Self-assembly in helical columnar mesophases and luminescence of chiral 1H-pyrazoles

Article abstract of DOI:10.1002/chem.200901154

Chiral polycatenar lH-pyrazoles self-assemble to form columnar mesophases that are stable at room temperature. X-ray diffraction and CD studies in the mesophase indicate a supramolecular helical organization consisting of stacked H-bonded dimers. The liquid-crystalline compounds reported are 3,5-bis(dialkoxyphenyl)-1Hpyrazoles that incorporate two or four dihydrocitronellyl chiral tails. It can be observed that the grafting of these branched chiral substituents onto the 3,5-diphenyl-1H-pyrazole core has a beneficial role in inducing mesomorphism, because isomeric linear-chain compounds are not liquid crystalline; this is not the usual scheme of behav-ior. Furthermore, the molecular chirality is transferred to the columnar mesophase, because preferential helical arrangements are observed. Films of the compounds are luminescent at room temperature and constitute an example of the self-organization of nondiscoid units into columnar liquid-crystalline assemblies in which the functional molecular unit transfers its properties to a hierarchically built superstructure.

Full text of DOI:10.1002/chem.200901154

FULL PAPER
DOI: 10.1002/chem.200901154
Self-Assembly in Helical Columnar Mesophases and Luminescence of Chiral
1H-Pyrazoles
Eduardo Beltrꢀn,[a] Emma Cavero,[a] Joaquꢁn Barberꢀ,[a] Josꢂ Luis Serrano,[a]
Anabel Elduque,*[b] and Raquel Gimꢂnez*[a]
Abstract: Chiral polycatenar 1H-pyra-
zoles self-assemble to form columnar
mesophases that are stable at room
temperature. X-ray diffraction and CD
studies in the mesophase indicate a
supramolecular helical organization
consisting of stacked H-bonded dimers.
The liquid-crystalline compounds re-
ported are 3,5-bis(dialkoxyphenyl)-1H-
pyrazoles that incorporate two or four
dihydrocitronellyl chiral tails. It can be
observed that the grafting of these
branched chiral substituents onto the
3,5-diphenyl-1H-pyrazole core has
beneficial role in inducing mesomor-
phism, because isomeric linear-chain
compounds are not liquid crystalline;
this is not the usual scheme of behav-
ior. Furthermore, the molecular chirali-
ty is transferred to the columnar meso-
phase, because preferential helical ar-
rangements are observed. Films of the
compounds are luminescent at room
temperature and constitute an example
of the self-organization of nondiscoid
units into columnar liquid-crystalline
assemblies in which the functional mo-
lecular unit transfers its properties to a
hierarchically built superstructure.
a
Keywords: chirality · liquid crys-
tals · luminescence · nanostructures ·
self-assembly
chemistry
·
supramolecular
Introduction
All of these characteristics are put into play in columnar
liquid crystals, in which molecular or supramolecular entities
are stacked and the molecular chirality can be transferred
and amplified through the formation of helical superstruc-
tures.[6] Moreover, desirable optical and electronic proper-
ties can be attained with columnar organizations consisting
of functional molecular entities.[7–12]
1H-Pyrazoles are structural building blocks that have the
potential to self-organize into a rich variety of superstruc-
tures through hydrogen bonding.[13] As part of our research
program, we have studied polycatenar 3,5-diaryl-1H-pyra-
zoles as promesogenic ligands in coordination compounds
with boron,[14,15] gold,[16,17] zinc,[18] and rhodium[19] in order to
obtain columnar mesophases. All of the complexes reported
were liquid crystalline, despite the variety of shapes and ge-
ometries, with the mesophases obtained at room tempera-
ture in most cases. However, the 1H-pyrazoles themselves
were not liquid crystalline, despite their elongated rigid
shape and the possibility of generating stackable dimeric or
trimeric structures by H-bonding. We therefore concluded
that H-bonding, although present in the condensed phases
of the 1H-pyrazoles, was not sufficient to induce and stabi-
lize the columnar stacking of molecules with such low
aspect ratios.
The self-assembly of molecular building blocks into complex
ordered systems is a subject of increasing research interest
and underpins the development of bottom-up approaches to
functional nanostructures.[1–4] The information encoded in
the molecular components is fundamental in yielding struc-
tures through supramolecular interactions, with exquisite
control of shape and function.
