Observation of Induced Luminescence and Thermochromism in Achiral Hydrogen Bonded Liquid Crystal Complexes

2020 ◽  
Vol 234 (10) ◽  
pp. 1709-1733
Author(s):  
A. Ramya ◽  
V. Balasubramanian ◽  
R. Jayaprakasam ◽  
V. N. Vijayakumar
Keyword(s):  
Liquid Crystal ◽  
Nematic Phase ◽  
Density Functional ◽  
Atomic Charge ◽  
Optical Microscope ◽  
Band Gap Energy ◽  
Stability Factor ◽  
Scanning Calorimetry ◽  
Interesting Phenomenon ◽  
Hydrogen Bonded

AbstractA novel hydrogen bonded liquid crystal (HBLC) complexes are obtained from the non-mesogenic (benzylmalonic acid) and mesogenic (p-n-alkyloxybenzoic acid, where n = 6, 7 and 8) compound via intermolecular hydrogen bonds (H-bond). H-bonds are experimentally confirmed by the Fourier transform infrared spectroscopic (FT-IR) studies and the same is validated using density functional theory (DFT). Induced thermochromism is observed by the polarizing optical microscope (POM) and its possible applications are reported. Phase transition temperature and their analogous enthalpy values, stability factor and span width are determined by the differential scanning calorimetry (DSC) studies. Band gap energy is calculated using UV-visible and photoluminescence spectrum. Hyper conjugative stabilization energy and atomic charge distribution is studied by the natural bond orbital (NBO) studies. Mulliken analysis clearly reveals the intermolecular interaction and steric effect of the HBLC complexes. An interesting phenomenon is that the observation of luminescence and thermochromism in the highly fluidity nematic phase. This peculiar behavior is attributed due to the intermolecular H-bonding interaction between the BMA and nOBA compounds and the effect of rotatory motion of the molecules in nematic phase. Luminescence increases when the spacer moiety decreases in the present complexes is also reported. In nematic phase, the molecules are in different degrees of the excited state which is correlated with the hyper conjugative energy through NBO studies.

Design, Synthesis and Characterization of Hydrogen Bonded Binary Liquid Crystal Complex from 4-Methoxycinnamic Acid and 4-Hexyloxybenzoic Acid (4MCA:6OBA)

2017 ◽  
Vol 231 (11-12) ◽  
Author(s):  
Thamilarasan Ranjeeth Kumar ◽  
Sankaran Sundaram ◽  
Thangaiyan Chitravel ◽  
Ramasamy Jayaprakasam ◽  
Vellalapalayam Nallagounder Vijayakumar
Keyword(s):  
Liquid Crystal ◽  
Binary Mixture ◽  
Tilt Angle ◽  
Phase Variation ◽  
Optical Microscope ◽  
Scanning Calorimetry ◽  
Smectic C ◽  
Ir Studies ◽  
Methoxycinnamic Acid ◽  
Hydrogen Bonded

AbstractHydrogen bonded liquid crystal (HBLC) binary mixture has been synthesized from mesogenic 4-methoxycinnamic acid (4MCA) and mesogenic 4-hexyloxybenzoic acid (6OBA) with different mole ratio. The mesomorphic phase behavior and corresponding phase transition temperatures along with the enthalpy values were investigated by differential scanning calorimetry (DSC). The characteristic textures of 4MCA+6OBA binary mixture were observed by using polarizing optical microscope (POM). Fourier transform infrared spectroscopic (FT-IR) studies confirm the formation of hydrogen bond in the present binary mixture. A note worthy observation in this complex is that pure mesogens have no smectic phase where as 4MCA+6OBA binary mixture exhibits a nematic phase along with higher order smectic C (Sm C) phase. Variation of mole ratio influences thermal properties such as phase peak, enthalpy values and thermal span width of the present HBLC binary mixture complex. The optical tilt angle of 4MCA+6OBA for smectic C phase and thermal stability factors have been investigated. Optical tilt angle for smectic C phase is determined and same is fitted to a power law.

