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[Display omitted] • MCA + HPA + nOBA, n = 6 to 12 (1:1:1 mol ratio) novel ternary liquid crystals (TLC) derived from asymmetric aromatic dicarboxylic acid. • Experimental, theoretical and structural studies have been carried out. • The highest thermal span width of smectic A and smectic F phases are identified in TLC. • Low kinetic stability in TLC endorse the extended smectic behaviour. Novel ternary liquid crystal (TLC) homologues series was designed and prepared from 4-methoxycinnamic acid (4MCA), homophthalic acid (HPA) and 4-n-alkyloxybenzoic acids (nOBA, where n = 6 to 12). The mesogenic behaviour, phase transition temperature, thermal span width and thermal stability factor of TLC (homologues series) were studied by polarising optical microscopy (POM) and differential scanning calorimetry (DSC) techniques. A noteworthy observation is that, TLC induces smectic A (batonnets texture) along with nematic and smectic F phases whereas, the Sm A is not perceived in the individual compounds while compared with the TLC. Further, the existence of smectic phases (Sm A and Sm F) are identified by temperature dependent X-ray diffraction (XRD) analysis. The same are correlated with DSC observations. Density functional theory (DFT) is used to optimize the molecular geometry of TLC. FMO and MEP study explores the molecular environment and quantum chemical behaviour of TLC. NBO, QTAIM and RDG analysis explicate the charge transfer with stabilization energy and non-covalent interactions. Density functional theory (DFT) calculations confirm the possible conformer of TLC. [ABSTRACT FROM AUTHOR]

Abstract: A novel series of hydrogen bonded ferroelectric liquid crystals (HBFLC) have been isolated. Phase transition temperatures obtained by differential scanning calorimetry (DSC) and textural observations elicited by polarizing optical microscope (POM) studies are discussed. Phase diagram is constructed from the above data. Salient feature of the present work is observation of a light modulation due to field induced transitions (FiT) in nematic and smectic C* phases. Tilt angle measurements in various FiT of smectic C* phase are discussed. One of the mesogens in nematic phase behaves like an optical modulator; helical pitch measurements support the above observation. [Copyright &y& Elsevier]

An interhydrogen bonded liquid crystal with complementary hydrogen bonding between succenic acid (SA) and pentyloxy benzoic acid (5OBA) referred as SA + 5OBA has been synthesized and characterized. Multiwalled carbon nanotubes (MWCNT) are dispersed in SA + 5OBA and the resultant complex is referred as SA + 5OBA+MWCNT. Both complexes exhibit liquid crystallinity with the presence of nematic phase. FTIR and NMR studies confirms the formation of the interhydrogen bonds. Transition temperatures and enthalpy values are obtained by DSC studies. Considerable hyteresis in dielectric permittivity has been observed in SA + 5OBA + MWCNT, which enable it to be used in device applications. An interesting observation in SA + 5OB A + MWCNT complexes is the field induced transition (FiT) in nematic phase, which is studied by conductance, permittivity, and helicoidal structure deformations. This complex can be used in light modulation applications. The liquid crystalline behavior together with the rate of crystallization in nematic phase of pure and MWCNT dispersed hydrogen bonded complex are discussed in relation to the kinetophase (which occurs prior to the crystallization). The molecular mechanism and dimensionality in the crystal growth are computed from the Avrami equation. The characteristic crystallization time (t*) at each crystallization temperature is deduced from the individual plots of log t and ΔH. The influence of MWCNT on crystallization kinetics in the nematic phase of an interhydrogen bonded liquid crystal is discussed. [ABSTRACT FROM PUBLISHER]

Supramolecular hydrogen bonded liquid crystals are formed by methoxy hydroquinone (MHQ) and alkyloxy benzoic acids are isolated and characterised. MHQ formed double hydrogen bonds with p-n-alkyloxy benzoic acids. Fourier Transform–Infrared studies confirm the hydrogen bond formation in the complex. Polarising Optical Microscopic (POM) studies revealed the textural information, while the transition and enthalpy values are experimentally deduced from Differential Scanning Calorimetry (DSC) studies. Phase diagram has been constructed from the POM and DSC data, respectively. Experimental data of optical tilt angle in Smectic C phase have been fitted to a power law and it has been observed that the temperature variation of the tilt angle follows Mean Field theory prediction. Present homologous are compared with hydroquinone alkyloxy benzoic acids complexes and the influence of methyl group on the occurrence of phases and its transition temperatures are discussed. [ABSTRACT FROM PUBLISHER]

