Thermal and optical characterization of a novel series of supramolecular liquid crystals

Article abstract of DOI:10.1016/j.physb.2012.05.029

Supramolecular hydrogen bonded liquid crystal (SMHBLC) homologous series is synthesized and characterized. Hydrogen bond is formed between p-n-alkyloxy benzoic acids (nOBA, where n=7 to 12) and Iodo substituted benzoic acid (I _mBA) respectively. The isolated homologs are characterized by various techniques like Polarizing Optical Microscopy (POM), Differential Scanning Calorimetry (DSC), ¹H Nuclear Magnetic Resonance Spectroscopy (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). From the POM and DSC studies phase diagram has been constructed and discussed. A new smectic ordering, labeled as smectic R, has been characterized which exhibits a ribbon like texture. This phase is observed in a complex pertaining to the undecyloxy carbon number. Tilt angle in smectic R phase and in traditional smectic C of all the complexes have been experimentally deduced and the results are fitted and so obtained β value concurrences with the Mean field theory predicted value.

Full text of DOI:10.1016/j.physb.2012.05.029

Physica B 407 (2012) 3709–3716
Contents lists available at SciVerse ScienceDirect
Physica B
journal homepage: www.elsevier.com/locate/physb
Thermal and optical characterization of a novel series of supramolecular
liquid crystals
n
N. Pongali Sathya Prabu a, D.M. Potukuchi b, M.L.N. Madhu Mohan a,
a Liquid Crystal Research Laboratory (LCRL), Bannari Amman Institute of Technology, Sathyamangalam 638 401, India
b Department of Physics, University College of Engineering, Jawaharlal Nehru Technological University, Kakinada 533003, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Supramolecular hydrogen bonded liquid crystal (SMHBLC) homologous series is synthesized and
characterized. Hydrogen bond is formed between p-n-alkyloxy benzoic acids (nOBA, where n¼7 to 12)
and Iodo substituted benzoic acid (ImBA) respectively. The isolated homologs are characterized by
various techniques like Polarizing Optical Microscopy (POM), Differential Scanning Calorimetry (DSC),
1H Nuclear Magnetic Resonance Spectroscopy (NMR) and Fourier Transform Infrared Spectroscopy
(FTIR). From the POM and DSC studies phase diagram has been constructed and discussed. A new
smectic ordering, labeled as smectic R, has been characterized which exhibits a ribbon like texture. This
phase is observed in a complex pertaining to the undecyloxy carbon number. Tilt angle in smectic R
phase and in traditional smectic C of all the complexes have been experimentally deduced and the
Received 17 February 2012
Received in revised form
10 April 2012
Accepted 11 May 2012
Available online 30 May 2012
Keywords:
Hydrogen bond
Cacoon texture
1H NMR
results are fitted and so obtained
b
value concurrences with the Mean field theory predicted value.
DSC
& 2012 Elsevier B.V. All rights reserved.
POM
Smectic R
1. Introduction
moiety. Complementary type HBLCs can also be materialized
[16–24] by the HB interaction of two organic acids, such that
each of them possessing an acid (–COOH) moiety [11–19] bears a
Liquid crystals [LC] are intermediate soft state materials that
posses the properties of anisotropic crystals and isotropic liquids.
As such, they exhibit distinct response. Materials scientists
launched [1–6] their investigations for the utility of this soft
matter through their design and adoptability in electro-optic
devices [7–10] as optical shutters, light modulators etc. In the
recent years, supra-molecular design of hydrogen bonded liquid
crystals (HBLC) gained importance as functional materials for
their synthesis and characterization with specific choice of
chemical functional groups. Initiative of HBLCs by Kato [2,7]
group has triggered the LC research to set in to a new direction
of research activity. The lower activation energies involved with
the HB interaction profoundly influence the thermal properties of
LC phases, viz., melting points, enthalpies and thermal stability.
The soft covalent (SC) interaction, if configured to spread adjacent
and along the essential core region of the molecule, it is believed
to originate to new mesophases with an operationally viability.
Further, intermolecular HB of complementary type in LC materi-
als is known to monitor the phase stability by the proper selection
of interacting components. HB in LCs can be realized by the
interaction between a proton donor moiety and a proton acceptor
d
hydroxyl (–O-Hþ ) group considered as a proton donor and a
d
carbonyl (–C¼Oꢀ ) group considered as a proton acceptor.
Nevertheless, HBLCs are also realized by the SC interaction
between proton rich aniline moieties and proton acceptor alde-
hyde moieties. In order to realize the LC phases of phases of
device interest in HBLC complexes, it is considered as a sufficient
condition that at least one of the moieties should be inherently
[18,21,24,25] mesogenic. Most of the reported cases [22,23] of
HBLCs deal with both of the moieties exhibiting mesogenic
[22,23] nature. However, HBLCs made up of two moieties which
are inherently non-mesogenic [20,26,27] are also reported. Mono
component [21,23] or multi component hydrogen bonded [21,22]
LC systems are also reported. An overview of literature in HBLCs
reveals HB interaction can enhance the thermal stability of device
relevant tilted phases and better their operating parameters.
In the wake of the extensive reports of functional groups and
their diversified utility, an attempt is made to design and isolate a
novel homologous series of HBLCs especially made up of benzoic
acids with meta-substitution (to promote transverse dipole
moment) and mesogenic nOBAs. A series of meta-substituted
(with Iodine atom) HBLCs prepared from 3-Iodobenzoic acids and
N-p-n-alkyloxy benzoic acids (where n represents the alkyloxy
chain length varied from 7 to 12) are presented, while the HB and
LC phases are characterized by IR, proton NMR, Polarized Optical
n Corresponding author. Tel.: þ91 4295 223 480; fax: þ91 4295 223 775.
E-mail address: mln.madhu@gmail.com (M.L.N. Madhu Mohan).
0921-4526/$ - see front matter & 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.physb.2012.05.029

