Copper nanoparticles (Cu NPs) were synthesized using NaBH₄ as reducing agent and increasing molar ratios of 50 % PEGylated polyamidoamine dendrimer of the third generation (PEG-PAMAM-G3) as a capping agent. The dendrimer-stabilized Cu NPs were evaluated as novel catalysts for the reduction of poorly soluble nitrocompounds in aqueous media. The nanocatalysts were characterized using transmission electron microscopy (TEM), ultraviolet-visible light (UV-vis) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and dynamic light scattering (DLS). UV-vis revealed the presence of localized surface resonance plasmon at 560 nm, whereas TEM analysis confirmed disperse and spherical Cu NPs of around 2.6-3.7 nm. The catalysts were successfully tested in the efficient aqueous reduction of 4-(4-nitrophenyl)-morpholine as model low solubility substrate using NaBH₄ as reducing agent. The best catalytic performance was attained by the catalyst having a PAMAM:Cu ratio of 0.4, which retained its activity throughout four catalytic cycles. The catalyst was also efficient in the aqueous reduction of two pharmaceutically relevant building blocks such as 4-(2-fluoro-4-nitrophenyl)morpholine) and 4-(4-nitrophenyl)morpholin-3-one. Our results suggest that PEG-PAMAM-G3 prevents Cu NPs agglomeration and flocculation, and enhances their stability in aqueous solution thus enabling their use in environmentally friendly catalytic processes.

使用NaBH ₄合成铜纳米颗粒（Cu NPs）作为还原剂，增加第三代50％聚乙二醇化聚酰胺型胺树枝状大分子（PEG-PAMAM-G3）作为封端剂的摩尔比。树枝状大分子稳定的铜纳米颗粒被评估为减少水性介质中难溶性硝基化合物的新型催化剂。使用透射电子显微镜（TEM），紫外可见光（UV-vis）光谱，核磁共振（NMR）光谱和动态光散射（DLS）对纳米催化剂进行了表征。紫外可见显示在560 nm处存在局部表面共振等离激元，而TEM分析证实分散和球形Cu NP约为2.6-3.7 nm。使用NaBH ₄成功地测试了催化剂在4-（4-硝基苯基）-吗啉作为模型低溶解度底物的有效水性还原中的能力作为还原剂。通过具有0.4的PAMAM∶Cu比的催化剂获得最佳的催化性能，该催化剂在四个催化循环中保持其活性。该催化剂在两种药物相关的结构单元如4-（2-氟-4-硝基苯基）吗啉和4-（4-硝基苯基）吗啉-3-酮的水性还原中也是有效的。我们的结果表明，PEG-PAMAM-G3可防止Cu NP的团聚和絮凝，并增强其在水溶液中的稳定性，从而使其可用于环境友好的催化过程。