Trimesic acid-based star mesogens with flexible spacer: Synthesis and mesophase characterization

Article abstract of DOI:10.1071/CH12258

A series of trimesic acid-based star mesogens containing an octamethylenoxy spacer and two-ring containing side arms with terminal alkoxy groups were synthesised by a divergent approach. A structurally similar mesogen containing a three-ring side arm was

Full text of DOI:10.1071/CH12258

CSIRO PUBLISHING
Aust. J. Chem.
Full Paper
http://dx.doi.org/10.1071/CH12258
Trimesic Acid-Based Star Mesogens with Flexible Spacer:
Synthesis and Mesophase Characterization
A
B
A C
,
A. Shanavas, T. Narasimhaswamy, and A. Sultan Nasar
A
Department of Polymer Science, University of Madras, Guindy Campus,
Chennai-600025, India.
B
Polymer Laboratory, CSIR-Central Leather Research Institute, Adyar,
Chennai-600020, India.
C
Corresponding author. Email: drasultannasar@yahoo.com
A series of trimesic acid-based star mesogens containing an octamethylenoxy spacer and two-ring containing side arms
with terminal alkoxy groups were synthesised by a divergent approach. A structurally similar mesogen containing a three-
ring side arm was also synthesised. All the mesogens and intermediates were characterised thoroughly using FT-IR,
1H NMR, 13C NMR spectroscopy, and elemental analysis techniques. The mesophase characteristics were identified by
hot stage optical polarising microscopy (HOPM) and differential scanning calorimetry (DSC), while X-ray was used to
confirm the existence of a smectic A (SA) phase. The HOPM and DSC results revealed the presence of rich
polymesomorphism in the star mesogens. The dominance of a SA phase in the series is attributed to the steric repulsion
associated with steric asymmetry. The change of the side arm from two rings to three rings was found to increase the
mesophase stability.
Manuscript received: 16 April 2012.
Manuscript accepted: 14 June 2012.
Published online: 19 July 2012.
Introduction
aggregation behaviour, charge carrier mobility, and nanometer-
scale properties have been reported recently.[25–27]
Thermotropic liquid crystals are a distinct class of molecular
crystals in which orientational order and flow behaviour are
uniquely combined.[1,2] Thus, these materials have found
applications in stimuli responsive systems.[3,4] Conventional
calamitic mesogens have been investigated extensively and are
usually built with rod-like molecules.[5–9] Another class of
mesogens that has attracted the keen attention of researchers is
discotics which are built with disc-like molecules.[10,11] How-
ever, the recent upsurge has been more on non-conventional
mesogens which essentially deviate from a rod-like or disk-like
shape and have molecular shapes like V or bent-core,[12] T,[13]
H,[14] l,[15] Æ,[16] c,[17] and dendrimers.[18,19] Among the non-
conventional liquid crystals, star mesogens have drawn con-
siderable attention in view of their structural similarity with
dendrimers.[20,21] Moreover, the C3 symmetry of these molec-
ular systems provides greater opportunity to investigate their
shape dependent properties in the mesophase.
The star mesogens, owing to their unique organisation in
the condensed phase, have been classified as hekates[22] (cyclic
trimers). The design of hekates is achieved by introducing
rod-like arms either directly or through a flexible spacer.
The remarkable feature of these mesogens is the change of
molecular shape driven by self organisation[23] when changing
the temperature. Thus, investigations of such an important class
of mesogens would provide more insights into the relationship
between structure and mesophase formation and this will be
useful to exploit the star mesogens for new applications.[24]
Trimesic acid core-based star mesogens with C3 symmetry, their
In this work, we report a series of trimesic acid (central core)
based mesogens consisting of a C8 spacer and two-ring contain-
ing side arms with terminal alkoxy chains and a structurally
similar mesogen containing three-ring side arms. Insertion of a
flexible spacer between the central phenyl ring and the side arms
could induce the molecules to display many mesophase
sequences, and increasing the side arm length improved the
mesophase stability.
Results and Discussion
Synthesis of Star Mesogens
Starmesogens basedona trimesicacid(central) coreconnected to
side arms through an octamethylenoxy spacer were synthesised
by a divergent approach as per Scheme 1. The side arms were
built with two phenyl rings linked through an azomethine unit and
adorned with terminal alkoxy chains whose length was varied
from C2–C16 (even carbons). The structural characterisation of
1
the target mesogens was accomplished by FT-IR, H, and 13C
NMR spectroscopic and elemental analysis techniques. 1H NMR
spectroscopy showed two singlets; one for the central phenyl ring
(8.8ppm) and another one for the side arm imine unit (8.3ppm).
The side arm phenyl ring protons showed four doublets typical of
a 1,4-disubstitution pattern (6.9–7.8ppm). The characteristic
oxymethylene protons of the spacer as well as the terminal chain
showed well resolved triplets at 3.9–4.3ppm. These spectro-
scopicfeatureswerefurther supportedby13C NMRspectroscopy.
Journal compilation Ó CSIRO 2012
www.publish.csiro.au/journals/ajc

B
A. Shanavas, T. Narasimhaswamy, and A. S. Nasar
NO2
OH
CH3
(CH2)8
OH
Br
(CH2)n
O
ϩ
DMF, 90°C
K CO
5 h
N
NH2
NO2
O
NO2
O
O
O
(H2C)8
O
(H2C)8
(H2C)8
O
O
O
(CH2)n
(H2C)8
O
O
O
O
Cl
O
CH3
OH
4a–h
1
Pd/C, H
O
O
O
O
O
O
O
O
O
O
O
O
Microwave
EtOH, 8 min
THF:EtOH
O
TEA, 2-butanone
0°C, 3 h
O
O
O
O
O
O
O
Cl
Cl
(CH2)8
(H2C)8
(H2C)8
(CH2)8
(H2C)8
(CH2)8
N
N
NH2
NH2
NO2
NO2
3
2
O
O
(CH2)n
CH3
(CH2)n
CH3
5a–h
Where, n ϭ 1, 3, 5, 7, 9, 11, 13, 15.
Scheme 1. Synthesis of star mesogens.
In the 13C NMR spectra, fifteen signals for the aromatic, ester,
azomethine, and oxymethylene carbons were observed for all the
mesogens in the region of 167–63 ppm, whereas the signals
corresponding to the methylene and methyl carbons appeared in
the region of 33–14 ppm with variations as the number of carbons
in the terminal chains varied from C2–C16. These spectroscopic
data unambiguously confirm the structure of the mesogens.