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N.P. Sathya Prabu et al. / Physica B 407 (2012) 3709–3716
Microscopy (POM) and Differential Scanning Calorimetry (DSC)
along with the device relevant optical properties exhibited are
also determined.
transverse dipole moment (mt) to influence the variance and
thermal stability of LC phases. They are found to be insoluble in
water and sparingly soluble in common organic solvents such as
methanol, ethanol, and benzene and dichloromethane. However,
ImBA:nOBAs exhibited a high degree of solubility in coordinating
solvents like dimethyl sulfoxide (DMSO), dimethyl formamide
(DMF) and Pyridine. All members of the present series of HBLCs
are found (Table 1) melt at temperatures below 97 1C.
2. Materials and methods
A Varian 300 MHz 1H NMR spectrometer is used to verify the
HBLC complex formation and to estimate the H-atom abundance.
An ABB FTIR MB3000 spectrometer and the MB3000 software are
used to confirm the hydrogen bonding. Optical textural observa-
tions were made with a Nikon polarizing optical microscope
(POM) equipped with Nikon digital CCD camera in conjunction
with an ACT-2U imaging software. An Instec HCS402-STC 200
temperature controller (70.1 1C) system is used for textural
studies. The liquid crystal sample is filled in to the cells (made
4. Results and discussion
4.1. 1H NMR studies
The 1H NMR spectrum exhibited by the ImBA:nOBA series of
HBLCs is presented in Fig. 2 (for n¼9 as representative). The
salient features of NMR spectrum are
up of polyimide buffed pre-treated and conductive coated 4 mm
spaced transparent glass plates) in its high temperature isotropic
state. The transition temperatures and corresponding enthalpy
values were obtained by DSC (Shimadzu DSC-60, Japan). Optical
extinction technique is used for the determination of tilt angle.
The p-n-alkyloxy benzoic acids (nOBA) and m-substituted benzoic
acid (ImBA) and solvents of HPLC grade for the synthesis were
procured from Sigma Aldrich, (Germany) and all the solvents used
were of HPLC grade.
(1) A singlet at
sponding to the TMS.
(2) A singlet in the vicinity of
dꢁ0 ppm infers the standard absorption corre-
dꢁ8.5 ppm infers the presence of
one H-atom of benzene ring of ImBA situated between
carboxylic acid moiety and I-atom. The higher value of
Chemical shift due to de-shielding effect (which is caused
by neighboring groups (i.e.–COOH and iodine moieties).
(3) A multiplet in the range of
dꢁ8.0–8.2 infers the presence of three
H-atoms of aromatic moieties in the adjacent C-atoms to the acid
moieties, i.e., one-H-atom adjacent to the ImBA’s acid moiety and
two-H-atoms corresponding to the nOBA’s acid moiety.
3. Synthesis of ImBA:nOBA series of HBLCs
Iodine substituted hydrogen bonded mesogens, viz., ImBA:
nOBA series of HBLCs are synthesized by the addition of one
mole of p-n-alkyloxy benzoic acids (nOBA, where n¼7–12) and
1 mole of Iodo substituted benzoic acid (ImBA) in N, N-Dimethyl
formamide (DMF). The dimeric form of nOBA is first converted in
to the monomeric form by dissolving nOBA in DMF. Then, they are
reacted with the ImBA dissolved in DMF. Further, the reactants
were subjected to constant stirring for 12 h at ambient tempera-
ture (30 1C) till a white precipitate in a dense solution is formed.
The white crystalline crude complexes so obtained by removing
excess DMF. The product is then re-crystallized with dimethyl
Sulfoxide (DMSO). The synthetic route and molecular structure of
the present HBLCs made up of p-n-alkyloxy benzoic acids with
m-iodo benzoic acid (ImBA:nOBA) is presented in Scheme 1,
where n represents the number of methyline (–CH2–) units in
alkyloxy chain of nOBA. It is anticipated that the meta-position of
Iodine atom on the molecular frame is expected to enhance the
(4) A singlet at
dꢁ7.9 indicates the presence of one H-atom
attached to the C-atom of the aromatic ring of ImBA situated
in para position of –COOH moiety.
(5) A multiplet around
dꢁ7.25 indicates the presence of one-H-atom
of aromatic ring of ImBA (total integrated intensity ꢁ2.0 is resolve
as that from one-H-atom of ImBA moiety, while the other-H-atom
relevant to the residual H-atoms of CDCl3 used as solvent).
(6) Multiplets at
dꢁ6.9 evinces the presence of two H-atoms
each on the C-atoms of the aromatic ring situated at the
p-position of –COOH moiety of nOBA.
OH
O
O
C
CnH2n+1
O
C
HO
I
Fig. 1. Molecular structure of ImBA: nOBA series.
Scheme 1. Scheme of ImBA: nOBA synthesis.

