Lewis acid-assisted detection of nerve agents in water

Abstract

The five-coordinate compound, Salen((t)Bu)Al(Ac), prepared in situ from Salen((t)Bu)AlBr and NH4Ac, forms Lewis acid-base adducts in aqueous solution with the G-type nerve agents, Sarin and Soman, and the VX hydrolysis product, ethylmethylphosphonate (EMPA). The resulting compounds, [Salen((t)Bu)Al(NA)](+)[Ac] (-) (with NA = Sarin, Soman, and EMPA) are sufficiently stable to be identified by ESI-MS. Molecular ion peaks were detected for every compound with little or no fragmentation. The distinctive MS signatures for the [Salen((t)Bu)Al(NA)](+) compounds provide a new technique for identifying nerve agents from aqueous solution. The energetics of the displacement of Ac(-) by the nerve agents to form [Salen((t)Bu)Al(NA)](+)[Ac](-) were determined computationally.

Group 13 Complexes of Chelating N2O2n− Ligands as Hybrid Molecular Materials

“…The Atwood group developed a strategy for the detection of these nerve agents based on the versatile coordination chemistry of aluminum supported by an N 2 O 2 2− Salen ligand [ N , N′ ‐alkylene bis(3,5‐di‐ tert ‐butylsalicylideneimine)] in aqueous solution using electrospray ionization mass spectrometry (ESI‐MS) (Figure ) . SalenAlBr complex 8 was transformed to the bis‐aqua adduct 9 in aqueous solution via loss of the bromide anion.…”

“…Group 13 complexes of N 2 O 2 nÀ ligands have shown utility in sensing applicationsa nd for the detection of small molecules. Examples can be classified into two categories, those where the N 2 O 2 nÀ ligands modulate reactivity at the group 13 element allowing for adducts to be formed and detected, [7,11] and those that exploit changes in the physical properties of group 13 complexes of N 2 O 2 nÀ ligands upon interaction with small molecules. [3][4][5][6][8][9][10] Nerve agents such as Sarin and VX are organophosphonate derivatives that irreversibly bind to the catalytic site of acetylcholinesterase, ane nzyme that hydrolyzes the neurotransmitter acetylcholine.…”

“…The Atwoodg roup developed as trategy for the detection of these nerve agents based on the versatile coordination chemistry of aluminum supported by an N 2 O 2 2À Salen ligand [N,N'-alkylene bis(3,5-ditert-butylsalicylideneimine)] in aqueouss olution using electrospray ionization mass spectrometry (ESI-MS) ( Figure 3). [7] SalenAlBr complex 8 [26] was transformed to the bis-aquaa dduct 9 in aqueous solution via loss of the bromidea nion.T he key species for nerve agent detection was formed via reaction of the six-coordinate complex 9 with ammonium acetate, to form the five-coordinate acetate adduct 10. While computational studies showed that the displacemento ft he acetate group from the complex by the nerve agentsw as not energetically favorable, the authors postulated that this reaction was driven by the hydrophobicity of the nerve agents themselves.…”

“…In this concept article, we focus on selectede xamples of group 13 complexes of N 2 O 2 nÀ ligands with unusual chirality, [1,2] sensing/detection capabilities, [3][4][5][6][7][8][9][10][11] utility in organic electronics, [12][13][14][15] and redox activity. [16,17] The use of N 2 O 2 nÀ ligands in main group coordination chemistry affords opportunitiestoexploit the chelate effect, and often results in the production of stable and robust complexes.T he addition of nitrogen/oxygen atoms to p-conjugated ligands can lead to extended electronic delocalization and stabilized frontier orbitals in the resulting complexes.G roup 13 elements are advantageous in this context as they can promote rigidity and induce chirality when coordinated to N 2 O 2 nÀ ligandsv ia strong covalent bonds to oxygen and nitrogen.…”

Nerve Gas Simulant Sensing by a Uranyl–Salen Monolayer Covalently Anchored on Quartz Substrates

“…[53,55,56,58] Recently,a ni mportants upramolecular-basedr ecognition of the DMMP by using ac avitand anchored onto ap orous silicon surfaceh as been reported. [68] In light of the supramolecular advantages,h erein we report on the first example of uranyls alen complexes able to recognizeD MMP through noncovalent interactions in solution. [64][65][66][67] Also, an excellent study was proposed by Atwood and co-workers, who used as alenaluminumc omplex as ap robe for the sarin ands oman Lewis base nerve agents in aqueous solution by ESI-MS experiments.…”