A series of halogen-substituted hydrogen-bonded liquid crystalline complexes have been designed and synthesised. A successful attempt has been made to form complementary hydrogen bonding between the dodecyloxy benzoic acid (12BAO) and halogen-substituted benzoic acids and the physical properties exhibited by the individual complexes are studied. The complexes obtained are analysed by polarising optical microscope (POM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and dielectric studies. The formation of complementary hydrogen bond is confirmed through FTIR spectra. An interesting feature of this series is the observation of a field-induced transition (FiT) in nematic phase. Another interesting phenomenon is the observation of a new smectic X phase (worm-like texture) in all the synthesised complexes. Dielectric relaxation studies in the smectic C phase of these hydrogen bonded complexes along with the Arrhenius and the Cole–Cole plots are discussed. Optical tilt angle in smectic C phase and the corresponding fitted data analysis concur with the Mean field theory prediction. [ABSTRACT FROM PUBLISHER]

Two hydrogen bonded ferroelectric liquid crystals (HBFLC) are dispersed with multi-walled carbon nanotubes (MWCNT) for achieving better thermal and electrical performance. Interesting feature of the present communication is the enhancement in the enthalpy value pertaining to isotropic-nematic transition in MWCNT doped liquid crystals compare to its pure counter parts. Dielectric relaxations studies are carried out in the pure and the MWCNT doped systems. It is observed that doping of MWCNT elevated the activation energies considerably. Optical shuttering action in one of the complex dispersed with MWCNT are discussed. [ABSTRACT FROM PUBLISHER]

Abstract: Novel homologs series of supra-molecular liquid crystals have been isolated. Hydrogen bond is formed between mandelic acid (MD) and various homologs of p-n-alkyloxy benzoic acids (nOBA) and has been confirmed by FTIR studies. Optical polarizing microscopic observations show that all these materials exhibit rich liquid crystallinity with various mesophases. Phase transition temperatures and enthalpy values are experimentally evaluated by DSC studies and the phase diagram of homologous series has been constructed. An interesting feature is the observation of thermally controlled reversible optical shuttering action in one of the homolog, wherein with the increment of temperature the homeotropic texture changes to homogenous texture of smectic F. Thus, this optical shuttering phenomenon is reversible. Optical tilt angle data of two homologs have been fitted to power law equation and it is found that the mean field theory prediction is valid. The light intensity profile in homeotropic region of smectic F in one complex has been experimentally analyzed and a steep sudden decrement of the intensity of light manifesting the distortion of the molecular alignment is experimentally found. [Copyright &y& Elsevier]

Abstract: A novel series of hydrogen bonded liquid crystals (HBLC) have been isolated with hydrogen bond forming between fluoro benzoic acid and various alkyloxy benzoic acids respectively. Phase diagram is constructed from the transition temperatures obtained by Differential Scanning Calorimetry (DSC) and Polarizing Optical Microscopic (POM) studies. A new Smectic ordering which is referred as Smectic R is characterized which exhibits a ribbon like phase. Declinations are observed on these ribbons manifesting the presence of the helicoidal structure. Another interesting feature is the observation of optical shuttering action in some of the complexes with the application of external stimulus in the entire thermal range of Nematic phase. Further this phenomenon is reversible in the sense that when the applied stimulus is withdrawn original texture of Nematic is restored. Unwinding of the helix coupled with molecular dipolar reorientation with the application of external field is supposed to be the major reasons for the observed phenomenon. [Copyright &y& Elsevier]

Abstract: Novel linear hydrogen bonded liquid crystal homologous series has been synthesized and characterized. Hydrogen bond is formed between hydroxy benzaldehyde and various benzoic acids which are varying from pentyl to dodecyl alkyloxy carbon numbers. Synthesized complexes are characterized by FTIR for inferring the formation of hydrogen bonds. Polarizing microscopy and DSC studies reveal various mesophases and their corresponding transition temperatures along with respective enthalpy values. Tilt angle and helix in Smectic C phase have been experimentally elucidated for most of the mesogens. A new technique for the temperature dependent FTIR studies has been proposed. The spectral results obtained by this technique are in good agreement with the conventional method. These FTIR studies bestow information about shifting and occurrence of new peaks in various mesophases thus enriching the knowledge on the chemical molecular environment of the mesogen. [Copyright &y& Elsevier]

