Flexible metal organic frameworks (MOFs) have attracted great interest for their dynamically structural transformability in response to external stimuli. Herein, we report a switchable "breathing" or "gate-opening" behavior associated with the phase transformation between a narrow pore (np) and a large pore (1p) in a flexible pillared-layered MOF, denoted as MOF-1das, which is also confirmed by SCXRD and PXRD. The desolvated phase (MOF-1des) features a unique stepwise adsorption isotherm for N-2 coupled with a pronounced negative gas adsorption pressure. For comparison, however, no appreciable CO2 adsorption and gate-opening phenomenon with stepwise sorption can be observed. Furthermore, the polar micropore walls decorated with thiophene groups in MOF-1des reveals the selective sorption of toluene over benzene and p-xylene associated with self-structural adjustment in spite of the markedly similar physicochemical properties of these vapor molecules.