Type Of Mesophase Research Articles

Unprecedented cubic mesomorphic behaviour of crown-ether functionalized amphiphilic cyclodextrins.

Amphiphilic supramolecular materials based on biodegradable cyclodextrins (CDs) have been known to self-assemble into different types of thermotropic liquid crystals, including smectic and hexagonal columnar mesophases. Previous studies on amphiphilic CDs bearing 14 aliphatic chains at the primary face and 7 oligoethylene glycol (OEG) chains at the secondary face showed that the stability of the mesophase can be rationally tuned through implemation of terminal functional groups to the OEG chains. Here, we report the syntheses of first examples of crown ether-functionalized amphiphilic cyclodextrins that unexpectedly form thermotropic bicontinuous cubic phases. This constitutes the first reported examples of cyclodextrins forming such phases, which are potentially capable of 3D ion transport. Lithium composites were made to assess lithium conduction in the material. XRD revealed the added lithium salt destabilizes the cubic phase in favour of the smectic phase. Solid-state NMR studies showed that these materials conduct lithium ions with a very low activation energy.

Innovative use of lipid mesophase dispersions for bisphenol A sequestration in water

HypothesisMesophase dispersions are promising colloids for removing micropollutants from water. We hypothesized that the complex internal nanostructure and tunable lipid/water interface amounts play a crucial role in absorbed quantities. Modifications in interfacial organization within the particles while trapping the micropollutant is assumed. ExperimentsWe formulated stable monolinolein-based dispersions with four types of mesophases (bicontinuous and micellar cubic, hexagonal, and fluid isotropic L2) by varying dodecane contents. The absorption of bisphenol A by these dispersions from water was monitored using molecular spectroscopy. At equilibrium, absorbed quantities by mesophase dispersions were compared to unstructured dodecane/water miniemulsions for two bisphenol concentrations. Structural changes during bisphenol incorporation were identified using small-angle X-ray scattering. FindingsLipid mesophase particles of submicron size showed greater bisphenol incorporation than dodecane/water miniemulsions, with cubosomes being most effective ones, absorbing twice as much as unstructured emulsions. Higher absorption levels are observed for more complex nanostructures with increased lipid/dodecane ratios. The incorporation of bisphenol affected the curvature of internal interfaces, potentially causing phase transitions and indicating that bisphenol settles at interfaces. Similar absorption levels in identical mesophases suggest a strong correlation between nano-structure and absorbed quantities.

An Up-to-Date Overview of Liquid Crystals and Liquid Crystal Polymers for Different Applications: A Review.

Liquid crystals have been extensively used in various applications, such as optoelectronic devices, biomedical applications, sensors and biosensors, and packaging, among others. Liquid crystal polymers are one type of liquid crystal material, combining their intrinsic properties with polymeric flexibility for advanced applications in displays and smart materials. For instance, liquid crystal polymers can serve as drug nanocarriers, forming cubic or hexagonal mesophases, which can be tailored for controlled drug release. Further applications of liquid crystals and liquid crystal polymers include the preparation of membranes for separation processes, such as wastewater treatment. Furthermore, these materials can be used as ion-conducting membranes for fuel cells or lithium batteries due to their broad types of mesophases. This review aims to provide an overall explanation and classification of liquid crystals and liquid crystal polymers. Furthermore, the great potential of these materials relies on their broad range of applications, which are determined by their unique properties. Moreover, this study provides the latest advances in liquid crystal polymer-based membranes and their applications, focusing especially on fuel cells. Moreover, future directions in the applications of various liquid crystals are highlighted.