C (SC) phase with characteristic Schlieren texture followed by
higher ordered smectic phases (SI & G) before reaching crystal-
lisation (Cr). All these HOPM observations were supported by
the DSC cooling scan where multiple peaks were observed
(Fig. 2). Since many of these phases were observed only during
the cooling cycle, they were classified as monotropic.
For the C6 isomer (5c), in the heating cycle of HOPM, a SA
phase was observed in addition to a N phase and accordingly
DSC showed three peaks corresponding to Cr–SA, SA–N, and
N–I transitions, respectively, where Cr refers to the crystalline
phase. On cooling, in addition to N and SA phases, other smectic
phases were also observed. In the HOPM cooling cycle, textures
of birefringent droplets for the N phase, focal conic fans for
the SA phase, broken fans withSchlieren texture for the SC phase,
and a focal conic fan with transient stripes for the SB phase were
observed. Accordingly, theDSCcoolingscanshowed asmanyas
five peaks, typical of mesogens exhibiting polymesomorphism.
The sample, however, did not show crystallisation till 258C by
HOPM and also by DSC. Thus, the transitions identified for the
C6 isomer (5c) include SC, SB, and SF, respectively, which were
supported by the transition enthalpy values as listed in Table 1.
Since these transitions (SC, SB, and SF) were noticed below the
melting temperature and observed only in a cooling cycle, they
were classified as monotropic phases. The appearance of SB was
further confirmed by DSC where the peak associated with SC–SB
was intense.
Hot Stage Optical Polarising Microscopy (HOPM)
and Differential Scanning Calorimetry (DSC) Studies
Table 1 lists the mesophase transition temperatures and the
enthalpyvaluesdeterminedfromDSCmeasurements;theheating
and cooling DSC traces are given Fig. 1 and Fig. 2, respectively.
The textures of the mesophase were identified using HOPM by
cooling the sample from an isotropic (I) phase. A good agree-
ment was noticed for the mesophase transitions observed by both
HOPM and DSC. The data clearly supported the enantiotropic
nature of some of the transitions across the series. In the case of
the C2 isomer (5a), on heating, a nematic (N) phase was
observed by HOPM and was confirmed by observing spherical
birefringent droplets on cooling the sample from the I phase.
Similarly, in the C4 isomer (5b), a N phase was observed during
the heating run.
On cooling the sample from the I phase, however, many
phases were observed. For instance, upon cooling, birefringent
spherical droplets were seen (Fig. 3) which coalesced to give
N threads along with homeotropy.[28] On further cooling, it
transformed to a smectic A (SA) phase where fan texture was
noticed. On continuous cooling this was changed to a smectic
In the case of the C8 isomer (5d), the heating scan of the
DSC showed Cr–SA and SA–I transitions. On cooling, it
exhibited three well resolved peaks associated with I–SA,

Trimesic Acid-Based Star Mesogens
C
Table 1. Differential scanning calorimetry (DSC) and hot stage optical
polarising microscopy (HOPM) data of star mesogens in cooling cycle
Square brackets indicate the monotropic phase. Isotropic: I, Nematic: N,
smectic A: SA, smectic C: SC, smectic I, SI, crystal G: G, crystallisation: Cr
5h
5g
SA
I
25
20
15
10
5
Cr
SA
Compound Transitions
Transition
DH
Phases
observed
by HOPM
I
SA
no.
observed
by DSC
temperature [kJ molꢀ1
]
Cr
SA
[8C]
5f
I
SA
5a
5b
I–N
134.8
135.7
120
3.3
4.3
2.9
0.08
1.4
0.4
N
Cr
SA
I–N
N SA SC SI G Cr
[N–SA]
[SA–SC]
[SC–SI]
[SI–G]
[G–Cr]
I–N
103
5e
I
SA
81.4
Cr
SA
77.6
69.4
16.8
5d
5c
5c
131.5
129.4
120
2.4
2.6
0.05
2.1
1.1
N SA SC
SB SF
I
SA
N–SA
Cr
SA
[SA–SC]
[SC–SB]
[SB–SF]
I–SA
91.4
87
N
SA
N
I
5d
5e
130
23.5
SA SB SF
Cr
SA
[SA–SB]
[SB–SF]
I–SA
100.6
96.4
2.9
1.3
5b
128.6
107
31.5
3.6
SA SB SF Cr
Cr
128
N
N
I
[SA–SB]
[SB–SF]
[SF–Cr]
I–SA
102.6
54.5
1.5
116
120
124
132
136
17.9
30.5
3.7
Exo up
Temperature [°C]
5f
121.8
102.4
95.9
SA SB SF Cr
SA SB SF Cr
SA SB SF Cr
[SA–SB]
[SB–SF]
[SF–Cr]
I–SA
Fig. 1. Differential scanning calorimetry traces (second heating runs) of
1.5
mesogens. See text for definition of phases.
53.6
10.2
40.1
6
5g
5h
126.8
107.2
104.2
64.4
[SA–SB]
[SB–SF]
[SF–Cr]
I–SA
2.8
Furthermore, in order to verify the rod-like behaviour of
these mesogens and to understand the role of the side arm length
on the meosphase stabilities, a molecule consisting of three
phenyl rings in the side arms with a dodecyloxy chain was
synthesised (7) (Scheme 2). The HOPM and DSC data revealed
the presence of N and SA phases over a wide temperature range
and were enantiotropic in nature as these phases were observed
both on heating and cooling cycles. On cooling the isotropic
phase (in HOPM), SC, SB, and SF phases were also observed in
addition to N and SA phases. This mesophase sequence was
similar to the two-ring side arms with terminal dodecyloxy chain
mesogens. Thus an increase in the length of the side arm (i.e. the
number of rings) not only retains the polymesomorphism but
also enhances the mesophase stabilities.
16.3
38.9
7.9
125.3
107.7
103.9
65.7
[SA–SB]
[SB–SF]
[SF–Cr]
1.5
18.9
SA–SB, and SB–SF, respectively. In HOPM, corresponding to
these transitions, textures of battonet formation (Fig. 4a) which
coalesced into a focal conic fan texture typical of the SA phase
(Fig. 4b) and concentric arcs on the fans which indicated
the transition from SA–SB phase (Fig. 4c) were observed.
These arcs persisted for a 28C temperature range and then
disappeared (Fig. 4d). Finally, Schlieren texture with retaining
fans (SF) due to paramorphosis[29] was observed. The other
higher homologues, namely the C10–C16 isomers (5e–5h) also
showed SA phase on heating and showed SB and SF phases in
addition to SA phase on cooling.
However, the transition temperatures for these homologues
showed variation due to an increase in terminal chain length.
Acomparisonofclearingtemperaturesacrosstheseriesindicated
a decreasing trend from C2–C12 isomers while C14 and
C16 showed a marginal increase in clearing temperatures.
