Figure 1.

a. CO₂ and H₂O adsorption sites in the pores of metal‐organic frameworks (MOFs). b. Experimental setup combining in situ Fourier transform infrared‐attenuated total reflection (FT‐IR ATR) spectroscopy with ultraviolet‐visible (UV‐vis) spectroscopy in diffuse reflectance (DR) mode from the attenuated total reflection (ATR) crystal's surface. c–e. Crystal structure of PCN‐222 (d), PCN‐223 (e), and neutral and protonated structure of the porphyrin linker (c). f. Ball‐stick representation of the structure of the Zr‐clusters surrounded by 8 and 12 tetrakis(4‐carboxyphenyl)porphyrin (TCPP) linkers, respectively (only phenyl‐rings of TCPP are shown for simplicity). Linkers coordinated via the carboxylate to one Zr atom for PCN‐223 are highlighted in yellow. g. Regions of interest studied in the FT‐IR ATR spectra during CO₂ adsorption into PCN‐MOFs and linker, including O−H stretching vibrations (region i)), asymmetric ν(C=O) stretching vibration of adsorbed CO₂ (region ii)), and fingerprint region of the PCN‐MOF vibrations (region iii)) All spectra were subtracted with the blank Si ATR crystal background.