Kinetically Controlled Synthesis OF Gold Nanoclusters And The Chirality Research

Because of its eternal value and stable chemical properties, the noble metal gold has attracted most people’s attention in the whole history. The gold in nanoscale has different chemical properties with the bulk gold. The kinetically controlled synthetic method of gold nanoclusters has been rapidly developed when Brust opened up the Bottom up method for the synthesis of gold nanoclusters in1994. Many monodispersed gold nanoclusters with precise atoms have been obtained. These gold nanoclusters that obtained have been characterized by many analytic methods. As the typical models, the properties of AU25and Au38nanoclusters have been studied intensively. On the basis of predecessors’ research work, we found the new method for the high yield synthesis of Au25(SC2H4Ph)18. The chiral thiolate was used to prepare chiral AU25nanoclusters. The main work of this paper is as follows:1Synthesis of Au26(SC2H4Ph)18nanoclusters via the kinetically controlled, slow reduction method. UV-vis spectra was used to detect the reaction, indicating the growth situation of the AU25in different reaction time. We proposed the possible mechanism of Au25growth in this reaction process. It is demonstrated that the yield of AU25is high and the product is easy to purify with this method. The method is different from the methods previous reported and provides the clue for the research of mechanism of AU25growth.2We choose the chiral R/S-2-phenylpropane-1-thiol to prepare the chiral Au25(SR*)18and rod-like [Au25(PPh3)10(SR*)5Cl2]2+nanoclusters via the kinetically controlled method. The product was characterized by UV-vis spectra,1HNMR, Matrix-Assisted Laser Desorption/Ionization (MALDI) mass spectra and thermogravimetric Analysis (TGA). Circular dichroism (CD) spectra was used to research the chirality of the as-prepared gold nanoclusters. The results indicate that the CD signals of chiral ligand capped Au25nanoparticles arise from the electronic state mixing of the ligands and surface gold atoms.3We prepared the Au25(SCH2CH2Ph)18-DME+nanocluster, which is different from Au25(SC2H4Ph)18-TOA+with the cation (DME:N, N-dimethyl-N-((2S,3R)-3-phenylbutan-2-yl)dodecan-l-aminium).1HNMR, MALDI-TOF mass spectra and TGA were used to confirm the product. The chirality was tested by CD spectra. We also dissolved the achiral [Au25(SC2H4Ph)18]TOA+in the chiral solvent to research that whether the chiral could induce the chirality of [Au25(SC2H4Ph)18]TOA+. The results showed that the electrostatic attraction between the chiral cation (DME+) and the anion [Au25(SC2H4Ph)18]-could not induce the chirality of Au25nanoclusters. The chiral solvent could not lead to the chirality of Au25clusters, either.