title: All-thiol-stabilized Ag44 and Au12Ag32 nanoparticles with single-crystal structures.
abstract: Noble metal nanoparticles stabilized by organic ligands are important for applications in assembly, site-specific bioconjugate labelling and sensing, drug delivery and medical therapy, molecular recognition and molecular electronics, and catalysis. Here we report crystal structures and theoretical analysis of three Ag44(SR)30 and three Au12Ag32(SR)30 intermetallic nanoclusters stabilized with fluorinated arylthiols (SR=SPhF, SPhF2 or SPhCF3). The nanocluster forms a Keplerate solid of concentric icosahedral and dodecahedral atom shells, protected by six Ag2(SR)5 units. Positive counterions in the crystal indicate a high negative charge of 4(-) per nanoparticle, and density functional theory calculations explain the stability as an 18-electron superatom shell closure in the metal core. Highly featured optical absorption spectra in the ultraviolet-visible region are analysed using time-dependent density functional perturbation theory. This work forms a basis for further understanding, engineering and controlling of stability as well as electronic and optical properties of these novel nanomaterials.
authors.affiliation: State Key Laboratory for Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
authors.forename: Huayan
authors.initials: H
authors.lastname: Yang
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Huaqi
authors.initials: H
authors.lastname: Huang
authors.forename: Lars
authors.initials: L
authors.lastname: Gell
authors.forename: Lauri
authors.initials: L
authors.lastname: Lehtovaara
authors.forename: Sami
authors.initials: S
authors.lastname: Malola
authors.forename: Hannu
authors.initials: H
authors.lastname: Häkkinen
authors.forename: Nanfeng
authors.initials: N
authors.lastname: Zheng