smectic A phase from
ambient temperature to 250 °C (decomposition temperature).
The mesomorphic properties were studied by polarizing optical
microscopy, differential scanning calorimetry and X-ray
diffraction. With the support of dilatometry, models for the
lamellar supramolecular arrangement of the salts are proposed
and its evolution is discussed as a function of the counter ions’
morphology.
Scheme 1: Mesogenic imidazolium synthesis [Reaction conditions: (i)
DMF, K2CO3, BrCnH2n+1, 60 °C, overnight; (ii) LiAlH4, THF, Ar, 4 h; (iii)
SOBr2, DCM, under Ar; THF dry, methylimidazole, inert atmosphere].
Results and Discussion
Synthesis and characterization
Our molecules are based on an organic calamitic structure in
which a polar rigid group (methylimidazolium head) is associ-
ated to a flexible aliphatic chain with 8 to 16 carbons. The
syntheses of all the compounds presented in this study began
with the preparation of the bromide imidazolium salts followed
by an anionic exchange step. Bromide derivatives 1n of 1-(4-
Scheme 2: Anion exchange in water.
alkyloxybenzyl)-3-methyl-1H-imidazol-3-ium with n = 8, 10, phase separation (n ≤ 10) or precipitation (n > 10) according to
12, 14, 16 have been synthesized in good yield (>82%) and on the chain length.
the gram scale. These compounds were obtained in three steps,
following slightly modified literature procedures. Methyl All imidazolium compounds (18–68, 110–610, 112–612, 114–614,
4-hydroxybenzoate was etherified with various 1-bromoalkanes 116–616) were purified by flash chromatography or crystalliza-
(CnH2n+1Br, n = 8, 10, 12, 14, 16) in the presence of K2CO3 in tion. Their structural characterizations and their purities were
DMF (yield > 96%), and the resulting amphipathic esters En established by 1H NMR, 13C NMR{1H}, FT-IR spectroscopy
reduced by LiAlH4 to the corresponding benzyl alcohols An. and elemental analysis.
The different resulting alcohols were converted quantitatively
into the intermediate 4-(alkoxy)benzyl bromides with thionyl Due to their close chemical structures, similar behaviour was
bromide. The final compounds 1n were then obtained by quat- observed during NMR characterization for all 1n samples as a
ernization of 1-methylimidazole with the bromides in refluxing function of concentration. A significant chemical shift related to
THF under inert atmosphere (Scheme 1).
the proton of the imidazolium head (Him), and in particular a Δδ
= 0.43 ppm (from low to high concentration) for the Him carried
To obtain the desired set of compounds, we performed as a final by the carbon atom between the two nitrogen atoms, was
step an anionic metathesis in water from 1n in order to give 2n, observed for 112. As already mentioned in a previous article
3n, 4n, 5n and 6n respectively with BF4−, PF6−, SCN−, CF3SO3− [21], these spectroscopic results clearly indicate the formation
and (CF3SO2)2N− anions (Scheme 2) in good yield, easily of aggregates in solution and underline the high sensitivity of
scaled up to gram quantities. In this part, we used the good solu- these protons to their environment.
bility of the bromide derivatives 1n in water to perform the
anionic exchange. By a simple addition in water solution of the This second point was definitively demonstrated by a NMR
corresponding lithium, potassium or sodium salts of the desired study performed as a function of the anionic species (constant
products, our targeted compounds were dearly obtained by concentration [c] = 3.1·10−2 mol·L−1) (Figure 1).
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Beilstein Journal of Organic Chemistry 2009, 5, No. 62.
Figure 1: 1H NMR spectrum (in CD2Cl2) of 110–610.
