Mesomorphism of binary systems of nonmesogenic compounds

Article abstract of DOI:10.1080/15421406.2011.604589

Three binary systems, each consisting of two nonmesogenic compounds, viz. p-tolual-p-phenetidine (M.P. 108.5C) [A] as the common component, and Methyl p-(p-n-butyloxy benzoyloxy) benzoate (M.P. 119.0C) [B₁], Ethyl-p-(p-n-butyloxy benzoyloxy) benzoate (M.P. 94.0C) [B₂], and n-Butyl p-(p-n-butyloxy benzoyloxy) benzoate (M.P. 130.0C) [B₃] as the second component, respectively, are studied with a view to understand the effect of terminal groups on nematic and/or smectic mesomorphism. Latent transition temperatures (LTT) of the constituent components A, B₁, B₂, and B₃ were determined by extrapolation. Binary system (A + B₁) induces a nematogenic mesophase while binary systems (A + B₂) and (A + B₃) both induce a smectic mesophase in addition to a nematic mesophase. Phase diagrams of the binary systems under investigation are plotted for the mole percent of component (A) versus the transition temperatures of each binary system as determined from polarizing optical microscopy. The texture of the nematic mesophase is of threaded type and that of the smectic mesophase is focal-conic fan shaped of the type smectic-A. Components A, B₁, B₂, and B₃ were prepared by established methods. Analytical data support the structure of molecules under investigation. Melting points of the constituent components match with data reported earlier.

Full text of DOI:10.1080/15421406.2011.604589

This article was downloaded by: [Florida State University]
On: 25 December 2014, At: 15:30
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Molecular Crystals and Liquid Crystals
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/gmcl20
Mesomorphism of Binary Systems of
Nonmesogenic Compounds
A. V. Doshi a , D. A. Odedara b & R. B. Patel c
a Matushri Virbaima Mahila Science and Home Science College,
Chemistry Department , Rajkot , Gujarat , India
b M. D. Science College, Chemistry Department , Porbander ,
Gujarat , India
c Department of Chemistry , K. K. Shah Jarodwala Maninagar Science
College , Ahmedabad , Gujarat , India
Published online: 27 Dec 2011.
To cite this article: A. V. Doshi , D. A. Odedara & R. B. Patel (2012) Mesomorphism of Binary
Systems of Nonmesogenic Compounds, Molecular Crystals and Liquid Crystals, 552:1, 97-103, DOI:
10.1080/15421406.2011.604589
To link to this article: http://dx.doi.org/10.1080/15421406.2011.604589
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the
“Content”) contained in the publications on our platform. However, Taylor & Francis,
our agents, and our licensors make no representations or warranties whatsoever as to
the accuracy, completeness, or suitability for any purpose of the Content. Any opinions
and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content
should not be relied upon and should be independently verified with primary sources
of information. Taylor and Francis shall not be liable for any losses, actions, claims,
proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or
howsoever caused arising directly or indirectly in connection with, in relation to or arising
out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &
Conditions of access and use can be found at http://www.tandfonline.com/page/terms-
and-conditions

