Mesomorphism dependence of a terminal or lateral alkoxy group

Article abstract of DOI:10.1080/15421406.2016.1190144

A novel homologous series of thermotropic mesomorphs has been synthesized and studied with a view to understanding and establishing the effect of molecular structure on mesomorphic properties with reference to rigidity and flexibility of the homologues series: RO-C₆H₄-CH?CH-CO-C₆H₄-OC₁₈H₃₇(n). The novel homologous series comprises 13 novel homologues (C₁ to C₁₈), from which 11 homologues are enantiotropically mesogenic (C₃ to C₁₈). Smectogenic mesophase commences from C₇ homologue, and nematogenic mesophase is exhibited by C₃ to C₁₈ homologues in enantiotropic manner. Thus, C₇ to C₁₈ homologues are enantiotropically smectogenic plus nematogenic. Textures of smectic phase are of the type A or C, and that of nematic phase are threaded or Schlieren as confirmed through an optical polarizing microscope equipped with a heating stage. Transition curve of a phase diagram behaved in a normal manner except N-I transition curve, which shows minor deviating trend (C₁₂ to C₁₈) from expected normal behavior. An odd-even effect is exhibited by N-I and Sm-N transition curves. Analytical, spectral, and thermal data confirm the molecular structures of novel homologues. Thermal stabilities for smectic and nematic are 52.7°C and 66.6°C, respectively, whose total mesophase lengths range from 12.0°C to 28.0°C. Thus, novel series of chalcones is a low melting series whose mesogenic transition temperatures vary between 38.0 and 86.0°C.

Full text of DOI:10.1080/15421406.2016.1190144

Molecular Crystals and Liquid Crystals
ISSN: 1542-1406 (Print) 1563-5287 (Online) Journal homepage: http://www.tandfonline.com/loi/gmcl20
Mesomorphism dependence of a terminal or
lateral alkoxy group
Ravindra Solanki & R. B. Patel
To cite this article: Ravindra Solanki & R. B. Patel (2016) Mesomorphism dependence of a
terminal or lateral alkoxy group, Molecular Crystals and Liquid Crystals, 634:1, 50-57, DOI:
10.1080/15421406.2016.1190144
To link to this article: http://dx.doi.org/10.1080/15421406.2016.1190144
Published online: 26 Sep 2016.
Submit your article to this journal
Article views: 2
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at
http://www.tandfonline.com/action/journalInformation?journalCode=gmcl20
Download by: [91.198.127.118]
Date: 28 September 2016, At: 02:24

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
, VOL. , –
http://dx.doi.org/./..
Mesomorphism dependence of a terminal or lateral
alkoxy group
Ravindra Solanki and R. B. Patel
Chemistry Department, K. K. Shah Jarodwala Maninagar Science College, Gujarat University, Ahmedabad,
Gujarat, India
ABSTRACT
KEYWORDS
Chalconyl derivative; liquid
crystal; nematic
enantiotropy; smectic
A novel homologous series of thermotropic mesomorphs has been syn-
thesized and studied with a view to understanding and establishing the
effect of molecular structure on mesomorphic properties with reference
=
to rigidity and flexibility of the homologues series: RO-C6H4-CH CH-
CO-C6H4-OC18H37(n). The novel homologous series comprises 13 novel
homologues (C1 to C18), from which 11 homologues are enantiotropi-
cally mesogenic (C3 to C18). Smectogenic mesophase commences from
C7 homologue, and nematogenic mesophase is exhibited by C3 to C18
homologues in enantiotropic manner. Thus, C7 to C18 homologues are
enantiotropically smectogenic plus nematogenic. Textures of smectic
phase are of the type A or C, and that of nematic phase are threaded
or Schlieren as confirmed through an optical polarizing microscope
equipped with a heating stage. Transition curve of a phase diagram
behaved in a normal manner except N-I transition curve, which shows
minor deviating trend (C12 to C18) from expected normal behavior. An
odd-even effect is exhibited by N-I and Sm-N transition curves. Ana-
lytical, spectral, and thermal data confirm the molecular structures
of novel homologues. Thermal stabilities for smectic and nematic are
52.7°C and 66.6°C, respectively, whose total mesophase lengths range
from 12.0°C to 28.0°C. Thus, novel series of chalcones is a low melting
series whose mesogenic transition temperatures vary between 38.0 and
86.0°C.
1. Introduction
Chalconyl derivatives are well known for their bioactivity as antibacterial, antifungal, anti-
malarial, and anticancer compounds [1, 2, 3, 4] but they are relatively less known as liquid
crystalline (LC) materials [5] whose potency and utility can be exploited to the benefit of
mankind in thermography and LC devices workable at low temperature or room temper-
ature [6, 7, 8]. Thus, the present investigation is planned to understand and establish the
effect of molecular structure on LC properties [9, 10, 11, 12] by synthesizing a novel homol-
ogous series, which consists of a chalconyl group, which links two phenyl rings, a varying n-
alkoxy group –OR and a fixed –OC18H37 (n) chain. The study involves synthesis, characteriza-
tion, transition temperatures, and texture determination by an optical polarizing microscope
(POM) equipped with a heating stage. The evaluated thermometric data will be discussed and
CONTACT Ravindra Solanki
ravindrasolanki@gmail.com
ence College, Gujarat University, Ahmedabad-, Gujarat, India.
Chemistry Department, K. K. Shah Jarodwala Maninagar Sci-
©  Taylor & Francis Group, LLC