The remarkable feature of these mesogens is the presence of rich
polymesomorphism despite narrow mesophase stabilities. Many
of the phases were found to be monotropic. In additional, in
spite of C3 symmetry, the appearance of mesophases typical
of calamitic mesogens indicated that the parallel orientation of
all the arms were preferred to the stacking of central phenyl ring
as columns.
Variable-Temperature X-Ray Diffraction (VT-XRD) Studies
The existence of a SA phase for a representative mesogen (5d)
was confirmed by variable temperature powder X-ray mea-
surements. The XRD pattern measured at 1258C is shown in
Fig. 5. The small angle region showed a sharp peak centred at
2y ¼ 2.538 andwideanglepeakat 2y ¼ 19.68. The corresponding
˚
d values for these reflections are 34.85 and 4.51 A, respectively.
A sharp reflection at a small angle region is typical for layer
ordering commonly observed for smectic phases.[30] The broad
hump observed at a wide angle suggests a liquid-like ordering
arising from the terminal octyloxy chains. Thus, the small angle
sharp reflection followed by the wide angle broad peak clearly
support the conventional calamitic mesophase rather than
columnar ordering. Furthermore, the length of each side arm was
˚
found to be ,35 A which was calculated from a space-filled
model of the mesogen. Acordingly, the d/L ratio was nearer

D
A. Shanavas, T. Narasimhaswamy, and A. S. Nasar
smectic mesophases in the present work would suggest a possi-
bility of a tripod conformation as shown in Fig. 6 where the three
arms of the mesogens are parallel to one another acting like
typical rod-like units. The driving force for the formation of a
tripod-like structure over a l shape could be due to the overall
volume occupied by the tripod being more favourable than the
l shape. Furthermore, in a l conformation, only two arms can
be parallel while the third arm is away from them. It is also
interestingtonotethat thefoldingofthethirdarmtoforma tripod
shape in these mesogens replicates the tapered shape which
is frequently encountered in tapered dendron-based mesogens
in the hierarchical assembly of shape persistent mesogens.[32]
The work pertaining to solid state 13C NMR experiments of these
mesogens in the mesophase is under progress.
The mesogens investigated in the present work were
decoupled from the central phenyl ring by flexible spacers that
enablethem toalignparalleltoeach other, whichwasresponsible
for layer ordering typical of smectic phases. The predominant
appearance of a SA phase in an enantiotropic manner in the series
clearly supported that the side arms are orienting parallel to each
other. Furthermore, such an arrangement contributed to lateral
interactions between the arms and accommodated the molecules
to organise in a layer fashion leading to orthogonal phases.
The appearance of monotropic rich poly(smectic) mesomorph-
sim in cooling suggested that the molecules adopt different
shapes in order to accommodate different organisations in low
temperature higher order phases. The stericrepulsions associated
with the steric asymmetry of molecules is responsible for poly-
mesomorphism observed in these mesogens.[33] Usually the
SA phase can be induced in calamitic mesogens either by
introducing lengthy terminal alkyl/alkoxy chains or polar termi-
nal substituents like cyano or nitro groups.[34] However, in the
present case, the predominant appearance of a SA phase is
attributed to steric repulsions associated with steric asymmetry
as noticed in the literature for structurally similar mesogens.[33]
SB
SF
SF
8
7
6
5
4
3
2
1
SA
SA
Cr
5h
5g
SB
SA
Cr
SB
SF
Cr
Cr
5f
SA
SF SB
5e
SB
SA
SF
5d
5c
N
SB
SA
SC
SF
SI
SA
Cr
N
SG
SC
5b
40
60
80
100
120
140
Exo up
Temperature [°C]
Fig. 2. Differential scanning calorimetry traces (second cooling runs) of
mesogens. See text for definition of phases.
Conclusions
Star mesogens based on trimesic acid were synthesised and the
mesophase characterisation was carried out using HOPM, DSC,
and VT-XRD techniques. Nematic and smectic A phases were
observed enantiotropically whereas all other higher order
smectic phases were observed monotropically across the series.
The notable features of the investigation were the presence of
rich polymorphism in the cooling cycle of the mesogens and the
observation of enhanced mesophase stability with retaining
polymorphism with the incorporation of an additional phenyl
ring in the side arm. It was found that the SA phase appeared
predominantly in these mesogens and is attributed to steric
repulsion associated with steric asymmetry, as observed for
structurally similar mesogens reported in the literature. A tripod-
like conformation, based on the d/L ratio calculated from X-ray
data, was proposed for the molecules in the mesophase.
Fig. 3. Hot stage optical polarising microscopy photograph of nematic
droplets of (5b) at 132.58C.
to 1 suggesting a conventional SA phase (monolayer). This is
consistent with HOPM and DSC data where the appearance of a
SA phase was unequivocally observed.
Experimental
Goring et al. observed a SC phase in structurally similar
trimesic acid-based star mesogens.[17] To explain the X-ray data,
they proposed a tuning fork conformation by taking into account
the d values. Attard et al. have studied structurally similar
mesogens based on a trimesic acid core.[31] The d values
observed by Attard et al. were twice the length of each side
arm (d ¼ 2L) and hence they considered a l conformation. In the
present work, the d values were comparable with the length of
one side arm (i.e. d ¼ L). The appearance of conventional
Materials
1,3,5-Benzenetricarbonyltrichloride, 4-hydroxybenzaldehyde,
4-nitrophenol, 4-dodecyloxybenzoicacid, 4-ethoxybenzaldehyde
(4a), 4-butoxybenzaldehyde (4b), 4-hexyloxybenzaldehyde
(4c), n-bromooctane, n-bromodecane, n-bromododecane,
n-bromotetradecane, n-bromohexadecane, palladium on char-
coal (Pd/C, 10 %), N,N0-dicyclohexylcarbodiimide (DCC),
and N,N-dimethylaminopyridine (DMAP) were purchased

Trimesic Acid-Based Star Mesogens
E
(a)
(b)
(c)
(d)
Fig. 4. Hot stage optical polarising microscopy photographs of (a) battonets formation of a smectic A phase of 5d at 130.28C,
(b) focal conic fan texture of a smectic A phase of 5d at 105.08C, (c) smectic A to smectic B phase transition of 5d at 100.68C, and
(d) smectic B phase of 5d at 99.38C.
from Aldrich and used without further purification. N,N0-
Dimethylformamide, tetrahydrofuran, ethanol, and methanol
(all obtained from S.D. Fine chemicals) were purified by stan-
dard procedures. Dichloromethane, ethyl acetate, diethyl ether,
n-hexane, 2-butanone, acetone, cyclohexane, toluene, isopropyl
alcohol, potassium hydroxide (pellets), Celite-540, anhydrous
potassium carbonate, and anhydrous sodium sulfate, were
obtained from Merck (India) and used as received. Triethylamine
(S.D. Fine chemicals)was distilled before use. 8-Bromooctan-1-ol
was prepared using the reported procedure.[35]
equipped with a high-resolution fast detector PIXCEL. The
˚
wavelength of the radiation used was 1.5418 A and the tem-
perature employed was 1258C.
