Takano Shinjiro, Tsukuda Tatsuya
Department of Chemistry, School of Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Elements Strategy Initiative for Catalysis and Batteries (ESICB), Kyoto University , Katsura, Kyoto 615-8520, Japan.
J Phys Chem Lett. 2016 Nov 17;7(22):4509-4513. doi: 10.1021/acs.jpclett.6b02294. Epub 2016 Nov 6.
Despite recent progress in the synthesis and characterization of optically active gold clusters, the factor determining optical rotatory strength has not been clarified due to the lack of structurally resolved, enantiomerically pure Au clusters. We addressed this issue by studying the correlation between the optical activity and geometrical structures of two types of Au clusters that were protected by chiral diphosphines: [Au(R/S-DIOP)Cl] (DIOP = 1,4-bis(diphenylphosphino)-2,3-o-isopropylidene-2,3-butanediol) and [Au(R/S-BINAP)(PPh)] (BINAP = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl). [Au(BINAP)(PPh)] showed stronger rotatory strengths than [Au(DIOP)Cl] in the visible region, while the Hausdorff chirality measure calculated from the crystal data indicated that the Au core of the former is less chiral than that of the latter. We propose that the optical activity in the Au core-based transition due to the deformed core is further amplified by chiral arrangement of the binaphthyl moiety near the Au core.
尽管在光学活性金簇的合成与表征方面取得了最新进展，但由于缺乏结构解析的、对映体纯的金簇，决定旋光强度的因素尚未明确。我们通过研究两种由手性二膦保护的金簇的光学活性与几何结构之间的相关性来解决这个问题：[Au(R/S-DIOP)Cl]（DIOP = 1,4-双（二苯基膦基）-2,3-邻异丙基亚基-2,3-丁二醇）和[Au(R/S-BINAP)(PPh)]（BINAP = 2,2'-双（二苯基膦基）-1,1'-联萘）。在可见光区域，[Au(BINAP)(PPh)]比[Au(DIOP)Cl]表现出更强的旋光强度，而根据晶体数据计算的豪斯多夫手性度量表明，前者的金核手性低于后者。我们提出，由于金核变形导致的基于金核的跃迁中的光学活性会被金核附近联萘部分的手性排列进一步放大。
