Induction of the columnar phase of unconventional dendrimers by breaking the C2 symmetry of molecules

Article abstract of DOI:10.1002/chem.201200933

Two triazine-based unconventional dendrimers were prepared and characterized by ¹H and ¹³C NMR spectroscopy, mass spectrometry, and elemental analysis. Differential scanning calorimetry, polarizing microscopy, and powder XRD studies showed that these dendrimers display columnar liquid-crystalline phases during thermal treatment. This is ascribable to breaking of their C₂ symmetry. The molecular conformations of prepared dendrimers were obtained by computer simulation with the MM3 model of the CaChe program in the gas phase. The simulation showed that the conformations of the prepared dendrimers are rather flat and disfavor formation of the LC phase. However, due to C₂-symmetry breaking, the prepared dendrimers have structural isomers in the solid state and thus show the desired columnar phases. This new strategy should be applicable to other types of unconventional dendrimers with rigid frameworks. Broken symmetry: Unconventional triazine-based dendrimers (see figure) were prepared and, according to studies by differential scanning calorimetry, polarizing microscopy, and powder XRD, they display columnar liquid-crystalline (LC) phases. Simulations indicate that the conformations of the dendrimers are rather flat and disfavor formation of the LC phase. However, due to C ₂-symmetry breaking, they have structural isomers in the solid state and thus show the desired columnar phases. Copyright

Full text of DOI:10.1002/chem.201200933

FULL PAPER
DOI: 10.1002/chem.201200933
Induction of the Columnar Phase of Unconventional Dendrimers by
Breaking the C2 Symmetry of Molecules
Long-Li Lai,*[a] Sheng-Wei Wang,[a] Kung-Lung Cheng,[b] Jey-Jau Lee,[c]
Tsai-Hui Wang,[d] and Hsiu-Fu Hsu[d]
Abstract: Two triazine-based uncon-
lar conformations of prepared den-
drimers were obtained by computer
simulation with the MM3 model of the
CaChe program in the gas phase. The
simulation showed that the conforma-
tions of the prepared dendrimers are
rather flat and disfavor formation of
the LC phase. However, due to C2-
symmetry breaking, the prepared den-
drimers have structural isomers in the
solid state and thus show the desired
columnar phases. This new strategy
should be applicable to other types of
unconventional dendrimers with rigid
frameworks.
ventional dendrimers were prepared
1
and characterized by H and 13C NMR
spectroscopy, mass spectrometry, and
elemental analysis. Differential scan-
ning calorimetry, polarizing microsco-
py, and powder XRD studies showed
that these dendrimers display columnar
liquid-crystalline phases during thermal
treatment. This is ascribable to break-
ing of their C2 symmetry. The molecu-
Keywords: dendrimers · liquid crys-
tals · nitrogen heterocycles · sym-
metry breaking
Introduction
Triazine-based dendrimers have been extensively stud-
ied.[11] Several series of dendrimers were first prepared by
Simanek and Lim[11c] and Takagi et al.,[11b] by using the tria-
zine moiety as a linkage. Interestingly, the triazine unit in
the dendritic framework has been observed to show strong
p–p interaction with tetrafluorobenzoquinone in solution,[12]
that is, the dendritic triazine moiety prefers face-to-face p–p
interaction in solid stacking, which in turn will favor forma-
tion of the columnar LC phase during the thermal process.