Coumarin Schiff base derivatives with terminal cyano group: Synthesis, Mesomorphic properties and DFT investigation

Coumarin Schiff base derivatives with terminal cyano group were synthesized and analysed for their mesomorphic behaviour. The homologous series CN6–16 (n = 6,8,10,12,14,14,16) with 4-cyano benzaldehyde, lower member (n = 6,8) exhibited enantiotropic nematic mesophase, while smectic A mesophase started appearing with n = 8 during cooling process. Enantiotropic smectic A mesophase was observed with higher chain length n = 10,12,14,16. Similar trend of mesomorphic properties was exhibited by Schiff base derivatives BPCN8–14. Introduction of cyano biphenyl at aldehyde end of the molecule has led to formation of stable smectic A mesophase as compared to that by compounds CN8–14. Introduction of ester linkage in Schiff based derivatives, compounds ECN10–12 and RECN10–12 showed smectic A mesophase with high clearing temperature. VT-XRD analysis of two compounds has confirmed orthogonal smectic A mesophase. Additionally, DFT calculations were carried out for all the newly synthesized compounds and compared with similar literature molecules for various structural and electronic parameters followed by their correlation with the mesophase type and stability.

Synthesis, mesomorphic behaviour, and DFT studies of biphenyl bis-ester Schiff base liquid crystals

A novel series of calamitic liquid crystals with rod-like structures, derived from biphenyl bis-ester, has been successfully synthesized. This was achieved through the condensation reaction of [1,1′-biphenyl]-4-yl 4-formylbenzoate with n-alkyl 4-aminobenzoate, where n ranges from 2 to 8, 10, 12, 14, 16, and 18. The synthesized compounds were characterized using FT-IR, 1H NMR, 13C NMR, and mass spectroscopy techniques. The liquid crystal behaviour of all synthesized compounds was investigated using Polarizing Optical Microscopy (POM) and Differential Scanning Calorimetry (DSC). It was found that all compounds within the homologous series exhibited mesogenic properties. The effect of molecular flexibility on the mesophase type and transition temperature range was systematically explored. Some compounds displayed a nematic phase, while others showed characteristics of the smectic A phase; additionally, certain compounds exhibited properties of both the nematic and smectic A phases. Furthermore, utilizing B3LYP/6–31++G (d,p) basis sets DFT level calculations and complete geometric optimization of the synthesized compounds was conducted. This optimization facilitated the examination of optimized geometrical structures, aspect ratios, dipole moments, polarizabilities, Frontier molecular orbitals, and molecular electrostatic potentials through DFT calculations.

Asymmetrical liquid crystals synthesis for effective sensing: Fluorescence investigations

Currently, a new set of asymmetrical dimeric molecules with a Schiff-base at one end and a chalcone alkali substitution by di-ether are made and their liquid crystal and fluorescence properties are investigated. The proposed chemical structure was confirmed by routine analytical methods using FT-IR and NMR spectroscopy. Additionally, polarized optical microscopy (POM); was used to assess the pointed compounds' liquid crystalline characteristics, while differential scanning calorimetry (DSC); was employed to confirm the compounds' transitions. The results report the length of the alkali chain at one end of the molecule is critical to the creation of the mesophase type. Compounds with medium-length chains exhibit nematic mesophases with moderate transition temperatures. The fluorescence of compounds was analyzed, with blue-emitting results indicating the presence of blue-light-emitting features. The 10a had higher ɛ; as well as red-shifted λmax; and Fmax; compared to the others and has blue light emission properties. Eventually; the expanding range of possible uses to include OLED material and fluorescent probes for sensing applications.

Physical and Thermal Characterizations of Newly Synthesized Liquid Crystals Based on Benzotrifluoride Moiety.

The mesomorphic stability and optical activity of new group-based benzotrifluoride liquid crystals, (E)-4-(((4-(trifluoromethyl) phenyl) imino) methyl) phenyl 4-(alkyloxy)benzoate, or In, were investigated. The end of the molecules connected to the benzotrifluoride moiety and the end of the phenylazo benzoate moiety have terminal alkoxy groups which can range in chain length from 6 to 12 carbons. The synthesized compounds' molecular structures were verified using FT-IR, 1H NMR, mass spectroscopy, and elemental analysis. Mesomorphic characteristics were verified using differential scanning calorimetry (DSC) and a polarized optical microscope (POM). All of the homologous series that have been developed display great thermal stability across a broad temperature range. Density functional theory (DFT) determined the examined compounds' geometrical and thermal properties. The findings showed that every compound is entirely planar. Additionally, by using the DFT approach, it was possible to link the experimentally found values of the investigated compounds' investigated compounds' mesophase thermal stability, mesophase temperature ranges, and mesophase type to the predicted quantum chemical parameters.

