The same transitions were observed in the second cycle of heating-cooling, however, with a slight but notable and systematic shift in the transition temperatures and a decrease of the peak areas as compared to the first cycle (Figure ). This is attributed to thermal degradation and decomposition upon exposure of the sample to the maximum cycling temperature of 300 °C seen in the first scan (while the decomposition signal and mass loss peak at 340 °C, the onset is observed even below 300 °C). Further confirmation is obtained from a run with five consecutive cycles of IL@CuBTC to a maximum temperature of 300 °C, shown in Figure . According to Figures S3a S3c, the downshift of transitions in the heating and cooling scans is continuous; a linear approximation of the degradation progress gives a decrease in the transition temperature of ~ 6 °C per cycle (R = 0.959). At the same time, we observe a slight change in sample mass after each cycle, which is a sign of partial decomposition of the composite (Figure ). Re-analyzing this sample obtained after the five-cycle/300 °C measurement, no phase transition could be observed.