Siu Timothy C, Imex Aguirre Cardenas M, Seo Jacob, Boctor Kirllos, Shimono Miku G, Tran Isabelle T, Carta Veronica, Su Timothy A
Department of Chemistry, University of California, Riverside, CA 92521, USA.
Materials Science and Engineering Program, University of California, Riverside, CA 92521, USA.
Angew Chem Int Ed Engl. 2022 Aug 1;61(31):e202206877. doi: 10.1002/anie.202206877. Epub 2022 Jun 14.
The first syntheses of functionalized sila-adamantanes via site-selective reactions are described. Mechanistic inquiry into the isomerization of sila-adamantane revealed new approaches for installing halides at the 2-position of the cluster. Meanwhile, isomerization via Lewis acid catalysts with non-nucleophilic counteranions provided access to sila-adamantane on the gram-scale, enabling us to discover strategies for substituting its 1-, 3-, 5-, and 7-positions with identical or distinct functional groups. Optical absorbance and density functional theory studies show that σ-withdrawing substituents at the 1-position strongly perturb optical absorbance in sila-adamantane, whereas substituents at the exocyclic and 2-position are optically inert. As silicon diamondoids are atomically precise models for silicon nanocrystals, our findings suggest that passivation at tertiary surface sites carries an outsized impact on the optical properties of surface-functionalized Si nanocrystals.
本文描述了通过位点选择性反应首次合成功能化硅金刚烷的过程。对硅金刚烷异构化的机理研究揭示了在簇合物的2-位引入卤化物的新方法。同时，通过具有非亲核抗衡阴离子的路易斯酸催化剂进行的异构化反应实现了克级规模的硅金刚烷合成，使我们能够发现用相同或不同官能团取代其1-、3-、5-和7-位的策略。光吸收和密度泛函理论研究表明，1-位的吸电子取代基会强烈干扰硅金刚烷的光吸收，而环外和2-位的取代基则没有光学活性。由于硅类金刚石是硅纳米晶体的原子精确模型，我们的研究结果表明，叔表面位点的钝化对表面功能化硅纳米晶体的光学性质有巨大影响。
