Ionic liquid crystals formed by self-assembly around an anionic anthracene core

Article abstract of DOI:10.1002/chem.200900721

We have designed and synthesised a series of modular, mesogenic complexes based on anthracene-2,6-di-sulfonate and trialkoxybenzyl-functionalised imidazolium cations. Each complex contains a central, rigid, dianionic anthracene core and two flexible monoc

Full text of DOI:10.1002/chem.200900721

FULL PAPER
DOI: 10.1002/chem.200900721
Ionic Liquid Crystals Formed by Self-Assembly around an Anionic
Anthracene Core
[
a]
[a]
[b]
[c]
Jean-Hubert Olivier, Franck Camerel,* Joaquꢀn Barberꢁ, Pascal Retailleau, and
[
a]
Raymond Ziessel*
Abstract: We have designed and syn-
thesised a series of modular, mesogenic
complexes based on anthracene-2,6-di-
sulfonate and trialkoxybenzyl-function-
alised imidazolium cations. Each com-
plex contains a central, rigid, dianionic
anthracene core and two flexible
monocations bearing paraffin chains
anchored on imidazolium rings. An-
thracene-2,6-disulfonate can be crystal-
tion has shown that the long paraffinic
chains are intercalated between the an-
thracene moieties. The dianion forms
columnar mesophases with trialkoxy-
benzylimidazolium cations, as identi-
fied by polarising optical microscopy
and X-ray scattering measurements.
Differential scanning calorimetry stud-
ies confirmed mesomorphic behaviour
from room temperature to about
2008C for alkyl chains containing 8, 12
and 16 carbon atoms. The strong lumi-
nescence of anthracene is maintained
in the mesophase and fluorescence
measurements confirmed the presence
of J aggregates in all cases. The new
functional materials described herein
provide an easy access to stable and lu-
minescent mesomorphic materials engi-
neered by an ionic self-assembly pro-
cess.
Keywords: anthracene · liquid crys-
tals · self-assembly · luminescence ·
mesophases
lised with various simple alkylammoni-
+
um ions and, in the case of
N ACHTUNGTRNENUG( CH ) -
3 2
ACHTUNGTRENNUNG( C H ) , a crystal structure determina-
16 33 2
Introduction
crystals have also been found to be interesting candidates
for the preparation of organic light-emitting diodes
(OLEDs) in which light is generated by electrical excita-
Supramolecular chemistry leading to nanosegregation pro-
cesses is a sophisticated tool for the design of new functional
[4]
tion.
[1]
[5]
liquid crystalline materials. The design of p-conjugated
In the family of p-conjugated acene units, the anthra-
cene nucleus, which has a high fluorescence quantum yield,
is of particular interest. Thus, anthracene derivatives have
been used in chemiluminescent formulations, as molecular
probes, in OLEDs and in organic field-effect transistors
liquid crystals is particularly appealing due to their possible
[2]
applications in electrochemical devices. Of especial inter-
est is their use as active components in solar cells because
some can carry charges and excitons more efficiently than
[
6]
[7]
[8]
[
3]
[9]
conjugated polymers. Luminescent p-conjugated liquid
(OFETs). The electronic performance in such organic elec-
tronic devices strongly relies on intermolecular order in the
solid state. With liquid crystalline materials, anisotropic in-
termolecular ordering can be finely tuned by appropriate
functionalisation and shaping of the molecules. The manifes-
tation of mesomorphic properties in p-conjugated molecules
is not easy to guarantee, however, and large numbers of
chemical modifications are usually necessary to obtain the
desired properties. This is probably the reason why, despite
the remarkable photophysical and -chemical properties of
anthracene, very few attempts have been made to prepare
mesogenic derivatives and to embed them in optoelectronic
[
a] J.-H. Olivier, Dr. F. Camerel, Dr. R. Ziessel
Laboratoire de Chimie Organique et Spectroscopies Avancꢀes
(
LCOSA)
Ecole Europꢀenne de Chimie, Polymꢁres et Matꢀriaux, CNRS
5 rue Becquerel, 67087 Strasbourg Cedex 02 (France)
2
fcamerel@chimie.u-strasbgfr
E-mail: ziessel@unistra.fr
[
b] Dr. J. Barberꢂ
Liquid Crystal Group, Departamento de Quꢃmica Orgꢂnica
Instituto de Ciencia de Materiales de Aragꢄn
Universidad de Zaragoza-CSIC, 50009 Zaragoza (Spain)
[
c] Dr. P. Retailleau
Laboratoire de Cristallochimie, ICSN—CNRS
Bꢅt 27 1 avenue de la Terrasse, 91198 Gif-sur-Yvette, Cedex (France)
[10]
devices.
A simple way to avoid tedious synthetic modifications
and to easily produce mesomorphic materials is to use the
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.200900721.
[11]
recently developed ionic self-assembly (ISA) process,
a
Chem. Eur. J. 2009, 15, 8163 – 8174
ꢆ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
8163

technique in which multiple charged organic species are or-
ganised by their association with oppositely charged amphi-
philic counterions. Hierarchical superstructures can then be
generated in an ISA process by the electrostatic interactions
between charged amphiphiles and oppositely charged oli-
goelectrolytes as the primary interaction and by hydropho-
bic and p–p interactions as the secondary interactions in the
self-organisation process. Additional interactions, such as
hydrogen-bonding, can also be introduced to further stabi-
lise and control the organisation of the assemblies. This
process (for the construction of liquid-crystalline materials
based on stepwise non-covalent interactions) allows easy
tuning of the properties of the emergent structures by the
careful choice of the alkyl volume fraction (internal solvent)
by simple exchange of the binding partner in the corre-
sponding assembly step without tedious synthetic opera-
tions.
Abstract in French: Une nouvelle sꢀrie de complexes mꢀs-
ogꢁnes obtenus par association ꢀlectrostatique entre lꢇan-
thracꢁne-2,6-disulfonate et des imidazoliums fonctionnalisꢀs
a ꢀtꢀ synthꢀtisꢀe. Les propriꢀtꢀs optiques et dꢇauto-organisa-
tion de ces complexes, constituꢀs dꢇun noyau rigide central
dianionique dꢇanthracꢁne et de deux cations flexibles ꢈ cœur
imidazolium, ont ꢀtꢀ ꢀtudiꢀes. Associꢀ ꢈ des dꢀrivꢀs dꢇam-
moniums portant de longues chaꢉnes carbonꢀes, lꢇanthracꢁ-
[12]
ne-2,6-disulfonate peut Þtre cristallisꢀ et la structure obte-
+
nue avec la cation
N
A
H
U
G
R
N
U
G
A
H
U
G
R
N
U
G
Standard, commercially available, charged surfactants are
commonly used and some more elaborate amphiphilic mole-
cules that introduce new functionalities, such as hydrogen-
bonding, chirality or polymerisable groups inside the ISA
3
2
16 33 2
de sꢀgrꢀgation entre les chaꢉnes grasses et le cœur rigide du
dꢀrivꢀ dꢇanthracꢁne. Par contre, associꢀ ꢈ des imidazoliums
fonctionnalisꢀs par des dꢀrivꢀs tris-alkoxybenzyl, une micro-
sꢀgrꢀgation peut Þtre engendrꢀe et des mꢀsophases colon-
naires ont pu Þtre observꢀes et identifiꢀes par POM ainsi
que par diffraction aux rayons X. Des ꢀtudes par calorimꢀ-
trie diffꢀrentielle ꢈ balayage (DSC) confirme le comporte-
ment mꢀsomorphe des complexes sur une large gamme de
tempꢀrature sꢇꢀtalant de 208C ꢈ 2008C avec des chaꢉnes al-
kyles ꢈ 8, 12, 16 atomes de carbone. Les propriꢀtꢀs de lumi-
nescence de lꢇanthracꢁne sont maintenues au sein des mꢀs-
ophases et des ꢀtudes par spectroscopie dꢇꢀmission confir-
ment la prꢀsence dꢇagrꢀgat de type J entre les fragments
aromatiques. Ces nouveaux complexes fonctionnels, obtenus
par auto-assemblage par voie ꢀlectrostatique, fournissent un
accꢁs rapide et simple ꢈ des matꢀriaux mꢀsomorphes et lu-
minescents.
