Mesomorphism dependence on halogenated chalconyl esters in terms of molecular flexibility/rigidity

Article abstract of DOI:10.1080/15421406.2016.1177887

Vinyl carboxy central group containing a novel chalconyl ester homologous series: RO.C₆H₄.CH ? CH.COO.C₆H₄.CH ? CH.CO.C₆H₄.I (para) have been synthesized and studied with a view to understand and establish the relation between thermotropic liquid crystalline (LC) behaviors and the molecular structure. Novel chalconyl ester homologous series consists of thirteen homologs (C₁–C₁₈). C₁–C₃ homologs are nonmesogenic, C₄ homolog is enantiotropic nematogenic and the rest of the homologs (C₅–C₁₈) are enantiotropically smectogenic plus nematogenic. Phase transition temperatures and textures of LC phase were determined by an optical polarizing microscopy (POM) equipped with a heating stage. Cr-M/I, Sm-N, N-I transition curves in a phase diagram behaved in normal manner. Sm-N and N-I transition curves exhibited odd-even effect from C₄–C₁₀ or nearby C₁₀ homolog. Textures of nematic phase are threaded or Schlieren and that of the smectic phase are of the type smectic A or C. Analytical and spectral data confirms the molecular structure of homologs. Thermal stabilities for smectic and nematic mesophases are 155.0 and 180.7, respectively, and their corresponding mesophaselengths are varied from minimum to maximum at 17.0°C–39.0°C as well as 15.0°C–30.0°C. Thus, it is middle ordered melting type series. The group efficiency orders derived on the basis of smectic and nematic thermal stabilities are as under: Sm: -C₆H₄.I > -C₆H₄.Cl > -C₄H₃S and N:- C₆H₄.I > -C₆H₄.Cl > -C₄H₃S from comparative study of structurally similar analogous series

Full text of DOI:10.1080/15421406.2016.1177887

Molecular Crystals and Liquid Crystals
ISSN: 1542-1406 (Print) 1563-5287 (Online) Journal homepage: http://www.tandfonline.com/loi/gmcl20
Mesomorphism dependence on halogenated
chalconyl esters in terms of molecular flexibility/
rigidity
Vinay S. Sharma & R. B. Patel
To cite this article: Vinay S. Sharma & R. B. Patel (2016) Mesomorphism dependence on
halogenated chalconyl esters in terms of molecular flexibility/rigidity, Molecular Crystals and
Liquid Crystals, 633:1, 80-90, DOI: 10.1080/15421406.2016.1177887
To link to this article: http://dx.doi.org/10.1080/15421406.2016.1177887
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Date: 31 August 2016, At: 15:15

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
, VOL. , –

http://dx.doi.org/./..
Mesomorphism dependence on halogenated chalconyl esters in
terms of molecular flexibility/rigidity
Vinay S. Sharma and R. B. Patel
Chemistry Department, K. K. Shah Jarodwala Maninagar Science College, Gujarat University, Ahmedabad, India
ABSTRACT
KEYWORDS
Vinyl carboxy central group containing a novel chalconyl ester homolo-
gous series: RO.C H .CH = CH.COO.C H .CH = CH.CO.C H .I (para) have
Enantiotropy; liquid crystals;
mesophaselength; nematic;
smectic
6
4
6
4
6
4
been synthesized and studied with a view to understand and estab-
lish the relation between thermotropic liquid crystalline (LC) behav-
iors and the molecular structure. Novel chalconyl ester homologous
series consists of thirteen homologs (C –C ). C –C homologs are non-
1
18
1
3
mesogenic, C homolog is enantiotropic nematogenic and the rest of
4
the homologs (C –C ) are enantiotropically smectogenic plus nemato-
5
18
genic. Phase transition temperatures and textures of LC phase were
determined by an optical polarizing microscopy (POM) equipped with
a heating stage. Cr-M/I, Sm-N, N-I transition curves in a phase diagram
behaved in normal manner. Sm-N and N-I transition curves exhibited
odd-even effect from C –C or nearby C homolog. Textures of nematic
4
10
10
phase are threaded or Schlieren and that of the smectic phase are of the
type smectic A or C. Analytical and spectral data confirms the molecu-
lar structure of homologs. Thermal stabilities for smectic and nematic
mesophases are 155.0 and 180.7, respectively, and their corresponding
mesophaselengths are varied from minimum to maximum at 17.0°C–
3
9.0°C as well as 15.0°C–30.0°C. Thus, it is middle ordered melting type
series. The group efficiency orders derived on the basis of smectic and
nematic thermal stabilities are as under: Sm: -C H .I > -C H .Cl > -C H S
6
4
6
4
4
3
and N:- C H .I > -C H .Cl > -C H S from comparative study of struc-
6
4
6
4
4
3
turally similar analogous series
Introduction
A liquid crystalline (LC) state [1] has proved its ability and importance in the benefit of
mankind in the various fields of scientific and technological applications [2–9]. Present inves-
tigation on thermotropic LC state have been planned with an aim to understand and establish
the effect of molecular structure on LC properties [10–14] of novel substances. Novel sub-
stances will be synthesized through homologous series consisting of two or three phenyl rings,
one or two central bridges, and two terminal end groups viz. –OR and –I, the left and right
sided polar terminal groups. One of the central groups will be –CH = CH–CO– which will
be bioactive and other will be vinyl carboxylate ester group. Thus, thermotropy which may be
useful for LC devices as well as bioactivity may be useful for LC devices and bioactivity which
CONTACT Vinay S. Sharma
ment, K. K. Shah Jarodwala Maninagar Science College, Gujarat University, Ahmedabad, India.
 Taylor & Francis Group, LLC
vinaysharma@gmail.com R. B. Patel
roshanpatel@gmail.com
Chemistry Depart-
©

