Symmetry Breaking of Atomically Precise Fullerene-like Metal Nanoclusters

Abstract

Here we report a neutral fullerene-like core−shell homosilver Ag 13 @Ag 20 nanocluster that is fully protected by an achiral bidentate thiolate ligand (9,12-dimercapto-1,2-closo-carborane, C 2 B 10 H 10 S 2 H 2 ), which crystallizes in centrosymmetric space group R3̅ . Continuous Cu doping in the dodecahedral shell first induced symmetry breaking to generate chiral Ag 13 @Ag 20-n Cu n (6 ≥ n ≥ 2) containing two acetonitrile ligands in space group P2 1 2 1 2 1 , and then produced symmetric all-thiolated Ag 13 @Ag 20-n Cu n (20 ≥ n ≥ 13) in the higher space group Im3̅ . The selectively copper-doped Ag 13 @Ag 20-n Cu n (6 ≥ n ≥ 2) cluster has its structure reorganized to a lower symmetry that shows chiroptical activity. Moreover, structural distortion of Ag 13 @Ag 20-n Cu n (6 ≥ n ≥ 2) further expanded in chiral R-/S-propylene oxide, which induced a more prominent core-based CD response. This work revealed a novel mechanism of chirality generation at the atomic level through asymmetric shell-doping of metal nanoclusters, which provides new insight into the origin of chirality in inorganic nanostructures.

Master key to coinage metal nanoclusters treasure chest: 38-metal clusters

“…Nanoclusters (1–3 nm) are a bridge between discrete atoms and plasma nanoparticles. 1–11 This intermediate transition state gives nanoclusters fascinating physicochemical properties, such as optics, 12–15 electrochemistry, 16–18 chirality, 19–27 and catalysis. 28–30 Therefore, it has received extensive attention from chemistry researchers and has become one of the hot topics of research in recent years.…”

Self‐Regulated Pathway‐Dependent Chirality Control of Silver Nanoclusters

“…[1,2] Some NCs possess intrinsic chirality, affording asymmetric atomic arrangements in their structures even in the absence of chiral ligands. [3][4][5][6][7][8][9][10][11][12][13][14][15][16] While the synthesis with achiral ligands leads to a racemic mixture of left-handed (or anticlockwise, AC-) and right-handed (or clockwise, C-) NCs, the use of enantiomeric ligands results in a deracemization through the preferential formation of one-handed NCs. [17][18][19][20][21][22][23][24] Recently, we found the intrinsic chirality in Ag 29 (BDT) 12 (TPP) 4 NC [25] (BDT: 1,3-benzenedithiol; TPP: triphenylphosphine), which is one of the most studied luminescent silver NCs, succeeding in their enantioseparation through a chiral column chromatography.…”

“…Chiral metal NCs with atomically precise compositions and structures have been attracting interest owing to their fascinating structural and chiroptical properties and potential applications [1, 2] . Some NCs possess intrinsic chirality, affording asymmetric atomic arrangements in their structures even in the absence of chiral ligands [3–16] . While the synthesis with achiral ligands leads to a racemic mixture of left‐handed (or anticlockwise, AC ‐) and right‐handed (or clockwise, C ‐) NCs, the use of enantiomeric ligands results in a deracemization through the preferential formation of one‐handed NCs [17–24] .…”

Chirality Induction in the Synthesis of Ag29 Nanoclusters with Asymmetric Structure

“…Recently, nanoparticle-based chiral materials have been attracting attention as an active research field due to their wide range of potential applications. − Chiral metal nanoclusters (NCs) are of particular interest due to their optical activity originating from well-defined asymmetric electronic and atomic structures. − The use of an enantiomeric ligand for the synthesis of chiral NCs readily leads to optically active NCs. The hybridization of electronic structures of chiral ligands induces a dissymmetric field to the electronic structure of NCs even with achiral geometries. − Meanwhile, the use of chiral ligands potentially gives rise to an energy difference between the intrinsically chiral NCs − with left- and right-handed atomic arrangements, leading to the selective formation of one-handed NCs (deracemization). − Chiral ligands interact with a NC core including a metal–ligand exterior shell with a chiral atomic arrangement in a diastereomeric manner. For example, a partial ligand exchange between an intrinsically chiral Au 38 NC and a chiral thiol proceeded in a diastereoselective manner, resulting in the preferential formation of one-handed NC .…”