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Lessons learnt with Coordination Cages and Lanthanide Complexes: Decoding Host-Guest Chemistry for Catalysis and Analyte Detection

Abstract

For decades, scientists have been captivated by the extraordinary optical characteristics of lanthanide ions, recognising their potential for optical sensing applications. We have pioneered the development of luminescent lanthanide-based complexes tailored for detecting metal ions, nucleotides, and hydrogen sulfide in both aqueous solutions and gaseous states (see Fig. 1 a and b).^1,2 The careful design of these complexes ensures supramolecular interactions between host and guest, leading to a luminescence change from 'off' to 'on,' crucial for effective time-gated signal detection. This approach is extremely beneficial for sensing analytes in biological and environmental solutions, eliminating interference from short-lived fluorescence.

Additionally, with our collaborators, our research also explores highly charged coordination cages, probing their host-guest chemistry with small molecules and evaluating their potential to detect and detoxify toxic organophosphorus compounds. These cages have catalytic properties, facilitating hydrolysis reactions in aqueous solutions, due to presence of hydroxide anions that accumulate at the exterior surface of the cage (Fig. 1 c and d).^3,4

The presentation will highlight discoveries in both these areas, with specific emphasis on the fundamental host-guest chemistry underlying the responses observed. The challenges encountered, insights gained and pitfalls encountered along the way will also be discussed.

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Figure 1. a) the hydrogen sulfide sensing principle of a lanthanide-based sensor; (b) paper discs illuminated with a UV lamp showing the ‘on’ to ‘off’ to ‘on’ of the sensor in the presence of copper(II) ions and hydrogen sulfide; (c) a schematic of the cage; (d) space filling diagram showing the hollow cavity of the cage.

References

¹ P. Mini, M. A. Springer, M. R. Grace, G. H. Dennison, K. L. Tuck, Chem. Commun., 2020, 56, 5605.

² P. Mini, S E. Walker, M. R. Grace, G. H. Dennison, K. L. Tuck, Dalton Trans., 2023, 52, 12235.

³ J. C. Dorrat, R. J. Young, C. G. P. Taylor, M. B. Tipping, A. J. Blok, D. R. Turner, A. I. McKay, S. Ovenden, M. D. Ward, G. H. Dennison, K. L. Tuck, Dalton Trans., 2023, 52, 11802, and unpublished work.

⁴ J. C. Dorrat, C. G. P. Taylor, R. J. Young, A. B. Solea, D. Turner, G. H. Dennison, M. D. Ward, K. L. Tuck, Chemistry–A European Journal, 2024, e202400501.