Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry , Zhejiang University , Hangzhou 310027 , P. R. China.
J Am Chem Soc. 2019 Oct 2;141(39):15675-15683. doi: 10.1021/jacs.9b07836. Epub 2019 Sep 24.
Aliphatic carboxylates are the most common class of surface ligands to stabilize colloidal nanocrystals. The widely used approach to identify the coordination modes between surface cationic sites and carboxylate ligands is based on the empirical infrared (IR) spectroscopic assignment, which is often ambiguous and thus hampers the practical control of surface structures. In this report, multiple techniques based on nuclear magnetic resonance (NMR) and IR spectra are applied to distinguish the different coordination structures in a series of zinc-blende CdSe nanocrystals with unique facet structures, including nanoplatelets dominated with {100} basal planes, hexahedrons with only three types of low-index facets (i.e., {100}, {110}, and {111}), and spheroidal dots without well-defined facets. Interpretation and assignment of NMR and IR signals were assisted by density functional theory (DFT) calculations. In addition to the identification of facet-sensitive bonding modes, the present methods also allow a nondestructive quantification of mixed ligands.
脂肪族羧酸根是稳定胶体纳米晶体最常见的表面配体。广泛用于确定表面阳离子位点和羧酸配体之间配位模式的方法是基于经验性的红外（IR）光谱分配，这通常是模糊的，因此阻碍了表面结构的实际控制。在本报告中，应用了基于核磁共振（NMR）和 IR 光谱的多种技术来区分一系列具有独特面结构的闪锌矿 CdSe 纳米晶体中的不同配位结构，包括以 {100} 基面为主的纳米板、只有三种类型低指数面（即 {100}、{110} 和 {111}）的六面体和没有明确定义面的球形点。通过密度泛函理论（DFT）计算来辅助 NMR 和 IR 信号的解释和分配。除了识别对晶面敏感的键合模式外，本方法还允许对混合配体进行无损定量。