Binary Mixtures of Hydrogen-Bonded Ferroelectric Liquid Crystals: Thermal Span Enhancement in Smectic X* Phase

2015 ◽  
Vol 70 (9) ◽  
pp. 757-774 ◽  
Author(s):  
Gopal Sangameswari ◽  
Nataraj Pongali Sathya Prabu ◽  
Mathukumalli Lakshmi Narayana Madhu Mohan
Keyword(s):  
Binary Mixtures ◽  
Thermal Equilibrium ◽  
Optical Microscope ◽  
Stability Factor ◽  
Benzoic Acids ◽  
Scanning Calorimetry ◽  
Ferroelectric Liquid Crystals ◽  
Binary Liquid ◽  
Smectic C ◽  
Hydrogen Bonded

AbstractThermotropic hydrogen-bonded ferroelectric binary liquid crystal mixtures comprising of N-carbamyl-l-glutamic acid (CGA) and p-n-alkyloxy benzoic acids (BAO) are investigated. Variation in the molar proportion of X and Y (where X=CGA+5BAO and Y=CGA+9BAO, CGA+10BAO, CGA+11BAO, and CGA+12BAO) comprising of four series yielded 36 binary mixtures. Optical and thermal properties of these mixtures are meticulously studied in the present article. In addition to the traditional phases, a novel smectic ordering namely smectic X* is observed in all the four series. The aim of the investigation is to obtain abundance occurrence of smectic X* with a large thermal span, and hence, the proportions of the binary mixtures are so chosen that the prelude task is accomplished. Optical tilt angle in smectic X* and smectic C* phases is experimentally determined, and a theoretical fit is performed. Phase diagrams of the four series are constructed from the data obtained from the differential scanning calorimetry and correlated with the phases recorded by the polarising optical microscope studies. Thermal stability factor and thermal equilibrium are also premeditated.

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.

Chiral Liquid Crystalline Polymers Containing Isosorbide Groups

2013 ◽  
Vol 781-784 ◽  
pp. 403-406
Author(s):  
Mei Tian ◽  
Zhi Xin Xu ◽  
Li Gao ◽  
Dan Shu Yao ◽  
Xiao Zhi He ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Main Chain ◽  
Liquid Crystalline Polymers ◽  
Optical Microscope ◽  
Liquid Crystal Polymers ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Crystalline Polymers

A series of new main-chain liquid-crystal polymers (LCPs) were prepared from sebacoyl chloride (SD) and various amount of 4, 4-Dihydroxy-2, 2-dimethyl Benzalazine (DDBA) and isosorbide (ISO). The liquid crystal (LC) properties were investigated by polarized optical microscope (POM), differential scanning calorimetry (DSC) and X-ray diffraction measurements. P1 exhibited a typical nematic thread texture, which contains no ISO. P2-P7 are Sc* and N LCPs, which exhibited broken fan-shaped texture and droplet texture. The introduction of chiral units into the polymers led to a change of mesomorphase, as compared with P1.

DYNAMIC RESPONSE OF CARBON NANOTUBES DISPERSED IN NEMATIC LIQUID CRYSTAL

NANO ◽  
2007 ◽  
Vol 02 (01) ◽  
pp. 41-49 ◽  
Author(s):  
SANG YOUN JEON ◽  
KYUNG AH PARK ◽  
IN-SU BAIK ◽  
SEOK JIN JEONG ◽  
SEOK HO JEONG ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Liquid Crystal ◽  
Electric Field ◽  
Dynamic Response ◽  
Nematic Liquid Crystal ◽  
Density Functional ◽  
Strong Electric Field ◽  
Optical Microscope ◽  
Analysis Of Dynamics ◽  
Vertical Cell

The alignment and dynamic response of carbon nanotubes (CNTs) in nematic liquid crystal (NLC) medium induced by strong electric field have been observed through polarizing optical microscope. Density-functional calculations suggest that LC molecule anchors helically to the CNT wall to enhance π-stacking with a binding energy of nearly -2.0 eV due to a considerable amount of charge transfer from LC molecule to CNT, resulting in the formation of excess charges and permanent dipole moment in CNTs. Under strong electric field, the motion of CNTs distorted the director of adjacent LC molecules. Our detailed analysis of dynamics revealed that the four-lobe textures in vertical cell and two vertical stripes in in-plane switching cell were strongly correlated, i.e., the side view of textures by the vertical motion of CNTs in vertical cell was similar to the textures in in-plane switching cell. Interestingly, the magnitude of textures in microscope was strongly dependent on the size of CNTs and the applied field strength. The statistical size distribution of textures similar to that of CNTs provided information for the degree of dispersion of CNTs.

Dynamiclly Functional Materials Based on Hydrogen-Bonded Liquid Crystals

2014 ◽  
Vol 926-930 ◽  
pp. 68-71
Author(s):  
Zhi Lian Liu ◽  
Xiao Hui Li ◽  
Zhen Ning Yu
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Hydrogen Bonds ◽  
Functional Materials ◽  
Optical Microscope ◽  
Supramolecular Complexes ◽  
Pyridine Derivative ◽  
Crystal Texture ◽  
Crystal Properties ◽  
Hydrogen Bonded

A new series of supramolecular hydrogen-bonded liquid cryatals complexes were synthesized based on pyridine derivative and 4-n-alkoxybenzoic acids. The formation of hydrogen bonds was verified by infrared spectra. The thermal behavior of supramolecular liquid crystals was studied using differential scanning calorimeter (DSC). The liquid crystal texture was revealed with polarizing optical microscope (POM). It demonstrats that all supramolecular complexes have good liquid crystal properties.