N.P. Sathya Prabu et al. / Physica B 407 (2012) 3709–3716
3711
Fig. 2. 1H NMR spectra of ImBA:9OBA complex.
A triplet in the vicinity of
H-atoms situated on the first –CH2 unit (adjacent to the
aromatic ring) of the alkoxy chain of nOBA.
dꢁ4.1infers the presence of two-
(7)
ImBA: 11OBA complex
(8) A triplet at
corresponding to the CH3 group of at the end of alkyl chain.
(9) Multiplets in the range from
dꢁ3.1 confirms the presence of three-H-atoms
80
40
0
d
ꢁ1.28 to 1.8 infer the presence
of 14 H-atoms pertaining to the remaining 7-methyline units
each possessing 2-H-atoms.
The singlet at
attributed to the trace level impurity of acetone used as cleaner.
The absence of NMR response (for 410) possibly to infer the
dꢁ2.1 infers the presence of two H-atoms
d
presence of two H-atoms of both of the hydroxyl moieties
(corresponding to the –COOH groups of ImBA and nOBA) is
attributed to the limitation of the NMR instrument (i.e., being
operated at 300 MHz). Hence, in the wake of the agreement
between the observed (points 1–9) number of H-atoms (through
the 1H NMR) and the expected (Fig. 1) number of H-atoms in the
HBLC complex, the purity of the HBLC product (to the extent of
H-atom abundance at spectroscopic levels) is confirmed.
3000
2250
1500
750
Wave number / cm-1
Fig. 3. FTIR spectra for ImBA:11OBA complex.
4.2. Fourier transform infrared spectroscopy (FTIR) studies
resulted for the appearance of black transmitted intensity (Plate 2)
implying the homeotropic arrangement of molecules. This texture
is frequently referred (Ref) as pseudo-isotropic texture. It appears
more black in color than that of isotropic brown color, and
somewhat less black than homeotropic jet black. As this phase
is originated from the nematic phase during the cooling process,
this phase is tentatively labeled as Nh phase. Further, cooling of
this homeotropic phase results for the growth of a texture (Plates
3a and b) with ribbon like appearance. Hence, this phase is
labeled as Smectic-R (Sm R). The texture shows large continuous
curved ribbons with considerable width, while texture possesses
canal like appearances. In each ribbon, disclination lines are
observed to vouch and evince for the possible helicoidal structure.
The dark part of the canal and its opposite handed viz; brighter
part is clearly visualized in the plates 3a and 3b characterize the
phase to be tilted. Such a texture is characterized and previously
reported by us [14] in HBLC mesogens which is referred as ribbon
phase and abbreviated as Smectic R. However, on further cooling
of Sm R phase, a cacoon like regions are observed (swarms in
Plate 4) are observed to grow. Since, the cacoon like textural
appearance is uncommon to the calamitic LCs, under the con-
sideration that it may be one or other form of smectic phases (to
be investigated) this cacoon phase is named as smectic-X1 phase.
The solid state (KBr) IR spectra recorded at RT for ImBA: nOBAs
are presented in Fig. 3 (for n ¼11, as representative). The presence
of an intense peak at 2924 cmꢀ1 is attributed [25,29–30] to the
possible shift of OH stretching and the participation of H-atom of
hydroxyl group of acid moiety. The IR absorption relevant to the
carbonyl stretching (4CQO) frequency is found to shift towards
lower side from 28 to 36 cmꢀ1 for the present cases of ImBA:nOBAs.
The shift of frequency and its appearance as single absorption line
confirms the participation of O-atom of carbonyl group of –COOH
moiety in its monomeric form.
4.3. Phase identification
The observed phase variance, transition temperatures and
corresponding enthalpy values through the POM and DSC (in
cooling and heating cycles) studies for the ImBA:nOBA series are
presented in Table 1.
4.3.1. Phase characterization through POM
ImBA:nOBAs are found to exhibit characteristic [28] textures as
presented in Plate 1–8. The Nematic phase exhibited schlieren
four brush (Plate 1) texture. Cooling of nematic phase in n¼11

