Heterocyclic benzoxazole-based liquid crystals: Synthesis and mesomorphic properties

Ha, Sie‐Tiong; Foo, Kok Leei; Subramaniam, Ramesh; Ito, Masato; Sastry, S. Sreehari; Ong, Siew Teng

doi:10.1016/j.cclet.2011.05.017

Cited by 3 publications

(5 citation statements)

References 34 publications

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“…Peaks at = 159.16 ppm further confirmed the presence of azomethine carbon and it is compatible with the value as stated in the literature [17]. Meanwhile, peaks at = 160.21 and 172.45 ppm indicated the presence of two carbonyl ester groups in the molecule [10,17].…”

Section: Resultssupporting

confidence: 89%

“…The synthetic protocol towards the title compounds, 4-(((4-n-alkanoyloxyphenyl)imino)methyl)phenyl thiophene-2-carboxylate (where = 6, 8, 10,12,14,16,18), is illustrated in Scheme 1.…”

Section: Synthesismentioning

confidence: 99%

“…New mesogens with heterocyclic compounds such as benzothiazole [6,8,9], benzoxazole [10], 1,2,4-oxadiazole [11], pyrimidine [12], and pyrazole [13] had attracted the interest of scientists, as the insertion of heteroatom will strongly influence the formation of mesomorphic phases. These heterocyclic structures generally incorporate unsaturated atoms, such as O, N, or S, and due to the high electronegativity of these atoms, it often results in reduced symmetry of the molecules and creates a stronger polar induction.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

New Homologues Series of Heterocyclic Schiff Base Ester: Synthesis and Characterization

Chong

Sarih

et al. 2016

Advances in Physical Chemistry

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A homologous series of liquid crystal bearing with heterocyclic thiophene Schiff base ester with alkanoyloxy chain (CH3(CH2)nCOO–, where n=4, 6, 8, 10, 12, 14, 16) was successfully synthesized through the modification of some reported methods. The structural information of these compounds was isolated and characterized through some spectroscopic techniques, such as FTIR, 1H, and 13C NMR and elemental analysis. Textural observation was carried out using a polarizing optical microscope (POM) over heating and cooling cycles. It was found that all synthesized compounds (3a–g) exhibited an enantiotropic nematic phase upon the heating and cooling cycle with high thermal stability. Moreover, a characteristic bar transition texture was observed for compounds 3f and 3g which have shown transition of nematic-to-smectic C phase. This has been further confirmed by obtaining relative phase transition temperature using the differential scanning calorimetry (DSC).

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Section: Resultssupporting

confidence: 89%

“…The synthetic protocol towards the title compounds, 4-(((4-n-alkanoyloxyphenyl)imino)methyl)phenyl thiophene-2-carboxylate (where = 6, 8, 10,12,14,16,18), is illustrated in Scheme 1.…”

Section: Synthesismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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New Homologues Series of Heterocyclic Schiff Base Ester: Synthesis and Characterization

Chong

Sarih

et al. 2016

Advances in Physical Chemistry

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“…Since then a number of methods for the synthesis of imines have been described [ 6 , 7 , 8 , 9 ]. Schiff bases have been drawing considerable attention due to their potential application in many areas such as liquid crystals [ 10 , 11 , 12 , 13 ], organic dyes [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ], catalysts [ 22 , 23 , 24 ], and intermediates in organic synthesis [ 25 , 26 , 27 , 28 , 29 , 30 ]. Moreover, many Schiff bases exhibit a broad range of biological activities [ 31 , 32 , 33 , 34 , 35 ].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, X-ray Structure, Spectroscopic Properties and DFT Studies of a Novel Schiff Base

Chen

Tsai

2014

IJMS

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A series of Schiff bases, salicylideneaniline derivatives 1–4, was synthesized under mild conditions and characterized by 1H NMR, HRMS, UV-Vis and fluorescence spectra, and single-crystal X-ray diffraction. In solid and aprotic solvents 1–4 exist mainly as E conformers that possess an intramolecular six-membered-ring hydrogen bond. A weak intramolecular C–H···F hydrogen bond is also observed in fluoro-functionalized Schiff base 4, which generates another S(6) ring motif. The C–H···F hydrogen bond further stabilizes its structure and leads it to form a planar configuration. Compounds 1–3 exhibit solely a long-wavelength proton-transfer tautomer emission, while dipole-functionalized Schiff base 4 shows remarkable dual emission originated from the excited-state intramolecular charge transfer (ESICT) and excited-state intramolecular proton transfer (ESIPT) states. Furthermore, the geometric structures, frontier molecular orbitals (MOs) and the potential energy curves for 1–4 in the ground and the first singlet excited state were fully rationalized by density functional theory (DFT) and time-dependent DFT calculations.

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“…The linking group is one of the determining factors that influences whether the target compound will exhibit a smectic phase instead of a nematic phase. The ester linking group generally favours lamellar packing due to the dipole-dipole interaction, which ultimately generates the smectic phase [22]. In the case of PPPABCn, conjugation over the entire molecule was achieved between the enone linking group and pyridyl core system, which led to expression of the smectic phase.…”

Section: Mesomorphic Behaviourmentioning

confidence: 99%

Synthesis and mesomorphic properties of new heterocyclic liquid crystals with Central Ester–Chalcone linkages

Lim

Yeap

et al. 2017

Journal of Taibah University for Science

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A series of new calamitic liquid crystals, 4-[3-(pyridin-4-yl)prop-2-enoyl]phenyl 4-alkyloxybenzoates, comprising a pyridyl core, ester-chalcone central linkage and terminal alkyloxy chain were synthesized and characterized. This series consists of four members that differ by the length of the alkyloxy chain (C n H 2n+1 O , where n = 10, 12, 14, 16). The structures of the title compounds were elucidated using spectroscopic and spectrometric techniques, such as FT-IR, NMR (1 H and 13 C) and EI-MS. The mesomorphic properties were studied using differential scanning calorimetry and optical polarizing microscopy. The decyloxy-containing compound was found to be non-mesogenic, whilst the compounds containing n-dodecyloxy to n-hexadecyloxy chains exhibited an enantiotropic smectic A phase with a fan-shaped texture. From the structure-property relationship study, it was proposed that the number of carbons in the alkyloxy chain must be at least 12 (n ≥ 12) to generate the smectic phase in the corresponding substituted ArCOOArCOCH CHC 5 H 4 N compounds.

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Heterocyclic benzoxazole-based liquid crystals: Synthesis and mesomorphic properties

Cited by 3 publications

References 34 publications

New Homologues Series of Heterocyclic Schiff Base Ester: Synthesis and Characterization

New Homologues Series of Heterocyclic Schiff Base Ester: Synthesis and Characterization

Synthesis, X-ray Structure, Spectroscopic Properties and DFT Studies of a Novel Schiff Base

Synthesis and mesomorphic properties of new heterocyclic liquid crystals with Central Ester–Chalcone linkages

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