Complex supramolecular arrangements can be obtained
from simple molecules by means of noncovalent interac-
tions, which encompass H-bonding, dipolar forces, Coulom-
bic interactions, p–p stacking, metal complexation, or a
combination of these. Chirality is another powerful element
to yield extended hierarchical organizations and functions.[5]
[a] E. Beltrꢀn, Dr. E. Cavero, Dr. J. Barberꢀ, Prof. J. L. Serrano,
Dr. R. Gimꢁnez
Department of Organic Chemistry
Facultad de Ciencias—Instituto de Ciencia de Materiales de Aragꢂn
Universidad de Zaragoza—CSIC, Pedro Cerbuna 12, 50009 (Spain)
Fax : (+34)976-762686
E-mail: rgimenez@unizar.es
[b] Dr. A. Elduque
Department of Inorganic Chemistry
Facultad de Ciencias—Instituto de Ciencia de Materiales de Aragꢂn
Universidad de Zaragoza—CSIC, Pedro Cerbuna 12, 50009 (Spain)
In the work described here, we successfully attempted to
induce columnar mesophases in purely organic 3,5-diaryl-
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1H-pyrazoles through the introduction of branched chiral
chains. In particular, the structures studied consist of 3,5-bis-
ACHTUNGTRENNUNG(alkoxyphenyl)-1H-pyrazoles that incorporate several chiral
(3,7-dimethyloctyl, also named dihydrocitronellyl) and/or
achiral (n-decyloxyl) aliphatic side chains, with the total
number ranging from four to six (Scheme 1). From the
tionally been obtained by Claisen condensation of an aceto-
phenone and a benzoate ester with NaH in 1,2-dimethoxy-
ethane heated to reflux. However, this reaction often gives
low yields and extensive hydrolysis of the benzoate ester,
and it is very sensitive to the storage conditions of NaH. For
this reason, we prepared the pyrazoles described in this
work by adapting a recently described one-pot procedure[20]
to our polyalkoxy starting materials. The method uses a
weaker base (lithium 1,1,1,3,3,3-hexamethyldisilazane or
LiHMDS) to generate the enolate of the acetophenone, low
temperatures, and acid chlorides, which are better electro-
philes than esters. The diketone was not isolated but was
treated directly with hydrazine hydrate to give the final 1H-
pyrazole (Scheme 2).
Self-assembly and structural characterization: Compounds
2(S)2C10 and 2(R)2C10, with two n-decyloxyl tails and two
dihydrocitronellyl tails, were isolated as liquid-crystalline
materials that crystallized after several weeks. Polarizing op-
tical microscopy and differential scanning calorimetry
(DSC) studies revealed that both enantiomers display a col-
umnar mesophase with pseudo-focal-conic textures on cool-
ing from the isotropic liquid (Figure 1). Isomeric compounds
4(S) and 4(R), with four dihydrocitronellyl tails, are thermo-
dynamically stable columnar liquid crystals at room temper-
ature (Table 1). The terminal chain structure is fundamental
in inducing mesomorphism, because the isomeric linear-
chain pyrazole (with four n-decyloxyl tails) is solid at room
temperature and melts to an isotropic liquid at 958C with a
high enthalpy.[21] The pyrazoles with five chains (2(S)3C10,
3(S)2C10, and 5(S)) are all isotropic liquids at room temper-
ature and glassify with no signs of crystallization or meso-
Scheme 1. Molecular structures of the chiral 1H-pyrazoles.
structural characterization, we
propose that H-bonded dimeric
species are present as the sec-
ondary structure of the com-
pounds and that these species,
in turn, self-assemble at room
temperature to give thermody-
namically
stable
columnar
liquid-crystalline
assemblies
Scheme 2. Synthetic pathway for the polycatenar 1H-pyrazoles. DMF: N,N-dimethylformamide; THF: tetrahy-
drofuran.
with helical organization. We
also show that films of these
compounds exhibit lumines-
cence in the mesophase, and this constitutes an example in
which the functional molecular unit (3,5-diphenylpyrazole)
transfers its properties to a hierarchically built superstruc-
ture.
