Nematic Mesophase Research Articles

Experimental and computational simulations of nematogenic liquid crystals based on cinnamic acid in pure and mixed state

ABSTRACT Homologous series of nematogenic azomethine liquid crystals bearing different terminal alkoxy-chain lengths, 4-(cinnamolyloxy)benzylidene-4ʹ-n-alkoxyanilines (In), were synthesised and investigated via practical and theoretical tools. Differential scanning calorimetry (DSC) and polarised optical microscopy (POM) were used for mesomorphic and optical investigations. While the computational simulations and geometrical parameter estimations were carried out using a DFT approach at B3LYP/6-31 G(d,p) level of theory. The results revealed that all of the investigated compounds showed to exhibit the enantiotropic nematic mesophase. The temperature range of the nematic phase depends on the length of the terminally attached flexible alkoxy chain. Theoretical calculations were conducted and found to confirm the experimental data values of the mesophase stability and its temperature range. Furthermore, the length of the terminal alkoxy chains showed to exhibit remarkable effects on the stability of the mesophase as well as their thermal and physical properties. The mesomorphic and optical properties determined were correlated with the theoretically calculated parameters and the study revealed that many factors in different extents contribute together to manifest the behaviour of the observed nematic phase. The binary phase diagram of two corresponding homologues was constructed and their binary phase thermal properties were discussed in terms of the temperature range of the nematic phase.

Blue Glow Sticks: Cinnamic Acids and Arylacrylonitriles with Liquid-Crystalline Properties and Highly Fluorescent

Five new π-conjugated chromophores derived from acrylic acid and acrylonitrile were synthesized and their thermal and photophysical behaviors were analyzed. They were designed and synthesized through Knoevenagel condensations between arylacetylenebenzaldehydes and a methylene group activated from cyanoacetic and malonic acids. The characterization of the target compounds was performed by Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (NMR), 13C NMR, thermogravimetric analysis (TGA), absorption and emission spectroscopy techniques. Arylcinnamic acids were obtained as pure E-isomers. On the other hand, arylacrylonitrile was obtained as a mixture of E/Z-isomers and the pure E-isomer was isolated in chromatographic columns. The liquid crystal properties were investigated through differential scanning calorimetry and polarized optical microscopy. All chromophores displayed smectic and nematic mesophases. These materials displayed intense fluorescence under UV-Vis light excitation. The maximum absorption peaks were observed between 342-356 nm while emission varied from 428 to 460 nm in chloroform solution. Higher values for the quantum fluorescence yield were associated with acrylic acids compared to arylacrylonitriles. The solvatochromism studies of the materials showed a significant increase in the red-shift of the fluorescence spectra as the polarity of the solvent increased. In some cases, a variation in the emission wavelength from the blue to the green region of the spectrum was observed.

Influence of 4-(2-S(+)-Methylbutyloxy)Benzoic Acid on Mesomorphic and Physico-Chemical Properties of 4-Butyl-4'-Octanoyloxyazobenzene

Mesomorphic, optical, dielectric, and orientation properties of nematic liquid crystal 4-butyl-4'-octanoyloxyazobenzene doped with chiral 4-(2-S(+)-methylbutyloxy)benzoic acid have been studied. The clearing temperatures of the mixtures were measured by polarizing microscopy. An estimation of the mesophase destabilization with the introduction of the dopant was carried out. The helix pitch of the induced chiral nematic mesophase was measured. The effect of the chiral dopant on anisotropic characteristics of the mesophase has been studied. An insignificant increase in the optical and dielectric anisotropy is associated with the formation of liquid crystal – dopant supermolecules due to hydrogen bonds –COOH…OCO–.

The wavelength-dependent optical transmission and birefringence of lyotropic nematic calamitic mesophase under a polarising microscope and its order parameter in comparison to Michel-Lévy interference colour chart

ABSTRACT In the present study, the optical transmissions of lyotropic nematic calamitic mesophase (NC) were measured depending on temperature for wavelengths of 440, 470, 510 and 694.3 nm in visible spectrum using polarised microscopy. For each wavelength, the birefringence was determined in the NC mesophase temperature region and it was observed that the smaller the wavelength in the visible region, the greater the birefringence. Using the birefringence, macroscopic order parameter was obtained depending on temperature and it was found to be approximately the same for each wavelength. Besides, the textural colour properties of the planar-oriented sample were observed under the microscope throughout the mesophase region. These colour attributes were compared with the Michel-Lévy interference chart and the birefringence was sensitively determined from the chart. This time, the order parameter was studied using the birefringence found from the chart. It was approximately the same as the order parameter found using the microscopy.

