Ratiometric and Concomitant �Turn-Off/On� Luminescence Switch Based on Covalent-Organic Frameworks for Nitrated Explosive Sensing in Aqueous Media

Patra, BC and Datta, S and Bhattacharya, S (2024) Ratiometric and Concomitant �Turn-Off/On� Luminescence Switch Based on Covalent-Organic Frameworks for Nitrated Explosive Sensing in Aqueous Media. In: Chemistry of Materials .

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Abstract

Luminescent covalent-organic frameworks (LCOFs) have great potential toward sensing explosive nitroaromatic compounds (NACs). However, intrinsically weak fluorescence properties of the imine-bonded COFs limit their use as efficient explosive sensors. We report herein tetraphenylethylene-based LCOFs, TPEPy and TPEB, which show �turn-off� fluorescence sensing upon the addition of different NACs through an intermolecular charge-transfer (ICT) process. Surprisingly, the TPEPy COF showed a fluorescence switching from �turn-off� to �turn-on� mode upon the addition of the highly acidic NAC, 2,4,6-trinitrophenol (TNP). The presence of a pyrene moiety presumably plays a crucial role in the �turn-off/on� property. The addition of TNP leads to the protonation of the imine-bonded N atom, and the columnar �-stacking of the pyrene unit within the TPEPy COF gives rise to aggregate-induced enhanced luminescence, which dominates over the ICT process. This might be responsible for the fluorescence �turn-on� of the TPEPy COF, and there is a large hypsochromic shift of the fluorescence emission maximum from λmax = 530 to λmax = 420 nm. This change in the fluorescence emission passes through the near-white light emission with CIE coordinates of (0.27, 0.35) (CIE coordinates of ideal white emission is 0.33, 0.33). © 2024 American Chemical Society.

Item Type:	Journal Article
Publication:	Chemistry of Materials
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to the publisher.
Keywords:	Explosive actuated devices; Luminescence of solids; Organometallics; Pyrene, Charge transfer process; CIE coordinates; Covalent organic frameworks; Fluorescence emission; Intermolecular charge transfer; Luminescence switches; Nitroaromatic compound; Ratiometric; Trinitrophenol; Turn offs, Fluorescence
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	23 Oct 2024 01:26
Last Modified:	23 Oct 2024 01:26
URI:	http://eprints.iisc.ac.in/id/eprint/86624

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