https://doi.org/10.1016/j.mtsust.2022.100149
“Aida et al. [12] reported that it is the modulation of the polar interaction between CO2 molecules and the channel wall rather than the steric effect that caused the CO2 desorption in AzoMOF15%. By using the polarity sensitive erythrosine B as a polarity probe, their results suggested that the interior channel of AzoMOF became less polar when the trans isomer content increased upon visible light exposure (Fig. 6). Meanwhile, considering that CO2 has a higher polarizability and similar size referring to Ar, the adsorption profiles of CO2 and Ar were also compared. Due to the higher cis content in AzoMOF15%, the channel wall exhibited higher polarity, which affected the packing mode of condensed CO2 molecules and thus led to the smaller capacity of adsorption. However, the Ar adsorption capacity of AzoMOF15% and AzoMOF1% kept similar because of the analogous molecular diameter of CO2 and Ar but no quadrupole moment of Ar referring to CO2. Therefore, CO2 experienced a primary polar effect instead of a steric influence in nanochannels of AzoMOF.”