Liquid crystal behavior of Ag(I) complexes based on a series of mesogenic 1,3,4-thiadiazole ligands

2-(4-Alkoxyphenyl)-5-(p-tolyl)-1,3,4-thiadiazoles (alkoxy: O(CH2) n H, n = 1–8) ( 6a–h ) (as a series of 1,3,4-thiadiazole derivatives) and their silver(I) complexes: bis(2-(4-alkoxyphenyl)-5-(p-tolyl)-1,3,4-thiadiazole)-silver(I) complexes (alkoxy: O(CH2) n H, n = 1–8) ( 7a–h ) were prepared and characterized with different techniques: microelemental analysis, FTIR, UV–Vis, 1H NMR, 13C NMR and mass (for the organic compounds) spectra, in addition to the molar conductivity measurements (for Ag(I) complexes). Liquid crystal behavior of the two series of compounds was evaluated using polarized light optical microscopy (POM). The study revealed that both series are enantiotropic liquid crystalline materials (exhibiting wide mesomorpic temperature ranges) with different behavior and properties. 6a–f displayed only nematic mesophase upon heating and cooling, while 6g and 6h exhibited both of SmC and nematic mesophases upon heating and cooling. Upon complexation of 1,3,4-thiadiazoles ( 6a–h ) to silver(I), the liquid crystal behavior and properties are significantly changed (different mesophases, and lower mesophase and clearing temperatures). However, 7b–h exhibited SmA mesophase upon heating and cooling, while 7a shows no mesomorphic properties (simply melted to isotropic liquid).

Magnified charge carrier conduction, permittivity, and mesomorphic properties of columnar structure of a room temperature discotic liquid crystalline material due to the dispersion of low concentration ferroelectric nanoparticles.

Liquid crystal nanocomposites have been a hot topic of research due to optimization of physical properties with such blending. There are several reports on enhancement of physical properties of nematic liquid crystals due to the blending of the nanomaterials. L. M. Lopatina and J. V. Selinger [Phys. Rev. Lett. 102, 197802 (2009)]10.1103/PhysRevLett.102.197802 have even proposed a theory based on experimental results for the enhancement of the properties of the nematic mesophase in the presence of ferroelectric nanoparticles. However, discotic liquid crystal nanocomposites are less studied. In the present experimental work, we have studied the effect of ferroelectric (BaTiO_{3}) nanoparticles on a room temperature discotic liquid crystalline material, namely 1,5-dihydroxy-2,3,6,7-tetrakis(3,7-dimethyloctyloxy)-9,10-anthraquinone. We investigated the physical properties of low concentration ferroelectric nanoparticle dispersed discotic columnar structure, using calorimetric, optical, x-ray diffraction, and dielectric spectroscopy tools. Results show that inclusion of ferroelectric nanoparticles in the discotic matrix consolidates the stability of the columnar matrix of the Col_{h} phase by virtue of their ferroic nature. An enhancement in charge carrier conductivity by several orders of magnitude at ambient conditions has been observed which makes such systems highly appropriate for one-dimensional conductors. Low concentration of BaTiO_{3} nanoparticles substantially enhanced permittivity of the system also. A molecular relaxation mode has been observed in the middle frequency range of the dielectric spectra. Enhancement of these important parameters could be possible due to the ferroelectric nature of the dispersed nanoparticles.

Synthesis and characterization of novel rod-like ester-based liquid crystalline homologous series: Effect of tert-butyl tail on mesomorphism

A new rod-like homologous series consisting twelve compounds with central ester linkage and terminal tert-butyl group, tert-butyl [4-(4’-n-alkoxybenzoyloxy)benzoates] has been synthesized and characterized through standard spectroscopic techniques like UV, FT-IR, 1HNMR, DSC, POM, and XRD. Methoxy and ethoxy derivatives are nonmesogenic. Nematic mesophase commences as enantiotropy from propyloxy derivative and persists up to the octadecyloxy derivatives. Smectic A mesophase commences as monotropy from propyloxy to the octadecyloxy derivatives. The mesomorphic properties of present series are compared with other structurally related series to evaluate the effect of terminal tert-butyl group on mesomorphism. Two derivatives are subjected to in vitro antimicrobial activity.

