Experimental and computational (DFT) studies on induced orthogonal smectic A∗ phase in hydrogen-bonded ferroelectric liquid crystals

2018 ◽  
Vol 32 (21) ◽  
pp. 1850223 ◽  
Author(s):  
P. Subhasri ◽  
R. Jayaprakasam ◽  
V. N. Vijayakumar
Keyword(s):  
Liquid Crystals ◽  
Molecular Orbital ◽  
Density Functional ◽  
Liquid Crystalline ◽  
Proton Acceptor ◽  
Dft Studies ◽  
Ferroelectric Liquid Crystals ◽  
Smectic A ◽  
Present Complex ◽  
Hydrogen Bonded

Hydrogen-bonded ferroelectric liquid crystals (HBFLC) are designed and synthesized from nonmesogenic chiral proton donor compound of (R)-([Formula: see text])-Methylsuccinic acid (MSA) and mesogenic proton acceptor compound of 4-undecyloxybenzoic acid (11OBA) in a different mole ratio. Intermolecular hydrogen bonds (H-bond) between the nonmesogenic and mesogenic compounds have been confirmed through experimental Fourier transform infrared spectroscopy (FTIR) and density functional theory (DFT) computational studies. The steric hindrance and inductive effects of the present complex and its influence on the structure are discussed. A rich phase polymorphism in the liquid crystalline complex has been studied using polarizing optical microscope (POM) and differential scanning calorimetry (DSC). The chiral phases observed in the present complex are due to the presence of lone pair (n) to anti-bonding ([Formula: see text]) transition symmetry which is validated by DFT studies. A noteworthy observation of induced smectic A[Formula: see text](Sm A[Formula: see text]) by quenching of traditional phase (nematic) has been identified and the reason for the same has been discussed by DFT studies. The unusual phase order of Sm A[Formula: see text], smectic C[Formula: see text](Sm C[Formula: see text]) and smectic G[Formula: see text][Formula: see text](Sm G[Formula: see text]) mesogenic phases are observed. The other liquid crystalline parameters are evaluated by experimental and theoretical calculations and the same has been compared. Increased tilt angle in liquid crystal (LC) molecules has been theoretically analyzed by natural bond orbital (NBO) studies. Stability of the HBFLC phases and its origination mechanism have been discussed with the help of highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO–LUMO) energies.

Thermal and optical characterization of multiple hydrogen bonded liquid crystals derived from mesogenic and non-mesogenic compounds: experimental and theoretical (DFT) studies

2020 ◽  
Vol 98 (5) ◽  
pp. 413-424 ◽  
Author(s):  
S. Sundaram ◽  
P. Subhasri ◽  
R. Jayaprakasam ◽  
V.N. Vijayakumar
Keyword(s):  
Liquid Crystals ◽  
Molecular Orbital ◽  
Density Functional ◽  
Nbo Analysis ◽  
Stability Factor ◽  
Dft Studies ◽  
Scanning Calorimetry ◽  
Lowest Unoccupied Molecular Orbital ◽  
Optical Applications ◽  
Hydrogen Bonded

A set of new cyclic multiple hydrogen bonded liquid crystals (HBLCs) have been designed and synthesized from citric acid (CA) and 4-dodecyloxybenzoic acid (12OBA). The presence of intermolecular hydrogen bonds (H-bonds) between non-mesogenic and mesogenic compounds has been confirmed by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy and density functional theory (DFT) studies. The hydrogen bonding interactions were explained from natural bond orbital (NBO) analysis using B3LYP/6-311G(d,p) level of theory. Additionally, the Mulliken atomic charges reveal the nature of charge distribution in the HBLC complex. The dynamics of phase transitions and the corresponding stability factor have been evaluated using polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and electrostatic potential (ESP) analysis. Highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies of the CA+12OBA complex is theoretically calculated and experimentally verified. It is found that the variation in the mole ratio in mesogenic with non-mesogenic compound induces the stabilized nematic (N) and smectic X (Sm X) phases. Photocatalytic activity of the CA+12OBA HBLC complex reveals the usage of its optical applications.

