Letter pubs.acs.org/ac
Quantitatively Monitoring the Size-Focusing of Au Nanoclusters and Revealing What Promotes the Size Transformation from Au44(TBBT)28 to Au36(TBBT)24 Lingwen Liao,†,∥ Chuanhao Yao,†,∥ Chengming Wang,‡,∥ Shubo Tian,† Jishi Chen,† Man-Bo Li,† Nan Xia,† Nan Yan,† and Zhikun Wu*,† †
Key Laboratory of Materials Physics, Anhui Key Laboratory of Nanomaterials and Nanostructures, CAS Center for Excellence in Nanoscience, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China ‡ Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China S Supporting Information *
ABSTRACT: “Size-focusing” is a well-recognized process and widely employed for the synthesis of atomically monodisperse metal nanoclusters. However, quantitatively monitoring the size-focusing of Au nanoclusters has not been achieved yet, and the in-depth understanding of the size focusing is far from completed. Herein, we introduce a facile, cheap, and powerful tool, preparative thin-layer chromatography (PTLC), to quantitatively track the size-focusing process, to reveal that mainly ∼3 nm nanoparticles promote the transformation from Au44(TBBT)28 to Au36(TBBT)24 (where TBBT is 4-tert-butylbenzenethiolate) and to improve the syntheses of Au44(TBBT)28 and Au36(TBBT)24. Our work further demonstrates the usefulness of PTLC in nanocluster research and advances one step toward understanding the “size-focusing” process of nanoclusters.
C
Chromatography is a common and facile technique to separate and purify the components in organic synthesis,30,31 food inspection,32 fullerene science,33−35 etc. Although some chromatography techniques such as liquid chromatography (LC),36,37 gel permeation chromatography (GPC),38,39 high performance liquid chromatography (HPLC),40−45 and size exclusion chromatograph (SEC)46−52 have been frequently used for the isolation and purification of thiolated Au clusters, it was not until early 2014 that Wu’s group reported the recycling of Au25(SCH2CH2Ph)18 by column chromatography packed by silica gel.53 Then, Pradeep’s group and Wu’s group independently illustrated the subtle separation of thiolated noble metal nanoclusters by thin-layer chromatography (TLC).54−56 Furthermore, Wu’s group utilized TLC to show the diversity of the products in the ion-precursor and ion-dose dependent antigalvanic reduction (AGR)57,58 and employed
ompared with their larger counterparts, the so-called metal nanocrystals in dimension between 2 and 100 nm,1,2 metal nanoclusters (