phase induction below room temperature. This is in sharp
contrast with the isomeric compound bearing five n-decylox-
yl tails, which is a solid and melts to an isotropic liquid at
578C.[15] Pyrazoles with six alkoxy tails (3(S)3C10 and 6(S))
are isotropic liquids at room temperature, as is the isomeric
pyrazole with six n-decyloxyl tails.[15]
Results and Discussion
Therefore, only the introduction of dihydrocitronellyl
chains in the compounds with four chains gives rise to a de-
crease in the melting point and the induction of mesomor-
phism, which provides evidence that the columnar organiza-
tions found with these molecules result from a delicate bal-
Synthesis: The synthesis of polycatenar 1H-pyrazoles is ac-
complished by the reaction of 1,3-diketones with hydrazine
hydrate. The precursor 1,3-diaryl-1,3-diketones have tradi-
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Helical Columnar Mesophases
FULL PAPER
2(S)2C10 and 2(R)2C10, for which no signs of crystallization
were observed during the experiments. The experiments
confirmed that the mesophase of the pyrazoles with four
chains is hexagonal columnar (Table 2). The hexagonal cell
Table 2. Powder X-ray diffraction data (d) for the mesophase at room
temperature.
Compound
dmeasured [ꢄ] dcalcd [ꢄ] hk Mesophase
parameters
2(S)2C10 and 2(R)2C10 22.8
22.9
13.2
11.5
10 Colh, a=26.4 ꢄ
11
20
13.3
11.5
4.6
4(S) and 4(R)
21.5
12.4
10.5
4.6
21.3
12.3
10.6
10 Colh, a=24.6 ꢄ
11
20
Figure 1. Microphotographs of the mesophases observed at room temper-
ature for a) 2(S)2C10, b) 2(R)2C10, c) 4(S), and d) 4(R).
parameter is slightly smaller for the all-dihydrocitronellyl-
substituted compounds 4(S) and 4(R), due to the shorter
length of the aliphatic tails in comparison with that of the n-
decyloxyl tails.
Table 1. DSC data for the mesomorphic 1H-pyrazoles.[a]
Compound
Thermal cycle
Peak phase-transition temperatures [8C]
(transition enthalpies [kJmolÀ1])
A study on a partially aligned sample of compound
2(S)2C10 revealed that the columns were oriented parallel
to the capillary axis and, hence, perpendicular to the X-ray
beam. In the oriented pattern (Figure 2a), a sharp maximum
2(S)2C10
1st heating
1st cooling
2nd heating
1st heating
1st cooling
2nd heating
1st heating
1st heating
1st heating
1st heating
1st heating
1st heating
1st heating
Cr[b] 58 (54.9) I
I 38 (1.2) Colh
Colh 47 (1.3) I
Cr[b] 58 (45.3) I
I 39 (1.9) Colh
Colh 47 (1.8) I
Colh 57 (2.6) I
Colh 56 (2.3) I
I[c]
2(R)2C10
4(S)
4(R)
2(S)3C10
3(S)2C10
5(S)
3(S)3C10
6(S)
I[c]
I[c]
I[c]
I[c]
[a] Cr: crystalline phase; Colh: columnar hexagonal mesophase; I: iso-
tropic liquid. [b] Transition only observed after the crystalline phase had
been left for several weeks at room temperature. [c] Isotropic liquid at
room temperature. No DSC peaks were detected below room tempera-
ture.
Figure 2. XRD patterns for the mesophase of a) 2(S)2C10 and b) 4(S).
appeared in the low-angle region; this can be assigned to
the (10) reflection from the two-dimensional hexagonal lat-
tice. A diffuse halo, which is characteristic of the liquid-like
order of the aliphatic chains, was also observed at wide
angles (4.6 ꢄ). The low-angle maximum is reinforced in the
equatorial region (plane perpendicular to the capillary axis).
In addition, a set of spots at middle angles was also ob-
served. These appeared in the meridional region (parallel di-
rection to the column axes), and they are related to the peri-
odic distances or local order within the column. The pair of
diffuse spots that appear at both sides of the meridian at
middle angles are indicative of a modulation of the electron-
ic density along the stacking direction. We attribute the
modulation to a helical stacking of the molecules in the
column.[25–31] The periodicity of the modulation is 20.6 ꢄ and
corresponds to the periodicity of the helix.
ance of weak supramolecular van der Waals side-chain inter-
actions, space filling, and H-bonding. This is contrary to the
usual scheme of behavior, in that a decrease of the transi-
tion temperatures caused by dihydrocitronellyl groups usual-
ly reduces the mesophase interval relative to that of the
analogous linear-chained columnar liquid crystals, due to the
existence of an increased degree of side-chain disorder.[22]
However, it is worth mentioning that for some well-estab-
lished discotic liquid crystals, like triphenylenes[23] or coro-
nenes,[24] stabilization of the columnar mesophase and in-
creased order has been observed upon the introduction of
branched lateral chains; this was attributed to an improve-
ment in the peripheral space filling around the aromatic
cores.