Synthesis of 8-(4-Nitrophenoxy)octan-1-ol (1)
In a 500 mL two necked flask, 12.5 g (90 mmol) of K2CO3
and 11.8 g (85 mmol) of 4-nitrophenol were added and dissolved
in 200 mL of DMF. The solution was stirred and heated to 908C
followed by the drop wise addition of 100 mL of a DMF solution
containing 18.8 g (90mmol) of 8-bromooctan-1-ol. The temper-
ature of the mixture was maintained at 908C for 5 h. The reaction
mixture was then allowed to cool to room temperature and
poured into 1 L of distilled water to obtain a precipitate. The
precipitate was filtered off, washed with distilled water, and
dried under vacuum. The product was recrystallised in a 1 : 3
ratio of ethyl acetate/hexane. The product was a pale yellow
coloured solid.
Yield: 75 %. mp 77–798C. nmax (KBr)/cmꢀ1 3514 (OHstr),
2925 and 2852 (CH2str), 1594 and 1501 (C¼Cstr aromatic), 1463
(CHben), 1339 (NO2str), 1260 and 1112 (C–O–Cstr). dH
(500 MHz, CDCl3) 8.16 (d, J 9.2, 2H, Ar-H), 6.93 (d, J 9.9,
2H, Ar-H), 4.00 (t, J 6.10, 2H, O–CH2), 3.63 (t, J 6.15, 2H,
O–CH2), 1.78–1.43 (m, 12H, CH2). dC (125 MHz, CDCl3)
164.32, 141.34, 125.99, 114.47, 68.93, 63.02, 32.78, 29.37,
29.34, 29.02, 25.92, 25.74. Anal. Calc. for C14H21NO4:
C 62.89, H 7.91, N 5.23. Found: C 62.56, H 7.70, N 5.15 %.
Measurements
The FT-IR spectra of samples were recorded by the KBr pellet
1
method on a Thermo–Mattson FT-IR spectrometer. H-NMR
and 13C-NMR spectra of the compounds were recorded using a
JEOL GSX 500 NMR spectrometer; the samples were dissolved
in CDCl3 and TMS was used as an internal standard. Elemental
analyses were recorded using Elemental Analyzer (CLRI,
Chennai) for CHNS, Model-Euro EA 3000, Euro Vector S.P.A.
Optical polarizing microphotographs were taken using an
Olympus BX50 polarizing microscope equipped with a Linkam
THMS heating stage, and TMS 94 temperature programmer with
a C7070 digital camera. The samples were placed between two
12 mm coverslips and were heated with a programmed heating
rate. DSC calibrated for enthalpy and temperature was per-
formed using a TA Instruments Q-10 series. The experiments
were carried out in a nitrogen atmosphere at a heating rate of
108C minꢀ1. Each sample was subjected to two heating and
cooling cycles and data obtained from the second heating
and cooling cycle was considered for discussion. The high-
resolution XRD patterns were obtained at CSMR, Bangalore,
India employing a PANalyticalX’Pert PRO diffractometer
Synthesis of Tris[(4-nitrophenoxy)octyl]benzene-1,3,5-
tricarboxylate (2)
Compound 1 (14.6 g, 55 mmol) and triethylamine (5.5 g,
55 mmol) were dissolved in 200 mL of 2-butanone. To this

F
A. Shanavas, T. Narasimhaswamy, and A. S. Nasar
O
HO
O
O
O
O
DCC/DMAP
ϩ
THF, r.t.
24 h
O
OH
O
(H2C)11
CH3
(H2C)11
CH3
6
O
NH2
3
O
(CH2)8
O
O
(CH2)8
O
O
H2N
O
Microwave
Ethanol
10 min
(CH2)8
O
O
NH2
O
(CH2)11
CH3
O
O
O
O
O
N
(CH2)8
O
O
O
O
(CH2)8
O
N
O
O
(CH2)8
O
O
N
H3C (CH2)11
O
7
O
CH3
(CH2)11
O
Scheme 2. Synthesis of star mesogens containing three-ring side arms.
solution, 100 mL of a 2-butanone solution containing 4.8 g
(18.3 mmol) of 1,3,5-benzenetricarbonyltrichloride was added
dropwise at 08C and the reaction mixture was stirred for 3 h at
room temperature. The triethylamine salt was filtered off and
then the solvent was evaporated. The solid obtained was
recrystallized in a 1 : 3 ratio of acetone/methanol. The product
obtained was a pale yellow coloured solid.
70
Yield: 55 %. mp: 49–518C. nmax (KBr)/cmꢀ1 3074 (CHstr
aromatic), 2932 and 2856 (CH2str), 1723 (C¼Ostr ester), 1595
and 1509 (C¼Cstr aromatic), 1468 (CHben), 1341 (NO2str), 1265
and 1109 (C–O–Cstr of ester). dH (500 MHz, CDCl3) 8.84 (s, 3H,
Ar-H), 8.17 (d, J 9.15, 6H, Ar-H), 6.93 (d, J 9.15, 6H, Ar-H),
4.38 (t, J 6.90, 6H, O–CH2), 4.04 (t, J 6.95, 6H, O–CH2), 1.81–
1.47 (m, 36H, CH2). dC (125 MHz, CDCl3) 165.20, 164.28,
141.36, 134.50, 131.55, 126.00, 114.46, 68.87, 65.90, 29.22,
29.20, 29.00, 28.69, 25.95, 25.91. Anal. Calc. for C51H63N3O15:
C 63.93, H 6.62, N 4.41. Found: C 63.71, H 6.51, N 4.48 %.
35
Synthesis of Tris[(4-aminophenoxy)octyl]benzene-
1,3,5-tricarboxylate (3)
0
0
5
10
15
20
25
30
Compound 2 (9.5 g, 9.92 mmol) was reduced under hydrogen
atmosphere in the presence of 0.95 g of 10 % Pd-charcoal cat-
alyst in 100 mL of 1 : 1 mixture of ethanol and tetrahydrofuran at
2θ [deg]
Fig. 5. X-ray diffraction pattern of mesogen 5d measured at 1258C.

