Diffuse reflectance spectroscopy (Figure ) allowed to study also the crystalline ZIF-62 starting material, which was synthesized in powder form. Extending spectroscopy into the NIR region provided additional data for comparing the crystalline precursor and the processed glass. Importantly, almost the full spectral fingerprint of the crystalline ZIF-62 is retained in the processed glass, in particular, without any new vibrations emerging. This is in agreement with previous observations that aside the release of trapped guest molecules, the relevant ZIF building units (imidazole and benzimidazole linkers) remain intact during glass processing.