Exploration of Gate-Opening and Breathing Phenomena in a Tailored Flexible Metal–Organic Framework

Flexible metal–organic frameworks
(MOFs) show the structural transition phenomena, gate opening and
breathing, upon the input of external stimuli. These phenomena have
significant implications in their adsorptive applications. In this
work, we demonstrate the direct capture of these gate-opening and
breathing phenomena, triggered by CO2 molecules, in a well-designed
flexible MOF composed of rotational sites and molecular gates. Combining
X-ray single crystallographic data of a flexible MOF during gate opening/closing
and breathing with in situ X-ray powder diffraction results uncovered
the origin of this flexibility. Furthermore, computational studies
revealed the specific sites required to open these gates by interaction
with CO2 molecules.