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
81
may be useful for its lyotropic study. Hence dual study of same novel compounds can be facil-
itated. Present study will include only synthesis, characterization, results and discussion will
be interpreted on the basis of molecular rigidity and flexibility [15–17] for thermometric data
of novel substances. Number of ester homologous series have been reported till the date [18–
2
5]. Group efficiency order on the basis of thermal stability and the early commencement of
mesophase will be derived from comparative study of analogous series.
Experimental
Synthesis
4
-n-alkoxy cinnamic acids (A) were synthesized by the alkylation of 4-hydroxy benzaldehyde
to form 4-alkoxy benzaldehyde and further reaction with Malonic acid in pyridine in presence
of few drops of piperidine as a catalyst [26], α-4-Hydroxy phenyl β-4 -iodo benzoyl ethylene
ꢀ
(
m.p 167°C, yield 76%) (B) was prepared by usual established method [27]. Final product
were prepared by the esterification of (A) and (B) [28]. Thus, the ester chalconyl homolog
derivatives were filtered, washed with sodium bicarbonate solution followed by distilled water,
dried and purified till constant transition temperatures obtained using an optical polarizing
microscope equipped with a heating stage. Alkyl halides, EtOH, KOH, Acetone, DCM, 4-
Iodo acetophenone, 4-Hydroxy benzaldehyde, dicyclohexyl carbodimide, Dimethyl amino
pyridine, Malonic acid etc., required for synthesis were used as received except solvents which
were dried and distilled prior to use. The synthetic route to the series is mentioned below as
scheme-1
Characterization
Representative homologs of a series were characterized by elemental analysis, Infrared spec-
1
1
troscopy, H NMR spectra, IR spectra were recorded on Perkin-Elmer spectrum GX, H NMR
spectra were recorded on Bruker using CDCl as solvent. Microanalysis was performed on
3
Perkin-Elmer PE 2400 CHN analyzer (Table 1). Transition temperature (Table 4) and LC
properties (Textures) were determined using an optical polarizing microscopy equipped with
heating stage and digital camera (POM). Texture images of nematic phase were character-
ized by miscibility method (Table 2), Decomposition temperatures (Table 3) were determined
using of Shimadzu DSC 60 differential Scanning Calorimeter with a heating rate of 5–10.0°C
−1
−1
min in air and it was calibrated with indium(156.6°C, 28.45 Jg ) Holland. Thermodynamic
quantities enthalpy (ꢀH) and entropy(ꢀS = ꢀH/T) are qualitatively discussed.
Analytical data
IR spectra in cm−1 for hexadecyloxy & octadecyloxy derivatives
Hecadecyloxy: 2924 (C-H str. of alkane), 2850 (C-H str. of –(CH -)n group of –OC H
2
16 33
gorup,1658 (C = O str. of carbonyl carbon of ester), 1600 (C = C str. of alkene), 1448, 1510,
1
571 (C = C str. of aromatic ring), 952, 1024 (C-H bending of alkene), 1170 (C-O str. of ether
linkage), 1251 (C-O str. of ester group), 1359 (C-H bending of alkene), 648, 570 (C-I str.). IR
data confirms the molecular structure.
Octadecyloxy: 2916 (C-H str. of alkane), 2870 (C-H str. of –(CH -)n group of –OC H
2
18 37
group, 1730(C = O str. of carbonyl carbon of ester), 1600(C = C str. of alkene), 1467, 1533,

