Switchable MOFs are unique materials, which are able to transform their crystal structure from a dense or less porous to a highly porous state and vice versa as response to the external stimuli. In order to get a deeper insights into switching mechanism, low-frequency vibrations, responsible for the lattice dynamic, typically appearing below 100 cm-1 (terahertz region) should be studied in details. Inelastic neutron scattering shows a plenty of advantages over optic spectroscopy methods, because of the different rules governing intensity of the vibrational features and therefore is highly suitable for detail investigation of the switching mechanism in flexible MOFs. Herein we apply for the beamtime for temperature-dependent and control gas atmosphere INS measurements on DUT-8(M) (M – Co, Zn and Cu), which will complement the data, collected earlier on DUT-8(Ni) system.