Core-Size Conversion of Au38(SCH2CH2Ph)24 to Au30(S-tBu)18 Nanomolecules

Au-38(SCH2CH2Ph)(24) nanomolecules upon etching with tert-butylthiol undergo core-size conversion to green-gold Au-30(S-tBu)(18) via Au-36(SCH2CH2Ph)(24-x)(S-tBu)(x) intermediate. The structural transformation from Au38 to Au30 indicates a strong steric effect due to the tert-butyl group of the exchanging ligand in contrast to electronic effect by ligands such as thiophenol, which transforms the Au-38(SCH2CH2Ph)(24) to Au-36(S-tBu)(24). In this work, fast reaction kinetics were observed and thermodynamically stable Au-30(S-tBu)(18) was obtained in molecular purity.