Mol. Cryst. Liq. Cryst., Vol. 552: pp. 97–103, 2012
Copyright © Taylor & Francis Group, LLC
ISSN: 1542-1406 print/1563-5287 online
DOI: 10.1080/15421406.2011.604589
Mesomorphism of Binary Systems
of Nonmesogenic Compounds
A. V. DOSHI,1 D. A. ODEDARA,2 AND R. B. PATEL3,∗
1Matushri Virbaima Mahila Science and Home Science College, Chemistry
Department, Rajkot, Gujarat, India
2M. D. Science College, Chemistry Department, Porbander, Gujarat, India
3Department of Chemistry, K. K. Shah Jarodwala Maninagar Science College,
Ahmedabad, Gujarat, India
Three binary systems, each consisting of two nonmesogenic compounds, viz. p-tolual-p-
phenetidine (M.P. 108.5◦C) [A] as the common component, and Methyl p-(pꢀ-n-butyloxy
benzoyloxy) benzoate (M.P. 119.0◦C) [B1], Ethyl-p-(pꢀ-n-butyloxy benzoyloxy) benzoate
(M.P. 94.0◦C) [B2], and n-Butyl p-(pꢀ-n-butyloxy benzoyloxy) benzoate (M.P. 130.0◦C)
[B3] as the second component, respectively, are studied with a view to understand the
effect of terminal groups on nematic and/or smectic mesomorphism. Latent transition
temperatures (LTT) of the constituent components A, B1, B2, and B3 were determined by
extrapolation. Binary system (A + B1) induces a nematogenic mesophase while binary
systems (A + B2) and (A + B3) both induce a smectic mesophase in addition to a nematic
mesophase. Phase diagrams of the binary systems under investigation are plotted for the
mole percent of component (A) versus the transition temperatures of each binary system
as determined from polarizing optical microscopy. The texture of the nematic mesophase
is of threaded type and that of the smectic mesophase is focal-conic fan shaped of the
type smectic-A. Components A, B1, B2, and B3 were prepared by established methods.
Analytical data support the structure of molecules under investigation. Melting points
of the constituent components match with data reported earlier.
Keywords Mixed mesomorphism, mixed melt, meshophase, smectic, nematic
Introduction
Some nonmesogenic substances have the potential to exhibit mesomorphic behavior; how-
ever, the mesophase does not appear because the temperature of the transition lies below the
normal melting point. Such substances in their binary mixtures with another nonmesomor-
phic substance can give rise to “mixed liquid crystal” formation over a range of temperature
and composition. The range of composition over which the mesophase exists depends upon
the degree of similarity in shape, size, polarity, and polarizability of the components to
cause anisotropic intermolecular forces of attractions of suitable magnitude, which can
keep properly aligned molecules and/or a sliding layered arrangement of molecules in the
binary mixture. Naturally, a search for their virtual transition temperatures by extrapolation
is of great importance.
∗Address correspondence to R. B. Patel, Department of Chemistry, K. K. Shah Jarodwala Man-
inagar Science College, Ahmedabad 380008, Gujarat, India. E-mail: roshanpatel770@gmail.com.in
97

98
A. V. Doshi et al.
Experimental
Preparation
The common component (A) of the binary system p-tolual-p-phenetidine was prepared by
refluxing equimolar proportions of p-tolualdehyde and p-phenetidine in alcohol for 2–3 h
by an established method [1].
The uncommon components were prepared by the method described by Lohar and
Doshi et al. [2–10] as shown in Scheme 1.
Scheme 1.
Similarly, methyl-p[pꢀ-n-butyloxy benzoyloxy] benzoates [B1] and n-butyl-p[pꢀ-n-
butyloxy benzoyloxy] benzoates [B3] were synthesized according to Scheme 1.
Method
Transition temperatures of the binary systems (i) A + B1, (ii) A + B2, and (iii) A + B3 and
of pure substances A, B1, B2, and B3 are determined by polarizing optical microscopy.
Preparation of Binary Mixtures
Binary mixtures of the binary systems (i) A + B1, (ii) A + B2, and (iii) A + B3 were
prepared by the established method of Lohar and Doshi et al. [2–10].
Results and Discussion
Binary systems A + B1, A + B2, and A + B3 consist of p-tolual-p-phenetidine as a
common component. The components under discussion are originally non-mesomorphic,

Mesomorphism of Binary Systems
99
Figure 1. Phase diagram 1.
but monotropic nematic mesomorphism in the case of binary system A + B1 and smectic
mesophase in addition to nematic mesophases in the case of binary systems A + B2 and
A + B3 are induced monotropically and enantiotropically, respectively. The respective
phase diagrams of the binary systems are shown in Figs 1–3, drawn from Tables 1–3.
The range of composition over which nematic and smectic mesophases appear in a binary
mixture are represented in Table 4, as determined from the respective phase diagrams of
the binary systems (Figs 1–3).
The components of binary systems under discussion individually do not form
mesophases either monotropically or enantiotropically, but binary mixtures exhibit mixed
mesomorphism over a range of composition and temperature, at constant pressure. Such
components are highly crystalline and are not readily supercooled from the amorphous
melt, which results in monotropic behavior. The net intermolecular forces of attraction
generated are anisotropic and of suitable magnitude within a definite range of composition
Figure 2. Phase diagram 2.

