Mesomorphic study of novel chalconyl-ester-based nonisomeric series: Synthesis and characterization

Article abstract of DOI:10.1080/15421406.2016.1262680

A newly designed homologues series: 3-(3-(4-(Dimethylamino) phenyl) acrylonyl) phenyl 3-(4-n-alkoxyphenyl) acrylate has been synthesized and studied through chalconyl ester linking group at (meta) position. The series consists of 13 compounds, in which C₁ to C₄ homologue are nonliquid crystal, while C₅ to C₁₈ exhibit nematic phase, and C₁₂ to C₁₈ shows smectic and nematic phase with enantiotropically manner. Mesophase image of present compounds are rod like, needle and threaded type textures investigated by POM. All this compounds were characterized by elemental analysis, FT-IR and ¹H NMR. The mesomorphism is measured by POM, DSC, and molecular packing is determined by XRD technique. The following synthesized chalconyl ester-based compounds C₅ to C₁₂ shows antibacterial as well as antifungal activity compared with corresponding standard drugs. Analytical and spectral data confirmed the molecular structures of homologous series.

Full text of DOI:10.1080/15421406.2016.1262680

Molecular Crystals and Liquid Crystals
ISSN: 1542-1406 (Print) 1563-5287 (Online) Journal homepage: http://www.tandfonline.com/loi/gmcl20
Mesomorphic study of novel chalconyl-ester-based
nonisomeric series: Synthesis and characterization
Vinay S. Sharma & R. B. Patel
To cite this article: Vinay S. Sharma & R. B. Patel (2017) Mesomorphic study of novel chalconyl-
ester-based nonisomeric series: Synthesis and characterization, Molecular Crystals and Liquid
Crystals, 643:1, 13-27
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Date: 27 February 2017, At: 02:31

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
, VOL. , –

http://dx.doi.org/./..
Mesomorphic study of novel chalconyl-ester-based nonisomeric
series: Synthesis and characterization
Vinay S. Sharma and R. B. Patel
Chemistry Department, K. K. Shah Jarodwala Maninagar Science College, Gujarat University, Ahmedabad,
Gujarat, India
ABSTRACT
KEYWORDS
Antibacterial;
enantiotropically;
mesophase; nematic; smectic
A newly designed homologues series: 3-(3-(4-(Dimethylamino) phenyl)
acrylonyl) phenyl 3-(4-n-alkoxyphenyl) acrylate has been synthesized
and studied through chalconyl ester linking group at (meta) position.
The series consists of 13 compounds, in which C to C homologue
1
4
are nonliquid crystal, while C to C exhibit nematic phase, and C12
5
18
to C18 shows smectic and nematic phase with enantiotropically man-
ner. Mesophase image of present compounds are rod like, needle and
threaded type textures investigated by POM. All this compounds were
1
characterized by elemental analysis, FT-IR and H NMR. The mesomor-
phism is measured by POM, DSC, and molecular packing is determined
by XRD technique. The following synthesized chalconyl ester-based
compounds C to C shows antibacterial as well as antifungal activity
5
12
compared with corresponding standard drugs. Analytical and spectral
data confirmed the molecular structures of homologous series.
GRAPHICAL ABSTRACT
1
. Introduction
Liquid crystal (LC) is an intermediate state of a matter in between the solid crystalline and
liquid. There are many kinds of LC materials with different molecular structures and shape.
Liquid crystal is mainly divided into two category; thermotropic and lyotropic. In both of
them, thermotropic liquid crystals behave a number of unique properties that have received
CONTACT Vinay S. Sharma
Science College, Gujarat University, Ahmedabad , Gujarat, India.
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/gmcl.
 Taylor & Francis Group, LLC
vinaysharma@gmail.com
Chemistry Department, K. K. Shah Jarodwala Maninagar
©

