66
V.N. Vijayakumar, M.L.N. Madhu Mohan / Journal of Molecular Structure 991 (2011) 60–67
Table 3
part of molecule. This result is in good agreement with reported
[35–37] HBFLC molecules.
Activation energies (eV) and relaxation frequencies (Hz) obtained in various phases of
CTy + nOBA and CTy + nBA HBFLC complexes.
HBFLC
Phase
Type
Temperature Relaxation Activation
6. Conclusions
(°C)
frequency, energy (eV)
fr (MHz)
i. Two novel series of inter hydrogen bonded ferroelectric
liquid crystals have been isolated.
ii. The positional influence of oxygen atom has been investi-
gated from the thermal and electrical characterization of
both the series.
CTy + 8OBA Cholesteric Type I 128
G⁄
85.1
5.25
4.15
9.20
5.05
0.11
0.03
0.04
0.02
Cholesteric Type II 128
G⁄
G⁄
85.1
CTy + 8BA
Type II 86
8.25
0.05
iii. Dielectric relaxations (Type I and Type II) and activation
energies have been carried out for various phases in
CTy + 8OBA and CTy + 8BA complexes.
illustrated in Figs. 10a and 10b. The dipole moments are classified
into two categories:
Acknowledgements
The type I relaxation mechanism is attributed to the longitudi-
nal dipole moment (
molecule. In the present series this longitudinal dipole moment
1) is observed as the oxygen molecule attached to the benzene
core on one side of the molecular structure of HBFLC.
The type II relaxation mechanism is attributed to the longitudi-
nal dipole moment (ll) situated at the flexible part of the molecu-
lar structure. This is depicted in Fig. 10a as oxygen molecule
pertaining to the carbon atom forming the hydrogen bonding
frame work. Further this arrangement of the hydrogen bonding
permits to have an electronegative oxygen atoms giving arise to
type II relaxations.
ll) situated at the corner of the rigid part of
The authors acknowledges the financial support rendered by All
India Council for Technical Education (AICTE), Department of Sci-
ence and Technology (DST), and Defence Research Development
Organization (DRDO), New Delhi. Infrastructural support provided
by Bannari Amman Institute of Technology is gratefully
acknowledged.
(l
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