Since we observed the partial decomposition of the samples upon physisorption of C2-C4 hydrocarbons and no new crystalline phases appeared in PXRD patterns, SEM imaging was applied to analyze the changes on the macroscopic scale (see Figure ). f') in which the crystal shape can still be estimated but the crystal underwent significant degradation. In case of n-butane (Figure ) and butadiene (Figure ), almost the entire initial habitus vanished and mainly fragments or strongly decomposed material is visible. These observations are in line with physisorption and PXRD results indicating the contraction of the MOF with increasing of the size of the guests. The decreasing size of the intact crystals and amount of fragmented larger crystals can be explained by a stabilization of smaller crystals due to a smaller ratio of inner and outer surface. Total pore volume evolution as a function of adsorption/desorption stress Hydrocarbon physisorption data shows a gradual decreasing amount of gas adsorption as the chain length of the adsorbate increases and as double bonds are introduced. Both effects are likely to increase the amount of adsorption/desorption stress on the framework: longer chains lead to an increase of van-der-Waals forces, and the presence of double bonds introduces the possibility for π-π interactions. Both factors lead to an increase of the adsorption enthalpy and adsorption stress, which leads to the framework contraction. The underlying phenomena and correlations are clearly discerned by plotting the total pore volumes (Figure ) determined in multiple cycles with C1 to C4 alkanes and alkenes: For methane we can observe the highest pore volume of 2.81 cm 3 •g -1 which was also observed in the nitrogen physisorption measurement. This value does not change significantly over three adsorption/desorption cycles. Meaning that for methane the energy input through the adsorption enthalpy in adsorption and capillary forces in desorption is insufficient to contract the structure, leading to a reproducible and repeatable adsorption over multiple cycles. This is reflected in the SEM images as the majority of the crystals remains intact, their faces remain plain, their geometric shape and surface do not change after multiple cycles.