Moderated Basicity of Endohedral Amine Groups in an Octa-Cationic Self-Assembled Cage

Courtney Ngai; Hoi-Ting Wu; Bryce da Camara; Christopher G Williams; Leonard J Mueller; Ryan R Julian; Richard J Hooley

doi:10.1002/anie.202117011

Moderated Basicity of Endohedral Amine Groups in an Octa-Cationic Self-Assembled Cage

Angew Chem Int Ed Engl. 2022 Mar 7;61(11):e202117011. doi: 10.1002/anie.202117011. Epub 2022 Jan 27.

Authors

Courtney Ngai¹, Hoi-Ting Wu¹, Bryce da Camara¹, Christopher G Williams¹, Leonard J Mueller¹, Ryan R Julian¹, Richard J Hooley¹

Affiliation

¹ Department of Chemistry and the UCR Center for Catalysis, University of California-Riverside, Riverside, CA, 92521, USA.

Abstract

A self-assembled Fe^II₄ L₆ cage was synthesized with 12 internal amines in the cavity. The cage forms as the dodeca-ammonium salt, despite the cage carrying an overall 8+ charge at the metal centers, extracting protons from displaced water in the reaction. Despite this, the basicity of the internal amines is lower than their counterparts in free solution. The 12 amines have a sliding scale of basicity, with a ≈6 pK_a unit difference between the first and last protons to be removed. This moderation of side-chain basicity in an active site is a hallmark of enzymatic catalysis.

Keywords: Coordination Chemistry; Enzyme Models; Molecular Recognition; Self-Assembly; Supramolecular Chemistry.

Publication types

Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Amines / chemistry*
Cations / chemical synthesis
Cations / chemistry
Ferrous Compounds / chemical synthesis*
Ferrous Compounds / chemistry
Ligands
Molecular Structure

Substances

Amines
Cations
Ferrous Compounds
Ligands

Grants and funding

R01 GM097569/GM/NIGMS NIH HHS/United States