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Excited state intramolecular proton transfer emission in bent core liquid crystals

Satapathy, Ashok K and Behera, Santosh Kumar and Kumar, Rajeev and Sandhya, K L and Yelamaggad, C V and Sahoo, Balaram (2018) Excited state intramolecular proton transfer emission in bent core liquid crystals. In: JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY, 358 . pp. 186-191.

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Official URL: http://dx.doi.org/ 10.1016/j.jphotochem.2018.03.02...

Abstract

We report the photophysics of two bent-core liquid crystals (BLCs), C56H67NO9 (BLC1) and C55H65NO9 (BLC2), containing a Schiff-base and two long alkyl chains at its two ends. The ground state dipole moment and the electronic structures of the BLCs were calculated using density functional theory (DFT). The dipole moments of the liquid crystals were estimated experimentally via solvatochromic shift of the absorption and fluorescence spectra. The dipole moments obtained experimentally are in quite good agreement with theoretically calculated values. In the fluorescence spectra of both the BLCs show an interesting feature, i.e., dual emission. This dual emission is explained via the presence of two tautomeric forms (keto and enol) of the BLCs in the excited state. The band at similar to 390-450 nm is assigned to the emission due to the keto-form, whereas the band at similar to 340-370 nm is due to the emission from the enol-form. Irrespective of the solvents used, the keto-band is more intense than the enol-emission-band. This intense emission from the keto-form of the tautomers is demonstrated via the excited state intramolecular proton transfer (ESIPT). From the time resolved fluorescence spectroscopy studies, a longer lifetime is obtained for the keto-band. The associated vibrational states observed in the emission spectrum are responsible for this longer lifetime. Our finding of the dual emissive nature of the liquid crystals in the visible range is potentially useful for high temperature liquid crystal display and sensing applications. (C) 2018 Elsevier B.V. All rights reserved.

Item Type: Journal Article
Additional Information: Copy right for this article belong to ELSEVIER SCIENCE SA, PO BOX 564, 1001 LAUSANNE, SWITZERLAND
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Depositing User: Id for Latest eprints
Date Deposited: 16 May 2018 15:57
Last Modified: 16 May 2018 15:57
URI: http://eprints.iisc.ac.in/id/eprint/59861

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