Application of NHC-modified Gold Nanoclusters in Photoredox Catalysis

点击翻译按钮获取中文摘要

N-heterocyclic carbenes (NHCs) have recently emerged as valuable alternatives to thiols or phosphines for the stabilization of metal surfaces, nanoparticles, and clusters. The neutral, electron-rich NHCs form a strong covalent bond with the metal, which is important in providing stability to metal nanoclusters.Thus far we have been able to synthesize a series of chiral Au13 nanoclusters via the direct reduction of achiral dinuclear Au(I) halide complexes ligated by ortho-xylyl-linked bis-N-heterocyclic carbene (bisNHC) ligands. A broad range of functional groups are tolerated as wingtip substituents, allowing for the synthesis of a variety of functionalized chiral Au13 nanoclusters. We have used single-crystal X-ray crystallography to confirm the molecular formula to be [Au13(bisNHC)5Cl2]Cl3, with a chiral helical arrangement of the five bidentate NHC ligands around the icosahedral Au13 core. This Au13 nanocluster is highly luminescent, with a quantum yield of 23%. The two enantiomers of the Au13 clusters can be separated by chiral HPLC, and the isolated enantiomers characterized by circular dichroism spectroscopy. The clusters synthesized by us show remarkable stability, including configurational stability, opening the door to further investigation of the effect of chirality on these clusters. Our preliminary results showed that this bisNHC Au13 nanocluster is friendly to cells and can be used for the cell imaging.