Structure design of photosensitive ionic liquid for CO2 capture

Organic molecules containing azobenzene (azo) groups commonly undergo cis-trans isomerization upon light irradiation. It has been constructed azobenzene into the cation of ionic liquid (IL) for CO2 capture. A series of the derivatives based on the reported photo-responsive IL (trans-azo-IL) have been further designed by modifying the ortho-, meta-, and para-site of azo group with different electron-donating and electron-withdrawing groups (-NH2, -OH, -OCH3, -CH3, -CN, -NO2). By investigating the matching of the frontier molecular orbital energy levels between ILs and CO2, the trans-cis isomerization energy, the binding energy between the cation and anion, the hydrogen bond interaction, the UV-visible absorption properties, and diffusion behavior by multiscale simulations, it found that -OH substituted on ortho-site of azo could further improve the performance of CO2 capture compared to the original structure. The results provide a novel strategy for the screening and design of functional IL in CO2 capture in the future.