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N.P. Sathya Prabu et al. / Physica B 407 (2012) 3709–3716
Table 1
ImBA:nOBA series of HBLCs.
ImBA:nOBA HBLC
Complexes for n
Phase variance Technique Melt
N
Nh/Sm X
Sm R
Sm X1
Sm C
Sm F
K
a
a
a
12
NXCF
DSC (h)
DSC (c)
94.5 (65.92)
96.0 (56.85)
119.4 (1.46) 100.7 (0.26)
96.7
87.1
78.5 (21.43)
78.6
(1.27)
97.00
(3.10)
87.3
POM
119.9
101.1
a
a
a
a
a
11
NNhRX1CF
DSC (h)
DSC (c)
104.0 (1.79)
123.2 (0.87) 104.2 (0.27) 102
(0.59)
102.5
97.1 (1.27) 95.3
(0.20)
95.6
78.2 (11.99) 73.9 (28.16)
POM
123.9
104.8
97.5
78.4
74.00
10
9
–
DSC (h)
DSC (c)
POM
88.5 (23.97)
91.4 (70.50)
83.3 (16.57)
83.6
a
a
a
NXCF
DSC (h)
DSC (c)
104.5 (1.34)
143.2 (1.52) 100.7 (0.89)
88.9 (16.74) 84.3
(2.74)
84.6
80.5 (22.08)
80.7
POM
143.8 101.2
89.3
8
7
–
DSC (h)
DSC (c)
POM
88.1 (14.00)
85.5 (19.65)
85.9
N
DSC (h)
DSC (c)
POM
88.2 (32.39) 102.0 (7.96)
102.0 (2.05)
78.4 (21.72)
78.7
102.5
It is interesting to note that two even complexes viz., ImBA:8OBA and ImBA:10OBA do not exhibit any mesogenic phases. The numbers given in parenthesis are the enthalpy
values in J/g.
a
monotropic, @ not resolved.
Plate 2. Psuedo-isotropic texture of Sm D phase for ImBA:11OBA at 104.8 1C.
Plate 1. Nematic schlieren texture of the ImBA:11OBA at 123.9 1C.
The swarms of cacoon like regions coalesce with further cooling,
as they manifest with a homogeneous textural pattern in plate 5.
On cooling the Sm X phase, a broken focal conic texture char-
acteristic of smectic C phase (Plate 6) originates which is found to
get established (Plate 7) as characteristic texture. Further cooling
of Sm C phase is found to result in the growth of colored
chequered board texture (Plate 8) characteristic of Smectic F
phase. As to ascertain the structural details and response for the
either to unknown smectic R and smectic X phases in the present
ImBA:nOBA series of HBLCs, further experimental investigations
are aimed whose results are presented in the up-coming sections.
transition temperatures and the enthalpy (DH) are presented in
Table 1. Initially, the sample is heated and held in its isotropic phase
for 2 min as it is allowed to attain thermal equilibrium. The results
of DSC are found to concur with the values from POM studies. From
Fig. 4, the thermogram for n¼11 seems to be rather complex as it
involves seven distinct transitions, viz., isotropic to Nematic;
Nematic to homeotropic nematic; homeotropic nematic to Sm R;
Sm R to Sm X1; Sm X1 to Sm C; Sm C to Sm F and Sm F to crystal,
with transition temperatures earmarked as 123.2 1C, 104.2 1C,
102.0 1C, 97.1 1C, 95.3 1C, 78.2 1C, 73.9 1C, with corresponding
enthalpy values of 0.87 J/g, 0.27 J/g, 0.59 J/g, 1.27 J/g, 0.2 J/g,
11.99 J/g and 28.16 J/g, respectively. While in the heating cycle,
two distinct transitions namely crystal to melt and Sm X1 to Sm R
are obtained at 96.0 1C and 104.0 1C, with corresponding enthalpy
values of 56.85 J/g and 1.79 J/g, respectively. For a clear visualization
of the DSC peaks relevant to the nematic to homeotropic nematic,
homeotropic nematic to Sm R, and Sm R to Sm X1 phase transitions,
the thermogram is expanded in the corresponding region as
4.3.2. Transition temperatures and enthalpy of LC phase transitions
by DSC
DSC thermograms of all the complexes are recorded in heating
and cooling cycle at scan rate of 5 1C/min and is presented in Fig. 4
(for n¼11 as representative), while the corresponding data of

