Sulfate is ubiquitous in nature and industry. Sulfate is the primary source of sulfur in the body, and sulfate deficiency can impact protein and enzyme function.1 In the remediation process of nuclear waste, the presence of sulfate is detrimental to the vitrification step, leading to larger volume and decreased stability of the treated waste. Attempts have been made to remedy this using common sulfate separation techniques, however, none have proved sufficient for implementation.2 Supramolecular chemists have envisioned the use of macrocycles and macromolecules in binding sulfate in aqueous environments for applications in sulfate sensing or extraction. This is a significant challenge due to the high hydration energy of sulfate, as well as its potential to present multiple protonation states.3 As such, very few receptors have been shown to interact strongly and selectively with sulfate in a competitive aqueous environment.
Sulfate receptors bearing squaramide groups have been gaining a lot of attention for their high affinity and selectivity for sulfate.4, 5 In this work we present a novel macrocyclic squaramide capable of strong interactions with sulfate, and a preference for sulfate over competing anions.
References
1 Leustek, T. The Arabidopsis Book/American Society of Plant Biologists, 2002, 1.
2 Custelcean, R.; Moyer, B. A. European Journal of Inorganic Chemistry, 2007, 2007 (10), 1321–1340.
3 Schaly, A.; Belda, R.; Garcia-Espana, E.; Kubik, S. Organic Letters, 2013, 15 (24), 6238–6241.
4 Qin, L.; Vervuurt, S. J.; Elmes, R. B.; Berry, S. N.; Proschogo, N.; Jolliffe, K. A. Chemical Science, 2020, 11 (1), 201–207.
5 Jing, L.; Deplazes, E.; Clegg, J. K.; Wu, X. Nature Chemistry, 2024, 16 (3), 335–342.