Design of unsymmetric coumarin chalcone derivatives with tunable self-assembling behavior

Unsymmetric coumarin chalcone derivatives were designed with unsymmetric alkoxy chain on both terminal of the molecules to find their effect on the overall mesomorphic properties. In the first homologous series, compounds with fixed octyloxy chain on chalcone end and varied alkoxy chain length at coumarin end of the molecule (n = 10,12,14,16,18) have been analyzed for their mesomorphic properties. In this series, all the Compounds showed stable enantiotropic SmC mesophase. In the second homologous series, compounds with fixed octyloxy chain on coumarin end and varied alkoxy chain length at chalcone end (n = 10,12,14,16,18) have been studied for their mesomorphic properties. In the second homologues series, compounds (n = 10,12) exhibited monotropic nematic mesophase. For higher analogues (n = 16,18), enantiotropic SmA mesophase was observed. Further, the powder X-ray diffraction analysis of the three compounds from both the series at 112 °C showed diffraction pattern quite close to identified mesophase type. To understand effect of variation of terminal chain, DFT theoretical study was carried out for both different series and tried to understand correlation between mesomorphic properties and structural parameters.

The influence of core fluorination on the phase behaviour of rod-like mesogens

ABSTRACT The effect of core fluorination on the mesomorphic properties of rod-like Schiff base-derived liquid crystalline materials was reported. For this purpose, two new series of laterally fluorinated Schiff base liquid crystals are synthesised and investigated in detail. The two series differ from each other’s in the length of the terminal alkoxy chain attached to one end of the aromatic core, where in the first series an octyloxy chain is used and in the second series it is replaced by a longer dodecyloxy chain. At the other end in both series of compounds, in addition to the nonsubstituted end (X = H) four different substituents were used (X = CH3O, C6H13O, CH3 and F). The molecular structures of all synthesised compounds were confirmed using different spectroscopic techniques. The molecular self-assembly was investigated using differential scanning calorimetry (DSC) and polarised optical microscope (POM). Depending on the length of terminal alkoxy chain at one end and nature of the substituent X at the other end, different types of mesophases were observed, including nematic and two different types of smectic phases.

Thermodynamic Morphological Study of Liquid Crystalline Compounds

Thermodynamic morphism study has been envisaged using search procedure of phase space of polymorphs at a prescribed temperature and pressure(NPT) of several azoxybenzenes based liquid crystalline compounds at room temperature using molecular structure, unit cell information and AMOEBA parameters employing Force Field computation (FFX) calculations. These calculations were carried out at various intermolecular strengths to understand the morphological walk of molecules with corresponding changes in free energy, change in a force field with a strength of the interactions and free energy difference between successive interaction strengths. This study will help us to understand the nature, range and type of mesophase in a series of azoxybenzene compounds.

New thiophene chalcones with ester and Schiff base mesogenic Cores: Synthesis, mesomorphic behaviour and DFT investigation