8
2
V. S. SHARMA AND R. B. PATEL
Scheme . Synthesis route to the series.
Table . Elemental analysis for () hexyloxy () heptyloxy () decyloxy () octadecyloxy derivatives.
%
Elements found
%Elements calculated
H
Sr. No.
Molecular formula
C H O I
C
H
I
C
I

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

  



C H O I
  
C H O I

  
C H O I

  
Table . Texture of nematic phase of C, C, C, C by miscibility method.
Sr. No.
Homolog
Texture

C
C
C
C
Threaded
Threaded
Schlieren
Schlieren




MOLECULAR CRYSTALS AND LIQUID CRYSTALS
83
−
− −
Table . Transition temperature (°C) and enthalpy (J g ) and entropy change (J g k ) by DSC
measurement.
Homologs or
Comp.
Heating
scan(°C)
Cooling
scan(°C)
ꢀH (-Jg 
−
)
ꢀH (Jg
−
)
ꢀS(J g
− −
k
)
− −
ꢀS(J g k )
Transition
C4
Cr-SmC
SmC-N
N-I
Cr-SmC
SmC-N
N-I
Cr-SmC
SmC-N
N-I
Cr-SmC
SmC-N
N-I
–

>


>


>


–

–


–


–


–
–
.
–
.
.
–
.
.
–
.
.
–
–
.
–
–
–
.
–
.
–
C7
.
.
–
.
.
–
.
.
–
.
.
–
.
.
–
.
.
–
.
.
–
.
.
–
.
.
–
C10
C14
>
1
579 (C = C str. of aromatic ring), 1004, 1062 (C-H bending of alkene), 1143, 1199 (C-O str.
of ether linkage), 1251 (C-O str. of ester group), 1309 (C-H bending of alkene), 690, 570 (C-I
str.). IR data confirms the molecular structure.
1
HNMR spectra in CDCl in δ ppm for heptyloxy & octyloxy derivative
3
Heptyloxy: 0.82 (t, 3H, -CH of –C H ), 1.29 (t, 4H, CH -CH -CH -CH -CH - OC H ),
3
7
15
3
2
2
2
2
7
15
1
-
(
.43 (p, 5H –CH -CH -CH - of –OC H ), 1.31 (q, 4H, -CH -CH ), 1.73(t, 2H,-CH -CH -of
2 2 2 7 15 2 3 2 2
OC H ), 4.06(t, 3H, -OCH -CH -of –OC H ), 6.51 & 7.59 (d, 2H, -CH = CH-), 7.2 & 7.74
7
15
2
2
7
15
4.01 H, middle phenyl ring), 7.65 & 7.97 (4H, third phenyl ring), 6.93 & 7.61 (4H, phenyl ring
with alkoxy chain). NMR data confirms the molecular structure.
Octyloxy: 0.82 (t, 3H, -CH of –C H ), 1.75(t, 4H, CH -CH -CH -CH -CH -CH -
3
8
17
3
2
2
2
2
2
OC H ), 1.29 (p, 5H –CH -CH -CH - of –OC H ), 1.31 (q, 4H, -CH -CH ), 1.73(t, 2H,-
8
17
2
2
2
8
17
2
3
CH -CH -of -OC H ), 3.93 (t, 3H, -OCH -CH -of –OC H ), 6.51 & 7.59 (d, 2H, -CH =
2
2
8
17
2
2
8
17
ꢀ
ꢀꢀ
Table . Transitiontemperaturesin°Cforseries. α--( -n-alkoxycinnamoyloxy)phenyl-β- -iodobenzoyl
ethylenes.
Transition temperatures in C
Sr.no
R = n-alkyl group
Smectic
Nematic
Isotropic

C
C
C
C
C
C
C
C
C
C
C
C
C
–
–
–
–
.
.
.
.
.
.
.
.
.
–
–
–
.
.
.
.
.
.
.
.
.
.
.












.
.
.
.
.
.
.
.
.
.




.
.