Trimesic Acid-Based Star Mesogens
G
4-Octyloxybenzaldehyde (4d)
Yield: 73 %. nmax (KBr)/cmꢀ1 2926 and 2855 (CH2str), 2733
(CHO), 1692 (C¼Ostr ester), 1601, 1577 and 1509 (C¼Cstr
aromatic), 1468 (CHben), 1160 (C–O–Cstr). dH (500 MHz,
CDCl3) 9.81 (s, 1H, -CHO), 7.69 (d, J 8.85, 2H, Ar-H), 6.91
(d, J 8.80, 2H, Ar-H), 3.96 (t, J 6.75, 2H, O–CH2), 1.73 (m, 2H,
CH2), 1.40 (m, 2H, CH2), 1.25 (m, 8H, CH2), 0.84 (t, J 6.85, 3H,
CH3). dC (125 MHz, CDCl3) 190.78, 164.32, 132.01, 129.77,
114.47, 68.44, 31.86, 29.38, 29.29, 29.12, 26.03, 22.72, 14.16.
Anal. Calc. for C15H22O2: C 76.87, H 9.46. Found: C 76.25,
H 9.41 %.
O
O
H
O
O
H
H
O
O
4-Decyloxybenzaldehyde (4e)
Yield: 73 %. nmax (KBr)/cmꢀ1 2924 and 2854 (CH2str), 2733
(CHO), 1694 (C¼Ostr ester), 1601, 1577 and 1509 (C¼Cstr
aromatic), 1468 (CHben), 1160 (C–O–Cstr). dH (500 MHz,
CDCl3) 9.75 (s, 1H, –CHO), 7.68 (d, J 9.15, 2H, Ar-H), 6.83
(d, J 9.10, 2H, Ar-H), 3.87 (t, 2 J 6.90, H, O–CH2), 1.67 (m, 2H,
CH2), 1.33 (m, 2H, CH2), 1.19 (m, 12H, CH2), 0.78 (t, J 9.85,
3H, CH3). dC (125 MHz, CDCl3) 190.47, 164.23, 131.87,
129.77, 114.40, 68.34, 31.90, 29.61, 29.41, 29.38, 29.23,
29.09, 26.00, 22.71, 14.11. Anal. Calc. for C17H26O2: C 77.81,
H 9.98. Found: C 77.39, H 9.96 %.
4-Dodecyloxybenzaldehyde (4f)
Yield: 73 %. nmax (KBr)/cmꢀ1 2924 and 2853 (CH2str), 2732
(CHO), 1695 (C¼Ostr ester), 1601, 1577 and 1508 (C¼Cstr
aromatic), 1467 (CHben), 1159 (C–O–Cstr). dH (500 MHz,
CDCl3) 9.80 (s, 1H, CHO), 7.74 (d, J 9.10, 2H, Ar-H), 6.92
(d, J 9.15, 2H, Ar-H), 3.96 (t, J 6.15, 2H, O–CH2), 1.74 (m, 2H,
CH2), 1.40 (m, 2H, CH2), 1.27 (m, 16H, CH2), 0.82 (t, J 9.80,
3H, CH3). dC (125 MHz, CDCl3) 190.72, 164.31, 131.99,
129.77, 114.76, 68.43, 31.98, 29.73, 29.68, 29.55, 29.41,
29.38, 29.12, 26.02, 22.75, 14.18. Anal. Calc. for C19H30O2:
C 78.56, H 10.41. Found: C 78.24, H 10.28 %.
Fig. 6. Tripod-like structure of star mesogens in the mesophase.
room temperature for 48 h. The Pd/C catalyst was removed by
filtering the reaction mixture through a Celite-540 filtering aid
and the evaporation of the solvents yielded the product. The
product was recrystallised in 1 : 3 mixture of ethyl acetate and
hexane. The product was a reddish brown coloured solid.
Yield: 92 %. mp 68–708C. nmax (KBr)/cmꢀ1 3469 and 3380
(NH2str free amine), 2929 and 2855 (CH2str), 1724 (C¼Ostr
ester), 1634 (NHben), 1512 (C¼Cstr aromatic), 1472 (CHben),
1236 (C–O–Cstr of ester). dH (500 MHz, CDCl3) 8.83 (s, 3H, Ar-
H), 6.73 (d, J 9.20, 6H, Ar-H), 6.62 (d, J 9.15, 6H, Ar-H), 4.36 (t,
J 6.90, 6H, O–CH2), 3.87 (t, J 6.90, 6H, O–CH2), 3.40 (br, 6H,
NH2), 1.79–1.73 (m, 12H, CH2), 1.44–1.38 (m, 24H, CH2). dC
(125 MHz, CDCl3) 165.25, 152.36, 139.87, 134.54, 131.55,
116.52, 115.70, 68.65, 65.93, 29.48, 29.38, 29.30, 28.72,
26.09, 26.01. Anal. Calc. for C51H63N3O9: C 70.55, H 7.31,
N 4.84. Found: C 70.38, H 7.21, N 4.83 %.
4-Tetradecyloxybenzaldehyde (4g)
Yield: 73 %. mp 75–778C. nmax (KBr)/cmꢀ1 2922 and 2848
(CH2str), 2724 (CHO), 1691 (C¼Ostr ester), 1603 and 1509
(C¼Cstr aromatic), 1467 (CHben), 1255 and 1106 (C–O–Cstr). dH
(500 MHz, CDCl3) 9.87(s, 1H, –CHO), 7.81 (d, J 9.20, 2H,
Ar-H), 6.97 (d, J 9.10, 2H, Ar-H), 4.02 (t, J 6.90, 2H, O–CH2),
1.80 (m, 2H, CH2), 1.45 (m, 2H, CH2), 1.25 (m, 20H, CH2), 0.87
(t, J 6.85, 3H, CH3). dC (125 MHz, CDCl3) 190.96, 164.37,
132.09, 129.77, 114.83, 68.52, 32.02, 29.75, 29.68, 29.41,
29.23, 29.13, 26.04, 22.78, 14.22. Anal. Calc. for C21H34O2:
C 79.18, H 10.75. Found: C 79.51, H 10.74 %.
Synthesis of 4-Alkoxybenzaldehydes (4d–h)
In a 500 mL two necked flask, 12.5g (90 mmol) of K2CO3
and 11.8 g (85 mmol) of4-hydroxybenzaldehyde wereadded and
dissolved in 200 mL of DMF. The mixture was stirred and heated
to 908C followed by the dropwise addition of 100 mL of a DMF
solution containing 90 mmol of n-bromoalkane. The temperature
of the mixture was maintained at 908C for 5 h. The reaction
mixture was poured into 1 L of distilled water and the product
was extracted with 300 mL (3 ꢁ 100 mL) of diethyl ether.