Most of the traditional disk-shaped molecules that exhibit
columnar LC phases have C3 or higher symmetry, and disks
efficiently self-assemble into columnar stacks through intra-
molecular p–p and/or H-bonding interactions.[13] Several tra-
ditional disk-shaped molecules with C2 symmetry showing
columnar LC phases have also been disclosed.[14] The intro-
duction of a chiral moiety into C2-symmetrical molecules or
tilting bent molecules to lead to the formation of columnar
LC phases is also possible but has rarely been reported.[15]
Owing to the versatile combination of cores, linkages, and
peripheral groups, the molecular conformations of dendrim-
ers are not as easy to control as those of traditional disk-
shaped compounds, which characteristically contain a rigid
disk-like core and a large number of surrounding flexible
chains. Hence, it remains challenging to develop a general
method for inducing columnar LC phases of dendrimers.[16]
Most dendrimers with columnar phases consist of rigid
cores, flexible linkages, and peripheral mesogens or func-
tional alkyl chains.[17] Induction of H-bonding interaction be-
tween dendrons, leading to the generation of columnar LC
phases, is another viable approach.[17,18] Dendritic columnar
mesogens containing rigid cores, rigid linkages, and flexible
peripheral chains are unconventional and very interesting
because their morphologies can be controlled by restricted
Dendrimers are monodisperse three-dimensional molecules
with a definite molecular weight, shape, and size. These mol-
ecules, consisting of cores, linkages, and peripheral groups,
can be prepared by convergent, divergent, and combinatori-
al methods.[1] Recently, dendrimers have been the subject of
much study due to their potential to function as catalysts,[2]
molecular micelles,[3] light-harvesting molecules,[4] drug-
transporting agents,[5] nanoparticle stabilizers,[6] sensors,[7]
and porous materials.[8] Dendrimers have also been observed
to exhibit columnar liquid-crystalline (LC) phases and have
found potential applications in light-emitting diodes, photo-
voltaics, and field-effect transistors,[9] because columnar
liquid crystals (LCs) often have good charge-carrier mobili-
ty, no grain boundaries, and uniform alignment.[9b,10]
[a] Prof. Dr. L.-L. Lai, S.-W. Wang
Department of Applied Chemistry, National Chi Nan University
No. 1 University Rd., Puli, Nantou, Taiwan 545
Fax : (+886)49-2917956
E-mail: lilai@ncnu.edu.tw
[b] Dr. L.-L. Cheng
Material and Chemical Research Laboratories
Industrial Research Institute, Hsinchu, Taiwan 300
[c] Dr. J.-J. Lee
No. 101 Hsin-Ann Rd., HsinChu Science Park
Hsinchu, Taiwan 300
[d] T.-H. Wang, Prof. Dr. H.-F. Hsu
Department of Chemistry, Tamkang University
Tamsui, Taiwan 251
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201200933.
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conformational freedom, and cavities may thus be created
within the dendritic framework for incorporation of guest
molecules.[17a,b,19]
Results and Discussion
The preparation of dendrimer [2N(C8)2G2N]2 and its precur-
sors has been reported previously.[11a,d] Dendrons 2N(C6)2G1-
Cl and N(Cn)2OCnG1-Cl (n=6, 8) were prepared according
to Scheme 1. Reaction of cyanuric chloride with two equiva-
Many traditional disk-shaped compounds with C3 or C2
symmetry have been observed to display columnar LC
phases, but very few unconventional dendrimers with C3 or
C2 symmetry that exhibit a columnar LC phase have been
described in the literature.[20] In our research on unconven-
tional dendrimers based on the triazine moiety, we previous-
ly prepared C3-symmetrical G2 and G3 dendrimers which
displayed a columnar LC phase during the thermal proc-
ess.[20b] In view of applications, lower generations of LC den-
drimers have advantages of correspondingly lower viscosity
and low cost of production. Previously, we showed that C2-
symmetrical [2N(C8)2G2N]2 (Figure 1) does not display any
Scheme 1. Preparation of dendrons 2N(C6)2G1-Cl and N(Cn)2OCnG1-Cl
(n=6, 8).
lents of dihexylamine in dry CH2Cl2 in the presence of trie-
thylamine gave 2N(C6)2G1-Cl in 98% yield. Reaction of cya-
nuric chloride with one equivalent of dihexylamine in dry
CH2Cl2 yielded compound I-6, which was further treated
with sodium hexyloxide in THF to give dendron
N(C6)2OC6G1-Cl in 92% yield (based on cyanuric chloride).