Original Mesogenic Citronellol-Based Stationary Phase for Both Normal- and Reversed-Phase HPLC Modes: Properties and Applications

In this work, the synthesis, characterization and chromatographic performance of a silica material chemically bonded with a liquid crystal based on terminal citronellol for HPLC separation were investigated. This bonded liquid crystal stationary phase denoted as LC-LCC8 resulted from the grafting of a mesogenic carboxylic acid, 3′-((3,7-dimethyloct-6-en-1-y1)oxy)-[1,1′-biphenyl]-4-carboxylic acid (LCC8), on 4-(1,1-dimethyldisiloxanyl)butan-1-amine. LCC8 was previously synthesized and characterized by proton NMR, and a nematic mesophase at 127 °C was confirmed by differential scanning calorimetry and microscopy. The resulting stationary phase LC-LCC8 was characterized by using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and elemental analysis. The granulometric distribution was evaluated by scanning electron microscopy (SEM) before and after grafting. An analytical column (150 mm × 2.1 mm × 5 µm) was packed with the stationary phase for the chromatographic study. The chromatographic behaviour of the stationary phase was first characterized using the Tanaka test, exhibiting an exceptionally high shape selectivity (αT/O = 3.9). In normal-phase mode, using a 92/8 cyclohexane/tetrahydrofuran (THF) (v/v) mixture as the mobile phase, the isomeric mixture (Z and E) of crotamiton was well separated. In reversed-phase mode, good selectivity was observed towards organic pollutants [polycyclic aromatic hydrocarbons (PAHs)] and pharmaceutical compounds (xanthines, steroids and antihistamines). The new bonded phase showed satisfactory results both in normal- and reversed-phases modes except in terms of peak shape. The temperature effect on the selectivity and resolution of LC-LCC8 was estimated by injecting different isomers at various temperatures ranging from 293 to 333 K, demonstrating an improved resolution of solutes at high temperatures, which was probably due to a change in orientation order of the grafted ligands.

DNA Origami Nano-Sheets and Nano-Rods Alter the Orientational Order in a Lyotropic Chromonic Liquid Crystal.

Rod-like and sheet-like nano-particles made of desoxyribonucleic acid (DNA) fabricated by the DNA origami method (base sequence-controlled self-organized folding of DNA) are dispersed in a lyotropic chromonic liquid crystal made of an aqueous solution of disodium cromoglycate. The respective liquid crystalline nanodispersions are doped with a dichroic fluorescent dye and their orientational order parameter is studied by means of polarized fluorescence spectroscopy. The presence of the nano-particles is found to slightly reduce the orientational order parameter of the nematic mesophase. Nano-rods with a large length/width ratio tend to preserve the orientational order, while more compact stiff nano-rods and especially nano-sheets reduce the order parameter to a larger extent. In spite of the difference between the sizes of the DNA nano-particles and the rod-like columnar aggregates forming the liquid crystal, a similarity between the shapes of the former and the latter seems to be better compatible with the orientational order of the liquid crystal.

Quantitative Calorimetric Studies of the Chiral Nematic Mesophase in Aqueous Cellulose Nanocrystal Suspensions

Aqueous suspensions of cellulose nanocrystals (CNC) can spontaneously form a chiral nematic mesophase at a critical concentration (c*). Unfortunately, no current analytical technique permits rapid detection of c*. Herein, we introduce a facile and accurate approach to assess c* rapidly (< 2 h) from a small sample volume and compare our results to those obtained by conventional methods. Our strategy employs isothermal titration calorimetry (ITC) to measure the heat of interaction, which can identify the onset of mesophase formation since it is sensitive to suspension viscosity and thus capable of detecting small changes in the suspension environment. We measure c* for CNC samples differing in surface charge and aspect ratio and find that lower aspect ratios and higher surface charges both increase c*. Our ITC results reveal the role of CNC interactions prior to visual observation of mesophase formation and elucidate effects related to nanocrystals and their suspensions.