[13]
materials, have been developed. In most of the amphiphil-
ic binding partners used in the cited ISA processes, the posi-
tive charge is localised on ammonium or phosphonate polar
head-groups and, to the best of our knowledge, no organic
functions with delocalised charge, such as an imidazolium
fragment, have been used in the ionic self-assembly process
to organise a negatively charged functional core.
In this report we describe ISA processes involving a dia-
nionic anthracene derivative and both simple alkylammoni-
um amphiphiles and mesogenic imidazolium species. The
aim of this work was to organise a luminescent p-conjugated
fragment into columnar liquid-crystalline materials. For this
purpose, commercially available double-tailed ammonium
surfactants and synthetic wedge-shaped amphiphilic mole-
[14]
cules with ammonium groups at the tip, known to be able
to organise charged molecules into mesogenic materials
through ISA processes, were selected as countercations. A
series of imidazolium cations carrying trialkoxyphenyl moi-
eties of various chain lengths, described earlier by Kato and
Abstract in Spanish: Hemos diseÇado y sintetizado una
serie de complejos mesꢄgenos modulares basados en antra-
ceno-2,6-disulfonato y cationes imidazolio funcionalizados
con tris ACHTUNGTRENNUNG( alcoxi)bencilo. Todos los complejos contienen un
[15]
nfflcleo central rꢃgido dianiꢄnico de antraceno y dos monoca-
tiones flexibles que portan cadenas parafꢃnicas ancladas en
los anillos de imidazol. El antraceno-2,6-disulfonato puede
co-workers,
was also selected, as these molecules are
known to form columnar mesophases over wide tempera-
ture ranges including room temperature. The idea was to
check the capacity of these mesogenic cations to generate
liquid-crystalline behaviour when in association with an
anionic anthracene derivative. The luminescence of the mes-
ophases duly obtained has been investigated in both the
liquid and solid states to evaluate the nature of the intermo-
lecular interactions engendered in the crystalline and meso-
morphic states.
cristalizarse con varios iones alquilamonio simples y, en el
+
caso de
N ACHTUNGTRENNUNG( CH ) ACHTUNGTRENNUNG( C H ) , la determinaciꢄn de la estructu-
3 2 16 33 2
ra cristalina ha mostrado que las cadenas parafꢃnicas largas
estꢂn intercaladas entre las unidades de antraceno. Con los
cationes tris ACHTUNGTRENNUNG( alcoxi)bencilimidazolio, el dianiꢄn forma mes-
ofases columnares identificadas por medidas de microscopꢃa
ꢄptica con luz polarizada y difracciꢄn de rayos X. Los estu-
dios de DSC confirman el comportamiento mesomorfo
desde temperatura ambiente hasta 2008C para cadenas al-
quꢃlicas que contienen 8, 12 y 16 ꢂtomos de carbono. La
fuerte luminiscencia del antraceno se mantiene en la mes-
ofase y las medidas de fluorescencia confirman la presencia
de agregados J en todos los casos. Los nuevos materiales
funcionales descritos aquꢃ representan un fꢂcil acceso a ma-
teriales mesomorfos luminiscentes estables generados por
un proceso de auto-ensamblaje iꢄnico.
Results and Discussion
Synthesis: The chemical structures of the ISA complexes are
depicted in Scheme 1. Double-tail dialkyldimethylammoni-
um bromide surfactants (DiC , n=16, 18) were purchased
n
from Aldrich and used as received without further purifica-
tion. The synthetic ammonium amphiphiles C amm with
n
iodide as the counterion were synthesised in good yields as
8164
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ꢆ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 8163 – 8174

Self-Assembled Ionic Liquid Crystals
FULL PAPER
Scheme 1.
previously described by the reaction of 3,4,5-tri-n-alkoxy-
benzoic acid chlorides (n=8, 12, 14, 16) with N,N-dimethyl-
firmed in all cases by elemental analysis and NMR spectros-
copy. In particular, the proton signal at 6.77 ppm, character-
istic of the aromatic protons of the trialkoxybenzyl
substituents, has twice the intensity of the anthracene signals
1,4-phenylenediamine dihydrochloride in dry dichlorome-
thane in the presence of triethylamine followed by alkyla-
[
14]
1
tion in iodomethane at reflux.
The 1-methyl-3-(3,4,5-
[C benzyl]Cl) were
at 7.68, 8.01, 8.26 and 8.60 ppm. The H NMR spectrum of
trialkoxybenzyl)imidazolium chlorides (
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
A
H
U
G
E
N
N
the ADS-C benzyl species is given in Figure 1 as a repre-
n
12
synthesised as previously described by the reaction of 1-
methylimidazole and the corre-
sentative case.
sponding 3,4,5-trialkyloxybenzyl
chlorides (n=8, 12, 16) in tolu-
[15]
ene at 808C overnight.
thracene-2,6-disulfonic
An-
acid
with potassium as the counter-
ion (ADS-K) was prepared ac-
cording to a published proce-
[16]
dure.
The ion associate complexes
formed between the anthra-
cene-2,6-disulfonate anion and
the various ammonium and imi-
dazolium cations were obtained
by cation metathesis. The com-
plexation was performed in
DMF and the complexes isolat-
ed by precipitation with water.
The ammonium complexes
were recrystallised from a di-
chloromethane/acetonitrile mix-
ture by slow evaporation of
CH Cl2 whereas the imidazoli-
2
um complexes were recrystal-
lised from hot DMSO. Com-
1
6
Figure 1. H NMR spectrum of ADS-C12benzyl in [D ]DMSO at room temperature, including peak assign-
plexation in a 2:1 ratio was con- ments and their integrals.
Chem. Eur. J. 2009, 15, 8163 – 8174
ꢆ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
8165

R. Ziessel et al.
Molecular structure of ADS-DiC16 by single-crystal X-ray
diffraction: Single crystals of ADS-DiC16 suitable for X-ray
diffraction were obtained by slow evaporation from a
CH Cl /CH CN solvent mixture. This compound crystallises
2
2
3
¯
in the triclinic space group P1 (a=9.832(5), b=16.397(7),
c=28.147(9) Š, a=73.52(4), b=81.93(3), g=78.01(3)8, V=
3
4240.31
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(300) Š , Z=2). Figure 2 shows the structure of
Figure 3. Projection of the crystalline structure of the ADS-DiC16 com-
plex along the b axis (hydrogen atoms have been omitted for clarity).
molecules. The anthracene units do not interact or form ag-
gregated species in the crystal structure and the fluoro-
phores are completely isolated within the layered system.
Crystalline salts of anthracene-2,6-disulfonate and single-tail
Figure 2. ORTEP view of the ADS-DiC16 complex with the principal
atomic numbering (thermal ellipsoids at the 50% probability level). Se-
+
ammonium surfactants (CH
A
H
U
G
E
N
N
(CH ) NH ; n=0–4) have al-
3
2
n
3
lected bond lengths [Š] and angles [8]: N1
ꢀ
C15 1.506(32), N1ꢀC16
ready been reported and it has been demonstrated that the
nature of the aggregated anthracene species as well as their
1
1
1
1
.516(30), N1ꢀC1B 1.518(17), N1ꢀC1A 1.521(16); C15-N1-C16
06.49(55), C15-N1-C1B 107.33(64), C16-N1-C1B 111.3(6), C15-N1-C1A
10.44(61), C16-N1-C1 111.01(62), C1B-N1-C1A 110.15(63), N1’-C15’
.490(25), N1’ꢀC16’ 1.507(31), N1’ꢀC1C 1.506(38), N1’ꢀC1D 1.524(24);
photophysical properties depend on the length of the carbon
[17]
chains.