8
4
V. S. SHARMA AND R. B. PATEL
Figure. DSCmeasurement(A) C homologatheatingconditionendothermicpeakat°C,whileatcooled

condition peak observed at °C. (B) C homolog, first endothermic peak at °C and second peak at


°C during heating stage, while in cooling stage two peak trace at °C and °C enantiotropically. (C)
C homolog, heating condition first endothermic peak observed at °C and second endothermic at °C

and at cooled condition two peaks are obtained at °C and °C. (D) C homolog, two endothermic peak

observed at °C and °C, while at cooling stage trace two peaks at °C and °C.
CH-),7.21 & 7.74 (4.01 H, middle phenyl ring), 7.56 & 7.97 (4H, third phenyl ring), 6.93 &
7
.61 (4H, phenyl ring with alkoxy chain). NMR data confirms the molecular structure.
Results and discussion
A novel chalconyl ester homologous series of LC (thermotropic) property determined from
ꢀ
condensation of dimeric trans cinnamic acids and α-4-Hydroxy phenyl β-4 -Iodo benzoyl
ethylene (m.p 167°C & yield 76%) is synthesized and evaluated their some thermometric data
to correlate mesomorphic behaviors and the molecular structure through molecular rigidity
and flexibility. Mesomorphism commences from C homolog. All the mesogenic homologs
4
are enantiotropically smectogenic plus nematogenic except C homolog which missed smec-
4
togenic character and exhibited only nematic character in enantiotropic manner. Transi-
tion temperatures (Table 4) as determined using an optical polarizing microscopy (POM)
equipped with heating stage are plotted versus the number of carbon atoms present in n-alkyl
chain ‘R’ of –OR group. DSC thermogram of C , C , C , C homologue is shown in Figure
4
7
10
14
1
during heating and cooling condition. Then, on linking like or related transition points;
Cr-M/I, Sm-N and N-I transition curves are obtained, showing phase behaviors of series as
shown in Fig. 2. Cr-M/I transition curve adopts a zigzag path of rising and falling with overall
descending tendency and behaved in normal manner. Sm-N transition curve initially rises

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
85
Figure . Phase behaviors of series.
and then passes through maxima at C12 homolog and descended as series is ascended with
exhibition of odd-even effect and behaved in normal manner. N-I transition curve initially
descended up to C homolog, ascended up to C homolog and then descended up to C18
7
10
homolog with exhibition of odd-even effect. Thus, it behaved in normal established manner.
Odd-even effect in Sm-N and N-I transition curves appeared up to nearby C or exactly at
10
C homolog respectively, and then it disappeared for higher homologs of longer n-alkyl chain
10
‘
R’ of –OR group. Thus, alternation and lowering of transition temperature as compared to
the corresponding trans n-alkoxy cinnamic acids are observed for present novel homologous
series. Transition curves for smectic and nematic are extrapolated to nonsmectogen C and
4
nonmesogen C homolog, respectively, to predict [29,30,31,32] their probable latent transi-
3
tion temperature (LTT) and to magnify the odd-even effects.
The changing of mesogenic behavior from homolog to homolog in the same novel series
is observed by varying number of carbon atom or atoms in n-alkyl chain ‘R’ of -OR group,
keeping the rest of the molecular part unchanged throughout a series. Textures of nematic
phase are threaded or schlieren and that of the smectic phase are of the type smectic A or
C. Analytical, thermal and the spectral data supported molecular structures of homologs.
Thermal stabilities for smectic and nematic are 155°C and 180.7°C, respectively, whose total
mesophaselength (Sm + N) are from 30°C to 58°C. The POM image and phase sequence at
cooled condition shown inFig. 3(i) and Fig. 3(ii), respectively.
The disappearance of dimerization of trans-4-n-alkoxy cinnamic acids and the lower-
ing of transition temperatures of corresponding novel homologs of present investigation is
attributed to the breaking of hydrogen bonding of trans vinyl carboxylic acids by esterifica-
tion process. The inexhibition of mesogenic behaviors by C , C and C homolog is due to the
1
2
3
low magnitudes of dispersion forces and low magnitudes of dipole-dipole interactions which
induces unsuitable magnitudes of intermolecular anisotropic forces of cohesion and closeness.
Instead, it induces high crystallizing tendency and abruptly breaks the crystal lattices under

8
6
V. S. SHARMA AND R. B. PATEL
Figure . (i). (a). Schlieren type texture of nematic phase of comp. C at °C. (b). Sm C phase of comp.C


at °C. (c). nematic phase of comp. C at °C. (d). smectic phase of comp. C at °C.


thermometric condition and sharply transform into isotropic liquid from crystalline state (or
vice versa) without passing through an intermediate state of existence LC. The exhibition of
smectic nematic mesophase formation is attributed to the suitable magnitudes of anisotropic
forces of intermolecular lateral and then end-to-end cohesion and closeness as a consequence
Figure . (ii). Phase sequence of C homolog on cooling condition.

