화학공학소재연구정보센터
Journal of the American Chemical Society, Vol.134, No.31, 13114-13120, 2012
Racemization of a Chiral Nanoparticle Evidences the Flexibility of the Gold-Thiolate Interface
Thiolate-protected gold nanoparticles and clusters combine size-dependent physical properties with the ability to introduce (bio)chemical functionality within their ligand shell. The engineering of the latter with molecular precision is an important prerequisite for future applications. A key question in this respect concerns the flexibility of the gold sulfur interface. Here we report the first study on racemization of an intrinsically chiral gold nanocluster, Au-38(SCH2CH2Ph)(24), which goes along with a drastic rearrangement of its surface involving place exchange of several thiolates. This racemization takes place at modest temperatures (40-80 degrees C) without significant decomposition. The experimentally determined activation energy for the inversion reaction is ca. 28 kcal/mol, which is surprisingly low considering the large rearrangement. The activation parameters furthermore indicate that the process occurs without complete Au-S bond breaking.