Small symmetry-breaking triggering large chiroptical responses of Ag70 nanoclusters

Abstract

The origins of the chiroptical activities of inorganic nanostructures have perplexed scientists, and deracemization of high-nuclearity metal nanoclusters (NCs) remains challenging. Here, we report a single-crystal structure of Rac-Ag70 that contains enantiomeric pairs of 70-nuclearity silver clusters with 20 free valence electrons (Ag70), and each of these clusters is a doubly truncated tetrahedron with pseudo-T symmetry. A deracemization method using a chiral metal precursor not only stabilizes Ag70 in solution but also enables monitoring of the gradual enlargement of the electronic circular dichroism (CD) responses and anisotropy factor gabs. The chiral crystals of R/S-Ag70 in space group P21 containing a pseudo-T-symmetric enantiomeric NC show significant kernel-based and shell-based CD responses. The small symmetry breaking of Td symmetry arising from local distortion of Ag−S motifs and rotation of the apical Ag3 trigons results in large chiroptical responses. This work opens an avenue to construct chiral medium/large-sized NCs and nanoparticles, which are promising for asymmetric catalysis, nonlinear optics, chiral sensing, and biomedicine.

Snapshots of key intermediates unveiling the growth from silver ions to Ag70 nanoclusters

“…S11 †). 14 Considering the structural similarity between Ag 24 and Ag 24 -C 2 F 5 (Fig. S12 †), Ag 24 was selected as the representative for illustration (Fig.…”

“…11 g So far, the detailed process from silver ions to NCs, including the reduction and nucleation process for metal NCs is still a black box. Recently, we reported a 20e Ag 70 nanocluster, ([NH 2 (CH 3 ) 2 ][Ag 70 S 4 (S i Pr) 24 (CF 3 COO) 20 ]), 14 using DMF as a reductant. The slow reduction process to Ag 70 in ten hours ( Fig.…”

Integrating-Sphere-Assisted Resonance Synchronous Spectroscopy for the Quantification of Material Double-Beam UV–Vis Absorption and Scattering Extinction

“…UV–vis spectrophotometry is the most used method in chemical, biological, and materials sciences for its high reproducibility and affordability. − However, quantitative decoupling of the light scattering and absorption contribution to the sample UV–vis extinction spectrum can be challenging for materials that cannot be approximated as pure light absorbers or scatterers. While the default unit of the UV–vis signal obtained with commercial UV–vis spectrophotometers is, to the best of our knowledge, invariably absorbance (the absorption extinction), what is quantified with these instruments is the light extinction, the sum of the material absorption and scattering extinctions.…”

Two SiO44–-Templated Ln23Ni20 Clusters with Magnetic Cooling and Stability

“…Persistent investigation on the synthetic methods demonstrates suitable ligand and anionic templates are the significant conditions to obtain giant 3d-4f nanoclusters. − With regard to the ligand-controlled hydrolytic method, according to hard–soft acid–base theory, 3d metal ions are inclined to coordinate with soft atoms (such as S and N), while the 4f metal ions tend to bond with hard atoms (such as O and F). , At the same time, the organic ligands containing hard and soft atoms are beneficial to establish giant 3d-4f clusters. For instance, iminodiacetic acid (H 2 IDA) with [N, O, O] donor sites has been widely utilized to construct an extremely diverse family of 3d-4f metal clusters. , Herein, the organic ligand H 2 DTA with multifunctional coordination sites [S, O, O] and a similar structure with H 2 IDA (as depicted in Figure ) is expected to assemble novel high-nuclearity 3d-4f clusters.…”