The organic layer was washed with 5 % aqueous KOH solution
followed by brine, and dried over anhydrous sodium sulfate. The
residue obtained after removal of the solvent was washed with
hexane. The product 4d was a colourless liquid, 4e and 4f were
colourless semi solids, and 4g and 4h were colourless solids.
4-Hexadecyloxybenzaldehyde (4h)
Yield: 73 %. mp 48–508C. nmax (KBr)/cmꢀ1 2918 and
2848 (CH2str), 2728 (CHO), 1692 (C¼Ostr ester), 1601 and
1509 (C¼Cstr aromatic), 1470 (CHben), 1164 (C–O–Cstr). dH
(500 MHz, CDCl3) 9.86 (s, 1H, –CHO), 7.82 (d, J 9.15, 2H,
Ar-H), 6.96 (d, J 9.15, 2H, Ar-H), 4.03 (t, J 6.75, 2H,
O–CH2), 1.80 (m, 2H, CH2), 1.43 (m, 2H, CH2), 1.24 (m,
24H, CH2), 0.87 (t, J 6.95, 3H, CH3). dC (125 MHz, CDCl3)
190.93, 164.37, 132.09, 129.79, 114.83, 68.52, 32.02, 29.78,
29.68, 29.55, 29.41, 29.23, 29.13, 26.04, 22.78, 14.22. Anal.
Calc. for C23H38O2: C 79.71, H 11.05. Found: C 79.29,
H 11.21 %.

H
A. Shanavas, T. Narasimhaswamy, and A. S. Nasar
Synthesis of Tris-{[(4-alkoxyphenyl)methylidene]
Tris-{[(4-octyloxyphenyl)methylidene]
aminophenoxyoctyl}benzene-1,3,5-tricarboxylate (5a–h)
aminophenoxyoctyl}benzene-1,3,5-tricarboxylate (5d)
In a typical experiment, 1.0 mmol of amine 3 and 3.0 mmol of
4-alkoxybenzaldehydes 4a–h were added to a 100 mL conical
flask. Ethanol (3 mL) was added to the conical flask, the reac-
tants mixed thoroughly, and the flask heated inside a microwave
oven (power 80 W) for 10 min. Every 1.5 min, the flask was
taken out and the contents were mixed thoroughly and the
process was repeated. The flask was allowed to cool to room
temperature and the solid obtained was washed with methanol
and recrystallised in 2-butanone. All the products obtained were
pale brown coloured solids.
Yield: 60 %. mp 1228C. nmax (KBr)/cmꢀ1 2928 and 2858
(CH2str), 1730 (C¼Ostr ester), 1612 and 1509 (C¼Cstr aromatic),
1468 (CHben), 1244 (C–O–Cstr of ester), 1163 (C–O–Cstr). dH
(500 MHz, CDCl3) 8.84 (s, 3H, Ar-H), 8.37 (s, 3H, –CH¼N),
7.79 (d, J 9.20, 6H, Ar-H), 7.18 (d, J 8.45, 6H, Ar-H), 6.94
(d, J 9.20, 6H, Ar-H), 6.89 (d, J 8.45, 6H, Ar-H), 4.36 (t, J 6.85,
6H, O–CH2), 3.99 (t, J 6.15, 6H, O–CH2), 3.94 (t, J 6.10, 6H,
O–CH2), 1.79 (m, 18H, CH2), 1.46 (m, 18H, CH2), 1.40 (m, 12H,
CH2), 1.28 (m, 24H, CH2), 0.88 (t, J 6.15, 9H, CH3). dC
(125 MHz, CDCl3) 165.20, 161.68, 157.94, 157.59, 145.18,
134.52, 131.58, 130.27, 129.36, 122.12, 115.02, 114.72,
68.24, 65.91, 31.90, 29.45, 29.39, 29.30, 29.29, 28.73, 26.10,
26.02, 22.71, 14.21. Anal. Calc. for C96H129N3O12: C 75.99,
H 8.57, N 2.76. Found: C 75.61, H 8.79, N 2.71 %.
Tris-{[(4-ethoxyphenyl)methylidene]
aminophenoxyoctyl}benzene-1,3,5-tricarboxylate (5a)
Yield: 60 %. mp 1218C. nmax (KBr)/cmꢀ1 2932 and 2857
(CH2str), 1724 (C¼Ostr ester), 1605 and 1509 (C¼Cstr aromatic),
1471 (CHben), 1246 (C–O–Cstr of ester), 1164 (C–O–Cstr).
dH (500 MHz, CDCl3) 8.84 (s, 3H, Ar-H), 8.37 (s, 3H, –CH¼N),
7.79 (d, J 8.45, 6H, Ar-H), 7.18 (d, J 8.40, 6H, Ar-H), 6.94
(d, J 8.40, 6H, Ar-H), 6.89 (d, J 8.40, 6H, Ar-H), 4.36 (t, J 6.10,
6H, O–CH2), 4.06 (q, J 6.90, 6H, O–CH2), 3.94 (t, J 6.15, 6H,
O–CH2), 1.79 (m, 36H, CH2), 1.43 (t, J 6.90, 9H, CH3).
dC (125 MHz, CDCl3) 165.20, 161.46, 157.88, 157.59, 145.18,
134.52, 131.58, 130.31, 129.41, 122.12, 115.02, 114.69, 68.26,
65.91, 63.70, 29.38, 29.29, 28.73, 26.09, 26.02, 14.86. Anal.
Calc. for C78H93 N3O12: C 74.07, H 7.41, N 3.32. Found:
C 74.38, H 7.38, N 3.38 %.
Tris-{[(4-decyloxyphenyl)methylidene]
aminophenoxyoctyl}benzene-1,3,5-tricarboxylate (5e)
Yield: 60 %. mp 1218C. nmax (KBr)/cmꢀ1 2925 and 2856
(CH2str), 1729 (C¼Ostr ester), 1611 and 1509 (C¼Cstr aromatic),
1468 (CHben), 1245 (C–O–Cstr of ester), 1163 (C–O–Cstr). dH
(500 MHz, CDCl3) 8.84 (s, 3H, Ar-H), 8.37 (s, 3H, –CH¼N),
7.79 (d, J 9.20, 6H, Ar-H), 7.18 (d, J 9.15, 6H, Ar-H), 6.94
(d, J 9.10, 6H, Ar-H), 6.89 (d, J 8.45, 6H, Ar-H), 4.36 (t, J 6.90,
6H, O–CH2), 3.99 (t, J 6.90, 6H, O–CH2), 3.94 (t, J 6.15, 6H,
O–CH2), 1.79 (m, 18H, CH2), 1.46 (m, 18H, CH2), 1.41 (m, 12H,
CH2), 1.27 (m, 36H, CH2), 0.88 (t, J 6.80, 9H, CH3). dC
(125 MHz, CDCl3) 165.20, 161.68, 157.91, 157.59, 145.18,
134.52, 131.58, 130.29, 129.36, 122.12, 115.02, 114.71,
68.24, 65.91, 32.00, 29.61, 29.50, 29.42, 29.39, 29.30, 28.73,
26.10, 26.02, 22.78, 14.24. Anal. Calc. for C102H141N3O12:
C 76.50, H 8.87, N 2.62. Found: C 76.18, H 8.76, N 2.6 %.