In these previous studies, in which short carbon
chains were used (n=0–4), it was shown that an increase in
the length of the alkyl chains led to a decrease in the dimen-
sionality of the anthracene arrangements from 2D to 1D.
The present structure, in which a 0D arrangement of anthra-
cene cores is observed, extends these previous observations.
C15’-N1’-C16ꢇ 108.90(58), C15’-N1’-C1C 112.24(62), C16’-N1’-C1C
1
07.28(65), C15’-N1’-C1D 108.44(63), C16’-N1’-C1D 108.92(63), C1C-
N1’-C1D 110.98(62).
ADS-DiC16 as well as the atomic numbering and labelling
scheme. The asymmetric unit contains one anthracene-2,6-
disulfonate dianionic molecule and two ammonium DiC16
cations in general positions (not localised on a symmetry el-
ement). The X-ray crystal structure confirms the 2:1 stoi-
chiometric ratio determined by NMR and elemental analy-
sis. The anthracene fragment is completely planar and the
substitutions at the 2- and 6-positions are also confirmed. In
one of the ammonium cations, the two long carbon chains
appear to be almost parallel and fully extended. In contrast,
in the other ammonium fragment, the two long carbon
chains point in opposite directions and one chain has a
strong bend at the eleventh carbon atom (C1-C11-C16=
Optical properties in solution: The spectroscopic data for
the ADS complexes in dilute solution are gathered in
Table 1. ADS-C amm, ADS-C amm and ADS-C amm
1
2
14
16
were found to be poorly soluble in dichloromethane. The
absorption spectra of the ADS-K salt in water and of the
ADS derivatives in dichloromethane and in DMF show
three main absorption bands centred around 341, 358 and
378 nm (see Figure 4 as a typical example), characteristic of
the vibronic spectrum of anthracene. The positions and in-
tensities of the absorption bands are not affected by the
nature of the solvent or the counterion (Table 1).
Excitation at 358 nm leads to a broad structured emission
band extending from 370 to 550 nm and displaying maxima
at around 396, 415 and 440 nm (Table 1 and Figure 4). The
fluorescence spectrum shows relatively good mirror symme-
try for the lowest-energy absorption transitions, which con-
firms that these transitions are weakly polarised and origi-
nate from the same state, typical of singlet emitters. The
weak Stokes shifts observed are in good agreement with a
singlet emitting state and the excitation spectra perfectly
match the absorption spectra, which is in keeping with a
unique excited state. The parameter that is strongly depen-
dent upon the nature of the solvent is the quantum yield,
which decrease from 47% in water to about 15–20% in
DMF and about 7% in dichloromethane. However, the
quantum yields measured in a given solvent do not depend
1
17.128). The nitrogen atoms are tetrahedral and the CꢀN
distances are almost identical.
A projection of the crystalline structure along the b axis is
presented in Figure 3. The crystalline network can be de-
scribed as being constructed of alternate layers of long
carbon chains and anthracene units stacked along the c axis.
The crystalline arrangement has some similarities with the
molecular organisation of a smectic phase. Segregation be-
tween the rigid aromatic part and the flexible carbon chains
seems to govern the molecular organisation, although
charge association must also have an influence. A close look
at the crystalline structure reveals that the bent carbon
chains (see the ORTEP view in Figure 2) carried by one of
the ammonium cations are stacked between the anthracene
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Chem. Eur. J. 2009, 15, 8163 – 8174

Self-Assembled Ionic Liquid Crystals
FULL PAPER
Table 1. Optical data measured in solution at 298 K.
ꢀ
1
ꢀ1
[a]
Solvent
water
l
abs [nm]
e [m cm
]
l
F
[nm]
F
F
ADS-K
382
3885
4120
3650
3800
5090
4120
3940
5400
4580
4140
5570
4140
4580
5990
5020
3000
4130
3330
3590
4890
3990
4010
5500
4570
3480
3600
3580
5220
6870
5905
4452
4801
4405
4550
6005
5040
3800
5190
4210
3560
4480
4170
3900
4230
4150
397
419
445
394
416
440
396
416
440
395
416
441
398
418
442
399
416
440
396
415
441
394
412
437
397
412
437
397
417
441
394
416
440
395
416
440
394
416
440
392
412
438
398
416
441
0.47
0.13
0.08
0.07
0.06
0.21
0.17
0.15
0.18
0.07
0.17
0.06
0.14
0.07
0.13
3
3
377
61
35
ADS-K
DMF
3
3
58
41
ADS-DiC16
ADS-DiC18
CH
CH
CH
2
2
2
Cl
Cl
Cl
2
2
2
378
3
3
378
3
3
379
3
3
376
3
3
58
41
58
42
ADS-C
ADS-C
8
amm
amm
60
43
8
DMF
DMF
DMF
DMF
Figure 4. Absorption, emission (lex =358 nm) and excitation (lem
=
58
41
4
1
16 nm) spectra of ADS-C12benzyl in dichloromethane (c=3.4”
ꢀ5
ꢀ1
ꢀ5
ꢀ1
0
moll ) and DMF (c=3.7”10 moll ).
ADS-C12amm
ADS-C14amm
ADS-C16amm
377
3
3
58
41
[
a]
376
Table 2. Thermal behaviour of the liquid-crystalline phases.
3
3
58
41
ꢀ1
Compound
Transition temperatures [8C] AHCTNUGTRENNUNG( DH ACHTUNGTRENNUNG[ Jg ])
ADS-DiC16
Cr 49 (33.8) Cr’ 170 (dec)
Cr’ 35 (ꢀ33.8) Cr
377
3
3
57
41
ADS-DiC18
Cr 45 (39.5) Cr’ 180 (dec)
Cr’ 25 (ꢀ40.1) Cr
ADS-C
ADS-C
8
benzyl
benzyl
CH
2
Cl
2
2
2
378
3
3
377
3
3
378
3
3
ADS-C
8
amm
Cr 20 (20.7) Cr’ 90 (1.9) Cr’’ 180 (dec)
Cr’’ 85 (ꢀ1.9) Cr’ 12 (ꢀ20.7) Cr
59
42
ADS-C12amm
ADS-C14amm
ADS-C16amm
Cr 66 (39.5) Cr’ 85 (8.7) Cr’’ 180 (dec)
Cr’’ 82 (ꢀ9.0) Cr’ 56 (ꢀ40.8) Cr
8
DMF
58
41
Cr 77 (29.7) Cr’ 99 (7.8) Cr’’ 170 (dec)
Cr’’ 96 (ꢀ7.8) Cr’ 66 (ꢀ30.8) Cr
ADS-C12benzyl
ADS-C12benzyl
ADS-C16benzyl
ADS-C16benzyl
CH
2
Cl
Cr 85 (36.5) Cr’ 106 (5.9) Cr’’ 170 (dec)
Cr’’ 102 (ꢀ7.2) Cr’ 69 (ꢀ35.7) Cr
58
41
ADS-C
8
benzyl
Col
h
73 (ꢀ19.1) Cr 129 (27.6) Iso
DMF
377
Iso 117 (ꢀ0.7) Col
Col 193 (1.2) Iso
h
3
3
58
41
ADS-C12benzyl
h
Iso 189 (ꢀ0.9) Col
h
CH
2
Cl
378
3
3
ADS-C16benzyl
Cr 47 (26.9) Col
Col
h
240 (dec)
59
41
h
31 (ꢀ28.52) Cr
a] Cr, crystalline phase; Iso, isotropic liquid; Col , hexagonal columnar
DMF
377
[
h
3
3
57
41
mesophase; dec, decomposition temperature (evaluated from the devia-
tion of the baseline on the DSC curve and confirmed by POM).