Powder X-ray diffraction (XRD) studies in the mesophase
were performed at room temperature on all compounds that
have a stable mesophase at that temperature, including
The supramolecular organization in the columnar meso-
phase can be envisaged by estimating the number of mole-
cules related to the periodicity of 20.6 ꢄ in a hexagonal cell
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R. Gimꢁnez, A. Elduque et al.
with a=26.4 ꢄ, which amounts to 8 for a density of about
1 gcmÀ3. This finding allowed us to propose a model with 2
pyrazoles per column stratum and a mean stacking distance
of 5.2 ꢄ. The two pyrazoles could interact through a double
intermolecular H-bond, which would give rise to a discotic
dimer. The size of the discotic dimer agrees well with the
measured hexagonal parameter for this mesophase (see
Table 2) and is fully consistent with the cell parameters pre-
viously measured in hexagonal columnar mesophases of sim-
ilar derivatives, for example, the covalently bound pyrazole
dimers derived from bis(pyrazolyl)methane (a=28.2 ꢄ)[18]
or the mononuclear rhodium–pyrazole complex with an an-
tiparallel arrangement of molecules along the column (a=
27.0 ꢄ).[19]
This situation is further supported by the fact that the
NH-stretching peak in the IR spectrum appears in the H-
bonded region (below 3200 cmÀ1). If the 1H-pyrazoles inter-
act by H-bonding in their solid state, this could give rise to
different structures depending on the steric and polarizabili-
ty effects of their substituents.[13,32] In particular, 3,5-diaryl-
stacking distance (5.2 ꢄꢅ2). This could be due to a modula-
tion of the electronic density along the column arising from
an interaction between the aromatic rings of one pyrazole
and its second nearest neighbor, which is rotated by 908
(Figure 3). Indeed, due to the X-like shape of the dimers,
the benzene rings of every two stacked molecules are locat-
ed on top of each other. The same orientation pattern was
observed for compound 2(R)2C10, which afforded a similar
superstructure.
In the case of the all-chiral compounds, we were able to
obtain a well-oriented pattern for 4S, and this confirmed
that a helical organization also exists in the columnar meso-
phase. In this case (Figure 2b), we could observe up to the
third order of a hexagonal symmetry along the equator; a
split scattering maximum assigned to the helical structure at
20.0 ꢄ; and meridional reflections at 10.2 and 5.1 ꢄ assigned
to additional electronic modulation along the stacking direc-
tion. These observations are consistent with the model pro-
posed in Figure 3, in which dimers are stacked regularly at
5.1 ꢄ and arranged in a helical fashion with a pitch of 40 ꢄ.
ACHTUNGTRENNUNGpyrazoles have been found to interact in dimers by double
intermolecular H-bonds[33–35] or in tetramers by four inter-
molecular H-bonds.[19,35,36] The dimeric species are planar,
but the tetrameric systems are globular and are therefore
less suitable for stacking in columns.
Optical properties: Absorption spectra were measured on
films of the 1H-pyrazoles at room temperature. The data
are collected in Table 3. In all cases, 2 main broad bands
The data are consistent with a columnar structure in
which the stacked dimers are mutually rotated around the
normal to their mean planes by an angle of 458 (Figure 3). If
their two-fold symmetry is taken into account, 4 dimers
make half a turn and, thus, the actual helical pitch is 41.2 ꢄ.
The additional sharp and intense maximum appearing at
10.3 ꢄ at the meridian is consistent with a certain local
order along the column, and this corresponds to twice the
Table 3. Absorption (labs) and emission data (lem) for film samples at
room temperature.
Compound
labs[a] [nm]
lem [nm]
2(S)2C10
2(R)2C10
4(S)
218, 267, 293sh, 310sh
218, 267, 293sh, 310sh
219, 270, 301sh, 314sh
219, 268, 301sh, 314sh
225, 260, 298sh
223, 263, 299
214, 272, 300
221, 274, 300
219, 302
350
350
347
347
344
344
342
351
353
4(R)
2(S)3C10
3(S)2C10
5(S)
3(S)3C10
6(S)
[a] sh: shoulder band.
were observed, the first centered at around 220 nm and the
second at 270 nm. The latter band has a shoulder at 300 nm
in the compounds with 5 or 6 aliphatic chains (samples that
are in the isotropic liquid state), but it is much broader, with
a second shoulder at 310 nm, for the compounds with 4
chains (which are measured in the columnar mesophase) as
a consequence of the supramolecular aggregation.