N.P. Sathya Prabu et al. / Physica B 407 (2012) 3709–3716
3713
Plate 3. a and b Ribbon like texture of Sm R phase with extinction positions for tilt angle in ImBA:11OBA at 102.5 1C.
Plate 4. Origin of cacoon like swarms of Sm X phase in ImBA:11OBA.
Plate 6. Transition of Sm X phase to Sm C phase with broken focal conic texture
for ImBA:11OBA.
Plate 7. Broken focal conic texture of Sm C in ImBA:11OBA at 95.6 1C.
Plate 5. Cacoon-like textured swarms grown for Sm X phase in ImBA:11OBA at
97.5 1C.
re-presented in Fig. 5. Owing to the following observations and their
comparison with the reports LCs that;
(c) Occurrence of homeotropic nematic phase (n¼11) at a lower
temperature than that of nematic phase, the homeotropic
nematic phase (Nh) observed for n¼11 is reassigned as Sm
D phase.
(d) Sm D to Sm R transition in cooling scan is found to accompany
with an enthalpy value of 0.59 J/g confirming its first order
nature. But, in heating scan transition is observed to accom-
pany with an enthalpy value of 1.9 J/g. Hence, occurrence of
Sm-R is confirmed as enantiotropic.
(a) The involvement of comparable and considerable amount of
enthalpy across the nematic to homeotropic nematic phase
transition.
(b) Pseudo-isotropic textural appearance which is comparable to
the reported characteristic textures [28] attributed to smectic
D phase.