[
ꢁ
a] Determined in water, dichloromethane and DMF solutions (c
ꢀ
5
3.10 m) using quinine bisulfate in 1.0N H
2
4 F
SO as reference (F =0.55
[
18]
in water, lexc =366 nm). All F
F
values are corrected for changes in re-
ders gradually turn light-brown. The imidazolium salts
appear to be more stable and degradation only occurs at
temperatures above 2408C.
fractive index.
on the nature of the counterion. The decrease in the quan-
tum yields in dichloromethane and in DMF is likely due to
resonance phenomena involving anthracene and the sol-
ADS-DiCn AHCTUNETGRNNUN(G n=16, 18): These two complexes display a single
reversible transition at 498C for ADS-DiC16 and at 458C for
ADS-DiC . POM showed that the compounds are birefrin-
1
8
[19]
vents.
gent from room temperature up to the degradation tempera-
ture. Thus, the materials are in an organised state from
room temperature up to 1708C. Microscopic observations
did not show any clear melting or isotropisation points and,
at this stage, the nature of the transitions observed by DSC
cannot be precisely assigned.
Thermal studies: The thermal behaviour of the ADS ionic
complexes was investigated first by polarising optical micro-
scopy (POM) and differential scanning calorimetry (DSC).
The transition temperatures and enthalpies are gathered in
Table 2. DSC measurements, POM analysis and NMR spec-
troscopy revealed that the ammonium complexes are stable
up to 170–1808C. Above this temperature, the white pow-
ADS-C amm (n=8, 12, 14, 16): All the as-prepared ADS-
n
C amm complexes appeared as crystalline powders between
n
Chem. Eur. J. 2009, 15, 8163 – 8174
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8167

R. Ziessel et al.
cross-polarisers. Two reversible thermal transitions were ob-
served in the DSC traces for each complex. The transition
temperatures increased with the length of the carbon chains.
However, POM performed upon heating revealed that the
morphology, the birefringence and the stiffness of the crys-
tallites remained intact up to 170–1808C. The observed tran-
sitions can likely be attributed to crystal–crystal transitions
(
internal reorganisations) and these complexes seem to lack
any mesomorphic properties.
ADS-C benzyl (n=8, 12, 16): The thermal behaviour of
n
ADS-C benzyl appears to be more complicated. The first
8
heating curve in the DSC trace shows an endothermic tran-
sition centred at 1298C. POM revealed that above 1358C
the material is in an isotropic fluid state (appears black be-
tween crossed-polarisers). Upon cooling (Figure 5a), a small
transition was detected at 1178C and POM performed
below this temperature revealed that the material entered
into a fluid birefringent mesomorphic state. A texture with
small domains readily developed but no clear textural as-
signment of the symmetry of the mesophase was possible.
On a second heating (Figure 5a), an exothermic peak was
observed at 738C. Such behaviour indicates that the meso-
phase stabilised after cooling was metastable and the energy
imported during the heating stage allowed the compound to
melt and to recrystallise in a more stable crystalline phase
(
1
Cr). On further heating, an endothermic peak centred at
298C was observed and is attributed to the melting of the
crystalline phase into the isotropic liquid. Such thermal be-
haviour is typical of compounds that have a tendency to
crystallise but with slow kinetics, probably induced by strong
steric constraints. At lower scan rates, enlargement of the
signal drastically decreases the intensity of the DSC peaks
and no additional information was obtained.
The initial DSC heating curve of the ADS-C benzyl com-
1
2
plex displays a broad transition centred at 1308C due to
some internal rearrangement. Melting of the compound into
an isotropic state was observed on heating to 1938C (Fig-
ure 5b). On cooling the isotropic liquid, the compound
became birefringent and a texture typical of a columnar
phase with pseudo-fan shapes was observed (Figure 6). The
concomitant observation of the soft nature of the material
indicates the existence of a mesomorphic state (see below).
The DSC heating curve of the ADS-C benzyl complex
Figure 5. DSC traces of a) ADS-C
c) ADS-C16benzyl showing the second heating curve (black) and the first
cooling curve (red).
8
benzyl, b) ADS-C12benzyl and
1
6
displays a broad, reversible transition after the first heating
cycle centred at 308C (Figure 5c). This broad transition is
typical of structural rearrangements (melting) of aliphatic
chains. Above this transition, the compound became fluid
and birefringent, good indicators of mesomorphic nature.
The absence of an isotropisation point before the degrada-
tion temperature of around 2408C prevented any definite
textural assignment of the phase symmetry.
room-temperature experiments were performed before the
high-temperature experiments to minimise any possible ef-
fects of thermal degradation. Therefore, for most of the
compounds the experiments were performed in the follow-
ing order: 1) room temperature in the virgin state, 2) room
temperature after heating to the temperature appropriate
for thermal treatment, in general a temperature above the
endothermic transition measured by DSC (temperatures for
the thermal treatment: ADS-DiC , 1208C; ADS-DiC ,
XRD characterisation and mesomorphic behaviour: All the
complexes were subjected to a range of temperature-depen-
dent wide- (WAXS) and small-angle (SAXS) X-ray scatter-
ing measurements to elucidate their morphologies. All the
1
6
18
1208C; ADS-C amm, 1108C; ADS-C amm, 788C; ADS-
8
12
C amm, 1208C; ADS-C amm, 1308C; ADS-C benzyl,
1
4
16
8
1498C; ADS-C benzyl, 1308C; ADS-C benzyl, 1308C) and
1
2
16
8168
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Chem. Eur. J. 2009, 15, 8163 – 8174

Self-Assembled Ionic Liquid Crystals
FULL PAPER
phases and characteristic of the liquid-like order of the hy-
drocarbon chains (Figure 7).
Figure 6. The ADS-C12benzyl compound observed by optical microscopy
at 1878C between crossed-polarisers (symbolised by the cross in the
corner of the picture).
8
Figure 7. XRD patterns of a) ADS-C benzyl in the hexagonal columnar
phase at room temperature after heating at 1108C, b) the same com-
pound under the same conditions in the small-angle region, c) ADS-
C
C
12benzyl in the hexagonal columnar phase at 1308C, and d) ADS-
16benzyl in the hexagonal columnar phase at 1308C.
3
) high-temperature experiment or experiments. The results
are gathered in Table 3.
As mentioned earlier, the behaviour of the ADS-C benzyl
[
a]
8
Table 3. X-ray characterisation of the liquid-crystalline phases. For
each compound the experiments were performed at various temperatures
in the order given in the table.
complex is peculiar for two reasons: 1) the mesophase froze
at room temperature, at least for some time (the time of the
exposure to X rays) and 2) when the frozen mesophase was
heated up to 1008C it crystallised. The X-ray results confirm
that the mesophase stabilised after cooling was metastable
and that heating allowed the compound to recrystallise in a
more stable crystalline phase (Cr).
Concerning the type of mesophase found in these com-
pounds, the set of one or two reflections found in the low-
angle region has two possible interpretations. 1) The diffrac-
tion peak(s) could be the first (and second)-order reflec-
tion(s) of a layer structure (smectic mesophase). In that case
the spacing of the first reflection (or the double of the
second reflection) is the layer thickness. 2) The peak(s) is
Compound
Temperature
8C]
Phase hkl
d
[Š]
meas
a
[Š]
S
[Š ]
2
[
[
b]
ADS-C
8
benzyl 25
Cr
Col
Cr
[
c]
2
1
5
h
100 32.2
200 16.1
37.2 1198
40.6 1429
44.5 1713
00
[
d]
4.5
[
b]
ADS-
25
Cr
Cr
[
c]
C
12benzyl
25
100 35.1
200 17.6
1
30
Col
h
h
[
[
d]
d]
4.6
[
b]
ADS-
16benzyl
25
Cr
Cr
Col
[
c]
C
25
30
100 38.5
4.6
1
[
a] dmeas is the measured diffraction peak spacing; hkl is the indexation of
the reflections of the Col phase; a is the lattice constant of the hexago-
nal columnar phase; S is the lattice area (S=a<d10 > for Col ); Cr, crys-
talline phase; Col , hexagonal columnar mesophase. [b] Virgin sample.
c] After thermal treatment (heating above the thermal transition and
(
are) the (100) (and (200)) reflection(s) from a hexagonal
h
[20]
columnar mesophase, the (110) reflection being absent.
h
h
The second interpretation is the most reasonable. This
[
conclusion is based on the following arguments. 1) The mo-
cooling to room temperature). [d] Diffuse, broad maximum.
