Glass materials exhibit vibrational anomalies, including the "boson peak" (BP), characterized by an abundance of low-frequency vibrational modes beyond the expectation in the Debye model. The BP is often described to correlate with disorder and density, but usually these two parameters increase when going from the crystalline to the glassy state. However, the metal- organic framework (MOF) glasses, a glass family discovered in 2015, offer a unique opportunity to study the BP as the MOF glasses usually feature a higher density than their isochemical crystals – in stark contrast to the vast majority of other glass families. Therefore, we here propose to collect inelastic X-ray scattering data to deduce the vibrational density of states of two MOF crystals (ZIF-4 and ZIF-zni with densities of 1.49 and 1.60 g cm-3, respectively) and their isochemical glass (density of 1.63 g cm-3) with the ultimately aim decouple the effect of density and disorder on the BP.