Study of Cr→SmA phase transition and hydrogen bonding in four-ring bent-core liquid crystal.
A newly designed asymmetrical four-ring bent-core compound (4'-n-decyloxyphenylazo)-phenyl-4-yl-3-[N-(4'-n-octadecyloxy-2-hydroxybenzylidene) amino]-2-methyl benzoate exhibiting liquid crystalline behavior was synthesized and characterized. The thermal and textural morphology were studied using differential scanning calorimetry and polarizing optical microscopy, respectively. The study of hydrogen bonding and dynamics of the phase transition has been performed at the molecular level using temperature dependent Fourier transform infrared (FTIR) spectroscopy. The spectral analysis of OH, CH2/CH3, CO, and CN stretching vibrational bands revealed clear signatures of Cr→SmA phase transition at 125°C. Density functional theory has been adopted for the geometry optimization and conformational study of the monomer using the B3LYP/6-31G(d) method. The conformational analysis has been performed to predict the most stable conformer along with the possible conformers using one-dimensional potential energy scan employing the same level of theory. The combination of experimental findings and theoretical analysis helped to understand the mechanism of phase transitions at the molecular level.
Department of Physics, University of Lucknow, Lucknow 226007, India.
Swapnil
S
Singh
Department of Physics, University of Lucknow, Lucknow 226007, India.
Harshita
H
Singh
Department of Physics, University of Lucknow, Lucknow 226007, India. Electronic address: tandon_poonam@lkouniv.ac.in.
Poonam
P
Tandon
Chemistry Department, Assam University, Silchar 788011, Assam, India.
Nirmalangshu
N
Chakraborty
Chemistry Department, Assam University, Silchar 788011, Assam, India.
N V S
NVS
Rao
Departamento de Física, Universidade Federal do Ceará, C.P. 6030, 60.455-900 Fortaleza, CE, Brazil.
A P
AP
Ayala
DSC; PES; POM; TD-FTIR and SmA phase