14
V. S. SHARMA AND R. B. PATEL
higher attention mainly due to their important role in temperature sensors, electro-optic dis-
plays, diodes, smart windows, laser and photonics, and semiconducting layers in organic field
[
1–4]. Thermotropic liquid crystal is formed when a solid is heated or an isotropic liquid is
cooled. In addition, the molecules having an extended rod-like shape often exhibit a ther-
motropic liquid crystalline phase for the smetic and the nematic states proposed by Friedel
et al. [5, 6]. The mesogenic behave of lyotropic liquid crystal is exhibited in solution and
depends on the concentration of solvents. In a few decades, chalconyl ester derivatives play
dual role. (i) Suitable in LC devices within definite range of temperature (ii) useful in phar-
maceutical preparation, anti-bacterial activity, anti-fungal, anti-malarial, anti-oxidant etc. [7–
1
2]. Importantly, the exhibition of the liquid crystalline state of any material depends upon its
molecular rigidity as well as flexibility [13–14]. Furthermore, it is also depends on molecular
geometrical shape, size, aromaticity, polarity, polarizability of the terminal, lateral, and cen-
tral groups, which induce suitable magnitudes of anisotropic intermolecular forces of attrac-
tions [15] as a consequence of the molecular rigidity and flexibility [16]. Liquid crystals are
synthetic and biological anisotropic soft matter materials formed by an isodiametric discs,
rods, V-shaped mesogenic units and amphiphiles that self-organize and assemble through
the above-mentioned interactions [17, 18, 19].
In present investigation, we are going to discuss the homologous series which consisted
of three phenyl rings bonded through –CH = CH-COO- and –CO-CH = CH- central
groups as well as varying left n-alkoxy terminal end group and a fixed –N(CH ) commonly
3
2
present in terminal side and its antibacterial, antifungal activity. Our group reported, LC prop-
erty based on chalconyl ester linkage group [20]. The group efficiency order and structure
relation with mesomorphism will be derived. According to literature, many heterocyclic-
based compounds that exhibit liquid crystalline property are widely applicable in electri-
cal, optical, biological, and medical field [21]. A number of chalcone having reported to
exhibit a broad spectrum of anti-bacterial, anti-fungal, anti-ulcer, anti-malarial [23]. The
presence of α, β-unsaturated functional group in chalcone (-CH = CH-CO-) is responsi-
ble for anti-microbial activity, which can be altered depending upon the type of substituent
present on the aromatic rings [24]. Thus, in present study, we synthesized chalconyl-ester
bases compounds and study mesomorphic property and its antibacterial and antifungal
activity [25].
2
. Experimental
2
.1. Materials
For present synthesized homologous series required materials: 4-hydroxy benzaldehyde, alkyl
halide (Lancaster, England, SRL Mumbai), 3-Hydroxy acetophenone, N,N dimethyl benzalde-
hyde, Malonic acid was purchased from (Sigma Aldrich), Anhydrous K CO (Finar Chem-
2
3
icals, India), Dicyclohexylcarbodimide (DCC) (Fluka) and N,N-dimethyl amino pyridine
DMAP) (Fluka) were used as received (Switzerland). The solvents were dried and purified
by standard method prior to use.
(
2
.2. Measurements
Melting points were taken on Opti-Melt (Automated melting point system). The FT-IR spec-
−1
tra were recorded as KBr pellet on Shimadzu in the range of 3800-600 cm . Microanalysis

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
15
was performed on Perkin-Elmer PE 2400 CHN analyser. The texture images were studied
on a trinocular optical polarizing microscope (POM) equipped with a heating plate and
digital camera. X-ray diffraction (XRD) were performed on a (X’ PERT MPD) makes Philips,
1
1
Holland. H NMR spectra was recorded on a 500 MHz NMR Bruker Advance- 400 in the
range of 0.5 ppm-16 ppm using CDCl solvent. The phase transition temperatures were mea-
3
−1
sured using Shimadzu DSC-50 at heating and cooling rates of 10°C min it was calibrated
with indium (156.6°C, 28.45 Jg ). Texture image of nematic phase were determined by a
−1
miscibility method.
2.3. Synthesis
Trans 4-n-alkoxy cinnamic acids (B) prepared by reported method [27]. (3-(4-(dimethyl
amino) phenyl)-1-(3-hydroxy phenyl) prop-2-en-1-one (C) was prepared by usual estab-
lished method [28]. Esters (D) were synthesized by a method reported in literature [29].
Thus, the Chalconyl - Ester homologue derivatives were filtered, washed with sodium bicar-
bonate solution, dried and purified till constant transition temperatures is obtain, using an
optical POM equipped with a heating stage. The synthetic route to a series is mentioned
in Scheme 1.