Abstract: Two series of inter hydrogen bonded ferroelectric liquid crystals have been isolated. In one of the series hydrogen bond is formed between p-n-alkyloxy benzoic acids and (S)-1,2-cholo-3-(4-hydroxy) phenyl propionic acid (CTy+ nOBA) while in the other it is formed between p-n-alkyl benzoic acids and (S)-1,2-cholo-3-(4-hydroxy) phenyl propionic acid (CTy+ nBA). Detailed synthetic route for the isolation of these compounds is discussed. Formation of the ferroelectric self assembly systems has been evinced through FTIR studies. The positional influence of oxygen atom is investigated from the thermal and electrical characterization of both the series. Polarizing optical microscope (POM) studies on CTy+ nBA hydrogen bonded complexes reveals that they exhibit single phase variance while the other complex CTy+ nOBA exhibit rich phase polymorphism. It is observed that the presence of oxygen atom enhances phase abundance. Phase diagrams for both the complexes are constructed from the DSC and POM studies. Dielectric relaxations and activation energies have been carried out for various phases in CTy+8OBA and CTy+8BA complexes. It has been observed that the oxygen atom originates type I relaxation process. Two molecular modeling have been assigned to account for the dielectric relaxation process observed in both the HBFLC series. [Copyright &y& Elsevier]

Abstract: Self-assembly systems formed by hydroquinone and alkyloxy benzoic acids are isolated and characterized. Hydroquinone formed double hydrogen bonds with p-n-alkyloxy benzoic acids. Various hydrogen bonded complexes have been synthesized with hydroquinone and pentyloxy to dodecyloxy benzoic acid, respectively. FTIR studies confirm the hydrogen bond formation in the complex. Polarizing Optical Microscopic (POM) studies revealed the textural information while the transition and enthalpy values are experimentally deduced from Differential Scanning Calorimetry (DSC) studies. Phase diagram has been constructed from the POM and DSC data. The members of the present homologous complexes are characterized by POM, DSC, optical tilt angle and dielectric studies. Odd–even effect has been evinced in enthalpy values and transition temperatures corresponding to the isotropic to nematic phase transition. Optical tilt angle in Smectic C phase data has been fitted to a power law and it has been observed that the temperature variation of the tilt angle follows Mean Field theory prediction. Results of Fourier Transform Infrared Spectra (FTIR), POM, DSC, tilt angle and dielectric studies are discussed. [Copyright &y& Elsevier]

Abstract: In a newly synthesized self assembled system, namely, hydrogen bonded liquid crystal, multi walled carbon nanotubes (MWCNTs) are dispersed. This self assembly system of liquid crystal is realized by formation of hydrogen bond between levo tartaric acid and undecyloxy benzoic acid. The proposed structure is confirmed by FTIR and P-NMR studies. Thermal and electrical properties of this system dispersed with MWCNT are studied. Alignment of carbon nanotubes in the nematic phase of the self assembled system is responsible for the observation of bistable electrical states namely ON and OFF. Optical textural observations of these two states are recorded and the light intensity complexly decays and unwinding of the helix with the application of external field indicates an optical shuttering action. It is interesting to note that a small threshold value of 3.5V/μm is sufficient to realize an optical shutter. DSC studied reveals that the enthalpy values pertaining to liquid crystal dispersed with MWCNT is approximately two fold to that of the pure liquid crystal. Results of conductance relating to the liquid crystal with MWCNT dispersion are discussed. [ABSTRACT FROM AUTHOR]

Abstract: A novel series of hydrogen bonded ferroelectric liquid crystals (HBFLC) have been isolated. Hydrogen bond is formed between non mesogen chiral ingredient (S)-1, 2–cholo-3-(4-hydroxy) phenyl propionic acid and mesogenic p-n alkoxy benzoic acids. Phase diagram is constructed from the transition temperatures obtained by differential scanning calorimetry (DSC) and polarizing optical microscopic (POM) studies. Thermal and electrical properties exhibited by a hydrogen bonded complex namely (S)-1,2–cholo-3-(4-hydroxy)phenyl propionic acid with octyloxy benzoic acid (CTy + 8BA) are discussed. Observation of dielectric hysteresis in CTy + 8BA makes it more suitable for device applications. Salient feature of the present work is observation of a field induced transitions in nematic phases pertaining to the above complex designated as FiT. This phenomenon has been confirmed by optical textures of POM, helicoidal measurements, optical intensity and dielectric studies. Four threshold electrical field values are noticed which in turn contributed to four new phases (E1, E2, E3 and E4) induced by electric field and helical pitch measurements supports the above observation. FiT is reversible in the sense that when applied field is removed the original texture is restored. [Copyright &y& Elsevier]

