Turn-off luminescence sensing, white light emission and magnetic studies of two-dimensional lanthanide MOFs

Manna, K and Sutter, J-P and Natarajan, S (2023) Turn-off luminescence sensing, white light emission and magnetic studies of two-dimensional lanthanide MOFs. In: Dalton Transactions, 52 (48). pp. 18449-18463.

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Abstract

The lanthanide metal organic framework compounds Ln(BPTA)1.5(Bpy)·0.5DMF (Ln = Y, Eu, Gd, Tb, Dy; 1a-5a) and Ln(BPTA)1.5(Phen)·0.5DMF (Ln = Y, Eu, Gd, Tb, Dy; 1b-5b) were prepared by employing 2,5-bis(prop-2-yn-1-yloxy)terephthalic acid (2,5-BPTA) as the primary ligand and 2,2�-bipyridine (1a-5a) and 1,10-phenanthroline (1b-5b) as the secondary ligands. Single-crystal structural studies on Gd(BPTA)1.5(Bpy)·0.5DMF (3a) and Dy(BPTA)1.5(Phen)·0.5DMF (5b) indicated that the compounds have a two-dimensional structure. The Y compound exhibits blue emission, and the other compounds exhibit emission in the expected regions (λex = 350 nm). White light emission was achieved by careful mixing of the red (Eu3+) and green (Tb3+) components in the blue emitting Y compound. Thus, Y0.96Tb0.02Eu0.02 (bpy) and Y0.939Tb0.06Eu0.001 (phen) were found to show white emission when excited using a wavelength of 350 nm. The introduction of N-N-containing ancillary ligands (i.e., bpy and phen) increased the overall quantum yield (QY) of white light emission to 31% and 43%, respectively. The high QY observed for the Tb and Eu compounds was found to be sensitive and selective for the fluorometric detection of azinphos-methyl pesticide and trinitrophenol (TNP) in an aqueous medium at the ppb level. The same behaviour was observed when utilising the compounds as onsite paper strip sensors. Their magnetic properties were also studied, revealing for the Tb and Dy derivatives slow relaxation of the magnetisation at low temperature. The present study highlights the usefulness of rigid �-conjugated molecules such as 2,2�-bipyridine and 1,10-phenanthroline in enhancing the many utilities of rare-earth-containing MOFs towards white light emission, the sensing of harmful and dangerous substances and magnetic properties. © 2023 The Royal Society of Chemistry.

Item Type:	Journal Article
Publication:	Dalton Transactions
Publisher:	Royal Society of Chemistry
Additional Information:	The copyright for this article belongs to Royal Society of Chemistry.
Keywords:	Crystal structure; Crystalline materials; Dysprosium compounds; Europium compounds; Ligands; Metal-Organic Frameworks; Organic polymers; Single crystals; Temperature; Terbium compounds, Bipyridines; Magnetic studies; Metal-organic framework compounds; Phenanthrolines; Secondary ligands; Terephthalic acids; Turn offs; Two-dimensional; White light emission; Y compounds, Rare earth elements
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	01 Mar 2024 05:36
Last Modified:	01 Mar 2024 05:36
URI:	https://eprints.iisc.ac.in/id/eprint/83804

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