Nonyloxy Benzoic Acid Research Articles

Chemically condensed liquid crystalline optical materials dielectric relaxation and phase variance of novel switching applications

Dielectric relaxations are studied at three different frequencies of a hydrogen bond liquid crystals composed of chloro benzoic acid with nonyloxy benzoic acid. The process of synthesis is described and the synthesized mesogen is a monophase variant with nematic phase. Hence, FT-IR studies conform the formation of hydrogen bond. Moreover, DSC studies enabled to examine the transition temperatures and corresponding enthalpy values. Profiles of dielectric loss variation with frequency from 5 Hz to 13 MHz are constructed and three different dielectric relaxations labelled as soft mode I relaxation, type II relaxation and type III relaxation at 1 KHz, 6577 KHz and 7654 KHz respectively are observed and investigated. Cole-Cole plots are constructed for all the dielectric relaxations. Arrhenius plots enabled to envisage the activation energies. For the first time in the history of liquid crystal dielectric work, we observed that in the present sample at higher frequency the process mentioned above is reversed. All the dielectric data points obtained at various temperatures when plotted they are found to converge at the ε∞ values and diverge at ε0 values. This process is referred as frequency cross over. Nematic growth order derived from dielectric studies is also presented.

<span>Induced twist grain boundary phase in the binary mixtures of cholesteryl caprylate and nonyloxybenzoic acid </span>

<span>Induced twist grain boundary phase in the binary mixtures of cholesteryl caprylate and nonyloxybenzoic acid </span>

Molecular Ordering and Nematic Character of Nonyloxy Benzoic Acid: Solvent and Thermodynamic Potentials Effect

Abstract: Benzoic acid derivative p-n-Nonyloxy Benzoic Acid (NOBA) has been chosen for the present investigation to analyze its properties under the effect of a polar aprotic solvent. Indication of stable phase has been examined by interaction-energy values both in pure form and in a polar aprotic solvent dimethylformamide (DMF, ε=38) for different modes of interaction. Complete neglect differential overlap (CNDO/2) method has been applied for net atomic charges and dipole moments at the atomic center. Modified version of Rayleigh–Schrödinger perturbation theory and multicentered-multipole expansion method have been used to regulate long-range intermolecular interactions, where short-range interactions have been studied by 6-exponential potential function. Details on phase behavior and phase stability of NOBA have been reported using statistical thermodynamic calculations of Helmholtz free energies and entropies in several modes of interaction. Keywords: NOBA, Interaction energy, Helmholtz free energy, Entropy, Stability.

Mesomorphism in H-bonded binary mixtures of guanazole with nonyloxy benzoic acid

The ability of liquid crystalline materials to feature self-assembly behavior has garnered attention in designing new aggregates for various functional applications. The structural influence of hydrogen-donating and accepting moieties on the liquid crystalline behavior of hydrogen-bonded assemblies of guanazole (G) with liquid crystalline nonyloxy benzoic acid (9OBA) is systematically investigated. Significant variations in the mesogenic behavior of the structurally diverse assemblies, ranging from smectic C to nematic phases were observed and evidenced by the X-ray diffraction as well as thermal studies. These binary mixtures exhibited low working temperatures as well as low crystallization temperatures. A comprehensive density functional theoretical analysis provided insight into the structure-property relationships of the various guanazole:9OBA supramolecular architecture.

Comprehension of logic gates through liquid crystals

In this article realization of logic gates through Fourier transform Infrared Spectroscopy (FTIR) spectral signatures is elaborated. A term opto-logic state is defined in such a way that any of the four spectral signatures (756 cm−1,1520 cm−1,2900 cm−1 and 3500 cm−1) assumed either logic-0 or logic-1 values depending on the preset conditions. As a representative case, three 2-input logic gates namely OR, AND and Ex-OR are derived. The input to these gates is treated with the four spectral signatures namely 756 cm−1, 1520 cm−1, 2900 cm−1 and 3500 cm−1 derived from two mesogens namely dodecyloxy benzoic acid and propyl benzoic acid abbreviated as12BAO and 3BA respectively. Thus four combinations of 00, 01, 10 and 11 are retrieved from the above mesogens. The output of OR, AND and Ex-OR gates are read through the FTIR spectra of Pentyl benzoic acid referred as 5BA, Nonyloxy benzoic acid & pentyl benzoic acid referred as 9OØ5 and Nonyloxy benzoic acid & ethyl benzoic acid referred as 9OØ2 respectively. Thus a proper selection of FTIR spectral signatures along with the corresponding mesogens can be experimented in realizing any desired gate.