Related to their morphologies and to their abilities to interact Calorimetry or DSC), direct polarized optical microscopy
with the imidazolium moiety, we observed significant variation (POM) observation and small angle X-ray diffraction studies
of the chemical shift of the Him between the two nitrogen (SAXS).
atoms:
δ = 10.61 ppm (Br− ); 8.83 ppm (BF4 − );
8.53 ppm (PF6−); 9.54 ppm (SCN−); 9.14 ppm (CF3SO3−); Thermic behaviour
8.63 ppm ([CF3SO2]2N−). We could also observe some modi- Due to their amphipathic structures, all imidazolium salts
fications of the spectrum for the protons of the first substituent interact more or less rapidly with the water contained in air.
group of the imidazolium core (N–CH3 and N–CH2) localized This property explains the presence of different amounts of
respectively around 4 ppm and 5.3 ppm.
water in the elemental analyses. Otherwise, water-free samples
can be obtained and used for the investigation of liquid crystal-
Correlated to the crystal structure of compound 112 these obser- line behaviour, if we conserved them under vacuum at 50 °C
vations were made on all the protons used for the organization during the night preceding the analysis (Figure 2).
of the polar part by multiple anion-cation and cation-cation
interactions [21]. These NMR studies carried out as a function The TGA realized on all samples indicated their good stability;
of the nature of the anion are a reflection of the modifications no degradation occurred below 220 °C (Figure 3). The analysis
that occur in the polar layer in function of the anion source in showed a degree of stability as a function of the anion but no
solution.
real tendency can be extracted as a function of chain length. In
all series the general order of stability order is SCN− ≈ Br− <
BF4− ≈ PF6− < CF3SO3− < (CF3SO2)2N−.
Investigation of the liquid crystalline behav-
iour
As expected most of the ionic compounds showed liquid crys- To avoid any phenomenon related to the sample preparation
talline properties [19,22-30]. Their characterization was the (purification, crystallisation, hydration) our reported DSC
result of the combination and interpretation of thermal studies results are obtained from the second thermic cycle (2nd heating
(Thermogravimetry Analysis or TGA, Differential Scanning and cooling) and all phase transitions described occurred in the
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Beilstein Journal of Organic Chemistry 2009, 5, No. 62.
Figure 2: TGA measurements of wet and water free 112 imidazolium
salt.
ionic liquids between −80 °C to 200 °C (ESI). The DSC graphs
for the compounds with short aliphatic chains exhibit a glass
transition during the cooling process rather than a crystalliza-
tion peak. In contrast, increasing the chain length (n > 10) we
have almost detected a crystalline transition. During the
following heating process, most of these compounds (n > 10)
show crystalline polymorphism with some rearrangement
between different solid organizations (cold crystallization,
transition crystal to crystal) (Table 1).
Figure 3: TGA measurements of the two entire series 110–610 and
114–614 (rate 10° C·min−1, in air).
The transitions between crystal and mesomorphic state and also
the clearing point increase with the chain length, allowing liquid
Table 1: Temperatures and enthalpy changes of the phase transitions for 18–10 to 68–10. G: Glass; Cr: solid; SmA: Smectic A phase; I: isotropic liquid;
Dec: decomposition.
1n–5n
Phase sequences
°C (kJ·mol−1)
2n–6n
Phase sequences
°C (kJ·mol−1)
18
38
58
G −15.6(–) SmA 155.1(0.4) I
I 155(0.45) SmA −30.7(–) G
28
48
68
G −29.1(–) SmA 71(0.3) I
I 69.9(0.4) SmA −36.1(–) G
G −26.1(–) Cr 34.8(0.15) I
I 33.6(0.2) Cr −31.9(–) G
Cr 33.7(24.3) SmA 50.9(0.35) I
I 50.2(0.28) SmA 7.1(25.6) Cr
G −44.3(–) I
I −51.9(–) G
G −59.4(–) Cr1 −14.5(29.9)a Cr2
26.7(36.3) I
I (–) G
110
310
510
G −14.5 (–) SmA 227(–)b I
I 227(–)b SmA −23.2(–) G
210
G −29.1 (–) Cr1 −0.1(17.9)a Cr2
30(18.0) SmA 143.4(0.47) I
I 142.5(0.88) SmA −29.7(–) G
G −26.2 (–) Cr1 7.1(24.2)a Cr2 66.3 (31.5) SmA 410
93.3(0.4) I
I 92.1(1.1) SmA −33.2(–) G
Cr 32.3(23.8) SmA 116.6(0.7) I
I 115.6(1.0) SmA 8(28.0) Cr
Cr1 −13.1 (5.6)a Cr2 5.31(1.4)a Cr3 13.5 (5.9)a
Cr4 45.66 (4.9) Cr5 56.37 (30.8) I
I −16.7(–) Cr1
610
Cr1 −24.1 (8.7)a Cr2 36.8(51.3) I
I −30.7(17.4) Cr1
aCold crystallisation, bTransition observed by POM.