Dendron N(C8)2OC8G1-Cl was prepared in 86% yield in a
similar manner. Dendrons X-G1NH, X-G2Cl, and X-G2NH
(X=2N(C6)2 or N(Cn)2OCn, n=6, 8) were prepared in 75–
90% yield as shown in Scheme 2. Reaction of X-G2NH with
X-G2Cl in THF in the presence of K2CO3 at 1708C in a
sealed tube for 72 h gave dendrimers [2N(C6)2G2N]2,
[N(C6)2OC6G2N]2, and [N(C6)2OC6G2N]2 in 60–90% yield,
Figure 1. Structures of [2N(Cn)2G2N]2 and [N(Cn)2OCnG2N]2 (n=6, 8).
LC phase.[20b] To improve the related properties, we first
varied the length of dendritic peripheral alkyl chains, a gen-
eral approach adopted for traditional rod-like LC materials,
and prepared [2N(C6)2G2N]2 (Figure 1), which also does not
exhibit any LC phase. Applying the concept of tilting bent
molecules to the dendritic system, we broke the C2 symme-
try of the triazine-based dendrimers and prepared
[N(Cn)2OCnG2N]2 (n=6, 8; Figure 1), which display a col-
umnar LC phase during thermal treatment. Interruption of
molecular symmetry has been adopted to prepare columnar
LC dendrimers with flexible linkages, in which the peripher-
al mesogens may play an important role in inducing the LC
phases.[21] To the best of the our knowledge, this is the first
time that, in the field of unconventional dendrimers, nonme-
sogenic dendrimers were successfully converted to mesogen-
ic dendrimers simply by breaking their symmetry. This
method may be important in designing LC dendrimers with
some specific properties. For example, a rigid disk-shaped
molecule with good light-emitting or electron transporting
property can be used as the dendritic core and then modi-
fied to display the desired mesogenic phase for better align-
ment, and this is a possible advantage over conventional
mesogenic dendrimers.
1
which were characterized by H and 13C NMR spectroscopy
and mass spectrometry. For example, the mass spectrum of
[N(C8)2OC8G2N]2 (Figure 2) clearly shows the correspond-
ing [M]+ peak at m/z 2367.5. All three dendrimers in the
current study, [2N(C6)2G2N]2, [N(C6)2OC6G2N]2, and
[N(C6)2OC6G2N]2, were further characterized by microanal-
ysis, and the errors for calculated and experimental percen-
tages of C, H, and N were within 0.3%.
As shown in Scheme 3, dendrimer [2N(C8)2G2N]2, which
melts at about 1328C on heating and solidifies at about
1178C on cooling, does not exhibit any LC behavior. Simi-
larly, dendrimer [2N(C6)2G2N]2 is not liquid-crystalline and
exhibits a melting point of about 2298C on heating and a
solidification point of about 2218C on cooling. The molecu-
lar structure of dendrimer [2N(C6)2G2N]2 is similar to that
of [2N(C8)2G2N]2, but the two have different peripheral
chain lengths. However, the melting point of [2N(C6)2G2N]2
is much higher than that of [2N(C8)2G2N]2, and the solidifi-
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Columnar Phase of Unconventional Dendrimers
FULL PAPER
Scheme 3. Phase-transition temperatures and corresponding enthal-
pies [kJmolÀ1
]
(in parentheses) of the dendrimers [2N(C8)2G2N]2,
[2N(C6)2G2N]2, [N(C6)2OC6G2N]2, and [N(C8)2OC8G2N]2. Cryst, Colrec
,
Colh, and Iso denote the crystalline, rectangular columnar, hexagonal col-
umnar, and isotropic phases, respectively. The transition temperatures
and corresponding enthalpies were recorded for the second cycles be-
tween the isotropic and room temperatures. [a] Two transitions signifi-
cantly overlapped; the enthalpies are integrated together. [b] Two transi-
tions partially overlapped and the enthalpy is integrated individually (the
values integrated together are shown in Figure S2 in the Supporting In-
formation).
