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1.
Vinay S. Sharma Deepak Suthar Anuj S. Sharma 《Molecular Crystals and Liquid Crystals》2018,665(1):100-118
In present study, we have synthesized two newly chalconyl-ester core LCs having variable side chain and fixed disubstituted butoxy group at another terminal end. All this compounds were well characterized by elemental analysis, FT-IR, 1H NMR. The mesomorphic properties of these compounds were observed by optical polarized light microscopy (POM) and also confirmed by using differential scanning calorimetry (DSC) and X-ray diffraction pattern (XRD). Detailed XRD investigation endorses the presence of the nematic phase in higher angle region and SmC phase in lower angle region. In addition, it is found that all the prepared materials display enantiotropic LCs phases except first four members in series-1 and first member in series-2. Thermal stability of SmC and nematic phase of series-1 is higher as compare to series-2. To get more insights, the DFT based HOMO, LUMO studies are carried out which supports intramolecular charge transfer interactions and stability in this class of mesogens. 相似文献
2.
A. V. S. N. Krishna Murthy M. Srinivasulu M. L. N. Madhumohan Y. V. Rao D. M. Potukuchi 《Molecular Crystals and Liquid Crystals》2018,664(1):46-68
Shiff based Linear Hydrogen Bonded Liquid Crystalline homologues, viz., (4)PyBD(4I)BrA-nOBAs for n = 2,3,4,5,6,7,8,10,11 and 12 are synthesized. 1H-NMR and 13C-NMR studies confirm the formation of HBLC and IR confirms the linear hydrogen bonding. Liquid crystal phase abundance, transition temperatures, enthalpy and order of transition are investigated by Polarized Optical Microscopy textural studies and Differential Scanning Calorimetry. Nematic, Smectic-A, -D, -C, Bhexatic, -BCrystal, -F, -I and –G phases are identified. Large LC phase variances, viz., NABhexFG and NACFG are exhibited by intermediate chain length with n = 5 and 6. A-C transition exhibited unique II-order nature. II-order nature for G-Solid transition explained. Phase diagram drawn with flexible chain length infers INA, and ACF and CIF MultiCritical Points and Lifshitz behaviour. NA TriCiritical Point predicted in [3+7] binary. Influences of chain length, linear HB and end polar(-Br) substitution for LC phase stability are is discussed. Results of Phase stability are discussed in the wake of the body of the data and reports in other LCs. DSC enthalpy suggests for utility of intermediate and higher homologues for device savvy tilted Smectic LC phases. 相似文献
3.
The molecular orientation and the dielectric anisotropy of the nematic liquid crystal (LC) 4-cyano-4′-n-heptylbiphenyl (7CB) and of TiO2-doped 7CB have been investigated. The dielectric properties of the LCs exhibit a relaxation peak that shifts to lower frequencies with increasing voltages. The relaxation frequencies of 7CB and 7CB/TiO2 liquid crystals were calculated and found to decrease as the bias voltage increases. This is attributed to molecular reorientation. The dielectric anisotropy of the LCs changes from the positive type to negative type and the static electric permittivity and dielectric anisotropy values were found to be lower for the 7CB/TiO2 system. 相似文献
4.
Yasuyuki Gotoh 《Molecular Crystals and Liquid Crystals》2014,593(1):61-77
With the aim of improving the properties of liquid crystal (LC) mixtures for VA-LCD and PSA-LCD, JNC has newly synthesized 2-(4’-ethoxy-2’,3’-difluorobiphenyl-4-yl)-5-alkenyltetrahydro-2H-pyran derivatives with alkenyl substituents as side chains, and then measured various physicochemical properties to compare their properties to LC compounds with alkyl substituents as side chains. We have shown that several LC compounds with side-chain alkenyl substituents lead to the development of a larger negative dielectric anisotropy (Δ?) than for side-chain alkyl substituents. We considered the reason for this using a quantum chemical calculation. As a result, it was found that, compared to alkylated compounds, there exist several LC compounds with side-chain alkenyl substituents, which have a higher existence probability of conformers with a β angle, making expression of a larger |Δ?| possible in an effective manner. It was understood from this study that the physicochemical properties of LC mixtures for VA-LCD and PSA-LCD, which consist of LC compounds as a structural component, newly developed by JNC, show useful properties. 相似文献
5.
In this study, the chemical structures and physical property dependencies of the electro-optical properties were investigated in polymer-stabilized blue phase (BP) using the four kinds of 4-n-alkyloxy-4′-cyanobiphenyl (n-OCB) homologue chiral nematic LCs. It was confirmed that the optical response time and Kerr coefficient in polymer-stabilized BP was varied with the molecular parity as determined by the alkyl chain length of the n-OCB homologue chiral nematic LC mixtures. 相似文献
6.
