Au38(SPh)24: Au38Protected with Aromatic Thiolate Ligands.
Au38(SR)24is one of the most extensively investigated gold nanomolecules along with Au25(SR)18and Au144(SR)60. However, so far it has only been prepared using aliphatic-like ligands, where R = -SC6H13, -SC12H25and -SCH2CH2Ph. Au38(SCH2CH2Ph)24when reacted with HSPh undergoes core-size conversion to Au36(SPh)24, and existing literature suggests that Au38(SPh)24cannot be synthesized. Here, contrary to prevailing knowledge, we demonstrate that Au38(SPh)24can be prepared if the ligand exchanged conditions are optimized, under delicate conditions, without any formation of Au36(SPh)24. Conclusive evidence is presented in the form of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), electrospray ionization mass spectra (ESI-MS) characterization, and optical spectra of Au38(SPh)24in a solid glass form showing distinct differences from that of Au38(S-aliphatic)24. Theoretical analysis confirms experimental assignment of the optical spectrum and shows that the stability of Au38(SPh)24is not negligible with respect to that of its aliphatic analogous, and contains a significant component of ligand-ligand attractive interactions. Thus, while Au38(SPh)24is stable at RT, it converts to Au36(SPh)24either on prolonged etching (longer than 2 hours) at RT or when etched at 80 °C.
Department of Chemistry and Biochemistry, University of Mississippi , Oxford, Mississippi 38677, United States.
Milan
M
Rambukwella
Department of Chemistry and Biochemistry, University of Mississippi , Oxford, Mississippi 38677, United States.
Shayna
S
Burrage
Department of Chemistry and Biochemistry, University of Mississippi , Oxford, Mississippi 38677, United States.
Marie
M
Neubrander
Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Trieste , Trieste I-34127, Italy.
Oscar
O
Baseggio
Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
Edoardo
http://orcid.org/0000-0001-5955-0734
E
Aprà
Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Trieste , Trieste I-34127, Italy.
Mauro
http://orcid.org/0000-0003-3700-7903
M
Stener
CNR-ICCOM, Consiglio Nazionale delle Ricerche, Pisa, I-56124, Italy.
Alessandro
http://orcid.org/0000-0001-5337-4450
A
Fortunelli
Department of Chemistry and Biochemistry, University of Mississippi , Oxford, Mississippi 38677, United States.
Amala
http://orcid.org/0000-0001-6942-5451
A
Dass