• Thiophene chalcones possessing Schiff base and ester mesogenic core have been synthesized. • Enantiotropic nematic (N) and Smectic A (SmA) phases were observed. • The impact of various connecting units, phenyl rings and of alkoxy chain length has been investigated. • Comparison with structurally similar compounds has been studied. • The DFT calculations of the thermodynamic and dimension parameters were conducted and correlated to mesomorphic behaviour. A new homologous series of thiophene-based mesogens, 4-((E)-((4-((E)-3-(thiophen-2-yl)acryloyl)phenyl)imino)methyl)phenyl-4-(alkyloxy)benzoate, TE- ( 2 – 18 ) in which thiophene heterocyclic unit at one end and long terminal alkoxy chains (C2-C18) at the other end were synthesized, characterized and studied for their mesomorphic and thermal behaviour. Differential scanning calorimetry (DSC) was used to investigate the phase transitions whereas types of mesophase were confirmed by polarized optical microscopy (POM). The mesomorphic investigation revealed that all new derivatives TE-(2 – 14) displayed an enantiotropic nematic phase (N) except the longer alkoxy chain ( n = 16 and 18) which are dimorphic in nature exhibited enantiotropic smectic A phase (SmA) in addition to enantiotropic nematic (N) phase. The mesomorphic behaviours of the new mesogens were investigated and discussed thoroughly and further compared with structurally similar compounds. Further, the optimised geometry of thiophene mesogens has been theoretically derived by the density functional theory (DFT) and the results revealed none co-planar structures for all compounds. The relationships between the calculated parameters, the polarizability, dimension parameters, have been used to illustrate the mesomorphic properties either the type of the texture or the mesomorphic range and stability.

2-Pyridinyl-Terminated Iminobenzoate: Type and Orientation of Mesogenic Core Effect, Geometrical DFT Investigation

A new liquid crystal series of pyridin-2-yl 4-[4-(alkylphenyl)iminomethyl]benzoate was synthesized and characterized for their mesomorphic behavior. These compounds contain Schiff base and carboxylate ester mesogenic cores, in addition to terminal alkyl chains with a different number of carbons. The structures were confirmed via FT-IR, and 1H NMR spectroscopy. The phase transitions were studied by differential thermal analysis (DSC) and the mesophase types were identified by polarized optical microscopy (POM). A comparative study was performed between the synthesized compounds and previously reported compounds. Density functional theory (DFT) calculations were included in the study to compute the dipole moment and the polarizability, as well as the frontier molecular orbitals and the charge distribution mapping, which impact the terminal and lateral interactions of the compounds. The theoretical results were discussed to confirm the experimental data and explain the mesomorphic behavior of the compounds. Finally, the energy gap, global softness, and chemical hardness were calculated to determine the suitability of the liquid crystalline compounds to be employed in applications.

Coumarin Schiff base-esters liquid crystals with symmetrical and unsymmetrical alkoxy chains: Synthesis, mesomorphic properties and DFT approach

Herein, two series of Coumarin Schiff base-esters liquid crystals have been prepared. The first series, Schiff base of 7-alkoxy-3-aminocoumarin with 4-formylphenyl 4-alkoxy benzoate with symmetric variation of alkoxy chain at the both end of the molecules were designed and synthesized. The second is Schiff base of 7-alkoxy-3-aminocoumarin with 4-formylphenyl 4-dodecyloxybenzoate. All these compounds were characterized using different analytical techniques such as FTIR, NMR and Mass spectral analysis. Both series were studied for their mesomorphic behaviour using differential scanning calorimetry (DSC) for the phase transitions and polarised optical microscopy (POM) to identify the type of mesophase. On varying the alkyl chain length at the both end of molecules systematically in the SCE series, compounds of chain lengths 2–8 exhibited an enantiotropic nematic (N) phase whereas SCE-8 exhibited enantiotropic smectic C (SmC) phase in addition to enantiotropic nematic (N) phase. Compounds of the symmetrical series n = 10–18 showed enantiotropic SmC phase. In the unsymmetrical series with n = 12 at aldehyde end of the molecule, enantiotropic nematic mesophase was observed for n = 2–14, while enantiotropic SmC mesophase was appeared from n = 6–18. The DFT theoretical calculations have been conducted for both the series to understand the mesomorphic behaviour of the investigated compounds. Moreover, they are compared with similar reported compounds to explain the relationship between the structural parameters and the mesomorphic behaviour.