Tris-{[(4-butoxyphenyl)methylidene]
aminophenoxyoctyl}benzene-1,3,5-tricarboxylate (5b)
Yield: 60 %. mp 1268C. nmax (KBr)/cmꢀ1 2930 and 2861
(CH2str), 1729 (C¼Ostr ester), 1611 and 1508 (C¼Cstr aromatic),
1467 (CHben), 1252 (C–O–Cstr of ester), 1161 (C–O–Cstr).
dH (500 MHz, CDCl3) 8.84 (s, 3H, Ar-H), 8.37 (s, 3H, –CH¼N),
7.79 (d, J 8.45, 6H, Ar-H), 7.18 (d, J 8.45, 6H, Ar-H), 6.94
(d, J 8.80, 6H, Ar-H), 6.89 (d, J 8.40, 6H, Ar-H), 4.36 (t, J 6.80,
6H, O–CH2), 3.99 (t, J 6.10, 6H, O–CH2), 3.94 (t, J 6.15, 6H,
O–CH2), 1.78 (m, 6H, CH2), 1.48 (m, 18H, CH2), 1.40 (m, 24H,
CH2), 0.99 (t, J 6.10, 9H, CH3). dC (125 MHz, CDCl3) 165.19,
161.68, 157.88, 157.59, 145.18, 134.52, 131.58, 130.31, 129.36,
122.12, 115.02, 114.71, 68.26, 67.92, 65.91, 31.33, 29.39,
29.31, 28.73, 26.10, 26.02, 19.32, 13.97. Anal. Calc. for
C84H105 N3O12: C 74.79, H 7.84, N 3.11. Found: C 74. 35,
H 7.75, N 3.09 %.
Tris-{[(4-dodecyloxyphenyl)methylidene]
aminophenoxyoctyl}benzene-1,3,5-tricarboxylate (5f)
Yield: 60 %. mp 1198C. nmax (KBr)/cmꢀ1 2925 and 2852
(CH2str), 1729 (C¼Ostr ester), 1611 and 1509 (C¼Cstr aromatic),
1469 (CHben), 1246 (C–O–Cstr of ester), 1164 (C–O–Cstr). dH
(500 MHz, CDCl3) 8.84 (s, 3H, Ar-H), 8.37 (s, 3H, –CH¼N),
7.79 (d, J 9.15, 6H, Ar-H), 7.18 (d, J 9.20, 6H, Ar-H), 6.94
(d, J 9.10, 6H, Ar-H), 6.89 (d, J 8.45, 6H, Ar-H), 4.36 (t, J 6.80,
6H, O–CH2), 3.99 (t, J 6.90, 6H, O–CH2), 3.94 (t, J 6.10, 6H,
O–CH2), 1.79 (m, 18H, CH2), 1.45 (m, 18H, CH2), 1.40 (m, 12H,
CH2), 1.26 (m, 48H, CH2), 0.87 (t, J 6.80, 9H, CH3). dC
(125 MHz, CDCl3) 165.20, 161.68, 157.91, 157.59, 145.21,
134.52, 131.58, 130.27, 129.36, 122.12, 115.02, 114.71,
68.24, 65.91, 32.00, 29.75, 29.68, 29.45, 29.45, 29.30, 29.29,
28.73, 26.10, 26.02, 22.78, 14.24. Anal. Calc. for
Tris-{[(4-hexyloxyphenyl)methylidene]
aminophenoxyoctyl}benzene-1,3,5-tricarboxylate (5c)
Yield: 60 %. mp 1248C. nmax (KBr)/cmꢀ1 2931 and 2859
(CH2str), 1730 (C¼Ostr ester), 1611 and 1509 (C¼Cstr aromatic),
1470 (CHben), 1244 (C–O–Cstr of ester), 1164 (C–O–Cstr).
dH (500 MHz, CDCl3) 8.84 (s, 3H, Ar-H), 8.37 (s, 3H, –CH¼N),
7.79 (d, J 8.90, 6H, Ar-H), 7.18 (d, J 8.45, 6H, Ar-H), 6.94
(d, J 9.15, 6H, Ar-H), 6.89 (d, J 8.40, 6H, Ar-H), 4.36 (t, J 6.80,
6H, O–CH2), 3.99 (t, J 6.90, 6H, O–CH2), 3.94 (t, J 6.10, 6H,
O–CH2), 1.79 (m, 18H, CH2), 1.46 (m, 18H, CH2), 1.40 (m, 12H,
CH2), 1.34 (m, 12H, CH2), 0.90 (t, J 6.10, 9H, CH3).
dC (125 MHz, CDCl3) 165.20, 161.68, 157.88, 157.59, 145.18,
134.52, 131.58, 130.31, 129.36, 122.12, 115.02, 114.71, 68.24,
65.91, 31.68, 29.39, 29.31, 29.26, 28.73, 26.10, 26.02, 25.80,
22.71, 14.16. Anal. Calc. for C90H117 N3O12: C 75.43, H 8.22, N
2.93. Found: C 75.08, H 8.15, N 2.91 %.
C108H153N3O12: C 76.96, H 9.14, N 2.49. Found: C 76.61,
H 9.02, N 2.41 %.
Tris-{[(4-tetradecyloxyphenyl)methylidene]
aminophenoxyoctyl}benzene-1,3,5-tricarboxylate (5g)
Yield: 60 %. mp 1258C. nmax (KBr)/cmꢀ1 2920 and 2851
(CH2str), 1731 (C¼Ostr ester), 1612 and 1508 (C¼Cstr aromatic),
1468 (CHben), 1246 (C–O–Cstr of ester), 1164 (C–O–Cstr). dH
(500 MHz, CDCl3) 8.84 (s, 3H, Ar-H), 8.37 (s, 3H, –CH¼N),
7.79 (d, J 9.15, 6H, Ar-H), 7.18 (d, J 9.15, 6H, Ar-H), 6.94 (d, J
9.20, 6H, Ar-H), 6.89 (d, J 8.40, 6H, Ar-H), 4.36 (t, J 6.90, 6H,
O–CH2), 3.99 (t, J 6.80, 6H, O–CH2), 3.94 (t, J 6.90, 6H,
O–CH2), 1.79 (m, 18H, CH2), 1.46 (m, 18H, CH2), 1.40 (m,

Trimesic Acid-Based Star Mesogens
I
12H, CH2), 1.26 (m, 60H, CH2), 0.88 (t, J 6.10, 9H, CH3). dC
(125 MHz, CDCl3) 165.20, 161.68, 157.93, 157.59, 145.18,
134.52, 131.58, 130.31, 129.36, 122.12, 115.02, 114.72,
68.24, 65.91, 32.00, 29.75, 29.72, 29.45, 29.39, 29.30, 28.73,
26.10, 26.02, 22.78, 14.24. Anal. Calc. for C114H165 N3O12:
C 77.37, H 9.39, N 2.37. Found: C 77.02, H 9.32, N 2.37 %.
