Absorption of atmospheric CO2 as carbonate inside the molecular cavity of a new tripodal hexaurea receptor.

A new hexaurea receptor has been synthesized, which absorbs atmospheric CO2 to produce an air-stable solid carbonate complex under normal conditions. Structural analysis of the carbonate complex with this receptor suggests that the carbonate is fully encapsulated within its highly organized intramolecular cavity via 12 strong NH···O bonds in the range of 2.703(3)-2.989(3) Å from six urea units, with each anionic oxygen coordinated via four NH···O bonds with two urea groups.