Fig. 3

Characterization of PT- and PY-COFs. a FT-IR characterization of PT- and PY-COFs. Free amine functionalities can be identified by the characteristic ν_N-H(stretch) in the region 3430 cm⁻¹–3190 cm⁻¹. The inset shows the presence of ν_{C=N(stretch).} b ¹³C ssNMR spectra with corresponding assignments. The unassigned signals correspond to the pyrene moiety and the phenyl rings. ¹⁵N ssNMR depicting the free amine functionalities in PT- and PY-COFs is shown on the right as an inset. c PXRD patterns of PT- and PY-COFs with corresponding Rietveld refinements (magenta) showing good fits to the experimental data (black) with minimal differences. The turquoise traces show the difference between the experimental data and the refinement. The corresponding Miller indices of the identifiable reflections are shown as well. d Argon sorption isotherms of PT- and PY-COFs at 87 K. Filled and open symbols represent the adsorption and the desorption branches, respectively