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
87
Figure . Structurally similar analog series.
of favorable molecular rigidity and flexibility, which maintain the floating of a sample sub-
stance with sliding layered molecular arrangement due to preoccupied lamellar packing of
molecules for definite range of temperatures and then continue floating with residual end to
end attractions which is suitable to facilitate floating of the same smectogenic molecular state
with statistically parallel orientational order for another higher ranged temperature to show
nematic mesophase formation under the influence of externally exposed thermal vibrations.
The exhibition of odd-even effect is due to added methylene unit to n-alkyl chain ‘R’ of –
OR group up to C or nearby C homolog. However, alternation of transition temperatures
10
10
diminishes or disappears for higher homologs of longer n-alkyl chain ‘R’ from and beyond
C homolog, because longer n-alkyl chain may coil or bend or flex or couple with major axis
10
of core structure of molecules. Thus, unexpected status of n-alkyl chain eliminates odd-even
effect.
The variations in mesomorphic properties and their magnitudes from homolog to
homolog in the same novel series of present investigation is attributed to the sequentially
and progressively added methylene unit or units at the n-alkyl chain ‘R’ which alters the
magnitudes of length to breadth ratio, permanent dipole moment across the long molecules
axis, dispersive forces, molecular polarity, polarizability, rigidity, flexibility, etc. affecting inter-
molecular cohesion and closeness. The extrapolation of Sm-N and the N-I transition curves
to C and C homologs for smectic and nematic, respectively, which suggests the possibility of
4
3
missing the corresponding mesophase formation because extrapolated curves matches with
Cr-N and Cr-I points of respective homolog. The changing trends in mesogenic behaviors of
present novel series 1 are compared with structurally similar analogs series X [33] and Y [34]
as mentioned in below Fig. 4.
Homologous series 1, X, and Y are identical with respect to two phenyl rings and one of
the central bridge (-CH = CH-CO-) commonly present linking middle and last phenyl rings
either homocyclic or heterocyclic which contributes partly to the total molecular rigidity, as
well as left n-alkoxy terminal end group –OR for the same analog or homolog from series to
series which partly contributes to total molecular flexibility. However, homologous series 1, X,
and Y differ with respect to central bridge –CH = CH-COO- linking first and middle phenyl
ring of series 1 and –COO- of series X and Y which contributes partly to the total molec-
ular rigidity. Moreover last phenyl ring bonded through –CH = CH-CO- common central
bridge with para substituted iodo or chloro group, i.e., (-C H .I and –C H .Cl) in series 1
6
4
6
4
and X, as well as a heterocyclic ring (-C H S), which partly contribute to the total molecular
4
3
rigidity and partly to the total molecular flexibility whose magnitudes differ from series to
series for the same homolog and from homolog to homolog in the same series. Thus, varia-
tions in mesogenic properties and the degree of mesomorphism for the same homolog from
series to series or from homolog to homolog in the same series will depend upon the differing
magnitudes of differing features like molecular rigidity and/or flexibility as well as differing

8
8
V. S. SHARMA AND R. B. PATEL
Table . Thermal stability in°C.
Series→
-C H I (series )
-C H Cl(series-X)
-C H S (series-Y)
 




Sm-N or Sm-I Commencement
of Smectic phase
.
C –C )
.
(C –C )
.
(
(C –C )




 
C
.
C
.
C
.
N-I Commencement of Nematic
phase
(
C –C )
C
(C –C )
C
.°C–.°C
(C –C )
C
.°C–.°C






