Here we elucidate the âcooperative effectâ of carboxylic acid/amine on the size, shape, and multicolor output of fluoride upconversion nanoparticles (UCNPs) utilizing the amidation reaction. During the synthesis of NaYF4 UCNPs using oleic acid (OA) and octadecylamine (OM) as ligands, the evolution of the reaction solution was monitored by FT-IR and proton nuclear magnetic resonance (1H-NMR) spectroscopy. It is shown that N-octadecyloleamide (OOA) was formed and tightly bonded to the surface of the fluoride UCNPs. FT-IR and 1H-NMR analyses point towards a two-step OOA formation mechanism where OA initially reacted with OM to form an acidâbase complex (C17H33CO2â +NH3C18H37) in reaction mixture, which further transformed into OOA before the nucleation of fluoride UCNPs at elevated temperature. Importantly, we find that the interaction of OOA with the surfaces of the fluoride UCNPs was stronger than that of OM, and that OOA could strongly quench the green-emitting levels of excited Er3+ ions. A series of control experiments and analyses demonstrate that OOA was not only responsible for the control of the size and shape of NaYF4: 20% Yb, 2% Er UCNPs, but also for the multicolor tuning of them. Those observations reveal that the âcooperative effectâ between carboxylic acid and amine results from the amidation reaction and its product. This paper provides us with some new deep insights into the âcooperative effectâ of carboxylic acid and amine during the synthesis of inorganic nanoparticles under thermolysis. Furthermore, other lanthanide-ion doped fluoride UCNPs with controlled size, shape and multicolor output can also be obtained in the same way.
在此,我们利用酰胺化反应阐明了
羧酸/胺对
氟化物上转换纳米粒子(UCNPs)的尺寸、形状和多色输出的 "协同效应"。在以
油酸(OA)和
十八胺(OM)为
配体合成 NaYF4 UCNPs 的过程中,利用傅立叶变换红外光谱和质子核磁共振(1H-NMR)光谱监测了反应溶液的演变。结果表明,在
氟化物 UCNPs 表面形成了 N-
十八烷基酰胺(OOA)并与之紧密结合。傅立叶变换红外光谱(FT-IR)和 1H-NMR 分析表明,OOA 的形成机制分为两个步骤:OA 与 OM 首先发生反应,在反应混合物中形成酸碱复合物(C17H33CO2â +NH3C18H37),然后在高温下
氟化物 UCNPs 成核之前进一步转化为 OOA。重要的是,我们发现 OOA 与
氟化物 UCNPs 表面的相互作用强于 OM,并且 OOA 能强烈淬灭激发 Er3+ 离子的绿色发光
水平。一系列对照实验和分析表明,OOA 不仅能控制 NaYF4: 20% Yb, 2% Er UCNPs 的尺寸和形状,还能对其进行多色调谐。这些观察结果表明,
羧酸和胺之间的 "合作效应 "来自酰胺化反应及其产物。本文为我们提供了在热解条件下合成无机纳米粒子过程中
羧酸与胺的 "协同效应 "的一些新的深刻见解。此外,用同样的方法还可以获得其他掺杂
镧系离子的
氟化物超微纳米粒子,这些粒子具有可控的尺寸、形状和多色输出。