flexible alkyl chains of [2N(C6)2G2N]2 is smaller, leading to
better crystallinity in the solid stacking. Such behavior disfa-
vors the formation of an LC phase in our case. The genera-
tion of LC phases for most rodlike materials involves in-
creasing the flexible-chain length to reduce their crystallini-
ty. This strategy failed for dendrimers in this study; den-
drimer [2N(C8)2G2N]2 does not display any LC phase during
thermal treatment, and its melting point and solidification
point are much lower than those of the shorter-chain ana-
logue [2N(C6)2G2N]2, although the peripheral alkyl chain
lengths only differ by two C atoms. To effectively modulate
the molecular crystallinity and induce columnar LC phases,
the C2 symmetry breaking strategy was adopted, and den-
drimers [N(C6)2OC6G2N]2 and [N(C8)2OC8G2N]2 were pre-
pared. Each of the dendrons N(Cn)2OCnG2-Cl and
N(Cn)2OCnG2-NH (n=6, 8) consists of two structural iso-
mers (Figure 3), which lead to isomer mixtures of dendrim-
ers [N(C6)2OC6G2N]2 and [N(C8)2OC8G2N]2 from the reac-
tion of N(Cn)2OCn-Cl with N(Cn)2OCn-NH (n=6, 8; Fig-
ure S1 in Supporting Information); the structure in Figure 1
Scheme 2. Preparation
[N(Cn)2OCnG2N]2 (n=6, 8).
of
dendrimers
[2N(C6)2G2N]2
and
Figure 2. MALDI-TOF mass spectrum of [N(C8)2OC8G2N]2.
cation points of [2N(C6)2G2N]2 and [2N(C6)2G2N]2 also
behave similarly. This may be due to the different crystallin-
ities of the two dendrimers. As demonstrated in Figure 1,
the peripheral chains of [2N(C6)2G2N]2 are shorter than
those of [2N(C8)2G2N]2 so the thermal vibration from the
Figure 3. Structural isomers of N(Cn)2OCnG2-Cl and N(Cn)2OCnG2-NH
(n=6, 8).
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L.-L. Lai et al.
shows only one of them. Most of them do not exhibit C2
symmetry.
As expected, [N(C6)2OC6G2N]2 exhibits a rectangular col-
umnar phase on heating (Scheme 3), and shows a small
domain texture under a polarizing optical microscope (Fig-
ure 4a). The mesophase range is only about 218C in the
The wide-angle halos at 5.4, 5.0, and 4.5 ꢁ are all attributa-
ble to the liquid-like correlation of the molten chains, show-
ing mixed stacking of N-alkyl and O-alkyl groups.
Dendrimer [2N(C6)2G2N]2 has a higher melting point but
does not display any LC behavior during the thermal proc-
ess. Similarly, dendrimer [2N(C8)2G2N]2 with a lower melt-
ing point also does not display any liquid-crystalline phase.
However, [N(C6)2OC6G2N]2 not only shows a lower melting
point compared to [2N(C6)2G2N]2, but also exhibits a colum-
nar phase on heating. These observations are interesting and
suggest that dendrimer [N(C8)2OC8G2N]2 is potentially col-
umnar mesogenic. Indeed, [N(C8)2OC8G2N]2 exhibits a col-
umnar phase, evidenced by its fan-shaped texture under a
polarizing optical microscope (Figure 4b). The mesophase
ranges are found to be about 568C on heating and 838C on
cooling, which are significantly wider than those of
[N(C6)2OC6G2N]2. The identity of the columnar phase of
[N(C8)2OC8G2N]2 was further investigated by powder XRD
(Figure 6). A sharp peak at 31.2 ꢁ was detected in the
Figure 4. POM textures of a) [N(C6)2OC6G2N]2 at 1408C on heating (top)
and b) [N(C8)2OC8G2N]2 at 1408C on cooling (bottom).
heating process. Dendrimer [N(C6)2OC6G2N]2 shows consid-
erable supercooling behavior and does not show any liquid-
crystalline phase in the cooling process, which was con-
firmed by successive differential scanning calorimetry,
powder XRD, and polarized optical microscopy (POM) in-
vestigations. The identity of the rectangular columnar phase
of [N(C6)2OC6G2N]2 was further studied by powder XRD.
