Department of Chemistry, Anhui University, Hefei, Anhui 230039, People's Republic of China.
Nano Lett. 2011 Sep 14;11(9):3963-9. doi: 10.1021/nl202288j. Epub 2011 Aug 11.
Chirality in nanoparticles is an intriguing phenomenon. Herein, we have devised a well-defined gold nanoparticle system for investigating the origin of chirality in nanoparticles. We have designed chiral thiols (R- and S-isomers) and synthesized chiral gold nanoparticles composed of 25 gold atoms and 18 ligands, referred to as Au(25)(pet)(18), where pet represents chirally modified phenylethylthiolate -SCH(2)CH(CH(3))Ph at the 2-position. These optically active nanoparticles are close analogues of the optically nonactive phenylethylthioalte-capped Au(25)(pet)(18) nanoparticles, and the latter's crystal structure is known. On the basis of the atomic and electronic structures of these well-defined Au(25) nanoparticles, we have explicitly revealed that the ligands and surface gold atoms of Au(25)(pet)(18) play a critical role in effecting the circular dichroism responses from the nanoparticles. Similar effects are also observed in chiral Au(25) rods. The mixing of electronic states of ligands with those of surface gold atoms constitutes the fundamental origin of chirality in such nanoparticles.
手性纳米粒子是一种有趣的现象。在此，我们设计了一种结构明确的金纳米粒子体系，用于研究纳米粒子手性的起源。我们设计了手性硫醇（R 和 S 异构体），并合成了由 25 个金原子和 18 个配体组成的手性金纳米粒子，称为 Au(25)(pet)(18)，其中 pet 代表在 2 位取代的手性修饰的苯乙基硫醇 -SCH(2)CH(CH(3))Ph。这些具有光学活性的纳米粒子是光学非活性的苯乙基硫醇封端的 Au(25)(pet)(18)纳米粒子的紧密类似物，后者的晶体结构是已知的。基于这些结构明确的 Au(25)纳米粒子的原子和电子结构，我们明确揭示了 Au(25)(pet)(18)中配体和表面金原子在影响纳米粒子的圆二色性响应方面起着关键作用。类似的效应也在手性 Au(25)棒中观察到。配体的电子态与表面金原子的电子态的混合构成了这些纳米粒子手性的基本起源。
