Decyloxy Benzoic Acid Research Articles

Distinct spectral line shifts in the Raman lines’ Stokes and anti-Stokes components with temperature in the liquid crystalline system 4DBA

An anomalous Raman phenomenon (ARP) refers to a scenario in which the Stokes and anti-Stokes frequencies of a Raman mode are different. Here we report that ARP introduces different line shifts in Stokes and anti-Stokes frequencies in 4-Decyloxy Benzoic acid with temperature across two thermally driven structural transitions: the smectic (S) to nematic (N) phase transition at 375 K and the nematic (N) to isotropic (I) transition at 390 K. Four Raman modes near 663, 773, 1128, and 1168 cm-1shift towards higher frequencies (blueshift) in the Stokes frequency and towards lower frequencies (redshift) in the anti-Stokes frequency with rise in temperature near S to N phase transitions. However, in the isotropic liquid phase, both the Stokes and anti-Stokes components exhibit a redshift as temperature increases, without any noticeable distinct spectral lineshifts. Our studies bring out the importance of phonon band structure in ARP.

Synthesis of mesogen-nanoparticle composites by doping 4-decyloxybenzoic acid with substrate-functionalized ZnO nanoparticle

Nanomaterials and Mesogenic materials are two important pillars of today’s science and technology, in the fields of both material and biological applications. Mesogens or liquid crystals (LC) are self-aggregated anisotropic fluids with long range order, and the nature of self-aggregation largely controls their physical and material properties. Doping of nanomaterials over liquid crystalline matrix can provide valuable tools for development of materials with new or improved properties. In the present work 4-decyloxybenzoic acid is taken as the mesogenic matrix. It is observed that, composite prepared by doping of 4-decyloxybenzoic acid mesogen matrix by ZnO nanoparticle pre-functionalized with the same mesogen, caused a marked alteration in the mesogenic behavior. With 3% doping of matrix pre-functionalized ZnO NP on 4- decyloxy benzoic acid, we could achieve a shift of about 31ºC in the N-Iso transition temperature and, a decrease of >10ºC for the onset of liquid crystallinity by this method without quenching any of the mesophases exhibited by the pure mesogen. The synthesized materials have been characterized by variable temperature Polarised optical microscopy (POM), DSC, FTIR, XRD, EDX, and TEM This process may be considered for preparation other nanoparticle-mesogen composites as well. It was observed that, the effect of doping on the transition temperature and enthalpy of 4-Decyloxybenzoic Acid can be significantly enhanced by pre-functionalizing the dopant (ZnO NP) with the substrate molecules and then mixing this substrate functionalized ZnO nanoparticle with the bulk substrate.

Terahertz (6-18 THz) spectroscopic characterization of benzoic acid class liquid crystals using Fourier Transform Infrared technique

Terahertz spectroscopic studies of 4-octyloxybenzoic acid, 4-decyloxybenzoic acid and 4-hexylbenzoic acid liquid crystals were performed using the Fourier Transform Infrared method. The materials are characterized by distinct absorption bands in the 6–18 terahertz frequency range. A good correspondence was observed between the experimental frequencies and theoretical frequencies of the single molecule obtained by Density Functional Theory calculations for all the three compounds. The spectra of the studied compounds had three bands, which appeared at similar frequencies and with the same vibration modes. 4-Octyloxybenzoic acid, 4-decyloxybenzoic acid and 4-hexylbenzoic acid had two absorption bands that appeared at similar frequencies and exhibited different vibration modes. This study interestingly demonstrates that even though compounds of an almost similar molecular structure might output bands at the same frequencies, the correspondence might not be apparent. The single molecule model frequencies and experimental frequencies for 4-decyloxybenzoic acid and 4-octyloxybenzoic acid further revealed that all the observed bands are due to intramolecular interaction. However, the 4-hexylbenzoic acid spectrum has one apparently intermolecular band. This work addresses the limitation in the intermediate terahertz spectroscopic studies of liquid crystals and furthermore emphasizes the robustness of Fourier Transform Infrared technique in identifying materials with similar attributes.

Binary mixtures of double hydrogen bond liquid crystals: chemical, optical, thermal investigations

Binary mixtures of double hydrogen bond liquid crystals are investigated by chemical, optical and thermal studies. These binaries exhibiting rich phase polymorphism, in which hydrogen bond is formed between Methyl Malonic acid (MM), heptyloxy benzoic acid (7BOA), and decyloxy benzoic acid (10BOA) abbreviated as MM + 7BOA and MM + 10BOA. MM + 7BOA (X) is considered as one of the variants while MM + 10BOA (Y) is considered as other variant. Appropriate molar ratio (0.1X to 0.9X and 0.1Y to 0.9Y) variation in the precursors leads to formation of nine binary mixtures.