Optical, thermal and electrical investigations in two homologous series of hydrogen bonded ferroelectric liquid crystals

Two novel series of complimentary hydrogen bonded ferroelectric liquid crystals (HBFLC) comprising of 14 mesogens are synthesised by mixing (R)-(+)-2-(Benzyloxy) propionic acid (BPA) with various alkyloxy/alkyl benzoic acids. First series yielded eight HBFLC mesogens namely (R)-(+)-2-(Benzyloxy) propionic acid mixing with various benzoic acids viz., pentyloxy benzoic acid (BPA + 5BAO), hexyloxy benzoic acid (BPA + 6BAO), heptyloxy benzoic acid (BPA + 7BAO), octyloxy benzoic acid (BPA + 8BAO), nonyloxy benzoic acid (BPA + 9BAO), decyloxy benzoic acid (BPA + 10BAO), undecyloxy benzoic acid (BPA + 11BAO) and dodecyloxy benzoic acid (BPA + 12BAO) respectively. The second series yielded six HBFLC mesogens namely (R)-(+)-2-(Benzyloxy)propionic acid mixing with various benzoic acids viz., propyl benzoic acid (BPA + 3BA), butyl benzoic acid (BPA + 4BA), pentyl benzoic acid (BPA + 5BA), hexyl benzoic acid (BPA + 6BA), heptyl benzoic acid (BPA + 7BA) and octyl benzoic acid (BPA + 8BA) respectively. The molecular structure of entire 14 mesogens is represented by ball and stick model. Phase identification is made by textural studies of various phases through Polarizing Optical Microscopy (POM), enthalpy values and phase transition temperatures are elucidated from Differential Scanning Calorimetry (DSC) studies. The homologues of the first series BPA + nBAO exhibited smectic B*and smectic G* phases while only smectic G* phase is observed in BPA + nBA. Formation of hydrogen bond in the synthesised mesogens is confirmed by FTIR spectra. Phase diagrams for both the series are constructed from POM and DSC studies. Dielectric relaxation studies in smectic B* and smectic G* phases are performed on selected mesogens.

Li+3 ion beam irradiation induced changes in the thermodynamic and electrical parameters of 4-n-(nonyloxy) benzoic acid

ABSTRACTLi+3 ion beam irradiation studies on 4-n-(nonyloxy) benzoic acid (NOBA) have been carried out. Thermodynamic measurements demonstrate that all the phase transition temperatures are depressed for low value of irradiation fluence as compared to those for the pure NOBA and thereafter increase linearly with increase in irradiation fluence. It has also been observed that the temperature range of N and SmC phases in the heating and cooling cycles is improved due to irradiation. Dielectric investigations show that both the transverse as well as the longitudinal components of the dielectric permittivity are increased as compared with those of the pure sample due to irradiation. The observed change in the thermodynamic and dielectric parameters is attributed to the increased concentration of NOBA monomers over the NOBA dimers due to fragmentation of the hydrogen bonding in some of the NOBA dimers.

Optical and thermal characterization of double hydrogen bonded liquid crystals: Binary mixtures

ABSTRACTMethyl Malonic acid (MM) forms hydrogen bonds with octyloxy benzoic acid (8OBA), nonyloxy benzoic acid (9OBA), decyloxy benzoic acid (10OBA) labeled as MM+8OBA, MM+9OBA, and MM+10OBA respectively, all three mesogens exhibit mesogenic properties. Nine binary mixtures are prepared with MM+8OBA and MM+9OBA by varying their molar proportions in steps of 0.1 to 0.9. Similarly nine more binary mixtures are prepared with MM+8OBA and MM+10OBA. Two binary series namely MM+8OBA & MM+9OBA and MM+8OBA & MM+10OBA are analyzed. Various chemical and physical studies of these binary mixtures are investigated which includes Nuclear Magnetic Resonance spectral studies, FTIR, Polarizing Optical Microscopy and Differential Scanning Calorimetry. Phase diagram of above two binary series are constructed. Thermal studies derived from the DSC data include evaluation of order of phase transition, odd even effect, thermal stability factor, thermal equilibrium and variation of specific heat with temperature.

Inductive effect for the phase stability in hydrogen bonded liquid crystals, x-(p/m)BA:9OBAs

A new series of hydrogen bonded liquid crystal (HBLC) complexes, made up with substituted benzoic acids (BAs) and nonyloxy benzoic acid, viz., x-(p/m)BA:9OBAs are reported for x = F, Cl, Br and –CH3 substituted at para (p) or meta (m) positions of BA moiety. Proton nuclear magnetic resonance (1H-NMR) spectrum confirms the HBLC complex. Infra red (IR) spectrum confirms linear, double and complementary type of hydrogen bonding (HB) between x-(p/m)BAs and 9OBA. The liquid crystal (LC) phases are characterised by polarisation optical microscopy (POM) and differential scanning calorimetry (DSC) techniques. x-(p/m)BA:9OBA exhibit N, C and G LC phase variance. HB induces tilted phases and enhances LC phase stability. The influence of configuration, size, electronegativity, electron directing capacity and inductive nature of substituent (x) is investigated for the stability of LC phases. An overview of the LC phase data indicates predominant ‘negative inductive effect’ in HBLCs with electron withdrawing substituents. Inductive effect operates effectively for para substitutions. Results are discussed in the wake of reports in other HBLCs.

