Lewis acid/base functionalized pore surface of porous structure provide specific interaction to different guest molecules based on their chemical nature. This can be exploited for efficient design of porous materials for small molecule separations. The purpose of this experiment is to elucidate the structure-activity relationship of flexible Lewis acid/base functionalized microporous isostructural pillared-layered metal-organic frameworks, Co6F6(BTTDMBA)2(bpy)3 and Co6F6(TPP)2(bpe)3 w.r.t guest molecules (CO2, O2, C2H4, C2H6).