Abstract: A novel series of chiral hydrogen bonded liquid crystals have been isolated. Hydrogen bond was formed between chiral nonmesogen ingredient levo tartaric acid and mesogenic p-n-alkoxybenzoic acids. Phase diagram was constructed from the transition temperatures obtained by DSC and polarizing optical microscopic (POM) studies. Thermal and electrical properties exhibited by three complexes namely LTA+8BA, LTA+7BA and LTA+5BA were discussed. Salient feature of the present work was the observation of a reentrant smectic ordering in LTA+8BA complex designated as Cr ∗ phase. This reentrant phenomenon was confirmed by DSC thermograms, optical textures of POM and temperature variation of capacitance and dielectric loss studies. Tilt angle was measured in smectic C∗ and reentrant smectic Cr ∗ phases. Another interesting feature of the present investigation was the observation of a field induced transition (FiT) in the LTA+nBA homologous series. Three threshold field values were noticed which give rise to two new phases (E1 and E2) induced by electric field and on further enhancement of the applied field the mesogen behaves like an optical shutter. FiT is reversible in the sense that when applied field is removed the original texture was restored. [Copyright &y& Elsevier]

In this context, we report the acoustic shock wave processing on amorphous Carbon quantum dots (a-CQD) such that its degree of graphitization and magnetic properties are analyzed. Analytical techniques such as the Raman spectrometer, high resonation–transmission electron microscopy (HR-TEM) and vibrating sample magnetometer (VSM) are utilized to understand the structural, morphological and magnetic properties changes under shocked conditions. The Raman spectroscopic data reveal that the I D /I G ratio is slightly reduced under shocked conditions and the observed values are 0.78, 0.77 and 0.75 for the respective 0, 150 and 300 shocked conditions. The formation of ultra-short-range graphitic nanostructures is confirmed by HR-TEM results at the 300-shocked condition. The most convincing and supporting results for the enhancement of the degree of graphitization are found by the outcome of the magnetic properties such that the saturation magnetization (Ms) is found to be linearly reduced with respect to the number of shock pulses and the observed values are 0.869, 0.757 and 0.710 emu/g for the 0, 150 and 300 shocked conditions, respectively. The electrical resistance of the a-CQD is found to be linearly reduced with respect to the number of shock pulses due to the reduction of sp3 carbon networks. The formation of crystalline graphitic nanostructures in amorphous CQD is explained on the basis of the hot-spot nucleation mechanism. Based on the obtained Raman, HR-TEM and VSM results, during the shocked conditions, slight enhancement of the graphitization is observed; however, from the structural stability point of view, the Carbon dots have high shock resistance than that of the amorphous carbon nanoparticles, multi-wall carbon nanotubes, and reduced graphene oxide nanoparticles. Hence, the title quantum dots can be strongly considered for the applications of device fabrication. [ABSTRACT FROM AUTHOR]

• Crystallographic phase stability of L-alanine at shocked conditions is reported. • Structure—chirality property relationship of the test sample is discussed. • The titled materials can be potential candidate for the device applications. • Shock wave physics can be an alternative technique to find the stable materials. Over the years, crystallographic phase transitions of the polar and non-polar amino acids under static high-pressure-temperature conditions have been well documented, especially after the development of the diamond anvil cell techniques. In contrast, the crystallographic structural science of such primary amino acids under dynamic shocked conditions is still to be explored substantially as it is in a premature stage which requires being loaded with a few possible deep insights whereby exploring the structural kinetics could be a reality. In the present context, we have performed the acoustic shock wave recovery experiment on non-polar amino acid of L-Alanine powder samples such that X-ray diffraction (XRD) and circular dichroism (CD) spectroscopic techniques have been enabled to investigate the structural and chiral stability under shocked conditions. Based on the observed results, it is observed that the crystallographic structure with the P 2 1 2 1 2 1 space group and the same chirality is maintained even at the 200-shocked condition with a transient pressure of 2.0 MPa. The observed dynamic shock wave loading structural stability outcome is identified to be well-matched with the previous static high-pressure compression results. [Display omitted] [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