Spectroscopic Studies of BA Class Liquid Crystals in the 6-15 THz Range Using the Fourier Transform Infrared (FT-IR) Method.

Fourier transform infrared spectroscopy was performed for two structurally similar liquid crystals: 4-octyloxybenzoic acid and 4-decyloxybenzoic acid in 6-15THz range. Density functional theory modeling at PBE0/def2-TZVPP level was used to assign the vibrational modes to each observed absorption peak. We observed six peaks that are common for both liquid crystals, assigned to the same vibrational modes and appearing at similar energies. Each of the samples also had additional peaks unique to itself. A strong absorption peak appears at about 280cm-1 for both samples; however, it corresponds to different vibrational modes for the two samples. This work shows that the spectroscopy in this often-neglected frequency range can easily distinguish structurally similar compounds.

Evaluation of the surface properties of 4-(Decyloxy) benzoic acid liquid crystal and its use in structural isomer separation.

The selectivity of 4-(Decyloxy) benzoic acid (DBA) liquid crystal in surface adsorption region (303.2–328.2 K) and thermodynamic region (423.2 – 433.2 K) was investigated by inverse gas chromatography at infinite dilution (IGC-ID). The selectivity parameters of the structural isomer series named butyl acetate, butyl alcohol, and amyl alcohol series were calculated for the DBA using IGC-ID technique. Additionally, the surface properties including dispersive surface energy (gS D), free energy (DGA S), enthalpy (DHA S), and acidity-basicity constants were calculated with net retention volumes obtained from IGC-ID experiment results. When the DHA S and DGA S are constants, DBA surface was found to be an acidic character (KD/KA @ 0.89).

Reduction of the order parameter and high electric conductivity of SWCNT doped smectic a liquid crystal

The effect of single-walled carbon nanotubes (SWCNTs) on the dielectric and conductivity properties of smectic A liquid crystal 4-nitrophenyl-4'- decyloxybenzoic acid has been studied. It was shown that the additive of SWCNTs with concentration of 0.5% leads to a decrease in the order parameter of the liquid crystal. In this case, the clearing point and the longitudinal component of the dielectric permittivity decreases while the transverse component increases. The incipient percolation effect promotes to the dominance of hopping electron conductivity over ionic conductivity, leading to an increase in specific conductance.

Fabrication of Ferroelectric Liquid Crystal Thermistor

Thermistor is fabricated using thermotropic ferroelectric liquid crystalline material. The design, performance, and characteristics of this fabricated liquid crystal (LC) device are demonstrated in this article. As a representative case, the characteristics of two ferroelectric LCs (FLCs), which exhibit positive and negative temperature coefficients of resistance, are detailed. An ambient temperature ferroelectric mesogen (S)-1-[4’-(octyloxy carbonyl) phenyl]-4-[2-chloro-(4-benzamido acetyl) phenyl propionato]-Benzoate yielded negative temperature coefficient thermistor, while dextro tartaric acid with p-n decyloxy benzoic acid ferroelectric mesogen was used as a positive temperature coefficient (PTC) thermistor. This endeavor was not reported in the literature, where thermotropic mesogens are being used for thermistor [PTC and negative temperature coefficient (NTC)] application. This thermistor possesses a wide temperature range (~69° C) with a resolution of $0.05~\mu $ AV−1 and accuracy of ±0.1 °C which is more competent than its conventional counterpart. Furthermore, the heat capacity of the LC-based thermistor device is 0.2 Jg−1 K−1 for PTC and 0.4 Jg−1 K−1 for NTC.

Effect of fullerenes C60 on dielectric properties and the threshold voltage of smectic A liquid crystal

Influence of fullerenes C60 on the threshold voltage, dielectric, and conductivity properties of smectic A liquid crystal 4-nitrophenyl-4′-decyloxybenzoic acid is investigated. It is shown that the transverse component of the real part of dielectric permittivity increases at the additive of fullerenes while the longitudinal component decreases. At this case, a maximum of dielectric absorption shifts to the high-frequency region. Conductivity increases at low frequencies and decreases at the high ones. Experimental results are explained on the base of the Maier-Meier theory for anisotropic liquids and also participation of fullerenes in ionic conductivity of liquid crystal.

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.

