This technique was chosen over traditional DSC because it is less prone to glass relaxation effects and because some of the samples feature weak glass transitions (see Supplementary Text). Using FDSC, we, however, identify clear glass transition temperatures (Tg) for all three ZIFs in the range of 130-140 °C (see Supplementary Table ), i.e. ~200 °C below that of the Tg of the unmodified glasses in the case of ZIF-4 and ZIF-62 as measured by traditional DSC (note that ZIF-8 does not melt at R=0) . This confirms the formation of glasses for all the co-melted samples.