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
51
interpreted in terms of molecular rigidity and flexibility [13, 14, 15, 16] and will be compared
with the structurally similar analogous series to derive the group efficiency order for smec-
tic and nematic, including conclusions. The homologous series with only ester and chalconyl
esters have been reported till date [17, 18, 19, 20, 21].
2. Experimental
2.1. Synthesis
4-Hydroxy benzaldehyde was alkylated using suitable alkylating agents (R-X) to give 4-n-
alkoxy benzaldehydes (A) by an established method [22]. 4-Octadecyloxy acetophenon (B)
is prepared by reported method [23]. Then (A) and (B) were condensed to obtain the final
products 4–n alkoxy4ꢀ-octadecyloxy phenyl ethylene by an established method [24]. The final
products were filtered, washed, dried, and purified until the constant transition temperatures
were obtained. The synthetic route to the novel homologous series of ethylene derivatives is
shown in Scheme 1.
Scheme . Synthetic route to the series.
2.2. Characterization
Representative homologues of the series were characterized by elemental analysis, infrared
spectroscopy, and 1H NMR spectra. IR spectra were recorded on Perkin–Elmer spectrum GX,
and 1H NMR spectra were recorded on a Bruker using CDCl3 as a solvent. Microanalysis was
performed on a Perkin–Elmer PE 2400 CHN analyzer (Table 1). Transition temperature and
LC properties (textures) were determined using an optical polarizing microscope equipped
with heating stage. Textures of some homologues for the nematic phase were determined by
a miscibility method (Table 2).