E. V. Popova A. P. Fedoryako L. A. Kutulya V. P. Seminozhenko 《Crystallography Reports》2005,50(2):316-319
Electromechanical effect in various liquid crystalline phases—nematic, smectic A, and smectic C—is studied. It is shown that a liquid crystal (LC) sample in the nematic phase does not differ from an electromechanical converter containing an isotropic dielectric and exhibits no features characteristic of LCs at electromechanical conversion. A phenomenon similar to the piezoelectric effect may occur in ferroelectric LCs due to their biaxiality. 相似文献
7.
Keon-Soo Jang 《Molecular Crystals and Liquid Crystals》2016,633(1):123-128
We synthesized a series of 4′-hydroxy-[1,1′-biphenyl]-4-yl alkanoate with a potentially reactive functional hydroxyl group as a LC precursor, which facilitates reaction with other chemical groups to tailor biphenyl-based liquid crystals (LCs) for specific applications. Several liquid crystalline materials were also synthesized based on these LC precursors to show high probability to generate various potential LCs. With increasing chain length, the melting point decreased and Rf (retardation factor: migration distance of substance ÷ migration distance of solvent front) of the synthesized LC precursor increased. This LC precursor series provides a useful first synthesis step to design tunable biphenyl/ester-based LCs. 相似文献
8.
A novel homologous series of α-4-(4′-n-alkoxy cinnamoyloxy) phenyl β-2″-nitro, 3″–4″ di methoxy benzoyl ethylenes, H2n+1CnO?C6H4?CH?CH?COO?C6H4?CO?CH?CH?C6H2(NO2) (OCH3)2 (n = 1–8, 10, 12, 14, 16, 18) has been synthesized. All these compounds have been characterized by suitable spectroscopic techniques. C1 homologue is nonmesogenic, while C2 homologue shows enantiotropic nematogenic property and the rest of the homologous (C3?C18) displayed enantiotropically smectogenic plus nematogenic phase. Phase transition temperatures and textures of the LC phase were determined by an optical polarizing microscopy (POM) equipped with a heating stage. The mesomorphic properties of these compounds were confirmed by differential scanning calorimetry (DSC) analysis. 相似文献
9.
The synthesis and mesomorphic properties of a new series of 2,4-bis(4′-npentyloxybenzoyloxy)- benzylidine-4″ -n-alkoxyaniline (DC5An) are reported. The molecular structure of compounds was confirmed by FTIR, 1H-NMR, 13C-NMR, mass spectroscopy and elemental analysis. The mesomorphic properties were studied by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) measurements. All compounds of the series exhibit nematic (N) and smectic C (SmC) phases. The first four homologues (DC5A1-DC5A4) display a N mesophase, whereas the highest homologues (DC5A5-DC5A10) exhibit an enantiotropic dimorphism N and SmC phases. The mesomorphic properties of the present series are compared and discussed with other structurally related series. 相似文献
10.
B. T. Thaker B. S. Patel Y. T. Dhimmar D. B. Solnki N. J. Chothani N. B. Patel 《Molecular Crystals and Liquid Crystals》2013,570(1):98-113
Two new mesogenic homologous series of Schiff base esters, 2-[4-(4′-n-Alkoxy benzoyloxy) benzylidenamino] 3-cyno thiophine (Series-A) and Schiff base cinnamates, 2-[4-(4′-n-alkoxy cinnamoyloxy) benzylidenamino] 3-cyano thiophene (Series-B), comprising a thiophene moiety were synthesized. Structural elucidation was carried out using elemental analysis and spectroscopic techniques such as FT-IR, 1H-NMR and 13C-NMR, and mass spectrometry. The mesomorphic properties and thermal stabilities of the title compounds were studied by using differential scanning calorimetry and optical polarizing microscopy. All the derivatives are mesomorphic in nature showing the nematic phase, and the higher members of Series-A show a smectic C phase whereas Series-B exhibits only the nematic mesophase. The mesomorphic properties of the present series are compared with other structurally related compounds. 相似文献
11.
N. A. Anurova V. A. Blatov G. D. Ilyushin O. A. Blatova A. K. Ivanov-Shitz L. N. Demyanets 《Crystallography Reports》2008,53(6):930-936
A new method was developed for studying voids and channels in crystal structures based on the Voronoi-Dirichlet partition
of crystal space, and 822 structurally characterized ternary compounds Li
p
X
q
O
r
were analyzed for the first time. For these compounds, the dimensionality was determined and the migration patterns of channel
systems capable of providing lithium-ion transport were constructed. The calculated coordinates of lithium atoms in the centers
of the voids are consistent (within 0.4 ?) with the known structural data. Among these compounds, 113 compounds have infinite
channel systems, 60 compounds (18 structural types, STs) have been described earlier in the literature as solid electrolytes,
and 53 compounds (23 STs) can be considered as potential one-, two-, or three-dimensional ionic conductors (13, 3, and 7 STs,
respectively).