+
lecular structure of the C benzyl cation contains three long
n
chains attached to the aromatic unit and the spatial require-
ments of these chains are impossible to fulfil in a smectic
structure owing to the mismatch between the cross-section
of the aromatic moiety and the total cross-section of the hy-
ADS-DiCn (n=16, 18) and ADS-C amm (n=8, 12, 14, 16):
n
The X-ray results indicate that none of these compounds is
mesomorphic at the temperatures studied. Instead, all the
patterns recorded at room temperature and at high tempera-
tures are characteristic of crystalline phases. Indeed, in all
cases the diffraction patterns are complex and contain a
high number of sharp maxima in the whole angular range,
which is typical of well-organised crystalline complexes.
[21]
drocarbon chains.
Instead, the chains have more space
available in a columnar structure in which they spread out
around the central core of the column. 2) If the mesophase
was smectic, very simple calculations would allow the molec-
ular cross-section to be estimated. If the density is known,
the molecular volume can be deduced from the molecular
3
ADS-C benzyl (n=8, 12, 16): At high temperatures these
mass (V =M/0.60221, with V the molecular volume in Š ,
n
m
m
ꢀ
3
compounds gave X-ray patterns characteristic of a liquid
crystal phase (Table 3). This was deduced from the presence
of one or two sharp reflections in the low-angle region and
the absence of maxima in the high-angle region, except for a
broad, diffuse halo, typically observed in all kinds of meso-
M the molecular mass and 1 the density in gcm ). Dividing
the molecular volume by the layer thickness (d) gives the
cross-section of a molecule in the plane of the smectic layer.
The calculated molecular cross-sections are 75/1 Š for
ADS-C benzyl, 84/1 Š for ADS-C benzyl and 92/1 Š for
2
2
2
8
12
Chem. Eur. J. 2009, 15, 8163 – 8174
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8169

R. Ziessel et al.
ADS-C benzyl. Because the density must be similar for the
16
three compounds (in fact, it is usually assumed that density
ꢀ
3
is close to 1 gcm
for organic compounds), this would
mean that the cross-section increases upon increasing the
number of carbon atoms in the chains (18% from n=8 to
n=16). This is not consistent with a smectic structure be-
cause lengthening of the hydrocarbon chains should increase
the length of the molecule but not its thickness. On the
other hand, if the mesophase is columnar hexagonal and we
deduce the molecular volume Vm by using the above equa-
tion, then the height of column h occupied by each molecule
can be estimated to be h=V /S, with S the area of the two-
m
dimensional hexagonal cell (S=admeas). The results of these
calculations are h=2.02/1 Š for ADS-C benzyl at room
8
temperature, h=2.08/1 Š for ADS-C benzyl and h=2.06/
1
2
1
Š for ADS-C benzyl. The variation is 3%, that is, the es-
16
timated values for h are practically the same for the three
compounds. This is consistent with the mesophase being col-
umnar, because for this kind of mesophase lengthening the
hydrocarbon chains is expected to increase only the diame-
ter of the column but not the stacking distance. It is evident
that one single molecule cannot be located in a “slice” of
about 2–2.1 Š thickness, but it is reasonable that two mole-
cules are contained in a “slice” of 4–4.2 Š, assuming a densi-
Figure 8. Suggested molecular organisation based on the X-ray data for
ADS-C benzyl complexes inside the hexagonal columnar phase.
8
central ionic region. In this way, optimal microsegregation
between the aliphatic and polar parts inside a disc is ensur-
ed. The hydrocarbon chains are able to efficiently fill the pe-
ripheral space around the columnar core. The mutual organ-
isation of these columns into a hexagonal lattice leads to the
formation of the mesophase. However, this is a simplified
model because, in fact, the molecules can aggregate in such
a way that the cations are randomly oriented, with just their
tips pointing towards the stacked anion column without the
need to form discrete discs.
ꢀ
3
ꢀ3
ty of 1 gcm (4.5–4.6 Š if the density is 0.9 gcm ). The S
values for the three compounds are, respectively, 1198 (at
2
RT), 1429 (at 1308C), and 1713 Š (at 1308C). These values
follow a logical evolution as they are proportional to the
molecular masses.
Note that for ADS-C benzyl, a crystallisation process was
1
2
observed by XRD at room temperature after the thermal
treatment whereas no peak associated with such a meso-
phase-to-crystal transition was detected by DSC. DSC and
XRD analysis imply different heating and cooling rates and
this behaviour can be explained by a tendency of the prod-
uct to slowly crystallise at low temperatures during the
XRD measurements.
Solid-state luminescence: The emission properties in the
solid state were also evaluated directly by using isolated
powders and a spectrophotometer equipped with an optical
fibre. The emission spectrum of the starting compound
ADS-K shows a broad emission band, weakly structured,
centred at 437 nm (Figure 9). The redshifts observed in the
emission spectra compared to the emission in fluid solution,
are attributed to the head-to-tail orientation or the J aggre-
Packing study of the ISA complexes in their liquid-crystal-
line phases: To gain some insight into the packing of the
2
ꢀ
[23]
ADS-C benzyl complexes inside the columnar liquid-crystal-
gates of the ADS ions in the solid state. A redshift of
the absorption spectrum, associated with the formation of
head-to-tail anthracene aggregates, should also be ob-
n
[22]
line phases, a standard geometrical treatment was applied.
As already mentioned, columnar packing is characterised by
the columnar cross-section Scol and the stacking periodicity h
along the columnar axis, both parameters being analytically
[24]
served. The photoluminescence spectra of all the as-pre-
pared ADS-C amm and ADS-DiC complexes present well-
n
n
linked through the relation hScol =ZV , with Z the number
structured emission bands with maxima located at 410, 435
and 460 nm at room temperature. The positions of the emis-
sion bands of these crystalline materials (cf. Table 1) are
comparable to those observed for the ADS ion isolated in
DMF or in dichloromethane. The introduction of long
carbon chains into the ammonium counterions results in the
isolation of the anthracene residues in crystalline solids, as
seen in the crystal structure of the ADS-DiC16 complex (see
above).
m
of molecules within a columnar stratum (disc) h thick and
Vm the molecular volume. In the XRD patterns, neither a
peak nor a halo related to the stacking periodicity h was ob-
served. In this situation, it is difficult to determine the
number of molecules per disc and only rough estimations
can be made. It was found (see above) that two molecules
are contained in a “slice” of 4–4.2 Š, assuming a density of
2ꢀ
ꢀ
3
ꢀ3
1
gcm (4.5–4.6 Š if the density is 0.9 gcm ). This implies
that each disc, generating columns by stacking, is formed by
two complexes (Figure 8). The ionic groups are located in
the centre of the disc and the peripheral chains surround the
For all the ADS-C benzyl complexes, a slight redshift of
the emission bands was observed, which indicates that the
trialkoxybenzylimidazolium fragments do not prevent the
n
[14]
8170
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Chem. Eur. J. 2009, 15, 8163 – 8174

Self-Assembled Ionic Liquid Crystals
FULL PAPER
Figure 10. Fluorescence spectra of ADS-C16benzyl at 1008C in the hexag-
onal columnar mesophase.
