Enantiomeric hexanuclear silver clusters: visible-near-infrared broadband emission and circularly polarized luminescence.

Abstract

Chiral metal clusters with solid-state circularly polarized luminescence (CPL) properties remain largely underexplored. In particular, those capable of emitting across the visible to near-infrared (NIR) region-an essential feature for optoelectronic and interdisciplinary applications-are extremely rare. To advance such materials, a chiral transfer strategy was adopted to prepare a pair of enantiomeric silver clusters, denoted as R/S-Ag6, through the utilization of enantiopure chiral ligands (R-BTTH or S-BTTH). Single-crystal X-ray diffraction analyses reveal that, enabled by chirality induction, the R/S-Ag6 clusters along with Ag6 cores and Ag6S6 skeletons are mirror-symmetric. This can be attributed to the steric hindrance effect of chiral ligands. Comprehensive characterization studies were conducted using UV-Vis absorption spectroscopy, circular dichroism, DFT calculations, steady-state/transient fluorescence spectroscopy, and CPL spectroscopy. Notably, the R/S-Ag6 clusters exhibit broadband emission spanning 500-1200 nm and highly efficient CPL. This study endows the pair of enantiomeric metal clusters with extensive application prospects in the fields of chiral optoelectronics, nonlinear optics, and chiral catalysis.