Original Russian Text ? N.A. Anurova, V.A. Blatov, G.D. Ilyushin, O.A. Blatova, A.K. Ivanov-Shitz, L.N. Dem’yanets, 2008,
published in Kristallografiya, 2008, Vol. 53, No. 6, pp. 987–993. 相似文献
12.
L. M. Blinov S. P. Palto V. V. Lazarev A. R. Geivandov S. G. Yudin 《Crystallography Reports》2006,51(5):843-849
An antiferroelectric liquid-crystal (LC) material formed of banana-shaped molecules in the sandwich metal-thin Langmuir-Blodgett
film-metal geometry, which is typical of solid-state technology, is investigated. Upon heating the thin-film elements, the
material passes to the high-temperature (68–127°C) LC B
2 phase, which, despite severe limitation on the film thickness (∼100 nm or less), exhibits antiferroelectric switching, which
was previously observed only in bulk samples (10 μm thick) of the LC studied. At film thicknesses smaller than ∼40 nm, ferroelectric
switching is observed, which is caused by the stabilization of the ferroelectric LC phase by the boundary surfaces. The largest
values of the switched polarization of films (∼400 nC/cm2) are comparable with the polarization of bulk samples. The coercive field increases with decreasing film thickness and reaches
∼106 V/cm for the thinnest films. This value corresponds to the intrinsic coercive field of the ferroelectric under conditions
of a strong surface effect, which suppresses domain processes.
Published in Russian in Kristallografiya, 2006, Vol. 51, No. 5, pp. 898–905.
Dedicated to the 60th Birthday of M.V. Kovalchuk
The text was submitted by the authors in English. 相似文献
13.
Vinay S. Sharma Rajesh H. Vekariya Anuj S. Sharma R. B. Patel 《Liquid Crystals Today》2017,26(3):46-54
In order to investigate the influence of the central linking group and the effect of flexibility on mesomorphism, we have synthesised a newly homologous series 3-(3-butoxyphenyl)-1-(4-n-alkoxy phenyl) prop-2-en-1-one (series-l) consisting of 13 homologues C1–C8, C10, C12, C14, C16 and C18. In the present series, mesophase commences from the C6 homologue. C1–C5 homologues did not exhibit liquid crystalline (LC) property, while C6–C12 homologues exhibited an enantiotropic nematic phase and the rest of the homologues C14–C18 displayed monotropic SmC and nematic mesophase. The transition temperatures of the synthesised compounds were determined by an optical polarising microscopy equipped with a heating stage. All newly synthesised compounds were confirmed by 1H-NMR, 13C-NMR, IR and elemental analysis. 相似文献
14.
A novel homologous series containing vinyl ester and azomethane central bridges and n-alkoxy as well as 3″,4″-dimethyl groups as flexible terminal/lateral groups viz. RO?C6H4?CH = CH?COO?C6H4?N?CH?C6H3-(CH3)2 have been synthesized and studied with a view to establishing the relation between molecular structure and thermotropic liquid crystal (LC) properties with reference to molecular flexibility within the series. The series consists of twelve homologues (C1 to C16). C6 and C7 homologues are smectogenic plus nematogenic and C8 to C16 homologues are only smectogenic, and the rest of the homologues (C1 to C5) are nonmesomorphic. Transition temperatures and the textures of the homologues were determined using an optical polarizing microscope equipped with a heating stage (POM). The textures of a nematic phase are threaded or Schlieren and that of a smectic phase are of the A or C type. Analytical, thermal and spectral data support the molecular structures. Smectic and nematic thermal stabilities are 116.85°C and 147.5°C, respectively. Whose Sm?N/I and N-I mesophase lengths are varied between 15°C to 21°C and 25°C to 62°C, respectively. The novel compounds are compared with structurally-similar series. 相似文献
15.
Nanoparticles (NPs) have emerged as extremely promising materials to alter and improve the properties of liquid crystals (LCs) used, for example, in device applications. In this paper, we summarise recent work from our lab that aims to provide a fundamental understanding of structure–property and composition–property relationships governing LC–NP interactions, which may point to new directions for major improvements in the efficiency of LCs used in display applications. A variety of LC hosts (phases) doped with surface-functionalised gold NPs have been systematically studied ranging from one-dimensionally ordered nematic over two-dimensionally ordered smectic to three-dimensionally ordered columnar phases. Significant progress with respect to LC–NP interactions was made for NP-doped nematic phases. Here, the observation of an unusual texture for Au NP-doped nematic LCs, that is, the formation of birefringent stripe textures and the induction of homeotropic alignment of the nematic LC similar to chiral finger (or fingerprint) textures, provided the basis for numerous experimental studies using Au NPs with different core sizes and surface functionalities. 相似文献
16.
