Chiral metal nanoparticles encapsulated by a chiral phosphine cavitand with the tetrakis-BINAP moiety: their remarkable stability toward ligand exchange and thermal racemization.

A chiral phosphine cavitand 1 induced the formation of chiral metal (Ru, Rh, Pd, Ag, Pt, and Au) nanoparticles (NPs). The ligand 1 of the chiral metal NPs prevents both thermal racemization and ligand exchange with a thiol, but the organic molecules can react with the metal surfaces. In contrast to the 1-protected Au NPs, the BINAP-protected Au NPs easily undergo ligand exchange and thermal racemization with aggregation.