Post combustion carbon capture is a complementary approach to research in renewable energy to combat the exponential increase of CO2 emission and global warming. An important outcome of enhancing gas separation in materials, for example, is the decrease in energy needed for separation of hydrocarbons. Metal-organic Frameworks (MOFs) have shown promise in this area because their high surface area, porosity and chemical/structural tailorability contribute to the preferential selective adsorption of gases. This work explores the incorporation of CO2 and hydrocarbons into a flexible framework, Zn2(bpdc)2(bpee), (bpdc= 4,4’-biphenyl dicarboxylate, bpee=1,2-bis(4-pyridyl)ethylene) using infrared (IR), Raman spectroscopy and van der Waals density Functional (vdW-DF) calculations. We present evidence for “gate opening” phenomenon, where the structure of the framework changes only upon adsorption of CO2and C2 hydrocarbon isomers but not for N2 or methane. Understanding the specifics of CO2 interaction with the framework was explored to identify parameters affecting its selectivity. We find that the high quadrupole moment of CO2 and its interaction through its carbon with the bpdc linker induces the transformations. The flexibility of the framework was found to be primarily due to the specific connectivity of the Zn metal center to the ligands, at one end in a monodnetate mode and at the other in a bidentate mode. The unexpected gate opening behavior in this same framework upon the adsorption of C2 hydrocarbon isomers was also studied. We find that the specific hydrogen bonding between the CH of the hydrocarbon and the C=O bond of the bpdc linker is responsible for this interesting behavior. Furthermore, the strength of the hydrogen bond was found to affect the gate opening pressure point. This effect points towards the potential of this framework for uses such as pressure swing adsorption based separation. In conclusion, we have identified specific interactions of CO2 and hydrocarbons in a flexible framework that lead to their selective adsorption properties. This knowledge allows the design of frameworks with optimized properties.