... Synthesis of -n-alkoxy benzaldehyde (A)
4
-n-Alkoxybenzaldehydes were synthesized by refluxing 4-hydroxybenzaldehyde (1 equiv.)
with corresponding n-alkyl bromides (1 equiv.) in the presence of K CO (1 equiv.) and dry
2
3
acetone as a solvent [26].
... Synthesis of trans -n-alkoxy cinnamic acid (B)
The resulting 4-n-alkoxybenzaldehydes were reacted with Malonic acid (1.2 equiv.) in the
presence of 1-2 drops piperidine as catalyst and pyridine as solvent, refluxing the reaction
mixture 3 to 4 hours to yield corresponding trans 4-n-alkoxy cinnamic acids (B), which was
confirmed by IR study [27].
... Synthesis of chalcone (C)
Chalcone (C) was prepared by usual established method reported in literature [28].
... Synthesis of ester derivatives (D)
The compound has been prepared by esterification of the appropriate 4-n-alkoxy cin-
namic acid (A) (2.02 mmol) and chalcone (C) (0.246 g, 2.02 mmol), dicyclohexylcar-
bodiimide (DCC) (0.457 g, 2.22 mmol) and dimethylaminopyridine (DMAP) in catalytic
amount (0.002 g, 0.2 mmol) in dry CH Cl (DCM) (30mL) was stirred at room temper-
2
2
ature for 48 h. The white precipitate of DCU is obtained which was isolated by filtration
and discarded, while the filtrate was evaporated to dryness. The resultant crude residue
was purified by column chromatography on silica gel eluting with dichloromethane, recrys-
tallization from methanol: chloroform (2:3) until constant transition temperatures were
observed [28].

1
6
V. S. SHARMA AND R. B. PATEL
Reaction Scheme
Scheme . Synthetic procedure of series-.

... Analytical data
Chalcone (C): FT-IR (KBr): 3016 (-C-H- str in CH ), 1743 (-C = O) stretch, 1512 (-C =
3
C-) str, 1365 and 1219 (-C-O str), 979 (-C = CH), 802 di-substituted aromatic ring (meta).
Butyloxy (C ): FT-IR (KBr): 636 Polymethylene (-CH -)n of –OC H , 839(–C-H- def.
4
2
4
9
di-substituted-meta), 759 Polymethylene (-CH -) of –OC H , 952 (–C-H- def. hydrocar-
2
4
9
bon), 1028 and 1068(-C-O-) Str, 1197 and 1228 (-C-O str in –(CH )n chain, 1427 and
2
1
427 (-C-H- def. in CH )1514 (-C = C-)str, 1604 and 1666 (-C = O group), 1726 (-COO-
2
1
ester group), 2850 and 2970 (-C-H str in CH ). H NMR: δH (CDCl , 400 MHz): 0.85-0.88
3
3
(
t, 3H, -CH of –OC H group), 1.36-1.38 (m, 2H, CH -CH -(CH ) -O-), 1.41 (p, 2H, -CH -
3 4 9 3 2 2 2 2
CH -CH -O-), 3.08 (s, 6H of –N(CH ) ), 4.00-4.02 (t, 2H, -CH -O-), 7.28-7.31 (d, 1H, -CH =
2
2
3 2
2
CH-COO-), 6.50 (d, 1H, -CH = CH-COO-), 6.93-6.95 (d, 1H, -CO-CH = CH-), 7.53-7.55 (d,
H, -CO-CH = CH-), 6.84-6.85 & 7.75-7.80 (4H, left side phenyl ring), 7.42-7.46 & 8.01-8.08
4H, central phenyl ring), 6.68-6.10 & 7.70-7.75 (4H, terminal phenyl ring side). Elemental
analysis of C H NO : Calc: C; 76.75%, H; 6.60%, O; 13.64%, N; 2.98%, Found: C; 76.70%,
1
(
30
31
4
H; 6.53%, O; 13.70%, N; 2.90%.

