Gas　storage/separation　is　a　typical　application　of　porous　materials　such　as　metal　organic　frameworks　(MOFs).　The　adsorption/separation　behavior　results　from　the　host-guest　and/or　guest-guest　interaction　and　equilibration　(host,　porous　material;　guest,　adsorbates).　Although　the　driving　forces　for　gas　adsorption　have　been　investigated,　a　detailed　picture　of　interactions　between　gas　molecules　and　MOFs　has　not　clearly　emerged.　Herein,　a　new　cobalt　microporous　MOF　[Co(tipb)(adc)](DMF)(3)(H2O)(1.5),　which　possesses　a　rare　self-interpenetrated　gra　topology,　has　been　prepared　with　both　tipb　and　H(2)adc　ligands　(tipb　=　1,3,5-tris(p-imidazolylphenyl)benzene,　adc　=　9,10-anthracenedicarboxylate).　This　MOF　shows　high　stability　and　exceptional　selective　adsorption　of　CO2　over　N-2,　O-2,　and　CH4.　In　particular,　a　theoretical　assumption　of　a　＂regional　dynamic　electric　field　effect＂　is　proposed　to　clarify　the　selective　adsorption.　Moreover,　we　suggest　that　the　proposed　effect　may　be　one　of　the　most　important　factors　impacting　gas　separation　and　storage　in　porous　materials.