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Beilstein Journal of Organic Chemistry 2009, 5, No. 62.
crystalline properties to exist from sub-ambient temperature (18, the series of compounds 5n with n < 12 (only a monotropic
28, 48) to very high temperature avoiding any isotropization mesophase was observed for 512), and finally for 38.
before decomposition of the material (molecules with long alkyl
chain n ≥ 12). In parallel, the nature of the anion (shape, size) Supramolecular arrangement
played an important role in the evolution of the clearing point. Despite the significant tendency of these molecules to form
In the same family (from 1n to 6n) the stability of the liquid spontaneously a single homeotropic monodomain (Figure 5a)
crystalline phase dramatically decreases, finally disappearing the nature of the mesophases could be quite easily assigned on
completely (Figure 4).
the basis of their optical textures if separated microscope slides
(100 μm spacer) were used.
This evolution will be more discussed later in regard to the
results obtained with the dilatometry study. In summary, only 9 The utilization of a spacer allows the formation of large
of the compounds did not show liquid crystal characteristics; 6n, oriented monodomains to be avoided and thus furtive forma-
which are constituted by the larger anion (bis[(trifluoromethyl)- tion of birefringent batonnets upon slow cooling from the
sulfonyl]amide), are ionic liquid compounds without any supra- isotropic melt, followed by developed focal conic texture
molecular organization into mesophase. This is also the case in (Figure 5b) can be clearly observed. These observations exem-
Figure 4: Transition temperatures of 114–614 as a function of the anion (Cr = crystal; SmA: smectic A phase; Iso: Isotropic Liquid; Dec: decomposi-
tion).
Figure 5: (a) Illustration of a single homeotropic monodomain, which is observed as a black isotropic texture under POM, (b) focal conic texture
observed at 80 °C with 18 (spacer Mylar foil 100 μm).
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Beilstein Journal of Organic Chemistry 2009, 5, No. 62.
plified the existence of a smectic-A phase for all ionic meso- Despite the untilted smectic layering and the tiny thermal
morphic compounds.
expansion of the molecular volume mainly due to the contribu-
tion of the alkyl tails, all compounds exhibited a very strong
The identification of all mesophases was supported by small- dependence upon temperature of the layer spacing. This evid-
angle X-ray diffraction. SAXS patterns were collected for the ence is the consequence of the evolution of the projection area
mesomorphic salts as a function of temperature (Figure 6). of a mesogen counter-ion assembly within the mean smectic
Typically, in all cases, in the large angle region, i.e. at ca. plane, the thickness of the aliphatic sublayer variating in
4.5–4.6 Å, a very intense and diffuse scattering halo was proportion since the spreading of the liquid alkyl chains occurs
observed, corresponding to the molten alkyl chain in liquid-like without volume variation [31]. This projection area, called
order (A), whilst in the low-angle part of the diffractogram one "molecular area" S, is equal to the ratio N·Vmol/d, in which d is
to three equidistant sharp and intense peaks were observed, the layer spacing, Vmol the molecular volume and N the number
characteristic of the layered organization.
of superposed mesogen counter-ion assemblies in the ionic
sublayer. Thus, the alkyl tails expelled from each side of the
sublayer containing the ions and the mesogens impose a bilayer
(N = 2) type of organisation on these sublayers, consisting of
two head-to-head facing ionic monolayers.
The resulting variations of S versus temperature T within the
analogous series of various anions but constant chain length
(see Figure 7) consist of steep increases, approximately linear
Figure 6: Diffraction small-angle X-ray pattern of the smectic phase of
212 recorded at T = 100 °C.