Synthesis and Structural Characterization of Some Lanthanide(III) Nitrate Complexes with a Mesogenic Schiff-Base, N,N’-di-4-(4’-heptadecyloxybenzoate) salicylidene-1,3-diaminopropane Derived from 2,4- dihydroxybenzaldehyde

Complexes of La(III), Pr(III), Nd(III), Sm(III), Gd(III) and Dy(III) with the Schiff-base, N,N′-di-4-(4’-heptadecyloxybenzoate)salicylidene-1,3-diaminopropane, (abbreviated as H2L) have been synthesized and characterized on the basis of elemental analyses, molar conductance, magnetic, electronic, infrared, 1H and 13C NMR spectral techniques. The nephelauxetic ratio (β), the bonding parameter (b1/2), Sinha’s parameter (%δ) and angular overlap parameter (η) have been calculated from the electronic spectra of Pr(III), Nd(III), Sm(III) and Dy(III) complexes. Infrared and NMR spectral data imply a bi-dentate bonding of the Schiff-base in its zwitterionic form (as LH2) to the Ln(III) ions through two phenolate oxygens, rendering the overall geometry around Ln(III) to distorted square antiprism. Polarized optical microscopy (POM) and differential scanning calorimetry (DSC) shows the liquid crystalline property of the ligand with a nematic (N) mesophase. Among the metal complexes, only that of the Gd(III) exhibits smectic B (SmB) and nematic (N) phases.

Coumarin substituted symmetric diaminopyridine molecules: Synthesis, mesomorphic characterizations and DFT studies

The 2, 6-diaminopyridine was symmetrically substituted with coumarins from a lateral side of the molecules. All the molecules characterized by standard spectroscopic methods such as infrared spectroscopy, and nuclear magnetic resonance spectroscopy techniques. Mesomorphic properties are evaluated by the differential scanning calorimetry and the polarized optical microscope. The measurements show that the lower members did not favour liquid crystal formation, while higher members are exhibiting liquid crystalline, namely Nematic mesophase. The DFT computations manifest the nature of liquid crystal geometrical aspects.

Liquid crystal and photoluminescent properties of a series of symmetrical 1,2-bis(4-alkoxybenzylidene)hydrazines bearing long-tails of hydrocarbon chain

ABSTRACT In this work, 1,2-bis[4-(n-alkoxy)benzylidene]hydrazine (n-alkoxy: O(CH2)nH, n = 11–18 or 20), a symmetrical series of azines (linear compounds with rod-like shape structure), were synthesised using a very simple two-step procedure as a part of our continuing effort in evaluating hydrophobic 1,2-disubstituted hydrazine compounds as photoluminescent liquid crystalline materials. The first step of the synthesis involved the alkylation of the OH group of 4-hydroxybenzaldehyde in basic medium using the Williamson method to obtain 4-alkoxybenzaldehydes. While the second step included the condensation reaction of hydrazine hydrate and appropriately 4-alkoxybenzaldehydes compounds (mole ratio 1:2, respectively) in acidic medium under ambient conditions. The prepared compounds were characterised and their structures elucidated depending upon infrared (IR), ultraviolet-visible (UV–Vis), nuclear magnetic resonance (1HNMR, 13CNMR, DEPT NMR, 2D 1H-1H-COSY and 2D 1H-13C- HSQC) and elemental analysis (CHN). Liquid crystalline behaviour and photoluminescent properties were studied using polarised light optical microscopy (POM), fluorescence emissions (FE), differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD) techniques. The studies showed that all of these compounds are enantiotropic liquid crystalline materials exhibiting smectic (SmA and SmC) and nematic (droplet and thread) mesophases . The study also displayed that all of the prepared compounds are photoluminescent in the crystalline and liquid crystal states.

Characterization of New H-Bonded Liquid Crystalline Complexes Based on Iminophenyl Nicotinate