Observation of paramorphic phenomenon and non-tilted orthogonal smectic phases in hydrogen bonded ferroelectric liquid crystals for photonic applications

A new class of hydrogen bonded ferroelectric liquid crystals (HBFLC) have been designed and synthesized by intermolecular hydrogen bonds between mesogenic 4-decyloxybenzoic acid (10OBA) and non-mesogenic (R)-(+)-Methylsuccinic acid (MSA) which have been confirmed through experimental and theoretical studies. Further, Mulliken population analysis clearly reveals that the existence of hydrogen bonds, strength and dynamic properties. Textural observation and its corresponding enthalpy values are analyzed by polarizing optical microscope (POM) and differential scanning calorimetry (DSC) respectively. Paramorphic changes in Sm C* phase due to the change of refractive index, which clearly reveal that the complex could be used for filtering action in photonic devices. The transition from lone pair to π* with large stabilization energy evidently exposes the chiral phases in the present HBFLC complex. Intermolecular interaction is analyzed by using natural bond orbital (NBO) studies. The highest energy in the HOMO-LUMO shows the stable phase in the HBFLC complex. Molecular structure of the HBFLC complex possesses the monoclinic which has been evinced through x-ray analysis. The randomly oriented bunch of homogeneous molecules in Sm A* phase of the HBFLC complex is reported.

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.

Influence of ZnO nanoparticles dispersion in Liquid Crystalline compounds – Experimental studies

In the present work synthesis and characterisation are carried on Liquid Crystalline compounds p-n-nonyloxy benzoic acid (9OBA) and p-n-un decyloxy benzoic acid (11OBA) compounds and with 1wt% ZnO nanoparticle dispersion. The Differential Scanning Calorimetry (DSC) technique is used to measure the phase transition temperatures. Further characterization done by various spectroscopic techniques like X-ray Diffraction spectrometric studies (XRD), Scanning Electron Microscopy studies (SEM), and Fourier Transform Infra Red Spectroscopy (FTIR). Textural determinations of the synthesized compounds were recorded by using Polarizing Optical Microscope (POM) connected with hot stage and camera. The results shows that the dispersion of ZnO nanoparticles in 9OBA and 11OBA exhibits NC phases as same as the pure compounds with reduced clearing temperature as expected. Further, the nematic thermal ranges are also increased while performing both DSC and POM with the dispersion of ZnO nanoparticles. Size dependence on bonding nature with LC compounds is established.

Influence of Hydrogen Bond on Thermal and Phase Transitions of Binary Complex Liquid Crystals

A novel supramolecular liquid crystal (LC) is synthesized from the binary complex of 4-decyloxy benzoic acid and cholesteryl acetate. Fourier transform infrared (FTIR) spectroscopic study confirms the formation of intermolecular hydrogen bond between the mesogens. Various mesophases and corresponding textural changes in the complex are observed by comparing with its constituents through polarizing optical microscopic (POM) studies. The thermal stability factor of smectic phase for present complex is calculated. An interesting observation of present work is that investigation of extended thermal span of mesomorphic phases, decreased enthalpy, a nematic phase with a high clearing point and a low melting point. This is due to an arrangement of molecular reorientations and the development of new associations by hydrogen bonding. Optical tilt angle for smectic C phase is determined and the same is fitted to a power law.

Thermal and optical studies on induced smectic phases of inter molecular hydrogen bonded liquid crystals between decyloxy benzoic acid and citric acid

ABSTRACTHydrogen bonded liquid crystal complex (HBLC) is prepared from mesogenic 4-decyloxy benzoic acid (10OBA) and aliphatic nonmesogenic citric acid (CA). Liquid crystal (LC) phases are investigated by polarizing optical microscopy (POM), differential scanning calorimetry (DSC) studies. Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (NMR) validate the intermolecular complementary, cyclic type of hydrogen bond (HB) and molecular environment in the designed HBLC complex. Mesomorphic phases like nematic, smectic X (Sm X) and smectic G (Sm G) are characterized by various textures and using different techniques such as POM, DSC and optical tilt angle measurements. Thermal span width and thermal stability factor for the observed phase is calculated. The complexes are prepared in different mole ratio and their corresponding influences on the phase transitions are discussed. Also it is observed that the HB units play a vital role in stabilizing the new Sm X phase. The variation in thermal stability of smectic phases due to the influence of aromatic cores and length of end chain in the different mole ratio of the present HBLC complexes are also discussed. The variation of tilt angle with respect to temperature in the smectic phase has been experimentally calculated and analyzed. The lowered melting and clearing transition temperatures and extended thermal span width in the Sm X phase are also reported.

Phase transition and thermal stability of reentrant smectic phase in mixture of liquid crystalline materials

ABSTRACTIn the present work, our investigation is to study the optical and thermal properties of the binary mixture of cholesteric and nematic compounds namely, decyloxy benzoic acid (DBA), and cholesteryl chloride (ChCl), which exhibits different liquid crystalline phases with reentrant smectic-A phase. The reentrant smectic-A phase has been observed at different concentrations and at different temperatures. The existence of reentrant smectic-A phase has been observed by optical microscopic studies. The temperature variation of optical anisotropy, X-ray and helical pitch of the cholesteric (N*) phase has also been discussed.

