Variation in morphology of gold nanoparticles synthesized by the spontaneous reduction of aqueous chloroaurate ions by alkylated tyrosine at a liquid–liquid and air–water interface
作者:Anita Swami、Ashavani Kumar、Moneesha D'Costa、Renu Pasricha、Murali Sastry
DOI:10.1039/b404391j
日期:——
We demonstrate the formation of gold nanocrystals of different morphologies using alkylated tyrosine (AT) as a reducing agent at a liquidâliquid and airâwater interface. The reduction of aqueous chloroaurate ions occurs in a single step wherein the AT molecule plays the multifunctional role of a phase transfer, reducing and capping agent. Gold nanoparticles formed at the airâwater interface are very thin, flat sheet or ribbon-like nanostructures, which are highly oriented in the (111) direction. On the other hand, reduction of aqueous chloroaurate ions at a liquidâliquid interface by AT molecules present in the organic phase yielded nanoparticles having predominantly spherical morphology but with no specific crystallographic orientation. The difference in morphology of the nanoparticles may be due to the different orientational and translational degrees of freedom of the AT molecules and gold ions at these two interfaces. The AT-capped gold nanoparticles were characterized by UV-vis spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and nuclear magnetic resonance spectroscopy (
1H NMR), while the LB films of flat gold sheets were also studied by X-ray photoemission spectroscopy (XPS).
我们展示了在液-液和空气-水界面上使用烷基化酪氨酸(AT)作为还原剂形成不同形态的金纳米晶体。水相氯金酸离子的还原是一个单一步骤,其中AT分子扮演着相转移、还原和覆盖剂的多功能角色。在空气-水界面上形成的金纳米颗粒非常薄,呈扁平片状或带状纳米结构,高度定向于(111)方向。另一方面,在液-液界面上,有机相中的AT分子还原水相氯金酸离子生成的纳米颗粒主要呈球形,但没有特定的晶体学取向。纳米颗粒形态的差异可能是由于AT分子和金离子在这两个界面上具有不同的取向和翻译自由度所致。AT覆盖的金纳米颗粒通过紫外-可见光谱、透射电子显微镜(TEM)、X射线衍射(XRD)和核磁共振光谱(1H NMR)进行了表征,而扁平金片Langmuir-Blodgett(LB)膜也通过X射线光电子光谱(XPS)进行了研究。