To understand these changes in melting and glass transition behavior upon water addition, we conducted a series of spectroscopic analyses on the water-containing Co(hmba)3[CoBr4] HCNGs, including in situ Raman spectroscopy measurements during the crystal melting and a subsequent cooling/heating cycle (Figure ), and ex-situ FT-IR spectroscopy measurements (Figure ). In agreement with the in situ FT-IR data reported in Ref. , we find no apparent changes in our exsitu FT-IR measurements upon the glass formation or water addition. However, the in situ Raman spectroscopy measurements show that a peak at ~1611 cm -1 (ascribed to the carbonyl vibration in hmba ) vanishes around the melting temperature (Figure ) without reappearing in the glassy state (Figure ). This clearly suggest that the carbonyl group is directly involved in the melting transition. To further probe any structural changes around the Co atoms, we measured the visible absorption spectra of the pristine and hydrated glasses (Figure ). We were unable to quantify the used film thickness and hence the absorption coefficient due to differences in thickness across the film. However, we find that higher water content leads to smaller absorption, in agreement with the expectation that the glass fraction of the sample is "diluted" by the added water. The large band around 6-700 nm present in all samples can be assigned to the crystal field splitting in [CoBr4] 2-, where Br -ligands are tetrahedrally coordinated to Co-centers, as (i) Br -is in the lowest splitting part of the spectrochemical series, and (ii) lower coordination is known to induce lower splitting.