Application of NHC-modified Gold Nanoclusters in Photoredox Catalysis

N-杂环卡宾（NHC）最近作为硫醇或膦的有价值的替代物出现，用于稳定金属表面、纳米颗粒和簇。迄今为止，我们已经能够通过邻二甲苯基连接的双-N-杂环卡宾（bisNHC）配体直接还原非手性双核Au（I）卤化物配合物来合成一系列手性Au 13纳米团簇。宽范围的官能团被容忍作为翼尖取代基，允许合成各种官能化的手性Au 13纳米团簇。我们已经使用单晶X射线晶体学来确认分子式为[Au 13（bisNHC）5Cl 2] Cl 3，具有围绕二十面体Au 13核心的五个双齿NHC配体的手性螺旋排列。这种Au 13纳米团簇是高度发光的，量子产率为23%。Au 13簇合物的两种对映体可以通过手性HPLC分离，并且分离的对映体通过圆二色谱表征。我们合成的团簇表现出显著的稳定性，包括构型稳定性，为进一步研究手性对团簇的影响打开了大门。我们的初步结果表明，这种bisNHC Au 13纳米簇是友好的细胞，可用于细胞成像。

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.