• Crystallographic phase stability of the poly-crystalline TGS sample at shocked conditions is reported. • XRD and Raman results show the stable crystal structure of poly-crystalline TGS samples. • Poly-crystalline sample has relatively high structural stability and shock resistance compared to the single crystal. Recent reports of shock wave experiments on non-linear optical (NLO) crystals have demonstrated outstanding results. Suitable candidates are currently being studied for industrial applications. For the present experiment, we have chosen tri-glycine sulfate (TGS) for the investigation of the structural properties after shock wave loaded conditions by employing X-ray diffraction and Raman spectroscopic measurements. The observed diffraction and spectroscopic patterns of the test polycrystalline sample reveal that the test sample does not undergo any crystallographic phase transition. But, there are several additional shoulder peaks observed and Raman measurements show that a few Raman bands appear while some disappear by the impact of shock waves due to the re-orientational effect of glycine molecules. The observed interesting results are discussed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Liquid crystalline complex has been designed from non-mesogenic citric acid (CA) and mesogenic 4-undecyloxybenzoic acid (11OBA) in different mole ratio by means of intermolecular hydrogen bond. Optimized geometry for CA + 11OBA (1:1) HBLC complex using density functional theory (DFT) at B3LYP level with 6-311G (d, p) basis set has been studied. Highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), hydrogen bond length/angle, electrostatic potential (ESP) and Mulliken charge distribution for the HBLC complexes are theoretically determined. Further atomic, molecular properties and charge transfer capability of present HBLC complex is evaluated from HOMO/LUMO energies. Theoretically calculated vibration frequencies of HBLC complex is validated through experimentally recorded Fourier transform infrared (FT-IR) spectrum. Characteristic features of various textures by polarizing optical microscopy (POM) and temperature dependent of various thermodynamic properties of CA + 11OBA complexes are carefully investigated. Enantiotropic nematogen and finger print smectic X textures along with their phase sequences are also analyzed. Structural and optical characteristics of present HBLC complexes are evinced by nuclear magnetic resonance ( 1 H NMR) and UV–Vis spectrophotometer (for band gap) techniques. The impact of mesogenic ratio (11OBA) on CA + 11OBA complex is also discussed. In this present work, a noteworthy observation of photocatalytic activity of CA + 11OBA HBLC complex is noticed. Also, textural changes with phase transition temperature, induced smectic phases, thermal range, enthalpy, and tilt angle are reported. Presence of H-bond in the HBLC complex and experimentally obtained results are compared with theoretical DFT studies. [ABSTRACT FROM AUTHOR]

A novel double hydrogen bonded ferroelectric liquid crystal (HBFLC) complex was isolated from (R)-(+)-Methylsuccinic acid (RMSA) and 4-Nonyloxybenzoic acid (9OBA). The presence of hydrogen bond between proton donor (RMSA) and proton acceptor (9OBA) molecules were characterized by FT-IR spectroscopy. Mesomorphic behavior and its phase transition temperature of the HBFLC complex (1:1 and 1:2 ratio) were studied by differential scanning calorimeter (DSC), polarized optical microscope (POM) and identified smectic A*, smectic C* and smectic G* phases by quenching of nematic. MSA + 9OBA HBFLC complex has strong dipole moment which is vertical to the lengthy molecular axis provide a pathway to the insight of smectic mesophases. Sm C* phase revealed paramorphic effect due to refractive index changes in the H-bond layers and leads violet to red color textures. Stabilization of the smectic phase by dipole-dipole interaction in the HBFLC complex was reported using density functional theory (DFT) analysis. Stability of the phase increase while increasing the mesogenic ratio in the present HBFLC complex was also discussed. The structure of the MSA + 9OBA HBFLC complex was optimized by B3LYP theory with the basis set of 6311-G (d, p). In natural bond orbital analysis, it was found that the high stabilization energy specified the intermolecular interaction among the molecules. Unlabelled Image • Self assembly behavior and segregation effect induce the chiral smectogenic phases by quenching of nematic phase. • HBFLC complex shows iridescent colors with respect to the temperature and decreases the thermal stability of Sm C* phase. • Sm A* phase improves the molecular alignment which increases the phase stability in the HBFLC complex. • MSA + 9OBA HBFLC complex exhibit undistributed focal-conic texture is transformed into paramorphic behavior of Sm C* phase. • Sm A* phase and its paramorphic behavior of Sm C* phase is used for optical filters and photodiode applications. [ABSTRACT FROM AUTHOR]