Hydrogen-bonding interactions in crown-(thio)urea complexes with anions, chemical warfare agents and simulants

ABSTRACT

Benzocrown ethers incorporating phenyl and nitrophenyl urea and thiourea moieties were synthesised. Both the nitrophenyl urea and thiourea derivative gave a fluoride-specific colorimetric response but only the urea derivative bound the organophosphonate nerve agent simulants dimethyl methylphosphonate (DMMP) and diisopropyl methylphosphonate (DIMP). This suggested an application as sensors for the nerve agents sarin, soman and cyclosarin which release fluoride upon hydrolysis. Although no fluoride-induced response was observed in the UV-visible spectrum, binding to soman was determined by ¹H NMR. DFT computational simulations suggested that the two crowns adopt different conformations in which both can bind fluoride but only the urea derivative can bind DMMP, DIMP and soman. The results show that, for this system, simulant- and soman-binding behaviours are in good agreement.

Graphical Abstract

KEYWORDS:

• Chemical warfare agents
• simulants
• macrocycles
• colorimetric sensors
• hydrogen bonding

Acknowledgments

PJC thanks the US Army Research Office (Contract W911NF-15-1-0624) for funding computational chemistry resources. MRS thanks Dr James Jones and Dr Rebecca Williams (Dstl) and the CBR Division NMR facility for NMR support.

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Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

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Additional information

Funding

This work was supported by the US Army Research Office [W911NF-15-1-0624].