52
R. SOLANKI AND R. B. PATEL
Table . Elemental analysis for butyloxy, heptyloxy, tetradecyloxy, and hexadecyloxy derivatives.
Elements found (%)
Elements calculated (%)
Sr. No.
Molecular formula
C
H
C
H
.
C
C
C
C
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
3. Analytical data
3.1. IR Spectra (KBr) in cm−1 for pentyloxy, octyloxy derivatives
–
Pentyloxy: 518, 657, (C H alkane), 761, 835, polymethylene (-CH2-)n of –OC5H11, 835 (–
C-H- def. di-substituted-Para), 894 polymethylene (-CH2-) of –OC18H37, 1074 (–C-H- def.
hydrocarbon), 1114 and 1172(-C-O-) Str, 1259 and 1303 and 1321, 1384 (-OCH2 group in
=
=
=
alkyl chain), 1461 (-C-H- Str) 1512, 1581 (-C C-) Str, 1606,1616 (-C O in CH CH- group),
2927 and 3033 (-C-H Str in CH3).
Octyloxy: 667 (C-H- alkane),725 polymethylene (-CH2-)n of –OC8H17, 829 and 894 (–C-
H- def. m di-substituted para and ortho aromatic ring), 975 (–C-H- def. hydrocarbon), 1024,
1060, 1116, 1164,1253 (-C-O-) Str of C18H37, 1301 and 1336 (-C-O Str in –(CH2)n chain, 1386,
=
=
=
1421 (-C-H- def. in CH2), (-C C- aromatic) Str, 1610, 1676 (-C O in CH CH- group), 2856
and 2923 (-C-H Str in CH3).
1
3.2. HNMR Spectra in CDCl3 in δ ppm for propyloxy and hexyloxy derivative
Propyloxy: 0.90 (t, -CH3 of -C3H7), 0.88 (t, -CH3 of -C18H37 chain), 1.29–1.76 (m, n-(CH2)n
chain of -OC3H7), 1.29–1.76 (m, n-polymethylene of -OC18H37 chain), 4.0–4.1 (s,-OCH2-
CH2- of OC3H7 chain), 4.0–4.2 (s, -OCH2-CH2- of OC18H17), 6.94–7.5 (s, phenyl ring) and
=
7.56–7.90 (s, -CO-CH CH linkage), 7.18–8.11 (s, p-di-substituted phenyl ring).
Hexyloxy: 0.88 (t, -CH3 of –C18H37), 1.20–1.76 (m, n-(CH2)n of -OC6H13 chain), 1.26–
1.76 (m, n-polymethylene groups of -OC18H37), 4.1 (s, -OCH2-CH2- of OC6H13), 4.1–4.4 (s,
=
-OCH2-CH2- of OC18H37), 6.94–7.15 (s, substituted benzene), 7.56–7.90 (s, -CO-CH CH
linkage), 7.6–7.8 (s, p-substituted phenyl ring).
4. Results and discussion
4-n-Alkoxybenzaldehyde and 4-octadecyloxyacetophenon (m.p. 54.0°C, yield 75.69%) are
non-mesomorphic components. However, the mesomorphism is induced in the linked-up
11 novel homologues to give thermotropic liquid crystals of low transition temperature. The
C1 and C2 homologues are non-liquid crystals. The C3 to C18 homologues are enantiotropic
nematogenic, which include C7 to C18 homologues as anti-tropically smectogenic in addition
Table . Textures of nematic phase by miscibility method for C, C, C, and C.
Sr. No.
Homologue
Texture
.
C
C
C
C
Schlieren
Threaded
Threaded
Schlieren
.
.
.

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
53
Table . Transition temperatures for homologous series
Homologous series: -n-alkoxy ꢀ-octadecyloxyphenyethylenes.
Transition temperatures (˚C)
Compound No.
n-alkyl chain CnHn+
Smectic
Nematic
Isotropic
.
.
.
.
.
.
.
.
.
.
.
.
.
C
C
C
C
C
C
C
C
C
C
C
C
C
—
—
—
—
—
—
—
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
—
.
.
.
.
.
.
.
to nematogenic character. The transition temperatures (Table 3), as determined by POM, were
plotted versus the number of carbon atoms present in n-alkyl chain “R” of –OR group and then
transition curves Cr-M/I, Sm-N, and N-I are obtained on linking like or related transition
points as shown in a phase diagram (Fig. 1), showing their phase behavior of novel series.
Homologous series: 4-n-Alkoxy 4ꢀ-octadecyloxyphenyethylenes.
The Cr-M/I transition curve adopts a zigzag path of rising and falling manner with over-
all descending manner, and behaved in a normal manner. The Sm-N transition curve rises,
passes through maxima at C14 derivative, and descends in a usual established expected man-
ner, but it rises at C18 derivative and shows a very short and sharp odd-even effect. An N-I
transition curve descended and then rises abnormally from C12 to C18 derivatives in unex-
pected manner and exhibited odd-even effect. Thermal stabilities are 52.7°C and 66.6°C for
Figure . Phase behavior of the series.