100
A. V. Doshi et al.
Figure 3. Phase diagram 3.
and temperatures (Table 4) as a consequence of similarity in molecular shape, size, polarity,
polarizability, and factors conducive to molecular alignment at an angle less than 90◦ to
the plane of the surface to cause mesophase formation. Intermolecular forces of adhesion
may cause a layered arrangement of molecules and hence form a smectogenic phase in
addition to a nematogenic mesophase as observed in the case of binary systems A + B2 and
A + B3. In the case of the present study, a common component p-tolual-p-phenetidine (A)
and added components B1, B2, and B3 possess two phenyl rings linked through a central
bridge and a rod-like shape with common OC4H9 terminal chains. Component (A) of
a binary system has highly polar and polarizable right terminal end group OC2H5. The
Table 1. Transition Temperatures of Binary system 1
Transition temperatures in ◦C
Sr. No.
Mole % A
Sm
Nm
Isotropic
1.
2.
3.
4.
5.
6.
7.
8.
9.
0.0
13.25
25.35
37.16
48.48
59.41
68.0
76.81
84.68
92.04
95.14
100.0
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
(85.0)
(83.5)
(82.0)
(81.0)
(78.0)
(78.3)
—
119.0
114.0
106.0
106.0
100.0
100.0
99.0
102.0
107.5
108.0
108.0
108.5
10.
11.
12.
—
—
Note: () indicates monotropic.

Mesomorphism of Binary Systems
101
Table 2. Transition Temperatures of Binary system 2
Transition temperatures in ◦C
Sr. No.
Mole % A
Sm
Nm
Isotropic
1.
2.
3.
4.
5.
6.
7.
8.
9.
0.0
13.71
26.44
37.94
44.52
58.95
67.36
76.75
85.03
92.86
96.5
—
—
(55.0)
—
—
—
—
—
—
—
—
—
94.0
92.0
90.0
88.0
87.0
(57.0)
(55.0)
(56.6)
(61.0)
(62.7)
(67.0)
—
—
—
—
96.0
101.0
102.0
105.0
107.0
108.5
108.5
10.
11.
12.
—
—
100.0
Note: () indicates monotropic.
changing part of all the binary systems A + B1, A + B2, and A + B3 involves different
right-side terminals of the molecules B1, B2, and B3 viz. COOCH3, COOCH2CH3,
and COOCH2CH2CH2CH3, respectively. These end groups are polarizable and polar,
which gradually increase the length of the molecules and hence result in an increase in
the length to breadth ratio. Consequently, intermolecular end-to-end and lateral forces of
attractions, and molecular polarizability increases from B1→ B2→ B3 in combination with
Table 3. Transition Temperatures of Binary system 3
Transition temperatures in ◦C
Sr. No.
Mole % A
Sm
Nm
Isotropic
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
0.0
12.5
20.69
27.4
38.88
50.78
60.75
69.37
78.31
86.38
93.23
96.71
100.0
—
(48.0)
(45.0)
(44.0)
—
—
—
—
—
—
—
—
—
—
55.0
46.0
45.0
47.0
48.0
50.0
(80.0)
(80.0)
(79.0)
(79.0)
—
130.0
102.0
98.0
96.0
94.0
94.0
100.0
102.0
105.0
108.0
108.5
108.0
108.5
—
Note: () indicates monotropic.

102
A. V. Doshi et al.
Table 4. Mole % of component (A) over which mesomorphism exists
Mesophase range in mole %
Sr. No.
Binary system
Smectic
Nematic
(i)
(ii)
(ii)
A + B1
A + B2
A + B3
—
27.5–38.0
13.5–40.0
37.0–84.5
27.5–78.0
13.5–93.0
the end groups OC2H5 and CH3 of component (A). Thus, resultant intermolecular
forces of adhesion in the mixed melt are generated which are anisotropic and of suit-
able magnitude to cause a statistically parallel orientational order of molecules in all the
binary systems, and intermolecular anisotropic forces of attractions are further strength-
ened to cause a lamellar molecular arrangement. Hence, binary system A + B1 induces a
monotropic nematic mesophase, binary system A + B2 induces a monotropic smectic and
nematic mesophases, and binary system A + B3 induces monotropic smectic, as well as
monotropic and enantiotropic nematic mesophases within a definite range of temperature
and composition. The intermolecular forces of adhesion for the binary mixtures of binary
systems A + B1, A + B2, and A + B3 in a mixed melt within some range of composition
other than that mentioned in Table 4 are not anisotropic and of suitable magnitude, which
do not induce any mesophase but pass directly into the isotropic liquid state from the solid
state, i.e., mesophase exhibition is restricted for such binary mixtures in which molecules
are disaligned under the influence of applied heat.
Both constituent components of all the three binary systems under present investigation
are chemically similar, and the melting point of the solid phase of the binary mixture falls
below the mesophase to amorphous liquid transition temperature of the mixed liquid crystal
phase, a temperature that lies between the two pure components. Such a mixture exhibits
Table 5. Comparison of LTT of component (A) and (B) of binary system
LTT in ◦C
Doshi and
Present
work
Doshi and Lohar, Joshi,
Odedra
Ganatra, Patel
S.
No.
X
Z
Y
Sm Nm Sm Nm
Nm
1.
(A) CH3
CH N
OC2H5
—
—
—
82.5
85.0
79.0
—
—
—
90.0, 86.5,
87.0, 84.0
102.0
93.0
80.0
—
2. (B1) C4H9O
3. (B2) C4H9O
4. (B3) C4H9O
COO
COO
COO
COOCH3
—
90.0 58.0 88.0
71.0 88.0
—
COOC2H5 59.0 79.0 60.0 78.0
62.0 80.0
COOC4H9(n) 60.0 108.0 66.0 100.0
69.0 100.0
—
—