As shown in Figure 5, two sharp peaks at 26.0 and 18.8 ꢁ,
indexed as d20 and d11, respectively, occur in the small-
angle region. The weak mid-angle signal at 12.2 ꢁ is indexed
as d40. The lattice constants are calculated to be a=51.9
and b=20.2 ꢁ. Due to the lack of characteristic reflections,
the symmetry of [N(C6)2OC6G2N]2 cannot be determined.
Figure 6. XRD pattern of [N(C8)2OC8G2N]2 at 1408C on cooling.
small-angle region and is indexed as d10. Two additional
weak signals at 18.2 and 15.9 ꢁ are indexed as d11 and d20,
respectively. The XRD pattern is indicative of a hexagonal
columnar phase and the lattice constant is calculated to be
a=36.0 ꢁ. The two broad wide-angle halos at 5.31 and
4.56 ꢁ are both attributable to the liquid-like correlations of
the molten chains of the mixed stacking of N-alkyl and O-
alkyl groups.
As shown in our previous work,[20b] C3-symmetrical G2
dendrimer ACTHUNTRGNE(UNG G2N~N)3T has a three-leaf fan conformation
and thus efficiently assembles into a columnar stack. Al-
though the three-leaf fan conformation of C3-symmetrical
G3 dendrimer ACHTNUTRGNEUNG(G3N~N)3T is not evident, the congestion
from the dendritic framework significantly deforms the mo-
lecular planarity. Both effects significantly reduce the face-
to-face p–p interaction between molecules in the solid
stacking, and thus the columnar LC phase is displayed
during thermal treatment.
As a model compound representing the new dendrimers
in Figure 1, [N(C8)2OC8G2N]2 was computed by using the
MM3 model to reveal its equilibrium molecular conforma-
Figure 5. XRD pattern of [N(C6)2OC6G2N]2 at 1408C on heating.
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Columnar Phase of Unconventional Dendrimers
FULL PAPER
tion. The simulation was carried out in the gas phase and,
for simplicity, only one structure, as shown in Figure 1, was
calculated. The starting conformation of N(C8)2OC8G1-Cl
was first established by combining one planar triazine with
one dioctylamine and octanol, in which all-trans conforma-
tion was adopted for the alkyl chains, and then optimized.
The equilibrium conformation of N(C8)2OC8G1-NH was
then obtained by combining optimized N(C8)2OC8G1-Cl
with piperazine in chair form and then optimized. The con-
formation of N(C8)2OC8G2-Cl was obtained by combining
one planar triazine with two optimized N(C8)2OC8G1-NH
units and then optimized. The conformation of
N(C8)2OC8G2-NH was obtained in a similar manner to that
[N(C6)2OC6G2N]2 and the noncolumnar LC behavior of
[2N(C6)2G2N]2 during the thermal process can be rational-
ized by using this concept.
In addition, the textures of both [N(C6)2OC6G2N]2 and
[N(C8)2OC8G2N]2 were obtained between untreated glasses
under a polarizing optical microscope. The texture of
[N(C8)2OC8G2N]2 is composed of larger domains than that
of [N(C6)2OC6G2N]2, which implies chain-length depend-
ence of dendritic alignment. More detailed studies of den-
dritic mesogens with mixed peripheral alkyl chains should
be worthwhile for their potential efficient alignment.
of
N(C8)2OC8G1-NH.
