The ability to rapidly detect, identify, and monitor chemical warfare agents (CWAs) is imperative for both military and civilian defense. Since most CWAs and their simulants have an organophosphonate group, which is a hydrogen (H)-bond acceptor, many H-bond donors have been developed to effectively bind to the organophosphonate group. Although thioureas have been actively studied as an organocatalyst, they are relatively less investigated in CWA detection. In addition, there is a lack of studies on the structure–property relationship for gas phase detection. In this study, we synthesized various thioureas of different chemical structures, and tested them for sensing dimethylmethylphosphonate (DMMP), a CWA simulant. Molecular interaction between DMMP and thiourea was measured by ¹H NMR titration and supported by density functional theory (DFT) calculations. Strong H-bond donor ability of thiourea may cause self-aggregation, and CH−π interaction can play an important role in the DMMP detection. Gas-phase adsorption of DMMP was also measured using a quartz crystal microbalance (QCM) and analyzed using the simple Langmuir isotherm, showing the importance of structure-induced morphology of thioureas on the surface.

中文翻译：

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硫脲对化学战剂模拟物检测的结构作用

快速检测，识别和监视化学战剂（CWA）的能力对于军事和民防都至关重要。由于大多数CWA及其模拟物都具有有机膦酸酯基团，该基团是氢（H）键受体，因此已开发出许多H键供体来有效结合有机膦酸酯基团。尽管已经对硫脲作为有机催化剂进行了积极的研究，但在CWA检测中对硫脲的研究相对较少。另外，缺乏用于气相检测的结构-性质关系的研究。在这项研究中，我们合成了具有不同化学结构的各种硫脲，并对其进行了测试，以检测CWA模拟物二甲基甲基膦酸酯（DMMP）。DMMP和硫脲之间的分子相互作用通过¹进行测量1 H NMR滴定并由密度泛函理论（DFT）计算支持。硫脲的强H键供体能力可能引起自聚集，并且CH-π相互作用在DMMP检测中起重要作用。还使用石英晶体微量天平（QCM）测量了DMMP的气相吸附，并使用简单的Langmuir等温线进行了分析，表明表面上硫脲的结构诱导形态非常重要。