Mesomorphism of Binary Systems
103
enantiotropic liquid crystal properties as observed in case of binary system A + B3. The
binary phase diagrams (Figs 1–3) further suggest that when one of the components of a
binary system is an ester, it induces mesomorphism. Induction of a smectic mesophase is
more common.
Latent transition temperatures (LTTs) derived by extrapolation for the components
A, B1, B2, and B3 are quite agreeable to the values of LTT reported earlier for the same
components. Thus, the concurrent values of LTT for the nonmesomorphic substances put
the extrapolation method on more sound ground. Values of LTT as determined and shown
in Table 5 are concurrent with permissible variation, though the first component of a binary
system changed. Thus, the present investigation supports the view that the nonmesomorph
is structurally similar to nonmesomorphic first or common component, and possesses
sufficiently polar groups. Of course, for greater dependability of the extrapolation method,
the eutectic points in such binary systems should preferably be in equilibrium with the
anisotropic liquids and the terminal groups of the nonmesomorphs should be sufficiently
polar. The evidence obtained by the present study raises the reliability and credibility of
the extrapolation method to determine LTT of a non-mesomorph.
Conclusion
The present investigation supports the views that:
• The intermolecular forces of adhesion between similar and dissimilar molecules
are anisotropic and of suitable magnitude that can restrict the molecules to disalign
causing the formation of mesophases a binary system.
• LTT determination of a nonmesogenic substance by extrapolation of a transition
curve of a phase diagram of a binary system can be done. Thus, the extrapolation
method acquires more reliability and credibility by the present investigation.
Acknowledgments
The authors give thanks to ex. Professor and Head, Dr. R. A. Vora, of the Department of
Applied Chemistry, Faculty of Technology and Engineering, M. S. University of Baroda,
Vadodara, for his valuable cooperation and suggestions in the work.
References
[1] Gray, G. W., & Winsor, P. A. (1974). Liquid Crystal and Plastic Crystals, Ellis Horwood:
Chichester.
[2] Lohar, J. M., & Doshi, A. V. (1993). Proc. Indian Acad. Soc. (Chem. Soc.), 105 (3), 203–214;
Acta. Ciancia Indica, XVIII C (3), 245; Doshi, A. V. (1987). Study of mesomorphism and
Exploration of its Characteristics, PhD thesis, Saurastra University, Rajkot.
[3] Doshi, A. V., & Joshi, N. N. (1993). J. Ind. Chem. Soc., 70, 807–809.
[4] Doshi, A. V., & Ganatra, K. J. (2000). J. Ind. Chem. Soc., 77, 332–325.
[5] Doshi, A. V., & Makwana, N. G. (2008). J. Ind. Chem. Soc., 85, 262–266.
[6] Doshi, A. V., & Patel, V. R. (2008). J. Ind. Chem. Soc., 85, 267–272.
[7] Doshi, A. V., & Prajapati, H. R. (2007). J. Ind. Chem. Soc., 84, 658–660.
[8] Odedra, D. A. (1998). Study of the Effect of Structure and Composition on Liquid Crystal state
of Substances, PhD thesis, Saurastra University, Rajkot.
[9] Doshi, A. V., Bhoya, U. C., & Trawadi, J. J. (2010). In: Poster Session in National Conference
of Liquid Crystals, Surat, India; Mol. Cryst. Liq. Cryst., Forthcoming.
[10] Doshi, A. V., & Prajapati, H. R. (2011). Der Pharma Chemica, 3 (1), 123–133.