A new metal-organic framework (MOF), [Co3(tzba)2(bpy)3(F)2]·DMF·C2H5OH·2H2O (1), has been constructed by solvothermal reaction of Co(NO3)2 with 4-(1H-Tetrazol-5-yl) benzoic acid (H2tzba) and 4,4'-bipyridine (bpy) mixed ligands. 1 shows an interpenetrated three-dimensional (3D) pillar-layered framework with the novel trinuclear [Co3(CN4)2(F2)] clusters. The π···π interactions existing among three bpy give rise to an uncommon tripillar in the framework. The framework reveals a reversible dynamic flexibility related to the solvent molecules. Meanwhile, the adsorption of CO2 exhibits an interesting gate opening-closing phenomenon which features the S-shaped isotherms with dramatic hysteretic desorption. The selective adsorption of CO2 over CH4 as well as the adsorption mechanism for CO2 were also discussed deeply. [ABSTRACT FROM AUTHOR]