The compounds exhibit a broad luminescence band in the
near-UV blue region when excited at either their absorption
maxima or at longer wavelengths (Figure 4). All of the com-
pounds display similar behavior, independently of their
physical state, and the spectra are related to the molecular
emission bands, which indicates little effect of the condensed
phase on the emission wavelength.
Circular dichroism (CD) and UV/Vis spectra of thin films
were measured in the hexagonal columnar phase in an
effort to prove further the existence of chiral supramolec-
ular structures. The samples were prepared on a quartz
Figure 3. Schematic representation of the dimeric association and pro-
posed molecular model for the columnar packing.
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Helical Columnar Mesophases
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For compounds 2(S)2C10 and 2(R)2C10, although helical
features were observed in the mesophase by XRD, the CD
spectra measured under the same conditions as before do
not show any signal. We attribute this behavior to the fact
that the helical organization present is not biased towards
any prevailing twist sense in these compounds.
Conclusions
We have shown that nondiscoid 3,5-diaryl-1H-pyrazoles
bearing dihydrocitronellyl chiral tails display columnar mes-
ophases at room temperature only if the compound contains
two dihydrocitronellyl chains and two n-decyloxyl chains or,
alternatively, four dihydrocitronellyl chains. Other combina-
tions do not yield liquid-crystalline assemblies, which pro-
vides evidence that the columnar organizations found in
these compounds result from a delicate balance of weak
supramolecular van der Waals interactions and H-bonding.
The current observations point to a hierarchical self-as-
sembly in which the 1H-pyrazoles self-assemble into disk-
like dimers through double intermolecular hydrogen bonds.
These dimers stack to form hexagonal columnar structures,
which in turn have a helical structure. Films of these com-
pounds exhibit luminescence in the mesophase. This consti-
tutes an example of the self-organization of nondiscoid func-
tional units into columnar liquid-crystalline assemblies.
Figure 4. Absorption (dashed line) and emission (solid line) spectra of
the mesophase of 2(S)2C10 at room temperature.
plate, heated to form the isotropic liquid, and cooled to
room temperature. The averaged CD spectra of compounds
4(S) and 4(R) show bands in the region of the absorption of
the compound (Figure 5). These bands are not present in
Experimental Section
Methods: The XRD patterns were obtained with a pinhole camera
(Anton–Paar) operating with a point-focused Ni-filtered Cu-Ka beam.
The samples were held in Lindemann glass capillaries (0.9 mm diameter),
and the patterns were collected on flat photographic film perpendicular
to the X-ray beam. Spacings were obtained by using Braggꢆs law.
Materials: Acetophenones and benzoates were prepared according to
methods previously reported for polyalkoxylated compounds.[15] Polyal-
koxylated acid chlorides were prepared by hydrolysis of the benzoates to
form the benzoic acids and reaction with oxalyl chloride. The chiral
alkoxy chains required for alkylation reactions were prepared by catalytic
hydrogenation of the commercially available (R)- or (S)-citronellyl bro-
mide.[37]
General procedure for the preparation of 1H-pyrazoles: LiHMDS
(1.05 mmol, 1.05 mL of a 1m solution in THF) was added dropwise to a
cooled (08C) solution of the polyalkoxylated acetophenone (1 mmol) in
dry toluene (10 mL) under argon. The mixture was stirred at 08C for
5 min, and then a solution of the corresponding acid chloride (1 mmol) in
dry toluene (10 mL) was added by cannula. The reaction mixture was
stirred at room temperature until completion (1–5 h). Acetic acid (2 mL),
ethanol (10 mL), THF (5 mL), and hydrazine hydrate (17.2 mmol,
0.8 mL) were added, and the mixture was stirred at 808C for 2 h. The
mixture was cooled to room temperature, poured into 1m NaOH
(50 mL), extracted with ethyl acetate (2ꢅ20 mL), dried, and evaporated
to dryness. The resulting residue was purified by flash chromatography
with the eluent indicated in each particular case.