A new double salt K2SiF6·KNO3 was found during determination of the solubility of K2SiF6 in aqueous potassium nitrate solutions. Unit cell parameters (P63/mmc, a = 5.6268(1) Å, c = 14.5186(6) Å, V = 398.09(2) Å3, Z = 2) and crystal structure have been determined. The compound is further characterized by RAMAN spectroscopy and X‐ray powder diffraction. Thermal properties were studied using DTA, DSC and in situ high‐ temperature X‐ray powder diffraction measurements. At 287 °C K2SiF6·KNO3 decomposes into its components KNO3 and K2SiF6 with an enthalpy of decomposition of about + 42 J·g‐1. Further thermal effects could be assigned to phase transformations of KNO3 whereby earlier literature data have been reconfirmed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
17.
Ali Jasim Hammood Ahmed Fadhel H. Kased Sameem R. Raseen Ivan Hameed R. Tomi Al-Ameen Bariz Omar Ali 《Molecular Crystals and Liquid Crystals》2017,648(1):114-129
A series of hydrophobic symmetrical azines: 1,2-bis[4-(n-alkoxy)benzylidene]hydrazine (where, n-alkoxy: O(CH2)nH, n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16, or 18) have been prepared following an efficient and practical method. These compounds have been synthesized via the condensation reaction of hydrazine hydrate and appropriately 4-(n-alkoxy) benzaldehydes in acidic medium under ambient conditions. The prepared organic compounds have been characterized and their structures were elucidated depending upon micro-elemental analysis and spectral data (IR, UV-Vis, 1HNMR, 13C{1H}NMR, 2D 1H-1H-cozy, 2D 1H-13C-HSQC, and mass spectra). Liquid crystalline behavior of the prepared compounds was studied using polarized light optical microscopy and differential scanning calorimetry techniques. This study revealed that all the compounds displayed enantiotropic liquid crystal properties, exhibiting smectic and nematic mesophases. 相似文献
18.
Three new series of mesogens have been synthesized by fixing 4-methoxy or 4-butoxy substituted phenyl ring in one side and 4-hydroxy, bromo or amino substituted phenyl group in the other side with different central linkage. The molecular structure of these series was confirmed by elemental analysis and FTIR and 1HNMR spectroscopy. The mesomorphic properties were studied by using differential scanning calorimetry (DSC) and optical polarizing microscopy (OPM). All the compounds of series [I] exhibit enantiotropic smectic B (SmB) phase. All the compounds of series [II] and [III] display SmB and nematic (N) phases. The mesomorphic properties were found to be dependent on the two terminal 4-substituted phenyl groups and the central linkage group. 相似文献
19.
Novel liquid crystal (LC) materials of ester derivatives were synthesized and studied with a view to understanding and establishing the effects of molecular structure on LC properties. The novel molecules consist of two phenyl rings bonded through –COO– central group and a laterally substituted methoxy group with –OCnH2n+1 as well as –COOCH3 terminal end groups, and yielded 12 homologous members of an ester series. The C1 to C3 members are nonmesomorphic, the C4 to C12 members are enantiotropic nematic only, and the C14 to C16 members are enantiotropically smectogenic in addition to nematogenic. Transition temperatures and the textures of LC state were observed through an optical polarizing microscope (POM) equipped with a heating stage. The textures of nematic phase are threaded or Schlieren, and that of smectic phase are focal conic of the type A or C. Transition curves of a phase diagram behave in normal manner with the exhibition of an odd-even effect (only N-I). Analytical and spectral data support the molecular structures of the novel ester derivatives. The LC properties of the present series are compared with structurally similar other known series. The average thermal stability of the series is 93°C for smectic and 120.88°C for nematic and the mesogenic phase length ranges between 2°C and 46°C. 相似文献
20.
M. L. Chauhan B. K. Patel S. N. Pandya A. V. Doshi 《Molecular Crystals and Liquid Crystals》2016,625(1):47-54
A novel ester homologous series of thermotropic liquid crystal (LC) has been studied with a view to understanding and establishing the relation between LC property and the molecular structure. The series consists of 11 members, the C1–C5 and C16 members of the series are nonliquid crystals. LC properties commence from the C6 homolog and continue up to the C14 homolog as enantiotropic nematic and smectic in addition to nematic. Transition temperatures of the homologs were determined by an optical polarizing microscope equipped with a heating stage. Textures of nematic phase are threaded or Schlieren and that of smectic is focal conic of the type-A. Analytical and spectral data confirm the structures of homologs. Thermal stability for nematic is 93 °C and 136 °C, respectively. The N–I and Sm–N transition curves of phase diagram do not exhibit odd-even effect. The N–I transition curve partly behaves in an abnormal manner. The Cr–I and Sm–N transition curves behave in normal manner. The LC behavior of the present series is compared with structurally similar known homologous series. 相似文献