As DUT-76(Cu) showed an exceptional ethene uptake in high-pressure adsorption experiments at 298 K we now aimed the in-depth fundamental studies of host-guest interactions with hydrocarbons of different lengths and degrees of saturation at their boiling points. When comparing the isotherms of ethane and ethylene already a significant influence of the degree of saturation is discerned (see Figure and). An almost identical uptake of ethane (45.5 mmol•g - 1 , TPV = 2.52 cm 3 •g -1 , at p/p0 = 0.40, 185 K) and ethylene (46.6 mmol•g -1 , TPV = 2.30 cm 3 •g -1 , at p/p0 = 0.40, 169 K) is reached in the first cycle. This is 0.3 and 0.5 cm 3 g -1 lower compared to methane and indicates that 10 and 18% of the DUT-76(Cu) sample respectively is irreversibly contracting during exposure to the adsorption stress. However, the three steps in the isotherm observed for nitrogen and methane are still visible. For both gases we observe two narrow hysteretic loops in the isotherms. The first one, similar to methane appears in the first step and the second one is observed between the second and third steps in the range of p/p0 = 0.1 -0.15. In the second physisorption cycle, however, the uptake of the two gases decreases significantly. Namely, for ethane a drop in gas uptake of about 20% to 36.8 mmol•g -1 (at p/p0 = 0.40, 185 K) is observed, whereas for ethylene this drop is more significant as the maximum uptake decreases to almost 50% to 26.1 mmol•g -1 (at p/p0 = 0.40, 169 K). The changes are obviously related to the desorption of the gas from the mesopore in the first adsorption/desorption cycle indicating that the framework is exposed to a larger stress upon desorption of ethylene. The second and third cycle isotherms show reversible behaviour with no hysteresis. This observation, as well as the fact that the sample was heated to 298 K and evacuated between measurements, also shows that the lower uptake is not due to adsorbate remaining in the pores but to changes in the framework itself.