Total mesophase lengths from
minimum to maximum from
t°C to t°C
°C–°C
C C

C C
C C
molecular polarity and polarizability etc. Following Table 5 represents some thermal data for
the series under comparative study.
All the three series under comparative study are
•
•
•
•
Smectogenic plus nematogenic in character.
Smectogenic thermal stabilities of series 1, X, and Y are in decreasing order.
Nematogenic thermal stabilities of series 1, X, and Y are in decreasing order.
Smectogenic and nematogenic mesophase commences the earliest from (C and C ) in
4
3
series X and then a little bit later from (C and C ) in case of present series 1 and the
5
4
latest from (C and C ) in case of series Y involving heterocyclic ring.
Lower mesophaselength are in decreasing order from series 1 to X to Y; but it is in
decreasing order from series X to 1 to Y.
8
7
•
The exhibition of smectogenic property from C , C , or C homolog by the series 1, X, and
4
5
8
Y, respectively, is attributed to the presence of lamellar packing of molecules in their preoc-
cupied crystal lattices in solid crystalline state due to the difference occurred in intermolec-
ular attractions by different central bridges linking first and middle phenyl rings viz. –CH =
CH-COO- and –COO- in which –CH = CH-COO- is longer and stronger than –COO- con-
taining –CH = CH- vinyl group, involving conjugated double bond, which increases molec-
ular rigidity more than –COO- central bridge. Therefore, the extent of molecular noncopla-
narity maintained favorably to facilitated smectic and nematic phase formation earlier than
the series X and Y. Simultaneously homologous series X and Y contain identically –COO-
central bridge linking first and middle phenyl rings differs in magnitudes of flexibility by –Cl
and –H of –C H .Cl and –C H S, respectively, in which –C H S does not contain any flex-
6
4
4
3
4
3
ible group (except –H) like –Cl. Thus, late commencement of smectic and nematic phase as
compared to series 1 and X is facilitated; by flexibility difference. Thus, suitable magnitudes
of anisotropic forces of intermolecular end-to-end and lateral cohesion and closeness which
maintain and facilitate either sliding layered molecular arrangement or/and then statistically
parallel orientational order of molecules in floating condition to cause smectic and/or nematic
mesophase formation for definite range of temperature, depending upon individual thermal
resistivity generated from constitutionally energy stored in each molecule of same homolog
from series to series and from homolog to homolog in the same series. Decreasing order of
smectic and nematic thermal stabilities is attributed to the decreasing order of mainly molec-
ular flexibility by tails ends and partly due to differences of vinyl carboxy and carboxy central
bridges which contributes to molecular rigidity. –I is more polarizable than –Cl and –H due
to size difference, the effectiveness of size difference reflects in the order of the thermal stabil-
ities and the lower and upper degree of mesomorphism of series 1 and Y. The exceptionally

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
89
highest value of upper degree of mesomorphism (72.2°C) of series X is attributed to the high
valued thermal resistivity towards exposed thermal vibrations induced by Vander waals forces
of higher magnitude causing intermolecular attractions for its (series-X) C homolog.
14
Conclusions
•
Novel chalconyl ester derivatives of thermotropic LC behavior is predominantly nemato-
genic and partly smectogenic whose smectogenic and nematogenic mesophaselengths
vary from 17°C to 39°C and 15°C to 30°C, respectively, and it is of middle ordered melt-
ing type.
•
Group efficiency order derived on the basis of (i) thermal stability (ii) early commence-
ment of smectic phase and (iii) total mesophaselengths for smectic and nematic are as
under.
(
i). Smectic: -C H .I > -C H .Cl > -C H S
6 4 6 4 4 3
(ii). Nematic: -C H .I > -C H .Cl > -C H S
6 4 6 4 4 3
(
(
iii). Smectic: -C H .Cl > -C H .I > -C H S
6
4
6
4
4
3
iv). Nematic: -C H .Cl > -C H .I > -C H S
6
4
6
4
4
3
(
v) (Smectic ± Nematic)
(
vi) Lower: -C H .I > -C H .Cl > -C H S
6
4
6
4
4
3
(
vii) Upper: -C H .Cl > -C H .I > -C H S
6 4 6 4 4 3
•
•
•
A phenomena of mesomorphism is very sensitive and susceptible to molecular structure
as a consequence of changing magnitudes of molecular rigidity and/or flexibility.
Present investigation is useful for the study of binary systems and can be useful for phar-
maceutical preparations due to their bioactivity.
Present study supports and raises the credibility to the conclusions drawn earlier.
Acknowledgments
Authors acknowledge thanks to Dr. R.R.Shah, principal and management of K. K. Shah Jarodwala Mani-
nagar Science College, Ahmedabad. Authors are also thankful to Dr. A.V.Doshi, Ex-principal of M.V.M.
Science and Home Sci. College – Rajkot for his constant support, inspirations, and help, as well as valu-
able suggestions as and when we needed during the course of present investigation. Authors thank to
NFDD Centre for the analytical and spectral services.
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