The very intense first sharp peak was directly correlated to the
periodicity value. In each system, the smectic periodicity
increases with the chain length and decreases with increasing
temperature, reflecting the higher thermal mobility of the alkyl
chains, concomitant with the compression of the smectic layers.
Interestingly also, the periodicity of the salts is closely correl-
ated to the anion species and the general order is Br− > BF4− ≈
SCN− > PF6− > CF3SO3−.
Dilatometric studies
Prior to the analysis of the molecular packing of the various
compounds in the smectic mesophase, the molecular volume
(Vmol) of one salt, 112, was measured by using a home built
high precision apparatus, incorporating temperature control
within 0.03 °C, relative density measurement within 0.01% and
absolute density measurement within 0.1%. The molecular
volumes of the other homologues and of the analogues with the
other counter ions were calculated with an accuracy of 0.5%
from the molecular volume measured before and from the
methylene and counter ion partial volumes.
Figure 7: Variation with the counter-ion of the molecular area S and of
the ionic sublayer thickness dc (including mesogenic segments) in the
smectic A phase for series: squares: 114; circles: 214; up triangles: 314;
down triangles: 414; diamonds: 514.
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Beilstein Journal of Organic Chemistry 2009, 5, No. 62.
with very similar slopes and with lateral shifts following the Unlike temperature and counter ion size, a chain length increase
different bulk of the anions. Anion substitution actually leads to induces only minor changes of S, the main effect being the
large variations of S, but very small variations of the ionic evolution toward steeper variations versus T (Figure SI-2 in
sublayer thickness dc (obtained by subtracting the aliphatic Supporting Information File 1). When plotting together the area
sublayer contribution, see Figure 7), the residual discrepancies isotherms ST and the area close to isotropization Smax, differ-
being explicable by the different shapes of the anions. This indi- ences in steepness and gaps clearly set the lower limit for the
cates that polymorphic evolution in the series is almost exclus- smectic packing (Figure 9).
ively due an anion size effect with no significant influence on
the segregation in sublayers. As a clear confirmation, close to
the isotropization temperatures, the values reached by S depend
on the chain length but are almost independent of the anion
(between 43 and 44 Å2 and around 47 Å2, for the C12 and the
C14 analogous series respectively, see Table SI-7 in Supporting
Information File 1).
So far the results are nearly identical to the ones already
discussed for a series with the same counter ions, C12 alkyl tails
but a small change in the mesogenic part [32]: from S and dc in
the smectic A phase and also from comparison with the crystal-
line organization it was deduced that the enormous difference
between the cross-section of the tails and the ionic lattice area is
compensated by the gathering of the ionic sublayer and by the
Figure 9: Variations with chain length of the maximum molecular
folding of the tails. As in the present case, the dependences
upon T of S and dc indicated the decrease of gathering degree
and therefore the increase of folding with increasing T. Thus the
compromise molecular areas are still 1.5 to 1.9 times larger than
the cross-sectional area of a molten but stretched aliphatic chain
(between 21 and 24 Å2, depending on T), from which a high
areas close to isotropization Smax and of the molecular area isotherms
ST in the smectic A phase for the series 1n with Br− counter-ion: solid
squares: Smax; open squares: S60 °C; open circles: S80 °C; open up
triangles: S100 °C; open down triangles: S120 °C; open diamonds:
S140 °C, crosses S160 °C; solid line and dotted lines are parabolic fit of
Smax and of ST, respectively.
degree of folding geometrically equivalent to 50° random tilting Remarkably, the gaps between the extrapolated isotherms seem
is deduced. Indeed, this significant folding of the tails is directly to vanish close to this low limit, for a chain length corres-
observed in oriented X-ray patterns (see Figure 8): despite the ponding roughly to the segments incorporated in the interface
very good alignment of the smectic layers deduced from the layer, because of the gathering of the ionic sublayers. (On the
narrow first and second order spots on the meridian, the diffuse basis of previous results [32], the calculated molecular area S0
band in the wide angle region occurring from the lateral packing and ionic sublayer thickness dc0 for flat layers are estimated to
does not lie on the equator but spreads over the whole azimuthal be 54 Å2 and 10 Å, respectively. S and dc values close to the
range.