The
conformation
of
Conclusion
[N(C8)2OC8G2N]2 was obtained by combining optimized
N(C8)2OC8G2-Cl with optimized N(C8)2OC8G2-NH and then
optimized.
In the optimized conformation of [N(C8)2OC8G2N]2,
shown as space-filling model in Figure 7, one G2 moiety par-
A strategy of breaking C2 symmetry for inducing columnar
phases of unconventional triazine-based dendrimers has
been demonstrated. By using this method, two second-gen-
eration unconventional dendrimers were observed to display
columnar phases during the thermal process. Although the
molecular conformation and molecular weight of
[N(C8)2OC8G2N]2 and [N(C6)2OC6G2N]2 are similar to those
of [2N(C8)2G2N]2 and [2N(C6)2G2N]2 (Scheme 3), only the
former display columnar phases on thermal treatment due
to C2-symmetry breaking. We believe that this approach
should be applicable to other unconventional dendritic sys-
tems. In particular, some disk-shaped molecular cores dis-
playing good light-emitting or electron-transporting proper-
ties can be modified by this approach to subsequently show
LC phases and better alignment. In addition, this approach
also leads to lower-generation dendrimers exhibiting colum-
nar phases, which not only efficiently reduces the synthetic
cost but also significantly reduces the viscosity of the den-
dritic mesogens.
Figure 7. Conformation of [N(C8)2OC8G2N]2. O red, N blue, C gray, H
omitted.
tially lies above the other G2 moiety due to the chair form
of the central piperazine unit. For [N(C8)2OC8G2N]2, the
molecular congestion from the peripheral alkyl chains and
dendritic frameworks seems not to significantly deform the
molecular planarity, and thus leads to a rather flat overall
structure, similar to that of [2N(C8)2G2N]2.[22] However,
[2N(C8)2G2N]2 does not exhibit any LC phase on thermal
treatment, but [N(C8)2OC8G2N]2 shows a columnar phase.
Similarly, [2N(C6)2G2N]2 does not display any LC behavior,
but [N(C6)2OC6G2N]2 does give a columnar mesophase
during the thermal process. The reason for the difference
Experimental Section
Preparation of dendrimers: Preparation of the dendrimer [2N(C8)2G2N]2
was the subject of earlier work.[11a,d] The dendrimers, [2N(C6)2G2N]2,
[N(C6)2OC6G2N]2, and [N(C8)2OC8G2N]2, were prepared as follows: X-
G2-Cl (1 mmol) and X-G2-NH (1 mmol) were added to a sealed tube,
containing THF (15 mL) and K2CO3 (0.5 g, 5 mmol). The resulting mix-
ture was heated at 1708C for 72 h. Water (20 mL) was added to the mix-
ture and the solution was extracted with CH2Cl2 (20 mLꢂ2). The com-
bined extracts were washed with water (20 mL), dried over MgSO4, and
concentrated at reduced pressure. The residue was purified by chroma-
tography (SiO2, 2.1ꢂ15 cm; eluent: THF) to yield the crude product,
which was further recrystallized from CH2Cl2/CH3OH (1/20) to give the
pure desired dendrimer.
[2N(C6)2G2N]2 (89.3%): 1H NMR (300 MHz, CDCl3, 258C, TMS): d=
0.89 (brs, 48H, 16ꢂCH3), 1.30 (brs, 92H, 48ꢂCH2), 1.58 (brs, 32H, 16ꢂ
CH2), 3.46 (brs, 32H, 16ꢂCH2), 3.80+3.82 (2 s, 40H, 20ꢂCH2);
13C NMR (75 MHz, CDCl3, 258C, TMS): d=14.06, 22.70, 26.99, 28.18,
31.84, 43.16, 46.96, 47.14, 165.10, 165.42, 165.49; MS calcd for C134H248N36
[M]+: 2363; found 2363; elemental analysis calcd (%) for C134H248N36: C
68.09, H 10.58, N 21.33; found C 68.09, H10.61, N 21.31.
