Molecular structural flexibility dependence of mesomorphism through ortho-substituted bromo group

Bhola, G.N.; Bhoya, U. C.

doi:10.1080/15421406.2016.1146941

Cited by 9 publications

(3 citation statements)

References 20 publications

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“…1,[35][36][37] Many of these studies have involved an investigation of the impact of the terminal groups on the phase-transition temperatures. 38 Also, the incorporation of -CH]Nlinkages to rigid phenyl rings provides a stepped core shape and helps retain the linearity of the molecular structure. Thus, this can enhance the stability of the formed mesophases.…”

Section: Introductionmentioning

confidence: 99%

New wide-stability four-ring azo/ester/Schiff base liquid crystals: synthesis, mesomorphic, photophysical, and DFT approaches

et al. 2020

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New four-groups-based azo/ester/Schiff base liquid crystals, ((4-substitutedphenylimino)methyl)phenyl 4-[2-(4-alkoxyhenyl)diazenyl]benzoate, In a-d , were synthesized and analyzed for their mesomorphic stability and optical activity. In these compounds, a terminal alkoxy group of variable chain length from n ¼ 6 to n ¼ 16 carbons is attached to the end of a phenylazo benzoate moiety and the other end of the molecules is connected to a different polar compact substituent X (CH 3 O, CH 3 , H, and Cl). FT-IR, 1 H NMR, mass spectroscopy and elemental analysis were carried out for molecular structure confirmation of the prepared compounds. The mesomorphic properties were confirmed using a combination of differential scanning calorimetry (DSC) and polarized light microscopy (PLM). The photophysical property was studied by UV-vis spectroscopy. All the prepared homologous series exhibited high thermal stability with a wide-temperature mesomorphic range. The thermal and geometrical parameters of the investigated compounds were estimated by density functional theory (DFT). The results revealed that all the compounds were not completely planar with a relatively high twisting moiety at the CH]N part and their twist angles were affected by the electronic nature of the attached X group. Moreover, the calculated quantum chemical parameters as determined by the DFT approach of the investigated compounds were related to the experimentally determined values of the mesophase thermal stability (T c ) and mesophase temperature ranges (DT SmA and DT N ) as well as the type of the mesophase.Scheme 1 Synthesis of (4-substituted phenylimino)methyl)phenyl 4-[2-(4-alkoxyphenyl)diazenyl]benzoate, In a-d .This journal is

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Section: Introductionmentioning

confidence: 99%

New wide-stability four-ring azo/ester/Schiff base liquid crystals: synthesis, mesomorphic, photophysical, and DFT approaches

et al. 2020

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“…It has been reported that the low molar mass calamitic LCs comprising two aromatic rings and one or more terminal substituent, i.e., 4-methoxybenzylidene-4 -butylaniline, are able to form a nematic phase at room temperature [17,[32][33][34]. Moreover, attachment polar groups between the two isomeric molecules could lead to a further decrease in the melting points of their mixed systems.…”

Section: Introductionmentioning

confidence: 99%

Mesomorphic, Optical and DFT Aspects of Near to Room-Temperature Calamitic Liquid Crystal

et al. 2020

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A new liquid crystalline, optical material-based Schiff base core with a near to room-temperature mesophase, (4-methoxybenzylideneamino)phenyl oleate (I), was prepared from a natural fatty acid derivative, and its physical and chemical properties investigated by experimental and theoretical approaches. The molecular structure was confirmed by elemental analysis, FT-IR (Fourier-Transform-Infrared Spectroscopy) and NMR (nuclear magnetic resonance) spectroscopy. Optical and mesomorphic activities were characterized by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The results show that compound (I) exhibits an enantiotropic monomorphic phase comprising a smectic A phase within the near to room-temperature range. Ordinary and extraordinary refractive indices as well as birefringence with changeable temperatures were analyzed. Microscopic and macroscopic order parameters were also calculated. Theoretical density functional theory (DFT) calculations were carried out to estimate the geometrical molecular structures of the prepared compounds, and the DFT results were used to illustrate the mesomorphic results and optical characteristics in terms of their predicted data. Three geometrical isomers of the prepared compound were investigated to predict the most stable isomer. Many parameters were affected by the geometrical isomerism such as aspect ratio, planarity, and dipole moment. Thermal parameters of the theoretical calculations revealed that the highest co-planar aromatic core is the most stable conformer.

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“…Recently, many researchers studied the design of the molecular deformation architecture influenced the mesophase formation [28,29,30,31], e.g., lattices of free space, fibers in twist-bend nematic phase [32,33], and oligomers [7,34,35,36]. Many of these studies have involved the investigation of the impact of terminal substituents on the temperature of phase transition [37].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Optical, and Geometrical Approaches of New Natural Fatty Acids’ Esters/Schiff Base Liquid Crystals

et al. 2019

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Schiff base liquid crystals, known as [4-(hexyloxy)phenylimino)methyl]phenyl palmitate (IA), [4-(hexyloxy)phenylimino)methyl]phenyl oleate (IIA) and [4-(hexyloxy)phenylimino)methyl]phenyl linoleate (IIIA), were synthesized from palmitic, oleic, and linoleic natural fatty acids. The prepared compounds have been investigated for their thermal and optical behavior as well as phase formation using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Molecular structures of all studied compounds were confirmed via elemental analysis, FT-IR, 1H NMR, and 13C NMR. Smectic phase is the observed mesophase for all compounds; however, their type and range depend upon the terminal alkanoate chains attached to the phenyl ring. Computational calculations, Density functional theory (DFT), energy difference of the frontier molecular orbital (FMOs), as well as the thermodynamic parameters of different molecular configurations isomers were discussed. It was found that the mesophase behavior and the geometrical characteristics were affected by the degree of unsaturation of fatty terminal chains. Furthermore, the geometrical structure of the CH=N linkage plays an important role in the thermal stability and optical transition temperature.

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Molecular structural flexibility dependence of mesomorphism through ortho-substituted bromo group

Cited by 9 publications

References 20 publications

New wide-stability four-ring azo/ester/Schiff base liquid crystals: synthesis, mesomorphic, photophysical, and DFT approaches

New wide-stability four-ring azo/ester/Schiff base liquid crystals: synthesis, mesomorphic, photophysical, and DFT approaches

Mesomorphic, Optical and DFT Aspects of Near to Room-Temperature Calamitic Liquid Crystal

Synthesis, Optical, and Geometrical Approaches of New Natural Fatty Acids’ Esters/Schiff Base Liquid Crystals

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