Furthermore, the modified ZIF-4 and ZIF-62 samples are transparent (see transmission data of ZIF-4-bImCl glass in Supplementary Fig. ) and we find it possible to produce defect-free samples with size of >1 cm for the modified ZIF-4, ZIF-8, and ZIF-62 glasses (Fig. ). This stands in significant contrast to the case of unmodified ZIF-62 and especially unmodified ZIF-4 glass, the quality of which are often impaired by partial decomposition and foaming 10 (Fig. ). Based on the observed transparency and the compositional analysis performed using energy-dispersive X-ray (EDX) spectroscopy (Fig. and Supplementary Fig. ), we infer that the samples are homogenous in the elements tested (C, N, Zn, Cl) at both the micro-and macro-scales, although we find depletion of Cl in the ZIF-62-bImCl sample (Supplementary Fig. ). In comparison, previous efforts to lower the melting point of ZIF-8 below its decomposition temperature using ionic liquids, which employed melting temperatures around 600 °C, created samples with sizes of <1 mm 12 . In addition to using bImCl as the modifier salt, we also find glass formation upon co-melting the ZIF crystals using benzimidazolium salts with bromide (Br -) and iodide (I -) as anions. In summary, we find similar Tg values and loss of crystallinity upon melt-quenching for the Br -and I -based salts as for the Cl -based salts (see XRD and calorimetry data as well as photographs in Supplementary