The approach of employing multivariate MOFs was used to fine-tune the mechanical properties of the flexible framework DUT-49. In situ XRD, NMR and physisorption studies showed that the partial incorporation of a more rigid linker into the DUT-49 framework enables stabilization of the metastable open pore phase, which led to a two-fold amplification of the expelled gas amount upon the “negative gas adsorption” transition.