54
R. SOLANKI AND R. B. PATEL
smectic and nematic respectively, whose maxima to minimum phase lengths are 05 to 11.0°C
and 6 to 21.0°C respectively. Thus, novel homologous series is low melting-type series. Analyt-
ical, spectral, and thermal data supported the molecular structures of homologues. Variations
in mesogenic properties and behavior from homologue to homologue in the same series are
observed with changing number of carbon atoms in n-alkyl chain “R” of –OR group, keeping
rest of the molecular part unaltered throughout the series.
The condensation of non-mesomorphs n-alkoxybenzaldehydes with 4-n-octadecyloxy
molecule extends molecular lengths, polarity and polarizability, rigidity and flexibility, per-
manent dipole moment across a long molecular axis, intermolecular end-to-end and lat-
eral attractions, suitable magnitude of dispersion forces and dipole–dipole interaction, etc.
These induce resistivity and misalignment of molecules at a 900 or/and less than 900 angle
with a plane of floating surface under the influence of exposed thermal vibrations to main-
tain floating with statistically parallel orientational order and/or with sliding layered molec-
ular arrangement for different range or ranges of temperatures to facilitate only nematic or
smectic plus nematic mesophase formation for C3 to C18 homologues. However, the miss-
ing of any sort of mesophase formation in case of C1 and C2 homologues is attributed to
their high crystallizing tendencies, which arise from low magnitudes of dispersion forces
and low magnitudes of dipole–dipole interaction. Thus, abrupt breaking of crystal lattices
on heating the sample substance takes place and sharply transform into isotropic liquid with-
out passing through liquid crystalline state. However, on cooling the same, none of the non-
mesomorphic homologues C1 and C2 exhibited monotropic mesophase in irreversible man-
ner but the homologues from C3 to C18 on similar cooling from isotropic state exhibit and
reappear to nematic and smectic phases. The odd-even effect observed for Sm-N and N-I
transition curves is due to the presence of number of carbon atoms as even and odd num-
bered in n-alkyl chain “R” of –OR group.
The disappearance of odd-even effect for higher homologues of longer n-alkyl chain “R” is
attributed to their coiling, bending, flexing, or coupling with principal axes of core structure of
respective molecules. Therefore, any unpredictable and unexpected deviations or any minor
or major abnormality, which appears in the behavior of transition curve or curves, can be
attributed to the unpredictable status of flexible n-alkyl chain “R” and/or –OC18H37 (n) end
groups, which may modify the magnitudes of flexibility and magnitudes of intermolecular
end-to-end and/or lateral cohesion and/or closeness. Lowering of molecular rigidity by only
two phenyl rings bonded through single central bridge lowers the numbers of inter-atomic
bonds and bond energy, which reflects the magnitudes of (࢞H) enthalpy change of a molecule,
and consequently lowers the molecular thermal resistivity toward exposed thermal vibrations.
Therefore, the lowering of transition temperatures, thermal stabilities for smectic and nematic
as well as mesophase lengths are observed. The changing trends in mesogenic properties and
behavior of present series 1 are compared with structurally similar analogous series X [25]
and Y [26] as mentioned in Fig. 2.
Figure 2 represents homologous series 1 of the present investigation as well as structurally
analogous X and Y selected for comparative study. Homologous series 1, X, and Y are identical
=
with respect to two phenyl rings and one central bridge –CH CH-CO- contributing to total
molecular rigidity and the left n-alkoxy terminals –OR for the same homologue from series
to series, which partly contributes to total molecular flexibility for the same homologue and
homologue to homologue in the same series. However, they differ with tailed end group, viz.
para -OC18H37 (n), meta -OC16H33 (n), and meta -OC14H29 (n) for the same homologue from
series to series and homologue to homologue in the same series, which partly contributes to
total molecular flexibility. Thus, variations in mesogenic properties and mesogenic behavior

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
55
Figure . Phase behavior of the series.
can be linked with differing features of their molecular structures, which differ with respect
to flexibility of tailed end groups differing by –CH2-CH2- and their position of substitutions
para or meta as shown in Fig. 2. Table 4 represents some evaluated thermometric data indi-
cating mesogenic behavior and the degree of mesomorphism for series 1, X, and Y under
comparative study.
Following are clear from Table 3:
ꢀ Homologous series under comparison are predominantly nematogenic and partly smec-
togenic in enantiotropic and/or monotropic condition.
ꢀ Smectogenic mesomorphism commences from C6 (series Y) or from C7 homologue.
ꢀ Nematogenic mesomorphism commences from C3 homologue in series 1, whereas it
commences from C2 homologue in series X and Y.
ꢀ Thermal stability for smectic is more for the series 1 as compared with series X and Y.
ꢀ Thermal stability for nematic is in increasing order from series 1 to series Y to series X,
i.e. series X > series Y > series 1.
ꢀ Total upper mesophase lengths are in decreasing order from series 1 to series X to series
Y, i.e. series 1 > series X > series Y.
Homologous series 1 has para substituted –OC18H37 (n) tailed end and linear geometrical
shape, whereas series X and Y have meta-substituted lateral –OC16H33 (n) and –OC14H29 (n)
tail ended groups. Therefore, length to breath ratio, intermolecular closeness, molecular and
functional group polarities and polarizabilities, permanent dipole moment across the long
Table . Relative thermal stability in°C.
Series →
Para –OCH(n)
Meta –OCH(n)
. to .
Meta –OCH(n)
. to .
Sm-I or Sm-N
Commencement of smectic phase
.
(C-C)
C
(Few degrees) (C-C) (Few degrees) (C-C)
C
.
C
.
N-I
.
Commencement of nematic phase
(C-C)
C
. to .
C C
(C-C)
C
. to .
C C
(C-C)
C
. to .
C
Total mesophase lengths in C minimum to maximum
C/C/C