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N.P. Sathya Prabu et al. / Physica B 407 (2012) 3709–3716
150
ImBA: nOBA
140
130
120
110
100
90
Isotropic
N
N
X
N
D
R
X
N
C
C
F
F
80
Crystal
70
6
7
8
9
10
11
12
13
Plate 8. Colored chequred board texture of Sm F in ImBA:11OBA at 78.4 1C.
Number of methyline units / n
Fig. 6. Phase diagram of ImBA:nOBA series. Nematic, Smectic X, Smectic C, Smectic F,
DSC Exothermic thermogram
ImBA: 11OBA
Smectic D and Smectic R phases are abbreviated as N, X, C, F, D and R respectively.
2.5
2.0
1.5
1.0
0.5
ImBA:nOBAs is presented in Fig. 6. The salient features of the
phase diagram for the ImBA:nOBAs reflects up on
(a) The HBLCs viz., ImBA:nOBAs exhibit nematic phase with
orientational order, Sm D LC phase with homeotropic ortho-
gonal alignment, titled smectic phases with layering order,
smectic-R, smectic-X and smectic F respectively. Nematic
phase prevails in all complexes which exhibited LC nature
with varying thermal spans.
(b) LC phases are quenched in even numbered intermediate
homologs (n¼8 and10).Quenching is attributed to the effec-
tive transverse dipole moment mt inherently possessed by
the molecule as I-atom is substituted at meta position of the
3-iodobenzoic acid.
120
110
100
90
80
70
(c) Two new phases, viz., Sm R and Sm X exhibiting hither to
un-reported textures along with a rarely reported Sm D phase
are exhibited by ImBA:nOBAs, which is assumed due to the
strategic position occupied to the electro-negative I-atom
with respect to the rigid core part of the LC complex.
(d) A quasi-2D ordered tilted hexagonally ordered Sm F phase is
found to follow and occur by cooling the tilted 1-D tilted Sm C
phase in the ImBA:nOBAs prevalently in odd-numbered higher
homologs.
Temperature /°C
Fig. 4. DSC thermogram of ImBA:11OBAcomplex in exothermic run.
(e) Odd–even effect is found to occur at the crystal melting points
(where crystal or solid phase changes in to LC phase with
heating) as a consequence of alternating contributions of axial
polarizabilities.
4.5. Order parameter in tilted LC phases
4.5.1. Smectic-C phase
Temperature variation of tilt angle y(T) reflecting the growth
of order parameter (Fig. 7) in SmC phase is measured by optical
extinction method [19] in ImBA: nOBAs ( for n¼9, 11 and 12). The
tilt angle is found to increase with decreasing temperature. It is
observed that
y(T) attains a characteristic maximum value. For
Fig. 5. Clear visualization of DSC exothermic thermogram of ImBA:11OBA complex.
higher homologs, viz., n¼11 and 12, the
y(T)max is observed to be
ꢁ16, while for the intermediate member viz., n¼9, it is found to
be ꢁ111. The large magnitudes of the tilt angle in higher homologs
are attributed to the enhanced orientational disorder introduced
by the lengthy flexible part of the molecule. Hence, higher
homologs with extended flexible part in HBLCs are argued to
contribute positively to the inclined [31] soft covalent hydrogen
4.4. Phase diagram for ImBA:nOBA series of HBLCs
Phase diagram constructed with the results of transition
temperatures and thermal stability (Table 1) exhibited by the

N.P. Sathya Prabu et al. / Physica B 407 (2012) 3709–3716
3715
14
Smectic C
ImBA : 11OBA
Smectic R
15
10
5
12
10
8
ImBA : 11OBA
ImBA : 9OBA
ImBA : 12OBA
6
4
2
0
0
0
2
4
6
8
10
12
0.0
0.5
1.0
(T-Tc) / °C
1.5
2.0
(T-Tc) / °C
Fig. 7. Temperature variation of tilt angle in smectic C phase for ImBA:nOBA
complexes (where n¼9, 11 and 12). Solid line denotes the theoretical fit, error
bars are shown to experimental points with respect to values predicted by mean
field theory.
Fig. 8. Temperature variation of tilt angle in smectic R phase of ImBA:11OBA
complex. Solid line denotes the theoretical fit, error bars are shown to experi-
mental points with respect to values predicted by mean field theory.
bonding interaction for the realization of tilted phases of applica-
tional interest.
(2) 1H NMR study confirms the environmental hydrogen atoms
existing in the complexes.
(3) Three new smectic orderings are noticed and characterized.
(4) The tilt angle measurements in smectic C and smectic R
phases are performed and the goodness of the fit is tested
with error bars.
The observed temperature variation of
power law relationship given by
y
(T) appears to follow a
yðTÞa
ðTCꢀTÞb,
ð1Þ
where TC represents the transition temperature,
b is the critical
exponent component value and T is the temperature at which y(T)
is experimentally determined.
Acknowledgments
The data of
is fitted (Fig. 7) to the Eq. 1 to study the growth of order
parameter in Sm C phase. The estimated values of
y(T) for the members of ImBA:nOBAs in Sm C phase
The authors as overall acknowledge blessings by Lordess
Bannari Amman. DMP acknowledges the financial support by
DST (DST/SR/S2/CMP-0063/2008), New Delhi, India. Infrastruc-
tural support provided by Bannari Amman Institute of Technology
and Jawaharlal Nehru Technological University are also gratefully
acknowledged.
b
for n¼9, 11
and 12 are found to be 0.4570.05; 0.5570.03 and 0.4570.01,
respectively. The solid line (drawn for the fit parameters) and the
error bars superposed (Fig. 7) over the observations reflect up on
the goodness of the fit and the consistency of the observations.
The estimated values of
b for the present members of ImBA:nOBAs
are found to be in the vicinity of Mean Field theory [32,33]
prediction to infer the long-range interaction of transverse dipole
moment for the stabilization of tilted smectic C phase.
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p-n alkyloxy benzoic acids are synthesized and characterized.

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