TY - JOUR
T1 - Interlocked catenane-like structure predicted in Au 24(SR) 20
T2 - Implication to structural evolution of thiolated gold clusters from homoleptic gold(I) thiolates to core-stacked nanoparticles
AU - Pei, Yong
AU - Pal, Rhitankar
AU - Liu, Chunyan
AU - Gao, Yi
AU - Zhang, Zhuhua
AU - Zeng, Xiao Cheng
PY - 2012/2/15
Y1 - 2012/2/15
N2 - Atomic structure of a recently synthesized ligand-covered cluster Au 24(SR) 20 [J. Phys. Chem. Lett., 2010, 1, 1003] is resolved based on the developed classical force-field based divide-and-protect approach. The computed UV-vis absorption spectrum and powder X-ray diffraction (XRD) curve for the lowest-energy isomer are in good agreement with experimental measurements. Unique catenane-like staple motifs are predicted for the first time in core-stacked thiolate-group (RS-) covered gold nanoparticles (RS-AuNPs), suggesting the onset of structural transformation in RS-AuNPs at relatively low Au/SR ratio. Since the lowest-energy structure of Au 24(SR) 20 entails interlocked Au 5(SR) 4 and Au 7(SR) 6 oligomers, it supports a recently proposed growth model of RS-AuNPs [J. Phys. Chem. Lett., 2011, 2, 990], that is, Au n(SR) n-1 oligomers are formed during the initial growth of RS-AuNPs. By comparing the Au-core structure of Au 24(SR) 20 with other structurally resolved RS-AuNPs, we conclude that the tetrahedral Au 4 motif is a prevalent structural unit for small-sized RS-AuNPs with relatively low Au/SR ratio. The structural prediction of Au 24(SR) 20 offers additional insights into the structural evolution of thiolated gold clusters from homoleptic gold(I) thiolate to core-stacked RS-AuNPs. Specifically, with the increase of interfacial bond length of Au(core)-S in RS-AuNPs, increasingly larger "metallic" Au-core is formed, which results in smaller HOMO-LUMO (or optical) gap. Calculations of electronic structures and UV-vis absorption spectra of Au 24(SR) 20 and larger RS-AuNPs (up to ∼2 nm in size) show that the ligand layer can strongly affect optical absorption behavior of RS-AuNPs.
AB - Atomic structure of a recently synthesized ligand-covered cluster Au 24(SR) 20 [J. Phys. Chem. Lett., 2010, 1, 1003] is resolved based on the developed classical force-field based divide-and-protect approach. The computed UV-vis absorption spectrum and powder X-ray diffraction (XRD) curve for the lowest-energy isomer are in good agreement with experimental measurements. Unique catenane-like staple motifs are predicted for the first time in core-stacked thiolate-group (RS-) covered gold nanoparticles (RS-AuNPs), suggesting the onset of structural transformation in RS-AuNPs at relatively low Au/SR ratio. Since the lowest-energy structure of Au 24(SR) 20 entails interlocked Au 5(SR) 4 and Au 7(SR) 6 oligomers, it supports a recently proposed growth model of RS-AuNPs [J. Phys. Chem. Lett., 2011, 2, 990], that is, Au n(SR) n-1 oligomers are formed during the initial growth of RS-AuNPs. By comparing the Au-core structure of Au 24(SR) 20 with other structurally resolved RS-AuNPs, we conclude that the tetrahedral Au 4 motif is a prevalent structural unit for small-sized RS-AuNPs with relatively low Au/SR ratio. The structural prediction of Au 24(SR) 20 offers additional insights into the structural evolution of thiolated gold clusters from homoleptic gold(I) thiolate to core-stacked RS-AuNPs. Specifically, with the increase of interfacial bond length of Au(core)-S in RS-AuNPs, increasingly larger "metallic" Au-core is formed, which results in smaller HOMO-LUMO (or optical) gap. Calculations of electronic structures and UV-vis absorption spectra of Au 24(SR) 20 and larger RS-AuNPs (up to ∼2 nm in size) show that the ligand layer can strongly affect optical absorption behavior of RS-AuNPs.
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U2 - 10.1021/ja208559y
DO - 10.1021/ja208559y
M3 - Article
C2 - 22280457
AN - SCOPUS:84863116814
SN - 0002-7863
VL - 134
SP - 3015
EP - 3024
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 6
ER -