56
R. SOLANKI AND R. B. PATEL
molecular axis, magnitudes of dipole–dipole interactions, magnitudes of dispersion forces,
molecular rigidity and flexibility, and end-to-end and lateral attractions vary more or less in
magnitudes for the same homologue from series to series, operating a phenomena of meso-
morphism and the degree of mesomorphism. Thus, the two opposing effects of intermolec-
ular attractions due to para- and meta-substituted tail ended n-alkoxy groups play role in
facilitating smectic and/or nematic mesophase formation through predominance of either
molecular polarity or polarizability factor. Hence, the misalignment of molecules either per-
pendicular or/and less than 90° on the floating surface causes appearance of smectic or/and
nematic-meso phase formation, either in reversible or irreversible manner, to facilitate favor-
ably or unfavorably in enantiotropic or monotropic mode. The early or late commencement
of mesophase formation is related with the extent of molecular non-coplanarity with the plane
of a floating surface. The para-substituted –OC18H37 (n), meta-substituted –OC16H33 (n) as
well as –OC14H29 (n) tail ended n-alkoxy groups are almost equally non-coplanar. Therefore,
mesophase smectic and/or nematic commences by the difference of one homologue only. The
observed difference can be attributed to the positional difference of tailed n-alkoxy-ended
groups, which causes difference in molecular polarizabilities. The observed difference in ther-
mal stabilities for nematic by one or six units is attributed to linear or nonlinear geometrical
shape, which is related with the positional status and induced degree of polarizability of n-
alkoxy tail-ended group for the same homologue whose magnitudes of energy stored (࢞H) in
a molecule vary from series to series. Therefore, the resistivity toward exposed thermal vibra-
tions and their corresponding intensity required different suitable magnitudes of mesophase
at different lengths with increasing side chain.
5. Conclusions
ꢀ Homologous series of novel chalconyl derivatives are predominantly nematogenic and
partly smectogenic whose total mesophase lengths vary between 12.0 and 28.0°C and
low melting type of series.
ꢀ Mesomorphism is very sensitive and susceptible to the molecular structure based on
positional substitution of a functional group and its polarizability.
ꢀ Present investigation may be useful for the display device to be operated at room tem-
peratures, and their property as bioactive can be exploited in the interest of mankind.
ꢀ The group efficiency order derived for smectic and nematic on the basis of (i) thermal
stability, (ii) early commencement of mesophase, and (iii) total upper mesophase length
are as under:
(i) Smectic
–OC18H37 (n) > –OC16H33 (n) = –OC14H29 (n)
Nematic
–OC16H33 (n) > –OC14H29 (n) > –OC18H37 (n)
(ii) Smectic
–OC14H29 (n) > –OC16H33 (n) = –OC18H37 (n)
Nematic
–OC16H33 (n) = –OC14H29 (n) > –OC18H37 (n)
(iii) Total mesophase length
Upper: –OC18H37 (n) > –OC16H33 (n) > –OC14H29 (n)
ꢀ Present investigation has supported and raised the conclusions drawn earlier.

