RESUMO
The structural configuration of thiolate-protected gold nanoclusters plays a pivotal role in elucidating the correlation between their structure and properties, comprehending their stability, and guiding experimental synthesis. In this study, utilizing the grand unified model and the ring model, we employed an innovative strategy of fusing triangular Au3 and tetrahedral Au4 elementary blocks by sharing a gold atom to design the gold core, predicting the structure of the Au40(SR)24 nanoclusters. Density functional theory calculations indicate that with the protective ligands simplified to methyl groups the energy of the predicted Au40(SR)24 is 0.45 eV lower than that of the experimentally reported Au40(o-MBT)24 nanoclusters, implying its substantial stability. Furthermore, the calculated UV absorption spectrum and circular dichroism spectrum of predicted Au40(SR)24 are consistent with the experimental results of Au40(SC2H4Ph)24 nanoclusters, suggesting that the predicted structure is a likely candidate for the structure of Au40(SC2H4Ph)24 nanoclusters.
RESUMO
Structural global searches employing highly efficient algorithms have been extensively applied for studying molecules and clusters. However, the code-aided spatial conformational determination of thiolated gold nanoclusters (AuNCs) has not been accomplished because of the complex structural architecture of AuNCs, especially when only the chemical formula of the cluster is known. Experiments have shown that the star [Au25(SR)18]-1 cluster can transform into the [Au25(SR)19]0 cluster. However, the crystal structure of the [Au25(SR)19]0 cluster has not been experimentally determined, and theoretical structural predictions for this cluster are challenging because no template cluster presents for [Au25(SR)19]0. Utilizing the grand unified model, this study succeeded in obtaining the structure of the [Au25(SR)19]0 cluster by using minimal computations, which was verified to be reasonable through stability analysis and experimental absorption spectrum confirmation. Although the predicted [Au25(SR)19]0 cluster has the same number of Au atoms as the [Au25(SR)18]-1 cluster, the structure is considerably altered, owing to the presence of a face-centered cubic kernel. This study provides insights for decoding the chemical formulas of AuNCs to determine their spatial conformations.