We utilize 1H NMR and UV-Vis-NIR spectroscopy to monitor the displacement of lead oleate (Pb(O2CR)2 R = C17H33) from the surface of lead sulfide nanocrystals with various dative (L-type) ligands such as amines (N,N,N′,N′-tetramethylethylene-1,2-diamine (TMEDA), tri-n-butylamine, n-octylamine) and phosphines (1,2-bis(dimethylphosphino)ethane, tri-n-butylphosphine). Our studies show that amines cause subsequent oriented attachment along the 100 plane and at room temperature upon displacement along with a broadening of the first exciton transition, while phosphines displace up to 60% of lead oleate with no nanocrystal fusing. Amine concentration in solution dictates the extent of attachment, with TMEDA being the most effective; as little as 0.02M in solution causes rod formation. We discuss this reactivity in light of acid/base chemistry along with attempts to synthesize larger ordered PbS structures.

Surface reactivity of lead sulfide nanocrystals

251st National Meeting (2016)

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