Thermal and Dielectric Investigations on Supramolecular Hydrogen Bonded Liquid Crystals

A novel series of linear supramolecular hydrogen bonded liquid crystals (SMHBLC) have been investigated. Complimentary hydrogen bonds are formed between p-n nonyloxy benzoic acid and various p-n alkyloxy benzoic acids whose carbon chain length varied from 5 to 12. The formed mesogens are characterized by Fourier Transform Infrared (FTIR) Spectroscopy, Polarizing Optical Microscopy (POM) and Differential Scanning Calorimetry (DSC). Phase diagram has been constructed through POM and DSC data. An interesting finding is the observation of a new smectic ordering, labeled as smectic X, which has been characterized by various thermal and electrical techniques. Optical tilt angle in smectic C and X phases have been measured. The theoretical mean field value β deduced from the experimental tilt angle values is observed to be in good agreement with the predicted value. Dielectric studies revealed a low frequency relaxation mechanism in smectic C phase and the corresponding activation energy has been calculated from the corresponding dispersion curves. A worth mentioning observation is the optical shuttering action of the mesogens in nematic phase. Light filtering action of these mesogens in nematic phase has also been evaluated. Low pass, high pass, and band pass filtering action has been observed and discussed.

Double Hydrogen Bonded Liquid Crystals: A Study of Light Modulation and Field Induced Transition (FiT)

A novel series of double hydrogen bonded liquid crystals have been isolated. Hydrogen bond was formed between non mesogen ingredient succinic acid and mesogenic p-n alkoxy benzoic acids. Phase diagram was constructed from the transition temperatures obtained by differential scanning colorimetry (DSC) and polarizing optical microscopic (POM) studies. Thermal and electrical properties exhibited by succinic acid and nonyloxy benzoic acid (SA + 9BA) were discussed. Interesting feature of the present investigation was the observation of a field-induced transition (FiT) in SA + 9BA hydrogen bonded complex. Three threshold field values are noticed which gives rise to two new phases (E1 and E2) induced by external bias voltage and on further enhancement of the bias voltage the mesogen behaves like an optical shutter, thus this hydrogen bonded complex mesogen acts as an effective light modulator. It was noticed that FiT was reversible, in the sense that when applied filed was removed, the original texture was restored, theoretical modeling and experimental results were presented.

Hydrogen-bonded complexes between mesogenic heterocyclic Schiff's bases and mesogenic 4- n -nonyloxybenzoic acid: mesomorphic behaviour, FTIR study and PM3 semi-empirical calculations

A new series of intermolecular hydrogen-bonded complexes has been obtained using mesogenic 4-n-nonyloxybenzoic acid and mesogenic 5-(4-pyridyl)-2-(4-n-alkoxy) benzylideneamino-1,3,4-thiadiazole moieties. The thermal and phase behaviour of these complexes were studied by thermal microscopy and differential scanning calorimetry. Intermolecular hydrogen bonding was studied by FTIR spectroscopy, from crystalline to the isotropic state. A study by PM3 semi-empirical calculations is also described.

Dielectric Anisotropy and AC Conductivity of Bicomponent Mixtures of Liquid Crystals Cholesteryl Pelargonate and Nonyloxybenzoic Acid

Dielectric constant (ε′) and electrical conductivity ([sgrave]) of the binary mixtures of cholesteryl pelargonate (ChP) and nonyloxybenzoic acid (NOBA) of different concentrations have been measured in the frequency range of 100 Hz to 10 MHz from room temperature to 150°C both in planar and homeotropic alignments. These mixtures do not show the dielectric dispersion upto 10 MHz. Dielectric constants parallel and perpendicular to helical axes (ε′∥ and ε′⊥) and the dielectric anisotropy (Δε′ = ε′∥ - ε′⊥) have been determined in different mesophases. Dielectric anisotropy (Δε′) of the mixtures changes sign from negative to a positive value for NOBA concentrations above 75 mole %. From the measured frequency dependent conductivity [sgrave](f), d.c. conductivity [sgrave](dc) has been obtained using the universal power law equation. Activation energy (W a) of the d.c. conduction process has been determined in different mesophases.

Thermodynamical Properties of Bicomponent Mixtures of Liquid Crystals Cholesteryl Pelargonate and Nonyloxybenzoic Acid

Abstract Transition temperatures, transition enthalpies and entropies of different mesophases of the binary mixture of cholesteryl pelargonate (ChP) and nonyloxybenzoic acid (NOBA) have been measured on a differential scanning calorimeter and optical textures of different mesophases have been confirmed on a polarizing microscope. Eutectic point has been observed at 28 ± 2 mole percent of NOBA from the variation of transition temperature, enthalpy and entropy of the crystal to mixed crystal phase and the mixed crystal phase to mesophase with concentration of NOBA. Stability of SmA phase increases on addition of NOBA. SmA* phase has been observed in between SmA and Ch phases for NOBA concentrations between 18 and 50 mole percent. A very wide cholesteric range of about 50 °C has been observed in cooling in the concentration range of 60 to 90 mole percent of NOBA.