between
[2N(C8)2G2N]2
[or
[2N(C6)2G2N]2)]
and
[N(C8)2OC8G2N]2 [or [N(C6)2OC6G2N]2)] should be the C2-
symmetry breaking. It is well known that compounds con-
taining structural isomers tend to give reduced overall inter-
molecular interactions in the solid state. For example, both
(R)-(À)-2-amino-1-propanol and (S)-(+)-2-amino-1-propa-
nol have a melting point of 24–268C, but the melting point
of (Æ)-2-amino-1-propanol is 88C.[23] The dendrimer
[N(C8)2OC8G2N]2, consisting of several possible structural
isomers with the same molecular weight (see Supporting In-
formation Figure S1), therefore should lead to less face-to-
face p–p interactions with adjacent molecules in the solid
stacking when compared with [2N(C8)2G2N]2. A similar
effect can be applied to dendrimers with C3 symmetry, re-
sulting in the formation of the columnar phase during the
thermal process. The columnar liquid crystallinity of
1
[N(C6)2OC6G2N]2 (59.7%): H NMR (300 MHz, CDCl3, 258C, TMS): d=
0.86–0.91 (m, 36H, 12ꢂCH3), 1.30–1.43 (m, 72H, 36ꢂCH2), 1.60 (brs,
16H, 8ꢂCH2), 1.71–1.81 (m, 8H, 4xCH2), 3.47–3.52 (m, 16H, 8ꢂCH2),
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L.-L. Lai et al.
3.82 (brs, 40H, 20ꢂCH2), 4.27 (t, J=6.9 Hz, 8H, 4ꢂCH2); 13C NMR
(75 MHz, CDCl3, 258C, TMS): d=14.03, 22.63, 25.72, 26.74, 27.66, 28.03,
28.97, 31.65, 31.71, 43.19, 47.04, 47.18, 66.57, 165.45, 165.91, 166.16,
170.74; MS calcd for C110H196N32O4 [M]+: 2030; found 2030; elemental
analysis calcd (%) for C110H196N32O4: C 65.05, H 9.73, N 22.07; found C
65.12, H 9.81, N 22.13.
[N(C8)2OC8G2N]2 (65.7%):1H NMR (300 MHz, CDCl3, 258C, TMS): d=
0.86–0.90 (m, 36H, 12ꢂCH3), 1.30–1.44 (m, 120H, 60ꢂCH2), 1.58 (brs,
16H, 8ꢂCH2), 1.72–1.81 (m, 8H, 4ꢂCH2), 3.47–3.52 (m, 16H, 8ꢂCH2),
3.82 (brs, 40H, 20ꢂCH2), 4.28 (t, J=6.9 Hz, 8H, 4ꢂCH2); 13C NMR
(75 MHz, CDCl3, 258C, TMS): d=14.10, 22.65, 26.05, 27.07, 27.69, 28.07,
29.01, 29.25, 29.32, 29.42, 31.85, 43.19, 47.14, 66.58, 165.44, 165.92, 166.16,
170.73; MS calcd for C134H244N32O4 [M]+: 2367; found 2367; elemental
analysis calcd (%) for C134H244N32O4: C 67.98, H 10.39, N 18.93; found C
67.96; H10.44, N 18.87.
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Acknowledgements
We thank the National Chi Nan University and the National Science
Council (NSC 98-2119M260-003 and NSC 100-2113M-260-006-MY2) for
financial support.
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15366
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2012, 18, 15361 – 15367

Columnar Phase of Unconventional Dendrimers
FULL PAPER
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Lai, S.-J. Hsu, H.-C. Hsu, S.-W. Wang, K.-L. Cheng, C.-J. Chen, T.-
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NG2.
Received: March 20, 2012
Revised: July 25, 2012
Published online: October 2, 2012
Chem. Eur. J. 2012, 18, 15361 – 15367
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
15367