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
17
Propyloxy (C ): FT-IR (KBr): 628 Polymethylene (-CH -)n of –OC H , 3020 (C-H Str.
3
2
3
7
of alkene disubstituted), 839 (-C-H- def. di-substituted- meta), 2924-2866 (C-H Str. of poly
methylene group of –OC H ), 1068 (-C-O), 1726 (C = O Str. of Carbonyl carbon of (–COO-
3
7
1
ester group), 1629 (C = C Str. of aromatic ring), 1309 (C-H bending of alkene). H NMR: δH
(
CDCl , 400 MHz): 0.85-0.88 (t, 3H, -CH of –OC H group), 1.31 (q, 4H, of –CH of –CH -
3 3 3 7 2 3
CH -CH -O-),1.34-1.39 (m, 2H, CH -CH -CH -O-), 1.42 (p, 2H, CH -CH -CH -O-), 3.08
2
2
3
2
2
3
2
2
(
(
s, 6H of –N(CH ) ), 4.00-4.02 (t, 2H, -CH -O-), 7.28-7.31 (d, 1H, -CH = CH-COO-), 6.50
3
2
2
d, 1H, -CH = CH-COO-), 6.90-6.91 (d, 1H, -CO-CH = CH-), 7.51-7.52 (d, 1H, -CO-CH
=
CH-), 6.82-6.86 & 7.72-7.82 (4H, left side phenyl ring), 7.40-7.48 & 8.01-8.07 (4H, central
phenyl ring), 6.67-6.12 & 7.71-7.78 (4H, terminal phenyl ring side). Elemental analysis of
C H NO : Calc: C; 76.48%, H; 6.37%, O; 14.06%, N; 3.07%, Found: C; 76.44%, H; 6.30%, O;
29
29
4
1
3.90%, N; 2.98%.
Octyloxy(C ): FT-IR (KBr): 640 Polymethylene (-CH -)n of –OC H , 725 Polymethylene
8
2
8
17
(
1
-CH -)n of -C H 817(–C-H- def. di-substituted -meta), 987 (–C-H- def. hydrocarbon),
2 8 17
068 (-C-O-) Str, 1344 and 1271, 1186 (-C-O) str in –(CH )n chain, 1344 and 1435 (-C-H-
2
def. in CH ),1531(-C = C-)str, 1622 (-C = O group), 1732 (-COO- ester group), 2850 and
2
1
2
927(-C-H str in CH ). H NMR: δH (CDCl , 400 MHz): 0.85-0.88 (t, 2H, -CH of –OC H
3
3
3
8
17
group), 1.31 (q, 3H, -OC H ),1.36-1.38 (m, 2H, CH -CH -(CH ) -O-), 1.42 (t, 2H, -CH -
8
17
3
2
2 6
2
CH -CH -O-), 1.72 (p, of –CH of –OC H ),3.08 (s, 6H of –N(CH ) ), 4.00-4.06 (t, 2H,
2
2
2
5
11
3 2
-
(
CH -O-), 7.28-7.31 (d, 1H, -CH = CH-COO-), 6.50 (d, 1H, -CH = CH-COO-), 6.93-6.95
2
d, 1H, -CO-CH = CH-), 7.53-7.55 (d, 1H, -CO-CH = CH-), 6.84-6.85 & 7.75-7.80 (4H, left
side phenyl ring), 7.42-7.46 & 8.01-8.08 (4H, central phenyl ring), 6.68-6.10 & 7.70-7.75 (4H,
terminal phenyl ring side). Elemental analysis of C H NO : Calc: C; 77.71%, H; 7.42%, O;
34
39
4
1
2.19%, N; 2.66%, Found: C; 77.67%, H; 7.38%, O; 12.17%, N; 2.62%.
Heptyloxy (C ): FT-IR (KBr): 680 Polymethylene (-CH -)n of –OC H , 817 (-C-H- def.
7
2
7
15
di-substituted meta), 3037 (C-H Str. of alkene di-substituted), 2920 (C-H Str. of poly methy-
lene group of –OC H ), 1720 (C = O Str. of Carbonyl in ester group), 1629 (C = C Str. of
7
15
alkene), 1600, 1506 (C = C Str. of aromatic ring), 1394 (C-H bending of alkene), 968 (C-
1
H bending of alkene). H NMR: δH (CDCl , 400 MHz): 0.85-0.88 (t, 3H, -CH of –OC H
3
3
7
15
group), 1.36-1.38 (m, 2H, CH -CH -(CH ) -O-), 1.41 (p, 2H, -CH -CH -CH -O-), 4.00-4.06
3
2
2 5
2
2
2
(
t, 2H, -CH -O-), 3.08 (s, 6H of –N(CH ) ), 7.26-7.32 (d, 1H, -CH = CH-COO-), 6.50 (d,
2
3 2
1
H, -CH = CH-COO-), 6.93-6.95 (d, 1H, -CO-CH = CH-), 7.53-7.55 (d, 1H, -CO-CH =
CH-), 6.84-6.83 & 7.72-7.80 (4H, left side phenyl ring), 7.41-7.46 & 8.01-8.08 (4H, central
phenyl ring), 6.68-6.10 & 7.70-7.75 (4H, terminal phenyl ring side). Elemental analysis of
C H NO : Calc: C; 77.26%, H; 7.04%, O; 12.87%, N; 2.81%, Found: C; 77.20%, H; 6.98%, O;
32
35
4
1
2.94%, N; 2.75%
. Result and discussion
.1. POM investigation
3
3
Transition temperatures (Table 2) obtained by optical cross POM equipped with a heating
stage. The phase diagram plotted transition temperatures versus number of carbon atoms
present in n-alkyl chain “R” of left alkyl chain (-OR) group is shown in Fig. 1. Transition
curve of Cr-I follows a zigzag path of rising and falling tendency. Sm-N transition curve
initially falls and passes through maxima at Tetradecyloxy (C ) homologue and descends
14
up to C18 homologue. Odd–even effect is observed between C to nearby C homologue,
5
7
odd–even effect and the alternation of transition temperature of homologues is depending

