Herein, we report
a facile postsynthetic linkage conversion
method
giving synthetic access to nitrone-linked covalent organic frameworks
(COFs) from imine- and amine-linked COFs. The new two-dimensional
(2D) nitrone-linked covalent organic frameworks, NO-PI-3-COF and NO-TTI-COF,
are obtained with high crystallinity and large surface areas. Nitrone-modified
pore channels induce condensation of water vapor at 20% lower humidity
compared to their amine- or imine-linked precursor COFs. Thus, the
topochemical transformation to nitrone linkages constitutes an attractive
approach to postsynthetically fine-tune water adsorption properties
in framework materials.