Two new 1:2 supramolecular H-bonded liquid crystalline complexes (SMHBCs) were prepared through double H-bond interactions between either isophthalic acid (A) or terephthalic acid (B) and a nicotinate Schiff base (I6). The formed complexes were thermally investigated by differential scanning calorimetry (DSC), and their phases were identified by polarized optical microscopy (POM) and UV-spectroscopy. The formation of 1:2 hydrogen-bonded complexes was confirmed through their Fermi-bands observed by FT-IR spectroscopy. The first system (I6/A) was found to possess enantiotropic smectic A and nematic mesophases. Induced broad range of smectic A phase was observed in I6/A complex which is not shown by their individual components. The second complex system (I6/B) was purely nematogenic. Density functional theory (DFT) calculations were applied to predict their geometrical parameters. Theoretical studies revealed that the isophthalic complex adopted the W-shape; while the U-shape was adopted by the terephthalic acid complex (I6/B). The linear geometry of the complex based on the isophthalic acid enhanced the mesomorphic behavior observed by the terephthalic complex; I6/B. Actually; the orientation of the two carboxylic groups was shown to highly affect the softness of the derived complex. On the other hand; the mapping orientation of the charge distribution can be used to explain the mesophase behavior. The photophysical characterization of isophthalic complex (I6/A) is also discussed

Benzoxazole-based nematic liquid crystals containing ethynyl and two lateral fluorine atoms with large birefringence

ABSTRACT New kinds of heterocyclic mesogenic compounds containing benzoxazole, ethynyl, and laterally fluorinated phenyl groups, namely 2-[4-[2-[4-alkoxyphenyl]ethynyl]-2,3-difluorophenyl]-benzoxazole derivatives (nPEDFPBx), are synthesized and evaluated. The compounds nPEDFPBx except nitro-substituted ones have enantiotropic nematic mesophases with mesophase ranges of 16–86°C and 29–108 °C on heating and cooling, respectively. The results show that introduction of two lateral fluorine atoms into molecule results in enhanced nematic mesophase stability. Meanwhile, nPEDFPBx displays much higher birefringence (0.507–0.624) than common tolane-based liquid crystals, which is ascribed to its large π-conjugated molecule composed of benzene, ethynyl, and benzoxazole mesogenic unit. The nPEDFPBx has a high potential to serve as a dopant for liquid crystal mixture.

Polymerization of Self-Assembled Tetraazaporphyrins

Polymerization of self-assembled supramolecular structures considerably increases their often limiting thermal and chemical stability, which widens their potential application in commercial products. Particularly interesting for self-assembled materials is the topochemical polymerization of diacetylenes to polydiacetylenes because it can be initiated photochemically and thermally without the need for additives, it proceeds with minimal structural changes, and it generates new functionality since polydiacetylene is a 1-dimensional organic semiconductor and absorbs visible light. Polydiacetylenes have been generated in single crystals, gel phases, thin films, and membranes but their formation in mesophases, such as liquid crystals, has been surprisingly little studied although higher ordered mesophases should support the topochemical polymerization of diacetylenes (1,3-butadiyne groups) and may give access to large domains of uniformly aligned materials. Presented here are tetraazaporphyrins that contain eight alkyl chains with diacetylene groups to probe their mesomorphism and conversion into multifunctional polydiacetylene materials. While incorporation of diacetylene groups supports columnar mesomorphism, successful photopolymerization required the presence of directing amide groups that suppressed columnar in favour of nematic mesomorphism. Still, polymerization of the nematic mesophase generated a soluble nematic polydiacetylene of significantly higher molecular weight (Mn = 77 kDa or 25 monomer units by GPC) than what has been obtained in gel phases of related compounds. Formation of polydiacetylene was confirmed by Raman spectroscopy and its nematic structure was verified by UV-vis spectroscopy, polarized optical microscopy, and X-ray diffraction. Both, its nematic structure and the incorporation of eight side-chains per discotic unit provide the polydiacetylene with sufficient solubility for casting thin films on substrates. AFM studies of films casted onto silicon wafers revealed a grid-like structure of connected nanofibers.

Investigation of dielectric and impedance spectroscopy from homeotropically aligned liquid crystal compound 8OBA

p-octyloxybenzoic acid (8OBA) is the 8th member of p-alkoxy benzoic acid homologous series. It exhibits nematic and smectic mesophase with high clearing temperature. This compound shows positive dielectric anisotropy. In this article, frequency dependent of dielectric permittivity and dielectric loss factor have been investigated from homeotropically aligned sample. Impedance spectroscopy which is one of the most important experimental tool to study electrical characterization of the material, have also been studied for this compound.