1
8
V. S. SHARMA AND R. B. PATEL
Table . Texture of nematic phase of C , C , C , C by miscibility method.




Sr. No.
Homologue
Texture

C
C
C
Schlieren
Schlieren
Threaded
Rod like



C
on odd and even number of methylene units present. Mesomorphic properties of present
homologues series were varied by increasing left alkyl chain and keeping right terminal part
N,N, Dimethyl –N(CH ) group. The geometrical shape of molecule keeping unchanged
3
2
throughout the series except changing of methylene carbon units. Texture of the nematic
phase observed by miscibility method (Table 1).
Presently investigated series consisted 13 (C to C ) homologues. C to C homologues are
1
18
1
4
nonliquid crystal (NLC) due to short alkyl spacer. In case of higher homologue, mesophase
formation is present due to long chain which increases the polarity and polarizability of
molecules.
The crystalline compounds placed on clear glass slide were heated to the isotropic state
and heating and cooling rate (2°C/min), respectively, and observing mesophase texture image
shown in Fig.-2, (a) for C homologue, the Sm C texture image observed at 130°C on heating
10
and cooling condition, (b) nematic mesophase texture of C12 homologue display at 148°C
enantiotropically manner, (c) rod-like mesophase image of Sm C phase for C homologue
16
at 110°C during heating and cooling condition, (d) rod-like textures image of Sm C phase of
C homologue at 102°C during heating and cooling conditions, respectively. In addition, we
18
conclude that, the mesophase exhibited during heating and cooling condition. In Figure S1
ESI), (a) threaded type texture image of nematic mesophase for compound C homologue
(
7
obtained enantiotropically manner at 146°C, (b) Schlieren-type nematic phase observed at
48°C for C homologue heating as well as cooling conditions.
1
6
Table . Transition temperatures in °C by POM.
-(-(-(Dimethylamino) phenyl) acrylonyl) phenyl -(-n-alkoxyphenyl) acrylate
Transition Temperatures in(˚C)
Compound No
n-alkyl chain C H
Sm
N
I
n
n+

C
C
C
C
C
C
C
C
C
C
C
C
C
—
—
—
—
—
—
—
—
—
.
.
.
.
—
—
—
—
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

















MOLECULAR CRYSTALS AND LIQUID CRYSTALS
19
Figure . Phase diagram of sereis-.
We have measured the phase sequence of C12 homologue at heating condition shown in
Fig. 3. At room temperature (a) shows solid crystal while applying heating at 126° shows
the formation of smectic phase (b), while at 146°C, nematic mesophase is observed in (c),
Figure . Mesomorphic textures of compounds obtained by POM (a) Sm C phase of C homologue on heat-

ing. (b) Nematic phase of C homologue on heating, (c) Sm C phase of C homologue on cooling, (d) Sm C


phase of C homologue on heating.