1.45 (m, 18H, CH2), 1.40 (m, 12H, CH2) 1.26 (m, 48H, CH2),
0.87 (t, J 6.80, 9H, CH3). dC (125 MHz, CDCl3) 165.23, 164.72,
163.75, 157.98, 157.15, 153.26, 144.62, 134.56, 134.13, 132.44,
131.56, 129.81, 122.30, 121.30, 115.04, 114.43, 68.44, 68.26,
65.93, 32.02, 29.74, 29.70, 29.66, 29.47, 29.39, 29.30, 29.19,
28.74, 26.08, 26.03, 22.80, 14.25. Anal. Calc. for
C129H165N3O18: C 75.73, H 8.12, N 2.05. Found: C 75.19,
H 8.03, N 2.12 %.
Tris-{[(4-hexadecyloxyphenyl)methylidene]
aminophenoxyoctyl}benzene-1,3,5-tricarboxylate (5h)
Yield: 60 %. mp 1268C. nmax (KBr)/cmꢀ1 2921 and 2850
(CH2str), 1729 (C¼Ostr ester), 1612 and 1509 (C¼Cstr aromatic),
1469 (CHben), 1247 (C–O–Cstr of ester), 1163 (C–O–Cstr). dH
(500 MHz, CDCl3) 8.84 (s, 3H, Ar-H), 8.37 (s, 3H, –CH¼N),
7.79 (d, J 9.15, 6H, Ar-H), 7.18 (d, J 9.15, 6H, Ar-H), 6.94 (d, J
9.20, 6H, Ar-H), 6.89 (d, J 8.40, 6H, Ar-H), 4.36 (t, J 6.90, 6H,
O–CH2), 3.99 (t, J 6.90, 6H, O–CH2), 3.94 (t, J 6.10, 6H,
O–CH2), 1.78 (m, 18H, CH2), 1.45 (m, 18H, CH2), 1.40 (m,
12H, CH2), 1.25 (m, 72H, CH2), 0.87 (t, J 6.85, 9H, CH3). dC
(125 MHz, CDCl3) 165.20, 161.68, 157.88, 157.59, 145.18,
134.52, 131.58, 130.31, 129.36, 122.12, 115.02, 114.69,
68.24, 65.91, 32.00, 29.78, 29.68, 29.46, 29.39, 29.29, 28.73,
26.10, 26.02, 22.78, 14.24. Anal. Calc. for C120H177 N3O12:
C 77.74, H 9.62, N 2.26. Found: C 77.58, H 9.55, N 2.23 %.
Supplementary Material
1H and 13C NMR spectra for the mesogens are available on the
Journal’s website.
Acknowledgements
T.N. thanks Dr A. B. Mandal, Director, CSIR-CLRI for his support and
encouragement. A.S. also thanks the Director, CSIR-CLRI for giving per-
mission to carry out the work in the polymer laboratory, CLRI. The authors
are thankful to Dr S. Krishna Prasad and Dr D. S. Shankar Rao, Scientists,
CSMR, Bangalore for powder X-ray measurements and discussions. The
financial support of the University of Madras and CSIR, New Delhi in
the form of a fellowship is gratefully acknowledged.
References
[1] P. J. Collings, M. Hird, Introduction to Liquid Crystals: Chemistry
andPhysics 1997 (Taylor & Francis: London).
Synthesis of 4-(4-Dodecyloxybenzoyloxy)benzaldehyde (6)
[2] G. R. Luckhurst, G. W. Gray, The Molecular Physics of Liquid
Crystals 1979 (Academic Press: New York, NY).
4-Dodecyloxybenzoic acid (5.5 g, 18 mmol) and 4-
hydroxybenzaldehyde (2.2 g, 18 mmol) were taken and
dissolved in 60 mL of THF. To this stirred solution,
dicyclohexylcarbodiimide (18 mmol) dissolved in 20 mL of
THF was added followed by the addition of 4-dimethylamino-
pyridine (1.8 mmol) and stirring was continued at room tem-
perature overnight. Filtration of solid dicyclohexyl urea and
subsequent evaporation of the solvent yielded a solid that was
purified by recrystallization in isopropyl alcohol. The product
was a colourless crystalline solid.
Yield: 75 %. mp 72–748C. nmax (KBr)/cmꢀ1 2916 and 2849
(CH2str), 2733 (CHO), 1734 and 1694 (C¼Ostr ester), 1602 and
1509 (C¼Cstr aromatic), 1463 (CHben), 1272 (C–O–Cstr of
ester). dH (500 MHz, CDCl3) 10.00 (s, 1H, CHO), 8.13 (d, J
8.85, 2H, Ar-H), 7.94 (d, J 8.90, 2H, Ar-H), 7.39 (d, J 9.15, 2H,
Ar-H), 6.97 (d, J 8.45, 2H, Ar-H), 4.02 (t, J 6.85, 2H, O–CH2),
1.81 (m, 2H, CH2), 1.46 (m, 2H, CH2), 1.30 (m, 16H, CH2), 0.87
(t, J 6.85, 3H, CH3). dC (125 MHz, CDCl3) 191.12, 164.34,
163.97, 156.00, 133.95, 132.52, 131.32, 122.71, 120.86, 114.51,
68.47, 32.02, 29.75, 29.74, 29.69, 29.66, 29.45, 29.16, 26.07,
22.79, 14.24. Anal. Calc. for C26H34O4: C 76.06, H 8.34. Found:
C 76.61, H 8.21 %.
[3] R. A. Reddy, C. Tschierske, J. Mater. Chem. 2006, 16, 907.
doi:10.1039/B504400F
[4] A. Jakli, A. Saupe, One- and Two-Dimensional Fluids: Properties of
Smectic, Lamellar and Columnar Liquid Crystals 2006 (Taylor &
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