A Synopsis on CO Capture by Synthetic Hydrogen Bonding Receptors.

Carbon dioxide (CO) is one of the most abundant greenhouse gases in Earth's atmosphere and responsible for global warming. Therefore, aerial CO capture and sequestration has become a major task for human community. Though several adsorbents for CO including activated carbon, zeolites, metal-organic frameworks (MOFs), and other surface-modified porous materials are well developed, the supramolecular approaches using synthetic hydrogen-bonding receptors are less explored. This review article highlights the synthetic development of various artificial receptors and their properties toward fixation of aerial CO as carbonate (CO ), bicarbonate (HCO ), or carbamate (-NHCOO/>NCOO) ions, induced by excess fluoride (F) or hydroxide (OH) ions as their tetrabutylammonium salts. The utilization of encapsulated carbonate/bicarbonate/carbamate complexes in anion exchange metathesis for separation of oxyanions from aqueous solutions are also discussed. In addition, the release of CO and regeneration of receptor molecules are described in a number of occasions. Most importantly, the formation of anion complexes as crystalline materials in solid-state is described in terms of supramolecular chemistry and correlated with their solution-state properties. Finally, the types of receptors containing various functional groups are scrutinized in CO uptake, storage, and release processes and hints of endeavours for future research are delineated.