Figure 9. Solid-state emission spectra of the as-prepared ADS-K, ADS-
DiC16, ADS-C benzyl, ADS-C12benzyl and ADS-C16benzyl complexes at
8
room temperature under excitation at 360 nm.
formation of aggregated anthracene species. The fact that
the redshift observed with the ADS-K complex (28 nm) was
larger than those observed with the ADS-C benzyl com-
n
plexes suggests that the distance between the anthracene
molecules with potassium counterions is shorter and thus
that stronger intermolecular interactions occur in the solid
state, which leads to higher-order aggregates. In the series of
ADS-C benzyl complexes, the redshift decreases with the
n
chain lengths (17 nm for n=8, 12 nm for n=12, 5 nm for
n=16) and this can be attributed to a decrease in the inter-
molecular interactions between the anthracene moieties as
the trialkoxybenzyl template becomes bulkier. The emission
band of the ADS-C benzyl complex was more extended,
8
even below 420 nm, an observation in keeping with stronger
intermolecular interactions in the solid state.
Temperature-dependent fluorescence measurements were
also performed on the liquid crystalline ADS-C benzyl (n=
n
8, 12, 16) compounds by using a heating stage. The lumines-
cence spectrum of ADS-C benzyl measured at 1008C in its
1
6
columnar mesophase displays a broad, structureless emission
band centred around 431 nm (Figure 10). This redshifted
broad emission band indicates that intermolecular interac-
tions between the anthracene moieties take place in the
mesophase and this is in line with the formation of a colum-
nar core containing mainly anthracene fragments (see
ꢀ
1
model). Upon cooling at 108Cmin , no real changes were
observed in the fluorescence spectra, in line with the DSC
measurements. The extension of luminescence up to 650 nm
in the mesophases is also indicative of the formation of
higher-order aggregates in the liquid-crystalline state.
Figure 11. A drop of ADS-C12benzyl observed by optical microscopy at
1
878C a) with a white light in transmission between crossed-polarisers
(
symbolised by the cross in the corner of the picture; classical texture)
and b) upon irradiation at 300<lex <350 nm.
The mesomorphic complexes were also examined by fluo-
rescence microscopy on a heating stage. Upon cooling, the
materials became liquid-crystalline, enabling the formation
of homogeneous thin films. The fluid materials showed a ho-
mogeneous blue luminescence, which is typical of anthra-
cene moieties (Figure 11). Note that the complexes were
still luminescent at elevated temperatures. Despite the for-
mation of well-defined textures with ADS-C benzyl, no do-
mains with different emissions have been observed at this
stage.
[14,25]
Conclusions
A series of functional salts have been synthesised by ionic
self-assembly from a charged luminescent anthracene core
1
2
Chem. Eur. J. 2009, 15, 8163 – 8174
ꢆ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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8171

R. Ziessel et al.
and various types of non-luminescent amphiphilic ammoni-
um and imidazolium cations. The crystal structure of the
ADS-DiC16 complex revealed that the long carbon chains
can be fully intercalated between the anthracene moieties
and that microsegregation between anions and cations will
be more difficult to induce with polyaromatic fragments and
long carbon chains. The affinity between the long carbon
chains and the anthracene core clearly prevents the forma-
tion of mesomorphic materials and stable crystal structures
were isolated. Solid-state fluorescence measurements per-
formed on these crystalline structures displayed emission
properties identical to those of the isolated molecules in so-
lution. The measurements confirm that the anthracene core
has a strong tendency to form crystalline structures with am-
monium cations carrying long carbon chains and that the ali-
phatic parts efficiently segregate the anthracene moieties.
The use of imidazolium in place of the ammonium cations
has allowed the formation of mesomorphic materials with
and n is the refractive index of the medium. The reference system used
was rhodamine 6G in methanol (fref =0.78, lexc =488 nm).
2
F½1 ꢀ expð ꢀ Arefln10Þꢂn
F
exp ¼ Fref
ð1Þ
2
ref
F
ref½1 ꢀ expð ꢀ Aln10Þꢂn
Differential scanning calorimetry (DSC) was performed on a Netzsch
DSC 200 PC/1M/H Phox instrument equipped with an intracooler, allow-
ing measurements from ꢀ658C up to 4508C. The samples were examined
ꢀ
1
at a scan rate of 10 Kmin by applying two heating and one cooling
cycles. The apparatus was calibrated with indium (156.68C). The phase
behaviour was studied by polarising optical microscopy (POM) on a
Leica DMLB microscope equipped with a Linkam LTS350 hot-stage and
a Linkam TMS94 central processor. The XRD patterns were obtained
with a pinhole camera (Anton-Paar) operating with a point-focussed Ni-
filtered CuKa beam. The samples were held in Lindemann glass capillaries
(
0.9 mm diameter) and heated, when necessary, with a variable-tempera-
ture oven. The patterns were collected on flat photographic film perpen-
dicular to the X-ray beam. Spacings were obtained by application of
Braggꢇs law.
General procedure for the synthesis of the [ADS-DiC
n
] complexes (n=
1
6, 18): The sulfonate salt (50 mg, 0.12 mmol) and 2 equiv of the DiC
n
2ꢀ
the negatively charged ADS core through an ionic self-as-
sembly process. The use of imidazolium-grafted-trialkoxy-
benzyl salts allowed the formation of columnar mesophases
with hexagonal symmetry, unambiguously identified by X-
ray scattering measurements at various temperatures and by
the typical textures observed between crossed-polarisers by
optical microscopy. From these data it is estimated that for
salts (0.24 mmol) were stirred overnight in DMF (25 mL) at 708C. After
cooling to room temperature, water was added to precipitate the com-
plex. The complex was washed with water (3”15 mL). After drying, the
precipitate was dissolved in CH
2 2
Cl and filtered through Celite to
remove any insoluble material. The complex was recrystallised from a
CH
2
Cl
2
/CH
3
CN mixture by slow evaporation of the dichloromethane.
1
ADS-DiC16: Isolated yield: 25%. H NMR ([D
6
]DMSO, 300 MHz): d=
3
0
.85 (t, J=6.7 Hz, 12H), 1.24 (brs, 104H), 1.615 (brs, 8H), 2.97 (s, 12H,
3
4
the ADS-C benzyl complexes, two associated pairs form
NCH
3
), 3.20 (m, 8H, NCH
2
), 7.68 (dd, J=8.8, J=1.6 Hz, 2H), 8.01 (d,
n
3
J=8.8 Hz, 2H), 8.27 (s, 2H), 8.59 ppm (s, 2H); IR (ATR): n˜ =2918 (vs)
discs able to pile up to form the column. The use of a highly
luminescent platform allowed the homogeneity and quality
of the thin films to be checked by fluorescence microscopy.
Solid-state fluorescence measurements showed that the an-
thracene anions were not fully isolated and that J aggregates
formed inside the mesophases. The use of ionic self-assem-
bled complexes provides a relatively easy way to produce
liquid-crystalline materials and thin films stable over a large
temperature range that are possibly useful for applications
in electrical devices. Work along these lines is in progress.
(
(
(
2 s 2
nasCH ), 2850 (vs) (n CH ), 1495 (m), 1468 (s), 1397 (w), 1375 (w), 1342
w), 1292 (w), 1276 (m), 1261 (m), 1236 (s), 1215 (vs), 1203 (vs), 1178
vs), 1152 (m), 1130 (w), 1089 (m), 1079 (vs), 1022 (vs), 958 (w), 926 (w),
ꢀ
1
908 (s), 900 (m), 869 (w), 860 (w), 831 cm (w); elemental analysis calcd
(%) for C82
H
152
N
2
O
6
S
2
: C 74.26, H 11.55, N 2.11; found: C 74.84, H
1
1.71, N 1.89.
