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The ever-present threat of the accidental or nefarious release of hazardous chemicals on civilian and military personnel highlights the need for rapid, standoff detection systems. Our research was motivated by a class of hydrogen-bond acidic sorbents that have shown tremendous potential for use as preconcentrator materials for organophosphorus-based chemical warfare agents (CWA). In this work, a series of functionalized bisphenol AF (BPAF)-based hydrogen-bond (HB) acidic sorbents were developed with the aim of providing highly selective and rapid-uptake vapor-collection materials for infrared or other standoff-based detection techniques. Quartz crystal microbalance (QCM) absorption studies of the nerve agent simulant, dimethyl methyl phosphonate (DMMP) revealed strong but reversible binding where gas–sorbent partition coefficients (K) greater than 1 × 108 (Log(K) >8) were observed. In addition, infrared spectroscopic techniques were used to evaluate the hydrogen-bonding characteristics of each sorbent in both dry air and upon exposure to nerve agent simulants vapors. Undesirable intermolecular sorbent–sorbent hydrogen bonding was eliminated in the BPAF sorbent containing bulky alkyl groups present at positions ortho- to the phenolic hydroxyls. Furthermore, we found that the BPAF-based sorbents exhibited unique infrared (IR) spectral signatures upon exposure to different chemicals, notably a characteristic redshift of the ν(O–H) mode, which was found to correlate to the hydrogen-bond basicity of the analyte vapor. By use of stand-off infrared-based sensing techniques coupled with the sorptive power of our hydrogen-bond acidic sorbents, we envision a simple path to the rapid detection of particularly hazardous chemicals with both class specificity as well as unique chemical identification capabilities.
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