low limit are of about 33 Å2 and 17 Å. With the hypothesis that
the interface layer goes from dc0 to (2dc−dc0), the calculation
results in chain segments incorporated in the interface layer that
contain on average about 7 methylene groups). Thus, this would
logically mean that smectic packing is only possible if the tails
are long enough to jut out of the diffuse interface with the ionic
sublayers and that the tail segments incorporated in the inter-
face do not contribute significantly to the weak dependence of S
upon chain length. Beyond the short chain limit, the major
influence of chain length concerns the stability of the smectic
packing revealed by the variation of Smax. Thus, increasing
chain length causes an important stabilization in the whole
explored domain, probably because of the better defined
sublayer alternation, extending the smectic packing to larger
molecular areas and to more disorganized chains. Nevertheless,
increasing chain length also dilutes the ionic sublayers, redu-
Figure 8: Grazing incidence X-ray pattern at 100 °C on the top of a 312
droplet, slowly cooled down from isotropic phase; for image contrast
compatibility with the surrounding zone, intensities inside the zone,
delimited by the black line and containing the first order reflection of
the lamellar stacking, are divided by one hundred.
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Beilstein Journal of Organic Chemistry 2009, 5, No. 62.
cing the correlations between them, and a higher limit should diately. The reaction was stirred for a couple of hours, and
therefore exist for the system, but for much longer tails than the dichloromethane was added. The organic layer was washed
longest grafted here (n = 16).
three times with water, dried on MgSO4 and evaporated under
reduced pressure.
Conclusion
We have synthesised different series of thermotropic ionic CnH2n+1 with n > 10
liquid crystals based on the imidazolium cation and containing The lithium, sodium or potassium salt of our desired anion was
anions varying with regard to their shapes, sizes and charge dissolved in water and added to an aqueous solution of a 1-(4-
localization. As expected, most of the imidazolium compounds alkyloxybenzyl)-3-methyl-1H-imidazol-3-ium bromide. A
show stable mesomorphism, which can be observed at sub- precipitation of the desired imidazolium salt occurred immedi-
ambient to very high temperature. Both the alkyl chain length ately. The reaction was stirred for a couple of hours. After cent-
and the anion type have a strong influence on the mesomorphic rifugation, the solvent was removed and the crude product was
behaviour.
washed twice with water. The product was finally obtained pure
by crystallization on a mixture from dichloromethane and
In regard to the different studies realized and more precisely to diethyl ether.
the dilatometry analysis, the most interesting feature of this
imidazolium architecture is its flexibility. This is highlighted, in
Supporting Information
the smectic A organization, by the ability of the system to
compensate the difference between the cross-section of the tails
and the ionic lattice area by the gathering of the ionic sublayer
and by folding of the tails. This environment-flexible cationic
organic backbone offers us, even in presence of large coun-
terions, the opportunity to elaborate ionic liquid crystals. The
1-(4-alkoxybenzyl)-3-methyl-1H-imidazol-3-ium cationic
moiety is a versatile smectogenic part which could in the near
future organise into supramolecular arrangements involving
numerous anions with specific functionalities.
Supporting Information File 1
Product characterization (spectroscopic and analytical
data), complementary information about the
characterization of the liquid crystalline properties (DSC,
X-Ray, dilatometry).
[http://www.beilstein-journals.org/bjoc/content/
supplementary/1860-5397-5-62-S1.doc]
Acknowledgments
This work was supported by the Institute for Physics and Chem-
Experimental
General procedure for imidazolium syntheses
The reactions were performed under Argon atmosphere.
