Probing N-Heterocyclic Carbene Surfaces with Laser Desorption Ionization Mass Spectrometry
Probing N-Heterocyclic Carbene Surfaces with Laser Desorption Ionization Mass Spectrometry
复制标题
用激光解吸电离质谱法探测 N-杂环卡宾表面
DOI：
10.1021/acs.analchem.1c02401
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发表时间：
2021
影响因子：
7.4
通讯作者：
Camden, Jon P.
中科院分区：
文献类型：
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作者：
Dominique, Nathaniel L.;Strausser, Shelby L.;Olson, Jacob E.;Boggess, William C.;Jenkins, David M.;Camden, Jon P.
N-杂环卡宾 (NHC) 自组装单层 (SAM) 在金表面的增殖源于其与传统硫醇-SAM 相比卓越的稳定性。 NHC-SAM 在金上的生物应用前景表明需要评估 SAM 分子组成的生物相容性技术（例如大生物分子检测和高通量）。在此，我们证明激光解吸电离质谱 (LDI-MS) 是 NHC 表面化学的强大且简便的探针。原型咪唑-NHC-和苯并咪唑-NHC-功能化AuNPs 的LDI-MS 仅产生[NHC2Au]+ 离子，而不产生较大的金簇。利用苯并咪唑-NHC 同位素体，我们探讨了单层如何堆积在单个 AuNP 上以及 NHC 连接后的不稳定性。通过与代表随机单层的二项式模型进行比较，对同配体和异配体[NHC2Au] + 离子进行定量分析。最后，通过 LDI-MS 信号跟踪硝基-NHC-AuNP 还原为胺-NHC-AuNP，说明 LDI-MS 探测锚定 NHC 的合成后修饰的能力，这对于 NHC 表面当前和未来的应用至关重要。
The proliferation of N-heterocyclic carbene (NHC) self-assembled monolayers (SAMs) on gold surfaces stems from their exceptional stability compared to conventional thiol-SAMs. The prospect of biological applications for NHC-SAMs on gold shows the need for biocompatible techniques (e.g., large biomolecule detection and high throughput) that assesses SAM molecular composition. Herein, we demonstrate that laser desorption ionization mass spectrometry (LDI-MS) is a powerful and facile probe of NHC surface chemistry. LDI-MS of prototypical imidazole-NHC- and benzimidazole-NHC-functionalized AuNPs yields exclusively [NHC2Au]+ions and not larger gold clusters. Employing benzimidazole-NHC isotopologues, we explore how monolayers pack on a single AuNP and the lability of the NHCs once ligated. Quantitative analysis of the homoleptic and heteroleptic [NHC2Au]+ions is performed by comparing to a binomial model representative of a randomized monolayer. Lastly, the reduction of nitro-NHC-AuNPs to amine-NHC-AuNPs is tracked via LDI-MS signals, illustrating the ability of LDI-MS to probe postsynthetic modifications of the anchored NHCs, which is critical for current and future applications of NHC surfaces.