Structural Study of Citrate Layers on Gold Nanoparticles: Role of Intermolecular Interactions in Stabilizing Nanoparticles
Structural Study of Citrate Layers on Gold Nanoparticles: Role of Intermolecular Interactions in Stabilizing Nanoparticles
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DOI：
10.1021/ja4097384
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发表时间：
2014-02-05
影响因子：
15
通讯作者：
Shumaker-Parry, Jennifer S.
中科院分区：
文献类型：
--
作者：
Park, Jong-Won;Shumaker-Parry, Jennifer S.
研究了柠檬酸盐在金纳米粒子上的吸附结构。红外（IR）和X射线光电子能谱（XPS）分析表明，柠檬酸根阴离子通过中心羧酸基团吸附在AuNP上。确定了吸附柠檬酸盐的独特结构，并提出了pH诱导的结构转变。红外光谱分析探测了悬挂的二氢阴离子（H（2）柠檬酸盐（-））和吸附的和悬挂的柠檬酸盐阴离子之间的羧酸基团的氢键。柠檬酸盐层之间的空间排斥粒子的稳定性的贡献的特点。基于结构的建模与文献中的扫描隧道显微镜（STM）和透射电子显微镜（TEM）图像一致，表明了与AuNP（111），（110）和（100）表面上自组装层形成相关的组织细节。柠檬酸盐层的吸附特性包括氢键柠檬酸盐链之间的相互作用、双层形成、表面覆盖和手性。讨论了分子间相互作用的吸附增益和分子结构/对称性对吸附的重要性。结合表面扩散和（1，2）-二羧基片段在Au（111）上的吸附几何学的双折射因子，H（2）柠檬酸根（-）阴离子有效地稳定了AuNPs的（111）表面。分子吸附层中分子间相互作用的详细了解为纳米颗粒的形成和稳定提供了见解。我们希望这些发现将是相关的其他纳米粒子稳定的羟基羧酸基氨基酸，并在NP为基础的界面研究和应用具有广泛的影响。
The structure of citrate adlayers on gold nanoparticles (AuNPs) was investigated. Infrared (IR) and X-ray photoelectron spectroscopy (XPS) analyses indicate citrate anions are adsorbed on AuNPs through central carboxylate groups. A unique structure of adsorbed citrate is determined, and a pH-induced structural transition is presented. IR analysis probes dangling dihydrogen anions (H(2)Citrate(-)) and hydrogen bonding of carboxylic acid groups between adsorbed and dangling citrate anions. A contribution of steric repulsion between citrate layers to particle stability is characterized. Structure-based modeling, which is consistent with scanning tunneling microscopy (STM) and transmission electron microscopy (TEM) images in the literature, suggests organization details relating to the formation of self-assembled layers on (111), (110), and (100) surfaces of AuNPs. Adsorption characteristics of the citrate layer include the interaction between hydrogen-bonded citrate chains, bilayer formation, surface coverage, and chirality. The enthalpic gain from intermolecular interactions and the importance of molecular structure/symmetry on the adsorption are discussed. Combining the enthalpic factor with surface diffusion and adsorption geometry of (1,2)-dicarboxyl fragments on Au(111), H(2)Citrate(-) anions effectively stabilize the (111) surface of the AuNPs. The detailed understanding of intermolecular interactions in the molecular adlayer provides insight for nanoparticle formation and stabilization. We expect these findings will be relevant for other nanoparticles stabilized by hydroxy carboxylate-based amino acids and have broad implications in NP-based interfacial studies and applications.