20
V. S. SHARMA AND R. B. PATEL
Figure . Phase sequence of C homologue at heating condition by POM.

isotropic of mass at 156°C during heating condition (d). Observed phase sequence is repeated
again during cooled condition and also confirmed by DSC analysis.
The non-mesomorphicity of C to C homologue is attributed short alkyl spacer and low
1
4
magnitudes of dispersion forces and lower magnitudes of dipole–dipole interaction and elec-
tronic vibrations cause high-crystalline tendency to directly transform into isotropic mass by
breaking of crystal lattices. The presence of smectic phase due to increasing the chain length
and increase flexibility, polarity and polarizability in which sliding moving the arrangement
of molecules nearness to each other to cause smectic mesophase (C12 to C ) homologue.
18
Though, at cooling stage the identical mesophase is perceived. The exhibition of nematic
property (C to C ) by appropriate magnitudes of anisotropic forces end to end attractive
5
18
cohesion and closeness of molecules in statistically parallel in floating conditions that directly
associated to its rigidity as well as flexibility exposed thermal vibrations.
Here, we have compared the mesomorphic property of presently investigated series-1 with
structurally similar series-X, which was reported by our research group [30] mentioned in
Fig.-4.
Homologous series (1) and X are identical with respect to three phenyl rings bonded
through chalconyl central bridge and series 1 has more ethylene part compare to series-X.
Moreover, both series-1 and X are identical with respect to left flexible n-alkoxy (-OR) group
for the same homologues for desired series; but differ from homologue to homologue in the
same series due to -meta substituted chalconyl linkage in series 1. However, similar termi-
nal group in both series. Thus, they differ with respect to their geometrical shapes linearity
and nonlinearity for the same homologue series to series, respectively. Hence, the variants in
Figure . Structurally similar analogous series.

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
21
Table . Relative thermal stabilities in °C.
Series

X
Smectic-nematic Or Smectic-isotropic Commencement of smectic phase
Nematic- isotropic Commencement of nematic phase
Total upper and lower mesophase length range in °C.
.(C -C )C
.(C -C )C
 

 

.(C -C )C
.(C -C )C



 

. to . C C
. to . C C




mesomorphic properties for the homologue from series to series are observed due to differ-
ing magnitudes of molecular rigidity and geometry present in between series-1 and X; under
comparative study.
From Table 3, it indicates that presently investigated series-1 and series-X which was cho-
sen for comparison are smectogenic in addition to nematogenic, whereas, smectic property
commences late from C homologue of a series-1. However, it commences earlier from C
7
5
homologue by series-X. Nematic property commences from C homologue in series-1 and it
5
commences from C homologue, respectively, in case of series X. Smectic and nematic thermal
4
stability of present series 1 is higher as compared to series-X. Total upper and lower mesophase
length is in increasing order from series-X to series-1. The result specifies, total thermal sta-
bility of mesophase in Series 1 is higher than series X.
The space-filling diagram indicates that the energy minimizes in both series (X) and (Y),
respectively (Fig. 5). The geometrical shape of series 1 its look as bent core and its length is
higher due to the presence of ethylene (-CH = CH-) with carboxy (-COO) linking group as
compared to series X. Therefore, it proves that they differ with respect to combined effects
of molecular rigidity and flexibility, including intermolecular distance and molecular polar-
izability which operates LC behaviors of series. The addition of double bond in the system
increases the polarizability and length of the molecule 31
Figure . Space filling diagram of series- and X.

2
2
V. S. SHARMA AND R. B. PATEL
Figure . DSC measurement: (a) C homologue, (b) C homologue, (c) C homologue, and (d) C homo-




logue.
3
.2. DSC analysis
The thermal behavior of homologues series were investigated by differential scanning
calorimetry (DSC). The results are shown in Fig. 6 and the value of enthalpy (ꢀH) and entropy
(
1
ꢀS) are mention in Table 4, (a) C homologue, heating condition first endothermic peak at
25°C, which indicates the presence of SmC. While second peak observed at 152°C shows
12
nematic phase. At cooled condition, the endothermic peak was traced at 112°C and 148°C
which was confirmed by POM. (b) C homologue, one endothermic peak traced at 161.2°C
5
in heating stage, while on cooling stage again one endothermic peak observed at 158.52 and
−
− −
Table . Phase transition temperature (°C) and enthalpy (J g ) and entropy change (J g k ) by DSC
measurement.
Heating Peak Cooling Peak
temperature temperature
Microscopic Microscopic
temperature temperature
ꢀH (-Jg 
−
)
ꢀH (Jg
−
)
ꢀS(J g
− −
k
)
ꢀS(J g
− −
k )
Comp.
C
Transition
Cr-SmC
SmC-N
N-I
Cr-SmC
SmC-N
N-I
Cr-SmC
SmC-N
N-I
(°C)
(°C)












