Synthesis, Mesomorphism and Photoluminescence of a New Class of Anthracene-based Discotic Liquid Crystals

De, Joydip; Setia, Shilpa; Pal, Santanu Kumar

doi:10.1002/slct.201600717

Cited by 8 publications

(8 citation statements)

References 64 publications

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“…The synthesis started from the condensation of gallic acid in the presence of concentrated sulfuric acid to give 1,2,3,5,6,7-hexahydroxy anthraquinone 1 in good yield . The controlled alkylation of 1 with 1-bromalkanes in the presence of NaOH and DMSO gave the corresponding 1,5-dihydroxy-2,3,6,7-tetraalkoxyanthraquinones 2.1 – 2.5 . Ditriflification of compounds 2.1 – 2.5 was carried out with trifluoromethanesulfonic anhydride and pyridine at room temperature to get 2,3,6,7-tetrakis(alkyloxy)-9,10-dioxo-9,10-dihydroanthracene-1,5-diyl bis(trifluoromethanesulfonate) 3.1 – 3.5 .…”

Section: Resultsmentioning

confidence: 99%

Phase Behavior of a New Class of Anthraquinone-Based Discotic Liquid Crystals

Gupta

Bala

et al. 2017

Langmuir

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Five novel columnar liquid crystalline compounds (4.1-4.5) consisting of a central anthraquinone core carrying four alkoxy chains (R = n-CH, n-CH, n-CH, n-CH, and 3,7-dimethyl octyl) with two diagonally opposite 1-ethynyl-4-pentylbenzene units were synthesized, and their phase transitions were investigated between changes in the molecular structure and their self-assembly into the columnar mesophases. Small and wide-angle X-ray scattering (SAXS/WAXS) studies were performed to deduce the exact nature of the mesophases, and their corresponding electron density maps were derived from the intensities of the peaks observed in the diffraction patterns. A comparison of compounds with different alkoxy chains indicated that the soft crystal columnar rectangular (Cr) phase was stable at lower temperature for the shortest peripheral alkoxy chain (4.1; R = n-CH) and was found to exhibit the columnar hexagonal (Col) phase and then the discotic nematic (N) phase with increasing temperature. In contrast, increasing the peripheral chain length to n-CH or the branched one (4.2 and 4.5) stabilized the Col phase at lower temperature and showed the N phase at higher temperature. Further increase in chain length (4.3 and 4.4; n-CH, n-CH) demonstrated the formation of the N phase. Conductivity measurement in the Col mesophase was found to be almost 10 times higher in magnitude than the corresponding Cr phase. The HOMO-LUMO band gap of all the compounds was found to be in the range from 2.79 to 2.82 eV, which is quite less and comparable with the optical energy band gap.

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Section: Resultsmentioning

confidence: 99%

Phase Behavior of a New Class of Anthraquinone-Based Discotic Liquid Crystals

Gupta

Bala

et al. 2017

Langmuir

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“…The shearability of the textures in one direction has been shown at RT (Figure S9 a and b in the Supporting Information). An unspecific texture with the growth of smaller domains was displayed (Figure a) ,. The phase remained stable over a wide temperature range and was cleared at 106 °C with an enthalpy change (Δ H ) of 6.2 kJ mol −1 .…”

Section: Resultsmentioning

confidence: 99%

Room‐Temperature Columnar Nematic and Soft Crystalline Columnar Assemblies of a New Series of Perylene‐Centred Disc Tetramers

Bala

Gupta

et al. 2017

Chemistry A European J

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Three new oligomeric perylene (PE) tetraester derivatives, consisting of a PE-based core with four pentaalkynylbenzene units attached through flexible alkyl spacers, are reported. These derivatives were investigated for their mesomorphic properties and thermal, photophysical, and electrochemical behaviour. Small- (SAXS) and wide-angle X-ray scattering (WAXS) studies were performed to deduce the exact nature of the phases. To resolve overlapping reflections and facilitate their indexing, grazing-incidence SAXS/WAXS experiments were carried out on oriented thin films on indium tin oxide (ITO)-coated glass substrate. The corresponding electron density maps were derived from the intensities observed in the diffraction pattern. Whereas compounds with shorter alkyl spacers (n=6 and 8) were found to self-organise into soft crystalline columnar assemblies, those with longer spacers (n=10) exhibited a liquid-crystalline columnar nematic mesophase. This is in contrast to previous reports that describe highly symmetric 2D hexagonal and rectangular columnar structures of PE-based mesogens. The morphology of self-assembly was found to transform from soft crystal columnar to nematic columnar phase through simple variation in the number of alkyl spacers. All compounds exhibited excellent fluorescence emission properties with a very good quantum yield and large band gap. Apart from high solubility and good quantum yield, these compounds can serve as standards to measure quantum yields of unknown samples. These compounds also display green luminescence and may find applications for various optoelectronic devices.

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“…In 2016, Pal and co-workers prepared five new substituted anthracene derivatives 68 containing six alkyl chains ( Scheme 15 ) [ 48 ]. The authors synthesized hexahydroxyanthraquinone 65 and modified the functional groups in compound 65 and its derivative 66 according to reported methods.…”

Section: Reviewmentioning

confidence: 99%

“…The authors synthesized hexahydroxyanthraquinone 65 and modified the functional groups in compound 65 and its derivative 66 according to reported methods. Although other methodologies were available, the authors chose to employ lithium aluminum hydride (LAH) to reduce the substituted anthraquinones 67 to the corresponding anthracenes 68 , to obtain very good yields (81–90%) [ 48 ].…”

Section: Reviewmentioning

confidence: 99%

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Recent advances in the syntheses of anthracene derivatives

Baviera

Donate

2021

Beilstein J. Org. Chem.

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Anthracene and anthracene derivatives have been extensively studied over the years because of their interesting photophysical, photochemical, and biological properties. They are currently the subject of research in several areas, which investigate their use in the biological field and their application in OLEDs, OFETs, polymeric materials, solar cells, and many other organic materials. Their synthesis remains challenging, but some important preparative methods have been reported, especially in the last decade. This review presents an update of the recent strategies that have been employed to prepare anthracene derivatives. It encompasses papers published over the last twelve years (2008–2020) and focuses on direct and indirect methods to construct anthracene and anthraquinone frameworks.

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Synthesis, Mesomorphism and Photoluminescence of a New Class of Anthracene-based Discotic Liquid Crystals

Cited by 8 publications

References 64 publications

Phase Behavior of a New Class of Anthraquinone-Based Discotic Liquid Crystals

Phase Behavior of a New Class of Anthraquinone-Based Discotic Liquid Crystals

Room‐Temperature Columnar Nematic and Soft Crystalline Columnar Assemblies of a New Series of Perylene‐Centred Disc Tetramers

Recent advances in the syntheses of anthracene derivatives

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