4-(Alkyloxyphenyl)methanol (An) and thionyl bromide were
dissolved in dry DCM. TLC monitored the progress of reaction
until no more alcohol was observed. The solvent was removed
under vacuum and the intermediate 1-bromomethyl-4-alkyloxy-
benzene was used directly without further purification. This
bromo derivative and freshly distilled 1-methylimidazole were
stirred in THF during two days. After evaporation to dryness,
the residue was purified by flash chromatography on silica gel
column (elution DCM/MeOH, MeOH 0% to 9%) followed by
flash chromatography on alumina gel column (elution DCM/
MeOH, MeOH 3% to 8%) or by a recrystallisation from DCM/
Et2O.
istry of Materials Strasbourg, and University of Strasbourg.
References
1. Binnemans, K. Chem. Rev. 2005, 105, 4148–4204.
doi:10.1021/cr0400919
2. Ohno, H., Ed. Electrochemical Aspects of Ionic Liquids;
Wiley-Interscience, 2005.
3. Endres, F.; Abbott, A. P.; MacFarlane, D. R., Eds. Electrodeposition
from Ionic Liquids; Wiley-VCH: Weinheim, 2008.
4. Wasserscheid, P.; Welton, T., Eds. Ionic Liquids in Synthesis;
Wiley-VCH: Weinheim, 2003.
5. Song, C. E.; Roh, E. J. Chem. Commun. 2000, 837–838.
doi:10.1039/b001403f
6. Song, C. E.; Shim, W. H.; Roh, E. J.; Choi, J. H. Chem. Commun.
2000, 1695–1696. doi:10.1039/b005335j
7. Dupont, J.; de Souza, R. F.; Suarez, P. A. Z. Chem. Rev. 2002, 102,
3667–3692. doi:10.1021/cr010338r
8. Taubert, A. Acta Chim. Slov. 2005, 52, 183–186.
9. Mazille, F.; Fei, Z.; Kuang, D.; Zhao, D.; Zakeeruddin, S. M.;
Grätzel, M.; Dyson, P. J. Inorg. Chem. 2006, 45, 1585–1590.
doi:10.1021/ic051751a
General procedure for anion metathesis in
water
CnH2n+1 with n ≤ 10
The lithium, sodium or potassium salt of our desired anion was
dissolved in water and added to an aqueous solution of a 1-(4-
alkyloxybenzyl)-3-methyl-1H-imidazol-3-ium bromide. A
slight precipitation of the desired imidazolium occurred imme-
10.van Rantwijk, F.; Sheldon, R. A. Chem. Rev. 2007, 107, 2757–2785.
doi:10.1021/cr050946x
11.Parvulescu, V. I.; Hardacre, C. Chem. Rev. 2007, 107, 2615–2665.
doi:10.1021/cr050948h
Page 8 of 9
(page number not for citation purposes)

Beilstein Journal of Organic Chemistry 2009, 5, No. 62.
12.Taubert, A. Angew. Chem., Int. Ed. 2004, 43, 5380–5382.
doi:10.1002/anie.200460846
License and Terms
13.Taubert, A.; Steiner, P.; Mantion, A. J. Phys. Chem. B 2005, 109,
15542–15547. doi:10.1021/jp051262w
This is an Open Access article under the terms of the
Creative Commons Attribution License
14.Dobbs, W.; Suisse, J.-M.; Douce, L.; Welter, R. Angew. Chem., Int. Ed.
2006, 45, 4179–4182. doi:10.1002/anie.200600929
15.Yamanaka, N.; Kawano, R.; Kubo, W.; Masaki, N.; Kitamura, T.;
Wada, Y.; Watanabe, M.; Yanagida, S. J. Phys. Chem. B 2007, 111,
4763–4769. doi:10.1021/jp0671446
(http://creativecommons.org/licenses/by/2.0), which
permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.
16.Yamanaka, N.; Kawano, R.; Kubo, W.; Kitamura, T.; Wada, Y.;
Watanabe, M.; Yanagida, S. Chem. Commun. 2005, 740–742.
doi:10.1039/b417610c
The license is subject to the Beilstein Journal of Organic
Chemistry terms and conditions:
17.Desigaux, L.; Sainlos, M.; Lambert, O.; Chevre, R.;
Letrou-Bonneval, E.; Vigneron, J.-P.; Lehn, P.; Lehn, J.-M.; Pitard, B.