—


—


—
—

—
.
.
—
.
.
—
.
.
—
.
.
—
.
.
—
.
.
—
.
.
—
.
.
—
.
.
—
.
.
—
.
.
—
.
.
—
.
.
—
C
C
C
Cr-SmC
SmC-N
N-I
—
.
.
—
—
.
—


.
—

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
23
Figure . Phase sequence of C homologue.

second peak at 162°C during heating stage, while in cooling stage two peaks were observed at
75°C and 125°C. In POM investigation, smectic phase was not detected. However, nematic
phase is confirmed. (c) C homologue, two endothermic peaks observed corresponding heat-
1
16
ing condition first endothermic peak observed at 101°C confirmed the presence of SmC and
second endothermic at 128°C, that confirm the nematic mesophase. At cooling condition,
two peaks are at 130°C and 95°C that indicate the presence of mesophase smectic as well as
nematic phase that was also measured by POM. (d) C homologue, one sharp endothermic
8
peak observed at 142°C, endothermic peak at 90°C exhibit due to possibility of solid crystal
which was confirmed by POM. At cooled condition, the single peak was traced at 138°C.
Previously in Fig. 3, we measured the phase sequence of C homologue which was con-
12
firmed by DSC analysis with trace two endothermic peaks which confirmed the presence of
smectic and nematic phase at heating and cooling condition shown in Fig. 7.
3
.3. XRD (X-ray diffraction) analysis
To investigate the structure of the observed smectic phase, we have performed XRD measure-
ment to correlate with DSC and POM results (Fig. 8). According to the graphical proposed
mechanism, the molecular are arranged in layers, although, the long axes of the molecules
are tilted to the layers planes shown in Fig. 9. In Fig. 8, X-ray pattern show diffraction peaks
in the small angle diffraction region corresponded to a smectic layer structure. A sharp low-
ꢀꢀ
ꢀꢀ
angle peak (2θ = 1–4 ), a mid-angle region peak (2θ = 6–9 ) were observed during X-ray
Figure . XRD traces of compound (a) C and (b) C measured at transition temperature.



24
V. S. SHARMA AND R. B. PATEL
Figure . Representation of molecular packing of smectic phase in present series.
investigation. The reflections for the small-angle area correspond to a smectic layer struc-
˚
ture. The d-spacing of the reflections observed for C at 2θ = 3.39, 5.4, 8.8, were 29.42 A and
6
˚
˚
reflections observed at 11.42 A, 7.21 A, respectively, while the corresponding figures for C at
8
˚
˚
˚
2
θ = 4.80, 5.20, and 9.82 were 31.12 A, 12.13 A, and 6.42 A. Which is approximately nearer
to its molecular length. The presence of alkyl chain in C and C homologue may increase the
6
8
arrangement of molecules layered and induce smectic mesophase.
3
.4. Biological evaluation
In the present work, the focus has been drawn on designing new structural entities of chal-
cones by incorporating para hydroxy acetophenone and para-substituted aldehydes into chal-
cone scaffolds to evaluate the prospective effect on biological activity, particular antibacterial
and antifungal. Newly synthesized chalconyl-ester compounds C , C , C , C , C , C were
5
6
7
8
10
12
examined for antimicrobial activity against four pathogenic micro-organism viz. E. coli, P.
aeruginosa (Gram −ve) and S. aureus, S. pyogenus (Gram +ve) bacterial strains. The antifun-
gal activities were carried out with C. albicans, A. niger, and A. clavatus at various concentra-
tion. The synthesized compounds showed good activity results against E. coli, P. aeruginosa
(
Gram −ve) and S. aureus, S. pyogenus (Gram +ve). The ampicillin, gentamycin, chloram-
phenicol, ciprofloxacin, nystatin, and greseofulvin were used as the standard drug for gram-
positive, gram-negative, and fungal strains, respectively. The minimum inhibitory concen-
tration (MIC) was evaluated by the broth dilution method. However, in case of antifungal
activity, comp.C , C , C , C , and C showed good results in C. Albicans at 500 µg/mL which
5
6
7
8
12
was equivalent to standard drug greseofulvin.
... In vitro antibacterial activity
Table 5 shows that all the newly synthesized compounds were found to exhibit good to
moderate activity against specific microbial strains. Initially, we screened all the synthe-
sized compounds (C to C ) for their antibacterial activity in vitro by using both dilution
5
12
method. The in vitro antibacterial results confirmed that some of the chalconyl-ester hybrids
exhibited antibacterial activity against various strains of E. coli, P. aeruginosa (Gram −ve)
and S. aureus, S. pyogenus (Gram +ve) as shown in Table 4. Antibacterial results were
comparatively nearer to the standard drug ampicillin as compared to other drug. Compound
C (125 µg/mL MIC) gives results for E. coli at higher concentration. While, C to C
5
6
12
showed activity (100 µg/mL MIC) against E. coli, which is nearer to the standard value
of ampicillin. Furthermore, compound C10 and C12 having excellent growth inhibition at
lower concentration (62.5 µg/mL MIC) as compared to standard drug. Compound C to C12
7

