As societys demand for energy increases and more CO2 emissions are produced, it becomes imperative to selectively capture CO2 and decrease the amount emitted to the atmosphere. Here, we present a flexible and porous metal-organic framework (MOF), [Co-3(OH)(2)(btca)(2)] (1) (where btca = benzotriazole-5-carboxylic acid), which exhibits excellent CO2 uptake (223.7 mg g(-1) at 273 K and 104.7 mg g(-1) at 298 K) and better selectivity for CO2/N-2 (46.3 at 273 K) . During the sample preparation or after an exchange process, compound 1 could trap guest molecules [dimethylformamide (DMF)] into the channels and then yield an isostructural product [Co-3(OH)(2)(btca)(2)].0.5DMF (1.0.5DMF). 1.0.5DMF hardly adsorbs N-2, O-2, and H-2 but favorably captures CO2 in the entire pressure range measured, responded by highly selective CO2/N-2 gas separation with Henrys law selectivity of 79.6.