Mesomorphic state and types of mesophases

The paper presents basic types of liquid-crystalline phases obtained in different ways and supermolecular arrangement in those phases. Characteristic features of molecular structure of mesogens are discussed, moreover their influence on liquid-crystalline properties are described too. Examples of the effect of intermolecular interactions on the phase situation of a liquid crystal are given. Keywords: liquid crystals, mesophases, polymorphism, mesogens, molecular structure

New Advanced Liquid Crystalline Materials Bearing Bis-Azomethine as Central Spacer.

In this study, a homologous series of novel liquid crystalline compounds bearing the bis-azomethine central linkage (–CH=N-N=CH–), namely ((1E,1′E)-hydrazine-1,2-diylidenebis(methanylylidene))bis(4,1-phenylene) dialkanoate (In), was synthesized, and the mesophase and thermal properties were investigated theoretically and experimentally. The molecular structures of the prepared compounds were determined using elemental analysis, NMR, and FT-IR spectroscopy. The mesophase transitions were detected by differential scanning calorimetry (DSC), and the mesophases were identified using polarized optical microscopy (POM). The results indicated that the derivative with the shortest length (I5) was purely nematogenic, while the other homologues (I9 and I15) possessed SmC mesophases. The optimal geometrical structures of the investigated group were derived theoretically. The estimated results demonstrated that all homologues were mesomorphic, and their type depended on the length of the terminal chains. Computations based on density functional theory (DFT) were used to explain the experimental data. The calculated dipole moment, polarizability, thermal energy, and molecular electrostatic potential all showed that it was possible to predict the mesophase type and stability, which varied according to the size of the molecule.

Photo-Orientation of Liquid Crystals on Azo Dye-Containing Polymers.

In this communication, we summarise our results related to light-induced orientational phenomena at liquid crystal–polymer interfaces. We investigated photoalignment for various nematics at the interface with the photosensitive polymer layer polymethyl methacrilate functionalised with azo dye Disperse Red 1. It was found that the efficiency of photoalignment exhibits marked differences depending on the structure of the rigid core of the liquid crystal molecules. It was demonstrated that the photo-orientation process is also significantly affected by the type of mesophase in which irradiation is carried out. The observations highlight the importance of the mutual influence of the polymer and the liquid crystal in light-induced processes.

Cholesterol-based nonsymmetric dimers comprising phenyl 4-(benzoyloxy)benzoate core: the occurrence of frustrated phases

ABSTRACT The synthesis and mesomorphism of sixteen new nonsymmetric liquid crystal dimers formed by covalently attaching cholesterol with a three-ring mesogenic core, namely, phenyl 4-(benzoyloxy)benzoate, via an ω-oxyalkanoyl spacer are described. The lengths of the terminal chain attached to the three-ring core, as well as those of the ω-oxyalkanoyl spacer, have been varied; accordingly, they have been grouped into four sets. They display an enantiotropic chiral nematic (N*) behaviour with the isotropization temperature crossing over 200 oC. Four dimers having an odd-parity spacer were found to additionally show blue phase-I/II (BP-I/II), and the smectic A (SmA) phase. Twelve dimers with an even-membered spacer also stabilise either chiral smectic C (SmC*) or twist grain boundary (TGB) phase having SmC* slabs (TGBC* phase). The dimers with longer spacer and terminal tail favour the formation of the TGBC* phase. Thus, the lengths of both the terminal tail and the central spacer are seen to direct the type of mesophase and liquid crystal phase sequences to be formed. X-ray diffraction measurements have been carried out on representative samples to corroborate the structure of the mesophases. The N* phase has been probed with the aid of CD technique to figure out the handedness of the helicoidal structure.

