Volume 61, Issue 31 e202206877
Research Article

Site-Selective Functionalization of Sila-Adamantane and Its Ensuing Optical Effects

Timothy C. Siu

Timothy C. Siu

Department of Chemistry, University of California, Riverside, CA 92521 USA

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M. Imex Aguirre Cardenas

M. Imex Aguirre Cardenas

Department of Chemistry, University of California, Riverside, CA 92521 USA

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Jacob Seo

Jacob Seo

Department of Chemistry, University of California, Riverside, CA 92521 USA

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Kirllos Boctor

Kirllos Boctor

Department of Chemistry, University of California, Riverside, CA 92521 USA

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Miku G. Shimono

Miku G. Shimono

Department of Chemistry, University of California, Riverside, CA 92521 USA

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Isabelle T. Tran

Isabelle T. Tran

Department of Chemistry, University of California, Riverside, CA 92521 USA

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Dr. Veronica Carta

Dr. Veronica Carta

Department of Chemistry, University of California, Riverside, CA 92521 USA

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Prof. Timothy A. Su

Corresponding Author

Prof. Timothy A. Su

Department of Chemistry, University of California, Riverside, CA 92521 USA

Materials Science and Engineering Program, University of California, Riverside, CA 92521 USA

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First published: 23 May 2022
Citations: 14

Graphical Abstract

Mechanistic insight into the isomerization synthesis of sila-adamantane enables the regioselective functionalization of sila-adamantane at its 1-, 2-, 3-, 5-, and 7-positions. Substitution at the 1-position of the cluster core significantly impacts optical absorbance relative to exocyclic or 2-substitution.

Abstract

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.

Conflict of interest

The authors declare no conflict of interest.

Data Availability Statement

The data that support the findings of this study are available in the Supporting Information of this article.

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