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
57
Acknowledgments
Authors acknowledge thanks to Dr. R. R. Shah, principal of K. K. Shah Jarodwala Maninagar Science
College, Ahmedabad. Authors are also thankful to Dr. A. V. Doshi, Ex-principal of M.V.M. Science &
Home Sci. College, Rajkot for his constant support, inspiration, and help as and when needed during
the course of present investigation. Authors thank NFDD Centre for analytical and spectral services.
References
[1] Tadwee, I., Sahanashahi, V. R., & Syed, I. (2012). IJPRAS, 1(2), 6–11.
[2] Calliste, C. A., LeBail, J. C., Trouilar, P., Pouget, C., Chulia, A. J., & Duroux, L. J. (2001). Anticancer
Res., 21, 3949–3956.
[3] Rajesh, G., Mansi, K., Srikant, K., Babasaheb, B., Nagesh, D., Kavita., S., & Ajay, C. (2008). Chem.
Pharm. Bull., 56, 897–901.
[4] (a) Gaikwad, P. P., & Desai, M. T. (2013). Int. J. Pharm. Sci. Rev., 2(12), 40–52. (b) Rangasamy, M.,
& Parthiban, K. G. (2010). IJRAP, 1(2), 316–326.
[5] Reinitzer, F. (1888). Montsh, 9, 421.
[6] Narmura, S. (2001). Display, 22(1), 1.
[7] Kim, W. S., Elston, S. J., & Raynes, F. P. (2008). Diplays, 29, 458–463.
[8] Hertz, E., Lavorel, B., & Faucher, O. (2011). Nature Photon., 5, 783.
[9] Henderson, P. A., Niemeyer, O., & Imrie, C. T. (2001). Liq. Cryst., 28, 463–472.
[10] Imrie, C. T. (1999). Struct. Bond, 95, 149–192.
[11] (a) Gray, G. W. (1974). In: Liquid Crystal and Plastic Crystal, Chapter 4, Volume 1, pp. 103–153.
G. W. Gray, & P. A. Winsor (Eds.). (b) Gray, G. W. (1962). Molecular Structures and Properties of
Liquid Crystals, Academic Press: London.
[12] (a) Gray, G. W., & Winsor, P. A. (1974). The role of liquid crystals in life processes by Stewart, G.
T., Liq. Cryst. Plastic Cryst., 1, 308–326. (b) Gray, G. W. & Winsor, P. A. (1974). Liq. Cryst., Ellis
Horwood: Chichester, UK, 1(1) 103–153.
[13] Hird, M., Tyone, K. J., Gray, G. W., Day, S. E., & McDonell, D. G. (1993). Liq. Cryst., 15, 123.
[14] Collings, P. J., & Hird, M. (1997). Introduction of Liquid Crystal Chemistry and Physics, Taylor and
Francis: London.
[15] Marcos, M., Omenat, A., Serrano, J. L., & Ezcurra, A. (1992). Adv. Matter, 4, 285.
[16] Hird, M., Toyne, K. J., Gray. G. W., & Day, S. E. (1993). Liq. Cryst., 14, 741.
[17] (i) Suthar, D. M., & Doshi, A. V. (2013). Mol. Cryst. Liq. Cryst., 575, 76–83. (ii) Chauhan, H. N., &
Doshi, A. V. (2013). Mol. Cryst. Liq. Cryst., 570, 92–100. (iii) Chaudhari, R. P., Chahuan, M. L., &
Doshi, A. V. (2013). Mol. Cryst. Liq. Cryst., 575, 88–95. (iv) Bhoya, U. C.,Vyas, N. N., & Doshi, A.
V. (2012). Mol. Cryst. Liq. Cryst., 552, 104–110.
[18] Suthar, D. M., Doshi, A. A., & Doshi, A. V. (2013). Mol. Cryst. Liq. Cryst., 582, 79–87.
[19] (a) Demuse, D. (1988). Mol. Cryst. Liq. Cryst., 165, 45–84; (b) Demuse, D. (1988). Liq.Cryst., 5,
75–110.
[20] Imrie, C. T., & Luckhrust, G. R. (1998). Liquid dimers and oligomers. In: Handbook of Liquid
Crystal, Low Molecular Liquid Crystal., Vol. 2B, D. Demuse, J. W. Goodby, G. W. Graw, H. Spiess,
& V. Vill (Eds.), Wiley-VCH: Weinheim, Germany, pp. 801–833.
[21] Marathe, R. B., & Doshi, A. V. (2015). Mol. Cryst. Liq. Cryst., 623, 1–8.
[22] Nikitin, K. V., & Andryukhova, N. P. (2004). Can. J. Chem., 82, 571.
[23] Hasan, A., Abbas, A., & Akhtar, M. N. (2011). Molecule, 16, 7789–7802.
[24] Patel, R. B., Patel, V. R., & Doshi, A. V. (2012). Mol. Cryst. Liq. Cryst., 552, 3–9; Chaudhary, R. P.,
& Doshi, A. V. (2012). Der. Pharma. Chemica., 4(3), 1113–1119.
[25] Sharma, V. S., & Patel, R. B. (in press). Mol. Cryst. Liq. Cryst., DOI: 10.1080/15421406.
2016.1190502.
[26] Sharma, V. S., Jain, B. B., & Patel, R. B. (2016). ILCPA, 64, 69–76.