Proc. Natl. Acad. Sci. U. S. A. 2007, 104, 16534–16539.
doi:10.1073/pnas.0707431104
(http://www.beilstein-journals.org/bjoc)
The definitive version of this article is the electronic one
which can be found at:
18.Dobbs, W.; Heinrich, B.; Bourgogne, C.; Donnio, B.; Terazzi, E.;
Bonnet, M.-E.; Stock, F.; Erbacher, P.; Bolcato-Bellemin, A.-L.;
Douce, L. J. Am. Chem. Soc. 2009, 131, 13338–13346.
doi:10.1021/ja903028f
doi:10.3762/bjoc.5.62
19.Kato, T.; Mizoshita, N.; Kishimoto, K. Angew. Chem., Int. Ed. 2006, 45,
38–68. doi:10.1002/anie.200501384
20.Yoshio, M.; Ichikawa, T.; Shimura, H.; Kagata, T.; Hamasaki, A.;
Mukai, T.; Ohno, H.; Kato, T. Bull. Chem. Soc. Jpn. 2007, 80,
1836–1841. doi:10.1246/bcsj.80.1836
21.Dobbs, W.; Douce, L.; Allouche, L.; Louati, A.; Malbosc, F.; Welter, R.
New J. Chem. 2006, 30, 528–532. doi:10.1039/b600279j
22.Bowlas, C. J.; Bruce, D. W.; Seddon, K. R. Chem. Commun. 1996,
1625–1626. doi:10.1039/cc9960001625
23.Yoshio, M.; Mukai, T.; Kanie, K.; Yoshizawa, M.; Ohno, H.; Kato, T.
Adv. Mater. 2002, 14, 351–354.
doi:10.1002/1521-4095(20020304)14:5<351::AID-ADMA351>3.0.CO;2
-D
24.De Roche, J.; Gordon, C. M.; Imrie, C. T.; Ingram, M. D.; Ingram, A. R.;
Kennedy, A. R.; Lo Celso, F.; Triolo, A. Chem. Mater. 2003, 15,
3089–3097. doi:10.1021/cm021378u
25.Lee, K.-M.; Lee, Y.-T.; Lin, I. J. B. J. Mater. Chem. 2003, 13,
1079–1084. doi:10.1039/b210562d
26.Yoshio, M.; Mukai, T.; Ohno, H.; Kato, T. J. Am. Chem. Soc. 2004, 126,
994–995. doi:10.1021/ja0382516
27.Suisse, J.-M.; Bellemin-Laponnaz, S.; Douce, L.; Maisse-François, A.;
Welter, R. Tetrahedron Lett. 2005, 46, 4303–4305.
doi:10.1016/j.tetlet.2005.04.114
28.Chiou, J. Y. Z.; Chen, J. N.; Lei, J. S.; Lin, I. J. B. J. Mater. Chem.
2006, 16, 2972–2977. doi:10.1039/b600045b
29.Suisse, J.-M.; Douce, L.; Bellemin-Laponnaz, S.; Maisse-François, A.;
Welter, R.; Miyake, Y.; Shimizu, Y. Eur. J. Inorg. Chem. 2007,
3899–3905. doi:10.1002/ejic.200700251
30.Yazaki, S.; Kamikawa, Y.; Yoshio, M.; Hamasaki, A.; Mukai, T.;
Ohno, H.; Kato, T. Chem. Lett. 2008, 37, 538–539.
doi:10.1246/cl.2008.538
31.Cruz, C.; Heinrich, B.; Ribeiro, A. C.; Bruce, D. W.; Guillon, D.
Liq. Cryst. 2000, 27, 1625–1631. doi:10.1080/026782900750037185
32.Fouchet, J.; Douce, L.; Heinrich, B.; Welter, R.; Louati, A.
Beilstein J. Org. Chem. 2009, 5, No. 51. doi:10.3762/bjoc.5.51
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