2(S)2C10 and 2(R)2C10: Eluent: CH2Cl2; yield: 40%; 1H NMR
(400 MHz, CDCl3): d=0.85–0.89 (m, 18H), 0.95 (d, J=6.3 Hz, 6H),
1.14–1.40 (m, 36H), 1.40–1.75 (m, 10H), 1.77–1.94 (m, 6H), 3.98–4.12 (m,
8H), 6.67 (s, 1H), 6.89–6.92 (m, 2H), 7.20–7.22 (m, 2H), 7.25 ppm (m,
2H); 13C NMR (100 MHz, CDCl3): d=14.1, 14.2, 19.6, 19.7, 22.6, 22.6,
22.7, 24.7, 26.0, 26.0, 27.9, 29.2, 29.3, 29.4, 29.6, 29.7, 29.8, 29.9, 31.9, 36.2,
Figure 5. CD spectra of the mesophase of 4(S) (dashed line) and 4(R)
(solid line) at room temperature.
the isotropic melt or in solution, and the main signals ob-
served are related to wavelengths at which the UV/Vis spec-
tra show aggregation bands. When the compound bears the
enantiomeric chiral tail (4(S) versus 4(R)), the CD spectrum
obtained under the same conditions shows the opposite sign.
Therefore, formal optical activity is observed, and this arises
from a chiral superstructure in the mesophase that could
indeed correspond to a helical arrangement within the
column, as proposed from the oriented XRD pattern.
Therefore, the molecular chirality is transferred to the col-
umnar mesophase, because preferential helical arrange-
ments of opposite handness, depending on the chirality sign
of the dihydrocitronellyl side group, are observed.
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R. Gimꢁnez, A. Elduque et al.
+
1238 cmÀ1 (C O); MS (MALDI): m/z: 1158.0 [M ]; elemental analysis
calcd for C75H132N2O6: C 77.68, H 11.49, N 2.42; found: C 77.69, H 11.25,
N 2.47.
À
37.3, 39.2, 67.3, 67.5, 69.1, 69.2, 98.8, 110.8 (br), 113.5, 113.7, 118.1, 124.3
À
(br), 149.0, 149.1, 149.3 ppm; IR (neat, NaCl): n˜ =3152 (br, N H), 1614,
À1
À
À
1593, 1511, 1486, (C=N, Ar C C), 1256 cm (C O); MS (MALDI): m/z:
845.8 [M+]; elemental analysis calcd for C55H92N2O4: C 78.15, H 10.97, N
3.31; found for 2(S)2C10: C 78.09, H 10.86, N 3.23; found for 2(R)2C10:
C 78.27, H 10.95, N 3.26.
4(S) and 4(R): Eluent: hexane/ethyl acetate (8:1.7); yield: 60%;
1H NMR (400 MHz, CDCl3): d=0.87 (d, J=6.5 Hz, 24H), 0.95 (d, J=
6.5 Hz, 12H), 1.08–1.38 (m, 24H), 1.42–1.72 (m, 12H), 1.57–1.69 (m,
4H), 4.00–4.14 (m, 8H), 6.68 (s, 1H), 6.92 (d, 2H, J=8.3 Hz, 2H), 7.22
(dd, J=8.3, 1.7 Hz, 2H), 7.25 ppm (d, J=1.7 Hz, 2H); 13C NMR
(100 MHz, CDCl3): d=19.7, 22.6, 22.7, 24.7, 28.0, 29.9, 36.2, 36.3, 37.4,
39.3, 67.6, 67.7, 99.3, 111.2, 113.7, 118.3, 124.3, 149.4, 149.4 ppm; IR
Acknowledgements
We thank the following institutions for financial support: Gobierno de
Aragꢂn (project PM068/2007), MICINN (Spain), FSE (UE) (projects
MAT2006-13571-CO2-01, CTQ2006-15611-C02-01, and CTQ2008-03860)
and MICINN CSIC-I3 (project 200860I054).
À
À
(neat, NaCl): n˜ =3162 (br, N H), 1609, 1590, 1511 (C=N, Ar C C),
+
1262 cmÀ1 (C O); MS (MALDI): m/z: 845.9 [M ]; elemental analysis
À
[1] D. N. Reindhout, Supramolecular Materials and Technologies, Wiley,
New York, 1999.
calcd for C55H92N2O4: C 78.15, H 10.97, N 3.31; found for 4(S): C 78.01,
H 10.95, N 3.29; found for 4(R): C 77.95, H 10.85, N 3.24.