1
ADS-DiC18
7
2
:
Isolated yield: 41%. H NMR ([D
6
]DMSO, 400 MHz,
3
08C): d=0.87 (t, J=5.1 Hz, 12H), 1.27 (brs, 120H), 1.66 (brs, 8H),
3
.99 (s, 12H, NCH
3
), 3.23 (m, 8H, NCH
2
), 7.73 (d, J=9.0 Hz, 2H), 7.99
3
(
d, J=8.6 Hz, 2H), 8.29 (s, 2H), 8.53 ppm (s, 2H); IR (ATR): n˜ =2917
(vs) (nasCH
1
1
2
), 2850 (vs) (n
342 (w), 1292 (w), 1273 (w), 1261 (m), 1235 (s), 1216 (vs), 1202 (vs),
178 (vs), 1152 (m), 1130 (w), 1089 (m), 1079 (vs), 1022 (vs), 987 (w), 949
s 2
CH ), 1496 (m), 1468 (s), 1396 (w), 1378 (w),
ꢀ
1
(
w), 926 (m), 908 (s), 900 (m), 869 (w), 860 (w), 831 cm (w); elemental
analysis calcd (%) for C90 : C 75.15, H 11.77, N 1.95; found: C
5.44, H 11.52, N 1.70.
General procedure for the synthesis of the [ADS-C
(n=8, 12, 14, 16): The sulfonate salt (1 equiv) was dissolved in DMF
168 2 6 2
H N O S
7
Experimental Section
n
amm] complexes
1
1
13
The 300 ( H), 400 ( H) and 75.5 MHz ( C) NMR spectra were recorded
at room temperature using perdeuteriated solvents as internal standards.
ꢀ
1
(
n
2 mgmL ) and C amm (1 equiv per negative charge) was added. The
+
mixture was stirred at 608C for one night. After cooling, water was then
added and the precipitate washed with water and dried under vacuum.
A ZAB-HF-VB-analytical apparatus in FAB mode was used with m-ni-
trobenzyl alcohol (m-NBA) as a matrix. Chromatographic purification
was conducted using 40–63 mm silica gel. Thin-layer chromatography
Crystallisation from a CH
powders.
2 2 3
Cl /CH CN mixture gave the complexes as
(
TLC) was performed on silica gel plates coated with fluorescent indica-
1
ADS-C
8
amm: Isolated yield: 30%. H NMR (DMSO, 300 MHz): d=0.86
tor. FTIR spectra were recorded by using a Perkin–Elmer “spectrum
one” spectrometer equipped with an ATR diamond apparatus. UV/Vis
spectra were recorded by using a Shimadzu UV-3600 dual-beam grating
spectrophotometer with a 1 cm quartz cell. Fluorescence spectra were re-
corded on a HORIBA Jobin–Yvon Fluoromax 4P spectrofluorimeter
with a 1 cm quartz cell for solutions or an optical fibre for solids. Temper-
ature-dependent luminescence measurements were performed on thin
films by using the HORIBA Jobin–Yvon Fluoromax 4P spectrofluorime-
ter equipped with an optical fibre and a heating stage (Linkam LTS350
hot stage and a Linkam TMS94 central processor). All fluorescence spec-
tra were corrected. The fluorescence quantum yields (fexp) were calculat-
ed from Equation (1) in which F denotes the integral of the corrected
fluorescence spectrum, A is the absorbance at the excitation wavelength
(
m, 18H), 1.16–1.53 (m, 60H), 1.58–1.82 (m, 12H), 3.59 (s, 18H), 3.93 (t,
3
3
3
J=6.2 Hz, 4H), 4.04 (t, J=6.1 Hz, 8H), 7.25 (s, 4H), 7.68 (dd, J=8.8,
4
3
J=1.3 Hz, 2H), 7.95 (s, 8H), 8.01 (d, J=8.7 Hz, 2H), 8.27 (s, 2H), 8.59
(
(
(
s, 2H), 10.36 ppm (s, NH, 2H); IR (ATR): n˜ =3314 (br w) (nNH), 2922
s) (nasCH ), 2854 (s) (n CH ), 1666 (s) (nCO), 1606 (m), 1583 (s), 1542
s), 1513 (m), 1498 (s), 1468 (s), 1427 (s), 1410 (m), 1378 (w), 1331 (vs),
2
s
2
1
1
294 (w), 1275 (w), 1259 (w), 1219 (vs), 1182 (vs), 1110 (vs), 1082 (vs),
ꢀ
1
023 (vs), 986 (w), 960 (w), 936 (w), 911 (m), 874 (w), 846 (m), 812 cm
: C 69.85, H 8.86, N
(
w); elemental analysis calcd (%) for C94
H
142
N
4
0
14
S
2
3
.47; found: C 70.12, H 9.17, N 3.22.
1
ADS-C12amm: Isolated yield: 47%. H NMR (DMSO, 300 MHz): d=
0.85 (m, 18H), 1.08–1.55 (m, 108H), 1.57–1.84 (m, 12H), 3.59 (s, 18H),
8172
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Self-Assembled Ionic Liquid Crystals
FULL PAPER
3
3
8
.92 (m, 4H), 4.04 (m, 8H), 7.24 (s, 4H), 7.68 (d, J=7.9 Hz, 2H), 7.95 (s,
1364 (w), 1334 (m), 1223 (s), 1183 (s), 1113 (s),1095 (s), 1085 (s), 1024
(s), 992 (m), 968 (w), 922 (m), 873 (w), 837 (w), 817 cm (w); elemental
3
ꢀ1
H), 8.02 (d, J=8.8 Hz, 2H), 8.27 (s, 2H), 8.60 (s, 2H), 10.35 ppm (s,
), 2850 (s)
), 1665 (s) (nCO), 1609 (m), 1581 (s), 1545 (s), 1517 (m), 1499 (s),
NH, 2H); IR (ATR): n˜ =3301 (br w) (nNH), 2918 (s) (nasCH
2
analysis calcd (%) for C132
74.92, H 11.05, N 3.09.
226 4 12 2
H N 0 S : C 74.60, H 10.72, N 2.64; found: C
(
n
s
CH
2
1
1
1
8
473 (s), 1427 (m), 1409 (w), 1388 (w), 1333 (vs), 1294 (w), 1277 (w),
253 (w), 1222 (vs), 1196 (m), 1183 (vs), 1158 (m), 1129 (w), 1105 (vs),
083 (vs), 1026 (vs), 994 (w), 972 (w), 940 (w), 929 (w), 910 (m), 869 (w),
CCDC-720448 contains the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif
ꢀ
1
45 (m), 813 cm (w); elemental analysis calcd (%) for C118
190 4 14 2
H N 0 S :
C 72.57, H 9.81, N 2.87; found: C 72.64, H 10.44, N 3.22.
1
ADS-C14amm: Isolated yield: 39%. H NMR (DMSO, 400 MHz, 708C):
3
d=0.87 (t, J=6.5 Hz, 18H), 1.20–1.55 (m, 132H), 1.64–1.83 (m, 12H),
Acknowledgements
3
3
3
4
2
.62 (s, 18H), 3.99 (t, J=6.5 Hz, 4H), 4.07 (t, J=6.3 Hz, 8H), 7.27 (s,
H), 7.73 (d, J=9.4 Hz, 2H), 7.87–8.03 (m, 10H), 8.29 (s, 2H), 8.52 (s,
H), 10.12 ppm (s, NH, 2H); IR (ATR): n˜ =3314 (br w) (nNH), 2917
), 2850 (vs) (n CH ), 1665 (s) (nCO), 1609 (m), 1582 (s), 1546
2 s 2
s), 1516 (m), 1500 (vs), 1473 (s), 1466 (s), 1427 (m), 1388 (w), 1335 (vs),
294 (w), 1276 (w), 1259 (w), 1223 (vs), 1196 (m), 1184 (vs), 1158 (m),
129 (w), 1105 (vs), 1083 (vs), 1027 (vs), 997 (w), 973 (w), 939 (w), 929
w), 910 (m), 869 (w), 841 (m), 814 cm (w); elemental analysis calcd
3
This work was jointly supported by the University of Strasbourg through
the European School of Polymer and Materials Chemistry (ECPM) and
by the Centre National de la Recherche Scientifique (CNRS) of France.