Self‐Assembly of All‐DNA Rods with Controlled Patchiness

AbstractDouble‐stranded DNA (dsDNA) fragments exhibit noncovalent attractive interactions between their tips. It is still unclear how DNA liquid crystal self‐assembly is affected by such blunt‐end attractions. It is demonstrated that stiff dsDNA fragments with moderate aspect ratio can specifically self‐assemble in concentrated aqueous solutions into different types of smectic mesophases on the basis of selectively screening of blunt‐end DNA stacking interactions. To this end, this type of attractions are engineered at the molecular level by constructing DNA duplexes where the attractions between one or both ends are screened by short hairpin caps. All‐DNA bilayer and monolayer smectic‐A type of phases, as well as a columnar phase, can be stabilized by controlling attractions strength. The results imply that the so far elusive smectic‐A in DNA rod‐like liquid crystals is a thermodynamically stable phase. The existence of the bilayer smectic phase is confirmed by Monte‐Carlo simulations of hard cylinders decorated with one attractive terminal site. This work demonstrates that DNA blunt‐ends behave as well‐defined monovalent attractive patches whose strength and position can be potentially precisely tuned, highlighting unique opportunities concerning the stabilization of nonconventional DNA‐based lyotropic liquid crystal phases assembled by all‐DNA patchy particles with arbitrary geometry and composition.

Tunable naturally-derived oligomeric ionic liquids: phase behavior and liquid crystal profile

Ionic liquid crystals (ILCs) derived from functional compounds obtained from natural sources, such as fatty acids (FAs), are promising compounds due to their sustainable appeal, low cost, and nutritional value. To expand the application of naturally-derived ILCs, this work discloses the use of the oligomeric approach to tune the LC and melting profiles of ILCs derived from FAs (stearic and oleic acids) and choline by mixing them to their parent FA. The oligomeric systems were investigated through the characterization of the solid-[liquid crystal]-liquid (S-LC-L) thermodynamic equilibrium. S-LC transitions were modelled using Margules and Margules-UNIFAC approaches, with the former presenting better results. The systems presented melting profiles similar to eutectic mixtures with a nonideal behavior and formation of solid solutions. The reduction of the melting point and the LC temperature window was related to the concentration and presence of unsaturation in the molecular structure of the components. The LC mesophases were formed at a wide temperature and FA concentration range. Oleic acid-based system presented lower melting points and a broader LC temperature domain with possibly two types of mesophases (lamellar and inverted hexagonal). Therefore, the oligomeric approach promoted the tunability of the LC and melting profiles of naturally-derived ILCs, which might expand their industrial applicability as lubricants, solvents and reaction media for low or high temperature processes, or as structuring agents (e.g. melting profile modifier) for the design of natural-based products.

Synthesis, mesomorphic and geometrical approaches of new non-symmetrical system based on central naphthalene moiety

ABSTRACT New non-symmetrical homologues series based on central naphthalene moiety, (E)-4-(4-(hexyloxy phenyl diazenylnaphthalene-1-yl-4ʹ-alkoxybenzoate (I 6/n), were synthesised and their mesomorphic properties was investigated. The prepared group constitutes four homologues bearing two terminal alkoxy chains of different proportionation. Elemental analyses, FT-IR and NMR spectroscopy were carried out to elucidate their molecular structures. Examination of their mesomorphic properties, were conducted via differential scanning calorimetry (DSC) and polarised optical microscopy (POM). DSC and POM investigations indicated that all the synthesised homologues are monomorphic possessing the enantiotropic nematic (N) phase. A comparative study was conducted between the present investigated central naphthalene series (I 6/n) and their corresponding central benzene analogues (II 6/n). The results indicated that, the mesophase type and stability as well as the mesophase temperature are affected by the protrusion of the naphthalene group. Theoretical calculations are in accordance with the experimental values of the investigated series. Moreover, the location of naphthalene group in the centre of the molecular geometry, increases the rigidity of the molecule, thus affects their thermal and physical parameters. The experimentally determined nematic stability was correlated with the calculated parameters and the study reveals that there are many factors sharing together to different extents in the enhancement of the behaviour of the observed nematic phase, depending on the different proportionation of the terminal lengths.