Image enhancement using virtual contrast image fusion on Fe3O4 and ZnO nanodispersed decyloxy benzoic acid

Low contrast and noisy photographic pictures can be considerably improved by image-processing techniques. Techniques like histogram equalisation produce high-contrast images but often fail to preserve the colour texture information. To overcome this deficiency, a contrast-enhancement approach has been devised, using virtual contrast image fusion (in Haar wavelet domain). This technique has been evaluated by a study of the optical textures of nano-dispersed decyloxybenzoic acid with small quantities of Fe3O4 and ZnO added.

Phase diagram of bicomponent mixtures of liquid crystals: Cholesteryl myristate and decyloxybenzoic acid

Mixtures of two different liquid crystals (LCs) have been used to formulate a technologically viable LC operating at room temperature. Cholesteryl myristate (ChM) and decyloxybenzoic acid (DOBA) have been mixed in different molar ratios. Pure DOBA exhibits smectic C (SmC) and nematic (N) mesophases while pure ChM shows smectic A (SmA) and cholesteric (N*) mesophases. Transition temperatures have been determined using differential scanning calorimetry. Phase identification has been done using optical polarizing microscopy. Phase diagram shows the eutectic composition of ChM-DOBA system in the ratio 70:30 mole %. In this system, as the addition of DOBA is increased, stability of SmA phase of ChM increases up to 56 mole % of DOBA but as the addition of DOBA increases from 56 mole %, stability of SmA phase of ChM decreases and completely vanishes at about 80 mole % of DOBA. Range of SmC phase of DOBA (approximately 23°C) decreases rapidly with the addition of ChM and disappears at about 15 mole % of ChM. The maximum range of cholesteric (N*) phase in the binary system as observed in the heating cycle is about 24°C.

Thermal and morphological studies of liquid crystalline materials dispersed in a polymer matrix

Polymer dispersed liquid crystal (PDLC) films have been prepared by a combination of solvent-induced phase separation and thermal-induced phase separation techniques, for three mesogenic materials: 4-(undecyloxy) benzoic acid (UDBA), 4-(decyloxy) benzoic acid (DBA) and 4-(dodecyloxy) benzoic acid (DDBA) in poly(methyl methacrylate) (PMMA) as polymer matrix and tetrahydrofuran (THF) as common solvent. Differential scanning calorimetry and polarising optical microscopy are used for thermal and morphological investigations of prepared PDLCs, and findings are explained with the help of a suitable phase diagram. It is found that isotropic liquid–nematic transition temperature (TIN ) for these mesogens in the PMMA matrix decreases by about 2.8–5.6°C as compared with the pure mesogens. Methods based on the solubility parameter and the fraction of liquid crystal (LC) in LC-rich domains inside the PMMA matrix at different concentrations have been adopted to achieve an optimised condition for uniform dispersion of the film over a larger area. Remarkable changes in the droplet morphology of the mesogens confined in PMMA matrix as compared with their bulk counterparts have also been observed. Bipolar droplets and Maltese-type crosses are observed by POM for 75 and 30 wt% UDBA in the PMMA matrix.

Carbon Nanotubes Induced Changes in the Phase Diagram and Crystal Structure of 5CB Liquid Crystal

ABSTRACTMultiwall Carbon Nanotubes (MWCNTs) form a nematic liquid crystalline (LC) phase in their lyotropic form, enabling their mixing and coupling of their director to that of nematic LCs. An important aspect of this LC/MWCNT interaction, for applications other than display technology, is looking at the ways the MWCNTs affect the physical properties of the LCs. We study the effect of MWCNTs on the nematic to crystal (N-C) phase transition of 4-cyano-4-npentylbiphenyl (5CB). Our Differential Scanning Calorimetry (DSC) results show a dramatic increase in N-C phase transition temperature of 14°C for only 0.1% and of 20°C for 1% MWCNT, due to the crystal nucleation activity of the nanotubes. Using Polarized Microscopy we observe a change in the crystalline order of 5CB from spherulitic at 0% MWCNTs to a multidomain in presence of MWCNTs. The new crystals resemble those formed by a smectic LC 4- Decyloxybenzoic acid. This is in line with predictions from simulations, that the MWCNTs form smectic order in nematic 5CB at their interface. MWCNTs induced modifications of the crystal phase of 5CB promise to create controlled novel crystal forms for the purposes of optical transmission and other applications.