[2] F. J. M. Hoeben, P. Jonkheijm, E. W. Meijer, A. P. H. J. Schenning,
Chem. Rev. 2005, 105, 1491–1546.
[3] K. Kinbara, T. Aida, Chem. Rev. 2005, 105, 1377–1400.
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7, 343–354.
2(S)3C10: Eluent: CH2Cl2/ethyl acetate (20:1); yield: 56%; 1H NMR
(400 MHz, CDCl3): d=0.85–0.87 (m, 21H), 0.96 (d, J=6.5 Hz, 6H),
1.10–1.18 (m, 6H), 1.20–1.37 (m, 48H), 1.42–1.61 (m, 8H), 1.61–1.93 (m,
12H), 3.97–4.11 (m, 10H), 6.68 (s, 1H), 6.90–6.92 (m, 3H), 7.20 (dd, J=
8.4, 1.7 Hz, 1H), 7.24 ppm (d, J=2.0 Hz, 1H); 13C NMR (100 MHz,
CDCl3): d=14.1, 19.7, 22.6, 22.7, 22.7, 24.7, 26.1, 26.1, 28.0, 29.4, 29.4,
29.4, 29.6, 29.6, 29.7, 29.7, 29.7, 29.9, 30.3, 31.9, 31.9, 36.2, 36.3, 37.3, 39.3,
67.6, 67.7, 69.3, 73.5, 100.0, 104.5, 111.3, 113.7, 118.4, 149.2, 153.5 ppm;
À
À
IR (neat, NaCl): n˜ =3133, 3108 (br, N H), 1589, 1507 (C=N, Ar C C),
[8] T. Kato, N. Mizoshita, K. Kishimoto, Angew. Chem. 2006, 118, 44–
74; Angew. Chem. Int. Ed. 2006, 45, 38–68.
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1902–1929.
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Scalia, R. Judele, E. Kapatsina, S. Sauer, A. Schreivogel, M. Tosoni,
Angew. Chem. 2007, 119, 4916–4973; Angew. Chem. Int. Ed. 2007,
46, 4832–4887.
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2009, 729–739.
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2000, 56, 1018–1028.
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Angew. Chem. 1996, 108, 3048–3051; Angew. Chem. Int. Ed. Engl.
1996, 35, 2832–2835.
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1992, 11, 887–897.
[22] See, for example: a) D. M. Collard, C. P. Lillya, J. Am. Chem. Soc.
1991, 113, 8577–8583; b) S. T. Trzaska, H.-F. Hsu, T. M. Swager, J.
Am. Chem. Soc. 1999, 121, 4518–4519; c) K. Kishikawa, S. Furusa-
wa, T. Yanaki, S. Kohmoto, M. Yamamoto, K. Yamaguchi, J. Am.
Chem. Soc. 2002, 124, 1597–1605.
+
1258 cmÀ1 (C O); MS (MALDI): m/z: 1001.9 [M ]; elemental analysis
À
calcd for C65H112N2O5: C 77.95, H 11.27, N 2.80; found: C 77.72, H 10.99,
N 2.86.
3(S)2C10: Eluent: CH2Cl2/ethyl acetate (100:1); yield: 20%; 1H NMR
(400 MHz, CDCl3): d=0.86–0.88 (m, 24H), 0.93 (d, J=6.5 Hz, 9H),
1.12–1.40 (m, 42H), 1.42–1.65 (m, 10H), 1.65–1.79 (m, 4H), 1.80–1.91 (m,
6H), 3.98–4.08 (m, 10H), 6.66 (s, 1H), 6.85–6.92 (m, 3H), 7.19 (d, J=
8.3 Hz, 1H), 7.23 ppm (brs, 1H); 13C NMR (100 MHz, CDCl3): d=14.1,
19.6, 22.6, 22.6, 22.7, 22.7, 24.7, 24.7, 26.0, 26.0, 28.0, 29.3, 29.3, 29.4, 29.6,
29.6, 29.7, 29.8, 31.9, 36.5, 37.4, 37.5, 39.3, 39.4, 67.5, 69.3, 69.4, 71.7, 99.5,
104.3, 111.4, 113.8, 118.3, 149.4, 149.5, 153.4 ppm; IR (neat, NaCl): n˜ =
À1
À
À
À
3191, 3157, 3111 (br, N H), 1590, 1505 (C=N, Ar C C), 1259 cm (C
O); MS (MALDI): m/z: 1002.1 [M+]; elemental analysis calcd for
C65H112N2O5: C 77.95, H 11.27, N 2.80; found: C 78.08, H 11.35, N 2.61.
