Itteboina Ramakrishna, Madhuri U Divya, Ghosal Partha, Kannan Monica, Sau Tapan K, Tsukuda Tatsuya, Bhardwaj Shweta
CCNSB, International Institute of Information Technology-Hyderabad , Gachibowli, Hyderabad 500032, India.
School of Chemistry, University of Hyderabad , Gachibowli, Hyderabad 500046, India.
J Phys Chem A. 2018 Feb 8;122(5):1228-1234. doi: 10.1021/acs.jpca.7b10888. Epub 2018 Jan 29.
Developing efficient ways to control the nanocluster properties and synthesize atomically precise metal nanoclusters are the foremost goals in the field of metal nanocluster research. In this article, we demonstrate that the direct synthesis of atomically precise, hydrophilic metal nanoclusters as well as tuning of their properties can be achieved by an appropriate selection of reactants, binding ligand, and their proportions. Thus, a facile, single-step method has been developed for the direct synthesis of Au(SCHCOH) nanocluster in an aqueous medium under ambient conditions. The synthesis does not require any pH or temperature control and postsynthesis size-separation step. The use of a hydrophilic, bifunctional short carbon-chain capping ligand, HSCHCOH, allows tuning of cluster properties such as the photoluminescence and stability in an aqueous medium via the variation of pH of the cluster solution. By using a phase transfer catalyst, the nanoclusters can also be transferred into toluene solvent, which further enhances the nanocluster photoluminescence. The formation, composition, and purity of the product clusters have been characterized by using a number of methods such as the polyacrylamide gel electrophoresis, UV-visible and FTIR spectroscopies, transmission electron microscopy, energy dispersive X-ray analysis, thermogravimetric analysis, X-ray photoelectron spectroscopy, and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. Gold nanoclusters with properties such as water solubility, water-to-organic phase-transfer ability, and tunable stability and photoluminescence are promising for various studies and applications. The work reveals a few principles that can be helpful in the development of a general toolbox for the rational design of size-selective synthesis and properties tuning of the metal nanoclusters.
开发控制纳米团簇性质的有效方法并合成原子精确的金属纳米团簇是金属纳米团簇研究领域的首要目标。在本文中，我们证明了通过适当选择反应物、结合配体及其比例，可以实现原子精确的亲水性金属纳米团簇的直接合成及其性质的调控。因此，已开发出一种简便的单步方法，用于在环境条件下于水性介质中直接合成Au(SCHCOH)纳米团簇。该合成不需要任何pH或温度控制以及合成后尺寸分离步骤。使用亲水性双功能短碳链封端配体HSCHCOH，可通过改变团簇溶液的pH值来调控团簇性质，如在水性介质中的光致发光和稳定性。通过使用相转移催化剂，纳米团簇还可转移至甲苯溶剂中，这进一步增强了纳米团簇的光致发光。已使用多种方法对产物团簇的形成、组成和纯度进行了表征，如聚丙烯酰胺凝胶电泳、紫外可见光谱和傅里叶变换红外光谱、透射电子显微镜、能量色散X射线分析、热重分析、X射线光电子能谱以及基质辅助激光解吸电离飞行时间质谱。具有水溶性、水相至有机相转移能力以及可调稳定性和光致发光等性质的金纳米团簇在各种研究和应用中具有广阔前景。这项工作揭示了一些原理，有助于开发一个通用工具箱，用于合理设计金属纳米团簇的尺寸选择性合成和性质调控。
