Binding CO₂ from Air by a Bulky Organometallic Cation Containing Primary Amines

The organometallic cation 1 (Fe(bipy-NH₂)₃²⁺, bipy-NH₂ = 4,4'-diamino-2,2'-bipyridine), which was constructed in situ in solution, can bind CO₂ from air effectively with a stoichiometric ratio of 1:4 (1/CO₂), through the formation of "H-bonded CO₂" species: [CO₂-OH-CO₂]^- and [CO₂-CO₂-OH]^-. These two species, along with the captured individual CO₂ molecules, connected 1 into a novel 3D (three-dimensional) architecture, that was crystal 1·2(OH^-)·4(CO₂). The adsorption isotherms, recycling investigations, and the heat capacity of 1 have been investigated; the results revealed that the organometallic cation 1 can be recycled at least 10 times for the real-world CO₂ capture applications. The strategies presented here may provide new hints for the development of new alkanolamine-related absorbents or technologies for CO₂ capture and sequestration.