A family of azo‐bridged covalent organic polymers (azo‐COPs) was synthesized through a catalyst‐free direct coupling of aromatic nitro and amine compounds under basic conditions. The azo‐COPs formed 3D nanoporous networks and exhibited surface areas up to 729.6 m
2 g
?1, with a CO
2‐uptake capacity as high as 2.55 mmol g
?1 at 273 K and 1 bar. Azo‐COPs showed remarkable CO
2/N
2 selectivities (95.6–165.2) at 298 K and 1 bar. Unlike any other porous material, CO
2/N
2 selectivities of azo‐COPs increase with rising temperature. It was found that azo‐COPs show less than expected affinity towards N
2 gas, thus making the framework “N
2‐phobic”, in relative terms. Our theoretical simulations indicate that the origin of this unusual behavior is associated with the larger entropic loss of N
2 gas molecules upon their interaction with azo‐groups. The effect of fused aromatic rings on the CO
2/N
2 selectivity in azo‐COPs is also demonstrated. Increasing the π‐surface area resulted in an increase in the CO
2‐philic nature of the framework, thus allowing us to reach a CO
2/N
2 selectivity value of 307.7 at 323 K and 1 bar, which is the highest value reported to date. Hence, it is possible to combine the concepts of “CO
2‐philicity” and “N
2‐phobicity” for efficient CO
2 capture and separation. Isosteric heats of CO
2 adsorption for azo‐COPs range from 24.8–32.1 kJ mol
?1 at ambient pressure. Azo‐COPs are stable up to 350 °C in air and boiling water for a week. A promising
cis/
trans isomerization of azo‐COPs for switchable porosity is also demonstrated, making way for a gated CO
2 uptake.
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