Acid- and base-stable porous organic cages: shape persistence and pH stability via post-synthetic "tying" of a flexible amine cage.
Imine cage molecules can be reduced to amines to improve their chemical stability, but this introduces molecular flexibility. Hence, amine cages tend not to exhibit permanent solid-state porosity. We report a synthetic strategy to achieve shape persistence in amine cages by tying the cage vertices with carbonyls such as formaldehyde. Shape persistence is predicted by conformer stability calculations, providing a design basis for the strategy. The tied cages show enhanced porosity and unprecedented chemical stability toward acidic and basic conditions (pH 1.7-12.3), where many other porous crystalline solids would fail.
Department of Chemistry and Centre for Materials Discovery, University of Liverpool , Liverpool L69 7ZD, U.K.
Ming
M
Liu
Marc A
MA
Little
Kim E
KE
Jelfs
James T A
JT
Jones
Marc
M
Schmidtmann
Samantha Y
SY
Chong
Tom
T
Hasell
Andrew I
AI
Cooper