Phase Behavior Studies on ZnS Nanoparticles Doped Liquid Crystal Mixture

2016 ◽  
Vol 230 (10) ◽  
Author(s):  
Marimuthu Santhosh ◽  
Thangaiyan Chitravel ◽  
Ramasamy Jayaprakasam ◽  
Vellalapalayam Nallagounder Vijayakumar
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Optical Microscope ◽  
Stability Factor ◽  
Zns Nanoparticles ◽  
Chiral Compound ◽  
Cholesteric Phase ◽  
Blue Phase ◽  
Crystal Phases ◽  
Span Width

AbstractThe Liquid Crystalline (LC) mixture is prepared from chiral compound of cholesteryl nonanoate and non-chiral compound of biphenylpyrimidine. The phase change with temperature and corresponding textures of the LC mixtures are analyzed by Polarizing Optical Microscope (POM). LC mixture at its isotropic state is doped with 1% of ZnS nanoparticles and its influence on mesophases is discussed. Normally blue phase is identified within narrow thermal width. The note worthy observation is that the blue phase and cholesteric phase with extended thermal span width in the ZnS doped LC mixture. Also the thermal stability factor of the different liquid crystal phases is discussed.

Synthesis and Characterization of a New Organometallic Palladium Coordinated Liquid Crystal

2010 ◽  
Vol 428-429 ◽  
pp. 117-121 ◽  
Author(s):  
Jian Qiang Liu ◽  
Xing Cheng Zhang ◽  
You Yong Dai ◽  
Hong Di Xiao ◽  
Shi Shen Yan ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Optical Microscope ◽  
Resonance Spectroscopy ◽  
Functional Material ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Liquid Crystallinity ◽  
New Type ◽  
Clearing Temperature

A new organometallic palladium coordinated liquid crystal that is written by PdS4 has been synthesized by chelating reaction of the tetrachloropalladate (PdCl42-) and the star-like liquid crystal (S4) containing four butoxyazobenzene mesogens in its periphery. The structure and liquid crystallinity (LC) of PdS4 were characterized by infrared absorption spectroscopy (IR), ultraviolet absorption spectra (UV), nuclear magnetic resonance spectroscopy (NMR), elemental analysis (EA), polarizing optical microscope (POM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The phase behavior of PdS4 is Cr167N232I200N170Cr, its melting point and clearing temperature are higher than those of the free azo ligand S4, its mesophase range is broader than S4’s. It will be used as a new type photoelectric functional material in the future.

scholarly journals Thermal and Photophysical Studies of Binary Mixtures of Liquid Crystal with Different Geometrical Mesogens

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 223 ◽  
Author(s):  
Omaima A. Alhaddad ◽  
Hoda A. Ahmed ◽  
Mohamed Hagar ◽  
Gamal R. Saad ◽  
Khulood A. Abu Al-Ola ◽  
...  
Keyword(s):  
Binary Mixtures ◽  
Density Functional ◽  
Binary Systems ◽  
Uv Spectroscopy ◽  
Twist Angle ◽  
Optical Microscope ◽  
Geometrical Parameters ◽  
Scanning Calorimetry ◽  
Photophysical Studies ◽  
The Individual

Three binary systems were prepared by mixing of two different mesogenic derivatives, homologues, the first is azo/ester, namely 4-alkoxyphenylazo-4′-phenyl-4″-alkoxybenzoates (IIn+m) and the second is Schiff base/ester, namely 4-(arylideneamino)phenyl-4″-alkoxy benzoates (In+m). The two corresponding analogues from both series in the binary mixtures investigated are of the same terminal alkoxy chain length. Mesomorphic properties were investigated by differential scanning calorimetry (DSC) and phases identified by polarized optical microscope (POM). Photophysical studies were investigated by UV spectroscopy connected to a hot stage. Results were discussed based on constructed binary phase diagrams. All mixtures were found to exhibit eutectic compositions, with linear or slightly linear nematic and smectic A stability/composition dependences. Geometrical parameters were predicted applying density functional theory (DFT) calculations. Twist angle (θ), aspect ratio, dipole moment and the polarizability of the individual compounds were discussed and correlated with the experimental results to illustrate the enhanced the mesophase stability and the mesophase range of the mixture at the eutectic composition compared with those of their individual components.

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