The effects of surface ligands and counter cations on the stability of anionic thiolated M12Ag32 (M = Au, Ag) nanoclusters

The stabilities of [M12Ag32(SR)30]4− (M = Ag, Au and SR = SPhF2, SPhCF3, SPhF) clusters having the same structure but different surface ligands or counter cations were systematically studied. It was clearly revealed that a subtle structural change in the surface ligands or counter cations could significantly alter the overall stability of [M12Ag32(SR)30]4− although they all had an electronic structure of 18-electron superatom shell closure. SPhF2 was found as a better surface ligand than SPhCF3 or SPhF to stabilize [M12Ag32(SR)30]4−. And the use of more bulky [(PPh3)2N]+ as the counter cations was revealed to be more deleterious to the overall stability of [M12Ag32(SR)30]4− clusters than PPh4+. [Au12Ag32(SR)30]4− was much more stable than [Ag44(SR)30]4− with the same surface ligands and counter cations. An exceptional stability was observed on (PPh4)4[Au12Ag32(SPhF2)30] which was stable in DMF for more than 8 days in air at 80 °C. More research efforts are still needed to deeply understand why a small structural change could result in a significant change in the stability of noble metal nanoclusters.

Series of [M12Ag32(SR)30]4− (M = Ag, Au) clusters with −SPhF2, −SPhCF3 or −SPhF as surface ligands, and PPh4+ or [(PPh3)2N]+ as counter cations were prepared for studying how fine tuning of surface ligands and counter cations can significantly affect the stability of nanoclusters.Figure optionsDownload as PowerPoint slide