Mesomorphic properties improved via lateral fluorine substituent on benzoxazole-terminated mesogenic compounds

ABSTRACT Here, laterally monofluorinated heterocyclic mesogenic compounds, 2-[4-[2-[4-alkoxy-phenyl]-ethynyl]-3-fluorophenyl]-benzoxazole derivatives (nPEFPBx) with hydrogen, methyl and nitro terminal substituents (coded as nPEFPBH, nPEFPBM and nPEFPBN, respectively) at 5-position of benzoxazole unit, are synthesised and characterised. They display enantiotropic nematic mesophase with mesophase ranges of 22–30°C and 32–39°C on heating and cooling for nPEFPBH, 67–92°C and 87–115°C for nPEFPBM, 31–84°C and 42–51°C for nPEFPBN (n < 7), respectively, which is better than nonfluorinated and laterally difluorinated analogous . Improved mesophase property is ascribed to reduced dipole moment resulting from introduction of lateral fluorine atom in opposite direction of polar benzoxazole unit. This indicates that monofluorine substituent contributes to improve nematic mesophase for benzoxazole-terminated mesogenic compounds. In addition, the compounds nPEFPBx have high birefringence of 0.513–0.650 because of large π-conjugated mesogenic core composed of benzene, ethynyl and benzoxazole groups, which suggests a possible application in liquid crystal mixture to enhance birefringence. Meanwhile, except nPEFPBN, the compounds nPEFPBx show intense photoluminescence emission at 406–407 nm in methylene chloride solution with exciting them at absorption maxima.

Induced Wide Nematic Phase by Seven-Ring Supramolecular H-Bonded Systems: Experimental and Computational Evaluation.

New seven-ring systems of dipyridine derivative liquid crystalline 2:1 supramolecular H-bonded complexes were formed between 4-n-alkoxyphenylazo benzoic acids and 4-(2-(pyridin-4-yl)diazenyl)phenyl nicotinate. Mesomorphic behaviors of the prepared complexes were investigated using a combination of differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Fermi bands attributed to the presence of intermolecular H-bond interactions were confirmed by FT–IR spectroscopy. All prepared complexes possessed an enantiotropic nematic phase with a broad temperature nematogenic range. Phases were confirmed by miscibility with a standard nematic (N) compound. A comparison was constructed to investigate the influence of the incorporation of the azophenyl moiety on the mesomeric behavior of corresponding five-membered complexes. It was found that the present complexes observed induced a wide nematic phase with relatively higher temperature ranges than the five aromatic systems. Density functional theory (DFT) suggested the nonlinear geometry of the formed complex. The results of the DFT explained the nematic mesophase formation. Moreover, the π–π stacking of the aromatic moiety in the phenylazo acid plays an effective role in the mesomorphic thermal stability. The energy difference between the frontier molecular orbitals, HOMO (highest occupied) and LUMO (lowest occupied), and the molecular electrostatic potential (MEP) of the prepared complexes were estimated by DFT calculations. The results were used to illustrate the observed nematic phase for all H-bonded supramolecular complexes. Finally, photophysical studies were discussed which were carried out by UV spectroscopy connected to a hot stage.

New architectures of supramolecular H-bonded liquid crystal complexes based on dipyridine derivatives

ABSTRACT New two isomeric homologues series of dipyridine derivative liquid crystalline H-bonded complexes were formed through 2:1 intermolecular hydrogen bonding between 4-n-alkoxybenzoic acids and 4-(2-(pyridin-3-or-4-yl)diazenyl)phenyl nicotinate. The thermal and optical behaviours of these supramolecular H-bonded complexes were analysed through differential scanning calorimetry (DSC) and polarising optical microscopy (POM). The molecular structure of the new dipyridine bases were confirmed via elemental analysis, FT-IR, 1H-NMR, 13C-NMR spectroscopy. On the other hand, the formation of H-bonded supramolecular complexes was confirmed by the presence of Fermi bands in the FT-IR spectroscopy. DFT theoretical calculations of the predicted molecular geometry for the two present isomeric series were discussed. The results of the DFT calculations revealed that the orientation of the dinitrogen atoms of the dipyridine bases I and II for both H-bonded series affects many important parameters for the optical properties. Base I gives angular H-bonded complexes of higher energy and less softer than that of base II which gives linear complexes. The DFT calculations and the experimental results showed that the mesophase stability, geometrical confirmation are highly changed by the geometry of the H-bonded complexes. Moreover, their architectures change the phase from monotropic SmC phase observed in group IA–E to enantiotropic nematic mesophase for IIA–E.