Financial support from the MICINN-FEDER Spanish project CTQ2006-
15611-C02-01 is gratefully acknowledged. We are indebted to Professor J.
Harrowfield from ISIS in Strasbourg, for his comments on the manuscript
prior to publication.
(
vs) (nasCH
(
1
1
(
ꢀ
1
(
%) for C130
H
214
N
4
0
14
S
2
: C 73.61, H 10.17, N 2.64; found: C 73.95, H
1
0.49, N 2.99.
1
ADS-C16amm: Isolated yield: 40%. H NMR (DSMO, 400 MHz, 808C):
d=0.87 (m, 18H), 1.18–1.56 (m, 156H), 1.65–1.83 (m, 12H), 3.62 (s,
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3
3
1
(
8H), 3.99 (t, J=6.3 Hz, 4H), 4.07 (t, J=6.0 Hz, 8H), 7.27 (s, 4H), 7.73
3
d, J=9.0 Hz, 2H), 7.86–8.02 (m, 10H), 8.29 (s, 2H), 8.51 (s, 2H),
0.11 ppm (s, NH, 2H); IR (ATR): n˜ =3311 (br w) (nNH), 2917 (vs)
), 2850 (vs) (n CH ), 1665 (s) (nCO), 1609 (m), 1582 (s), 1546 (s),
516 (m), 1500 (vs), 1473 (s), 1466 (s), 1427 (m), 1388 (w), 1335 (vs),
292 (w), 1277 (w), 1252 (w), 1223 (vs), 1184 (vs), 1158 (w), 1129 (w),
106 (vs), 1084 (vs), 1027 (vs), 1015 (m), 990 (w), 969 (w), 940 (w), 910
1
(
n
asCH
2
s
2
1
1
1
ꢀ1
(
m), 869 (w), 847 (m), 812 cm (w); elemental analysis calcd (%) for
: C 74.49, H 10.48, N 2.45; found: C 74.82, H 10.88, N
142 238 4 14 2
C H N 0 S
2
.22.
General procedure for the synthesis of the [ADS-C benzyl] complexes
n=8, 12, 16): The sulfonate salt (1 equiv) was dissolved in DMF
2 mgmL ) and the C benzyl (1 equiv per negative charge) was added.
n
The mixture was stirred at 608C for one night. After cooling, water was
added and the precipitate was washed with water and dried under
vacuum. ADS-C12benzyl and ADS-C16benzyl were recrystallised in hot
8 2 2
DMSO and ADS-C benzyl was recrystallised in a CH Cl /AcOEt mixture
by slow evaporation of dichloromethane.
n
(
(
ꢀ
1
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5] J. E. Anthony, Chem. Rev. 2006, 106, 5028–5048.
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[
1
1
[8] a) Y.-H. Kim, D.-C. Shin, S.-H. Kim, C.-H. Ko, H.-S. Yu, Y.-S. Chae,
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ADS-C
0
(
(
9
2
(
1
8
8
benzyl: Isolated yield: 45%. H NMR (DMSO, 300 MHz): d=
.82–0.86 (m, 18H), 1.24–1.42 (m, 60H), 1.55–1.73 (m, 12H), 3.78–3.83
m, 10H), 3.92 (t, J=6.0 Hz, 8H), 5.24 (s, 4H), 6.78 (s, 4H), 7.66–7.69
m, 4H), 7.80 (s, 2H), 8.01 (d, J=8.7 Hz, 2H), 8.27 (s, 2H), 8.59 (s, 2H),
.15 ppm (s, 2H); IR (ATR): n˜ =2952 (w) (nasCH
867 (w) (n CH ), 2852 (vs) (n CH ), 1588 (m), 1564 (w), 1504 (m), 1469
m), 1453 (m), 1442 (m), 1382 (w), 1363 (w), 1334 (m), 1224 (s), 1189 (s),
113 (s), 1086 (s), 1023 (s), 965 (w), 952 (m), 930 (w), 907 (m), 873 (w),
33 (w), 816 cm (w); elemental analysis calcd (%) for C84
3
1
799–1805; c) S. Zheng, J. Shi, Chem. Mater. 2001, 13, 4405–4407;
3
d) G. Klärner, M. H. Davey, W. D. Chen, J. C. Scott, R. D. Miller,
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3 2
), 2924 (vs) (nasCH ),
s
3
s
2
1
7320–17333.
[
9] H. Meng, F. Sun, M. B. Goldfinger, G. D. Jaycox, Z. Li, W. J. Mar-
ꢀ
1
130 4 12 2
H N O S :
shall, G. S. Blackman, J. Am. Chem. Soc. 2005, 127, 2406–2407.
C 69.48, H 9.02, N 3.86; found: C 69.64, H 9.02, N 3.86.
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1
ADS-C12benzyl: Isolated yield: 70%. H NMR (DMSO, 200 MHz): d=
0
.80–0.86 (m, 18H), 1.12–1.71 (m, 120H), 3.76–3.83 (m, 10H), 3.92 (t,
J=6.4 Hz, 8H), 5.23 (s, 4H), 6.77 (s, 4H), 7.66–7.69 (m, 4H), 7.80 (s,
H), 8.01 (d, J=8.8 Hz, 2H), 8.26 (s, 2H), 8.60 (s, 2H), 9.14 ppm (s,
H); IR (ATR): n˜ =2957 (w) (nasCH ), 2919 (vs) (nasCH ), 2864 (w)
CH ), 2850 (vs) (n CH ), 1587 (m), 1562 (w), 1504 (m), 1465 (m), 1453
m), 1441 (m), 1384 (w), 1363 (w), 1335 (m), 1223 (s), 1190 (s), 1115 (s),
086 (s), 1023 (s), 965 (w), 952 (m), 930 (w), 907 (m), 873 (w), 833 (w),
16 cm (w); elemental analysis calcd (%) for C107
H 10.03, N 3.13; found: C 72.84, H 10.37, N 3.52.
3
3
2
2
1
3, 1622–1630; e) S. Norvez, F.-G. Tournilhac, P. Bassoul, P. Herson,
3
2
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(
(
n
s
3
s
2
1
8
ꢀ
1
178 4 12 2
H N 0 S : C 72.52,
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1
ADS-C16benzyl: Isolated yield: 65%. H NMR (DMSO, 300 MHz, 608C):
d=0.84–0.87 (m, 18H), 1.25–1.47 (m, 156H), 1.60–1.74 (m, 12H), 3.83–
.87 (m, 10H), 3.95 (t, J=6.4 Hz, 8H), 5.25 (s, 4H), 6.74 (s, 4H), 7.65–
.66 (m, 2H), 7,71 (d, J=8.4 Hz, 2H), 7.73–7.75 (m, 2H), 7.99 (d, J=
.8 Hz, 2H), 8.28 (s, 2H), 8.54 (s, 2H), 9.10 ppm (s, 2H); IR (ATR): n˜ =
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3
3
7
8
2
3
3
957 (w) (nasCH
3 2 s 3
), 2915 (vs) (nasCH ), 2862 (w) (n CH ), 2850 (vs)
CH ), 1587 (m), 1504 (m), 1469 (m), 1456 (m), 1441 (m), 1382 (w),
(
n
s
2
Chem. Eur. J. 2009, 15, 8163 – 8174
ꢆ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Received: March 19, 2009
Published online: July 11, 2009
8174
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ꢆ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 8163 – 8174