This study aims at the synthesis of gold nanoparticles (2–3 nm) functionalized with different nitroalkane-terminated thiols and investigates the chemical reactivity of these confined nitroalkanes towards aldehydes to yield β-nitroalcohols. Interfacial Henry reaction between fixed nitroalkane-terminated thiols with various aromatic and heteroaromatic aldehydes resulted in stereogenic centers on the surface of mixed-monolayer-protected gold nanoparticles (MMPNs). The ratio of the resulting diastereomers was determined by 1H NMR spectroscopy. It was found that some parameters such as the chain length of nitroalkyl and the nature of aromatic aldehyde play the main role in affecting the diastereomeric ratio on the surface of MMPNs. Certain trends have been analyzed from the data, and it can be inferred that some aldehydes approximately prefer the formation of anti diastereomers as the predominant products, while others give syn β-nitroalcohols. We have attributed this stereoselectivity to the packed layers, forceful lateral interactions (van der Waals), and intramolecular hydrogen bonding on the surface of modified gold nanoparticles that are able to suppress the role of solvent and intermolecular interactions.

中文翻译：

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通过非对映选择性界面亨利反应表面诱导在金纳米粒子上形成立体中心：核磁共振研究

本研究旨在合成用不同硝基烷烃封端的硫醇官能化的金纳米粒子（2-3 nm），并研究这些受限的硝基烷烃对醛的化学反应性，以产生 β-硝基醇。固定的硝基烷烃封端硫醇与各种芳香和杂芳香醛之间的界面亨利反应导致混合单层保护的金纳米粒子 (MMPN) 表面上的立体中心。所得非对映异构体的比例通过1H NMR光谱测定。发现硝基烷基的链长和芳香醛的性质等参数在影响MMPNs表面的非对映体比例方面起主要作用。从数据中分析了某些趋势，并且可以推断出，一些醛类近似倾向于形成反非对映异构体作为主要产物，而另一些则生成顺式 β-硝基醇。我们将这种立体选择性归因于填充层、强有力的横向相互作用（范德华）和改性金纳米粒子表面的分子内氢键，它们能够抑制溶剂和分子间相互作用的作用。