Chiral Eu(III) triple stranded dimetallic helicates: structural and luminescent properties Oxana Kotova 1,2 , Deirdre McAdams 1 , Patrycja Stachelek 3 , Jonathan A. Kitchen 1 , Chris Hawes 1 , Helen M. O’Connor 1 , Manuel Ruether 1 , Brendan Twamley 1 , Robert Pal 3 and Thorfinnur Gunnlaugsson 1,2* 1 School of Chemistry, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland, 2 AMBER (Advanced Materials and Bioengineering Research) Centre, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland, 3 Department of Chemistry, Durham University, South Road, Durham DH1 3LE, UK e-mail: kotovao@tcd.ie, gunnlaut@tcd.ie The interest in luminescent lanthanide(III)-based triple-stranded di-metallic helical motif systems stems from their structural organization resembling biological molecules and their potential use as materials in bio-, electronics, or environmental applications. [1] Since the ligand design principles leading to the formation of the helical structures with d -metal ions were established researchers also investigated the formation of analogous structures with lanthanides. In our research group, we based the ligand design on connecting two chiral half-helicate ligands either ( S ) or ( R ) 6-((1-(naphthalen-2-yl)ethyl)carbamoyl)picolinic acid through 4,4'-methylenedianiline spacer following on the previously discovered data. [2] In the current work, we investigated the formation of di-metallic Eu(III) triple stranded helicates (Figure 1) in the solution using NMR, mass-spectrometry, luminescence spectroscopy including circularly polarised luminescence (CPL) as well as single crystals X-ray crystallography techniques in the solid state.
Figure 1. (A) Self-assembly of Eu(III) helicates showing the crystal structure of L and Eu 2 L 3 with their red emission in CH 3 CN under UV light (λ ex = 365 nm); (B) Eu(III)-centred emission of Eu 2 L 3 (l ex = 283 nm) and (C) CPL emission spectra of D,D-(blue) and L,L-(red) enantiomers of Eu 2 L 3 (l ex = 300 nm). This work was supported by the SFI AMBER Center [12/RC/ 2278_P2]. References 1. D. E. Barry, D. F. Caffrey and T. Gunnlaugsson, Chem. Soc. Rev. 2016 , 45 , 3244–3274. 2. (a) F. Stomeo, C. Lincheneau, J. P. Leonard, J. E. O'Brien, R. D. Peacock, C. P. McCoy, T. Gunnlaugsson, J. Am. Chem. Soc. 2009 , 131(28) , 9636–9637; (b) S. Comby, F. Stomeo, C. McCoy, T. Gunnlaugsson, Helv. Chim. Acta 2009 , 92 , 2461–2473; (c) C. Lincheneau, R. D. Peacock, T. Gunnlaugsson, Chem. Asian J. 2010 , 5 , 500–504; (d) O. Kotova, S. Comby, K. Pandurangan, F. Stomeo, J. E. O'Brien, M. Feeney, R. D. Peacock, C. P. McCoy and T. Gunnlaugsson, Dalton Trans. 2018 , 47 , 12308–12317; (e) D. E. Barry, J. A. Kitchen, K. Pandurangan, A. J. Savyasachi, R. D. Peacock, T. Gunnlaugsson, Inorg. Chem. 2020 , 59(5) , 2646–2650.
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