Synthesis of novel perfluorinated supramolecular building block-stabilized gold nanocomposites

Abstract

The perfluorinated supramolecules(PSM) are highly microphase separated around the centers of their carboxylic core groups, and spontaneously self-organize into a hexagonal cylindrical structure in the bulk state. Among other PSMs, we selected the supramolecule, 3,5-Bis[3’,5’-bis(n-5,5,6,6,7,7, 8,8,9,9,10,10,11,11,12,12-Heptadecafluorododecan-1-yloxy)benzyl oxy]-benzoic acid (F8B-COOH) and fabricated gold nanoparticles using this supramolecule(F8B-COOH). To make the reaction site of F8B-COOH with metal ion, F8B-COOH dissolved in tetrahydrofurane (THF) was added NaOH. Then the carboxylic acid reacted with hydroxyl group by acid-base reaction and added $HAuCl_4$ aqueous solution to form $Au^{III}$ complex with F8B-COOH using ion transfer reaction. To check whether the complex was formed or not, IR spectra were obtained and the disappearance of C=O peak in FT-IR spectra means the formation of {F8B-COO^{-}-Au} (III) complex. To reduce gold ions, the solution was irradiated by UV lamp for 24, 36, 48 hr directly. After UV irradiation, the generation of gold nanoparticles was confirmed by the appearance of 550 nm peak in UV/visible spectra and transmission electron microscopy (TEM) images. The structure of F8B-COOH - gold nanocomposites in solution is Face centered Cubic (FCC) system through X-ray diffraction measurement. F8B-COOH-stabilized Au nanocomposites easily formed self-assembled two dimensional (2-D) superlattices with FCC packing assisting supramolecule structure. The XRD pattern of the ${[F8B-COO^{-}-Au^{III}Cl_3]}^{-}$ complex was not changed after UV reduction. This result means that the structure and spacing of this structure are preserved during photo-reduction by UV light. As a result, self-organization of the material with an organometallic core and perfluorinated tails gives rise to F8B-COOH-stabilized gold nanoparticles whose surfaces are completely covered with perfluorinated tails. Also the size of the final gold nanoparticles can be controlled the...