scholarly journals Smectic-A–smectic-C–smectic-C*multicritical point in ferroelectric liquid crystals

1994 ◽  
Vol 72 (22) ◽  
pp. 3558-3561 ◽  
Author(s):  
Shankar B. Rananavare ◽  
V. G. K. M. Pisipati ◽  
E. W. Wong
Keyword(s):  
Liquid Crystals ◽  
Multicritical Point ◽  
Ferroelectric Liquid Crystals ◽  
Smectic A ◽  
Smectic C

Uv Curable Liquid Crystals and Their Application

1996 ◽  
Vol 425 ◽  
Author(s):  
H. Takatsu ◽  
H. Hasebe
Keyword(s):  
Liquid Crystals ◽  
Light Scattering ◽  
Liquid Crystalline ◽  
Room Temperature ◽  
Polymer Network ◽  
Driving Voltage ◽  
Uv Curable ◽  
Good Thermal Stability ◽  
Photo Polymerization ◽  
Smectic A

AbstractSome classes of liquid crystalline monoacrylates having no methylene spacers in a side chain have been prepared. The liquid crystalline monoacrylates have effects to reduce the driving voltage and the hysteresis for a light scattering display of Polymer Network liquid crystals prepared by photo-polymerization-induced phase separation.By photo-polymerization of a chiral monoacrylate monomer in a nematic liquid crystalline host including a black dichroic dye, a polarizer free reflective Spiral Polymer Aligned Nematic (SPAN) Guest Host (GH) LCD exhibiting a low driving voltage has been fabricated. The effect of the spiral polymers made of some kinds of chiral monoacrylates for a Super Twisted Nematic (STN) LCD using SPAN liquid crystals is discussed.UV-curable liquid crystals showing nematic phases at room temperature have been developed. By in situ photo-polymerization, the UV-curable liquid crystals can be utilized for the retardation film with high quality and good thermal stability. The fabrication of various kinds of retardation film using the UV-curable liquid crystals is discussed.UV-curable liquid crystals having isotropic-nematic-smectic A phase sequence have been developed and the photo-polymerization at the state of their uniaxially oriented smectic A phases at room temperature is discussed. The polymerized film is optically uniaxial and transparent without light scattering.

scholarly journals Effect of smectic A temperature width on the soft mode in ferroelectric liquid crystals

2008 ◽  
Vol 104 (3) ◽  
pp. 034105 ◽  
Author(s):  
A. Choudhary ◽  
S. Kaur ◽  
J. Prakash ◽  
K. Sreenivas ◽  
S. S. Bawa ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Soft Mode ◽  
Ferroelectric Liquid Crystals ◽  
Smectic A

EFFECT OF DYNAMIC CONFORMATION DISTRIBUTIONS ON MOLECULAR TILT IN CHIRAL SMECTIC LIQUID CRYSTALS

1991 ◽  
Vol 05 (12) ◽  
pp. 821-826
Author(s):  
SIN-DOO LEE ◽  
J. S. PATEL ◽  
J. W. GOODBY
Keyword(s):  
Liquid Crystals ◽  
Energy Barrier ◽  
Liquid Crystalline ◽  
Characteristic Temperature ◽  
Anomalous Behavior ◽  
Rotational Barrier ◽  
Smectic Liquid Crystals ◽  
Smectic A ◽  
Sign Inversion

It is shown that for some chiral smectic A materials the field-induced molecular tilt undergoes a peculiar sign inversion with respect to the layer normal as the temperature increases. The induced molecular tilt vanishes at a characteristic temperature in the smectic A state. This anomalous behavior can be described in terms of a dynamically fluctuating mixture of at least two molecular conformers, separated by an energy barrier in their liquid-crystalline states. The energy barrier between these two conformers is found to be comparable to the rotational barrier in normal hydrocarbons.

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