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
25
Table . Result of antibacterial activity of the synthesized compounds.
ANTIBACTERIAL ACTIVITY
Minimal Inhibition Concentration
E. Coli
P. Aeruginosa
S. Aureus
S. Pyogenus
Sr. No
Code No.
MTCC 
MTCC 
MTCC 
MTCC 
Microgram/mL






C
C
C
C
C
C




.
.
100
.







100







250
.





.

100
.
Standard
Standard
Standard
Standard
Ampicillin
Gentamycin
Chloramphenicol
Ciprofloxacin






Table . Result of antifungal activity of the synthesized compounds.
ANTIFUNGAL ACTIVITY
Minimal Fungicidal Concentration
C. Albicans
A. Niger
A. Clavatus
Sr. No
Code. No.
MTCC 
MTCC 
MTCC 
Microgram/mL




C
C
C
C






>
>



>
>




C
Standard
Standard
Nystatin
Greseofulvin





showed activity against P. aeruginosa at (100 µg/mL MIC), which was nearer to comparable
standard drug. However, compound C (120 µg/mL MIC) and C (125 µg/mL MIC) showed
5
6
activity at higher concentration. Compound C exhibited good inhibitory activity with lower
10
concentration (62.5 µg/mL MIC) against S. Pyogenus.
... In vitro antifungal activity
Antifungal activity data (Table 6) displayed that the synthesized compound C to C showed
5
12
adaptable degrees of inhibition against the tested fungi C. Albicans, A. Niger, and A. Clavatus.
C. Albicans fungi was inhibited by C , C , and C at 500 µg/mL MIC which is equal to the
6
8
12
concentration of standard drug Greseofulvin. While inhibiting against A. Niger, A. Clavatus
fungi by compound C , C , and C at 200 µg/mL MIC, while all the other derivatives exerted
7
8
12
moderate to poor activity profiles.
Conclusions
In summary, we have synthesized successfully a novel homologues series with two different
linkage group containing liquid crystalline as well as antimicrobial activity. We have found
that the following synthesized homologous series shows nematogenic and partly smectogenic

26
V. S. SHARMA AND R. B. PATEL
behavior predominantly. We have confirmed the mesogenic property for compounds by DSC
and POM. Smectic phase of representative compounds were confirmed by X-ray diffractome-
ter (XRD) at their particular transition temperature. The antibacterial and antifungal activity
was determined by MIC (Broth dilution method).
Acknowledgments
Authors acknowledge thanks to Dr. R. R. Shah, principal of K. K. Shah Jarodwala Maninagar Sci-
ence College, Ahmedabad. Authors are also thankful to Dr. A. V. Doshi, Ex-principal of M.V.M. Sci-
ence College - Rajkot for his constant support, inspirations and help, as and when needed during the
course of present investigation. Authors thank to Centre of Excellence, Rajkot for the spectral
services.
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