ABSTRACT
Three sizes of atomically precise tiara-like structural Nin(SR)2n (n = 4, 5 and 6) are co-synthesized by a one-pot method and isolated using thin layer chromatography. The molecular formulas of Ni5(SR)10 and Ni6(SR)12 are determined using matrix-assisted laser desorption ionization mass spectrometry, and the tiara-like structures of Ni4(SR)8 and Ni6(SR)12 are proved using single-crystal X-ray crystallography. Nuclear magnetic resonance shows that Ni5(SR)10 has a similar tiara-like structure too. The electrochemical gap enlarges with the increase of the cluster size, which agrees with the calculated HOMO-LUMO gap and optical gap by TD-DFT, but the experimental optical gap is GO(Ni4(SR)8) > GO(Ni6(SR)12) > GO(Ni5(SR)10) due to Ni4(SR)8 owning a pseudo-optical gap at 2.0 eV.
ABSTRACT
A series of tiara like structural Pdn(SR)2n (5 ≤n≤ 20) nanoclusters were synthesized by using a modified Brust-Schiffrin route and isolated via thin layer chromatography, and further measured using MALDI-MS. A new crystal structure of tiara like structural Pd6(SC2H4Ph)12 was determined by single-crystal X-ray crystallography. The atomic distance of PdPd increased and the Pd-S bond length decreased with the increase in the n value in the optimized structure of Pdn(SR)2n (5 ≤n≤ 10), which were optimized by density functional theory at the B3LYP level. All these 16 Pdn(SR)2n nanoclusters exhibit weak emission at 620 nm with single band excitation at around 268 nm. The origin of emission of this series of clusters could be illustrated by using a ligand to metal charge transfer model.