5(S): Eluent: CH2Cl2/ethyl acetate (20:1); yield: 20%; 1H NMR
(400 MHz, CDCl3): d=0.87 (d, J=6.8 Hz, 30H), 0.93–0.97 (m, 15H),
1.10–1.21 (m, 30H), 1.45–1.77 (m, 15H), 1.78–1.94 (m, 5H), 3.97–4.15 (m,
10H), 6.68 (s, 1H), 7.20 (dd, J=8.2, 2.0 Hz, 1H), 7.24 ppm (d, J=2.0 Hz,
1H); 13C NMR (100 MHz, CDCl3): d=19.6, 19.7, 19.7, 22.6, 22.6, 22.7,
24.7, 24.7, 28.0, 29.7, 29.8, 29.9, 36.2, 36.3, 36.5, 37.7, 37.5, 39.3, 39.3, 39.4,
67.5, 67.6, 67.7, 71.7, 99.6, 104.4, 111.3, 113.7, 118.3, 123.9, 126.7, 138.6,
149.4, 149.6, 153.5 ppm; IR (neat, NaCl): n˜ =3140, 3108 (br, N H), 1588,
1506 (C=N, Ar C C), 1258 cm (C O); MS (MALDI): m/z: 1002.0 [M
]; elemental analysis calcd for C65H112N2O5: C 77.95, H 11.27, N 2.80;
found: C 78.15, H 11.38, N 2.76.
3(S)3C10: Eluent: hexane/ethyl acetate (10:1); yield: 39%; 1H NMR
(400 MHz, CDCl3): d=0.86–0.92 (m, 27H), 0.92–0.94 (m, 9H), 1.07–1.41
(m, 54H), 1.41–1.61 (m, 9H), 1.61–1.94 (m, 15H), 3.94–4.14 (m, 12H),
6.68 (s, 1H), 6.90 ppm (s, 4H); 13C NMR (100 MHz, CDCl3): d=14.1,
19.6, 22.6, 22.7, 22.7, 24.7, 26.1, 28.0, 29.4, 29.4, 29.6, 29.8, 30.3, 31.9, 36.4,
37.4, 37.5, 39.3, 39.4, 67.5, 69.3, 71.7, 73.5, 100.0, 104.4, 104.5, 153.5 ppm;
À
À1
+
À
À
À
À
IR (neat, NaCl): n˜ =3158, 3107 (br, N H), 1590, 1500 (C=N, Ar C C),
[23] B. Glꢇsen, W. Heitz, A. Kettner, J. H. Wendorff, Liq. Cryst. 1996,
20, 627–633.
[24] A. Fechtenkçtter, N. Tchebotareva, M. Watson, K. Mullen, Tetrahe-
dron 2001, 57, 3769–3783.
1236 cmÀ1 (C O); MS (MALDI): m/z: 1158.1 [M ]; elemental analysis
+
À
calcd for C75H132N2O6: C 77.80, H 11.49, N 2.42; found: C 77.69, H 11.31,
N 2.43.
6(S): Eluent: hexane/ethyl acetate (20:1); yield: 50%; 1H NMR
(400 MHz, CDCl3): d=0.86 (d, J=6.6 Hz, 36H), 0.92–0.95 (m, 18H),
1.08–1.40 (m, 36H), 1.46–1.65 (m, 12H), 1.65–1.80 (m, 6H), 1.81–1.92 (m,
6H), 3.96–4.11 (m, 12H), 6.69 (s, 1H), 6.91 ppm (s, 4H); 13C NMR
(100 MHz, CDCl3): d=19.6, 22.6, 22.7, 24.7, 24.7, 28.0, 29.7, 29.9, 36.5,
37.4, 37.6, 39.3, 39.4, 67.6, 71.7, 100.0, 104.6, 126.3, 138.8, 153.6 ppm; IR
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724–726.
À
À
(neat, NaCl): n˜ =3146, 3107 (br, N H), 1589, 1499 (C=N, Ar C C),
9022
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ꢃ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 9017 – 9023

Helical Columnar Mesophases
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Received: April 30, 2009
Published online: July 27, 2009
Chem. Eur. J. 2009, 15, 9017 – 9023
ꢃ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
9023