Decoding the Gate Opening Mechanism of the Flexible Framework RPM3–Zn upon Hydrocarbon Inclusion

Abstract

Although the existence of a gate-opening phenomenon in the flexible RPM3–Zn is well known, the actual mechanism remains a mystery. Here, we provide a full picture that unambiguously identifies and explains the gate-opening mechanism in RPM3–Zn upon exposure to various hydrocarbonsacetylene, ethylene, ethane, propane, and butaneby combining insights gained from calorimetry, adsorption isotherms, PXRD, in situ infrared spectroscopy, and ab initio simulations. We find that the key to gate opening in this framework is the stretching of a bond between an O and the Zn metal center (COO–Zn), acting as a “stabilizer”, which weakens the necessary support required for the structure to remain intact. Consequently, an increasing concentration of guest molecules exerts sufficient internal pressure to induce strong structural transformations in the unit cell shape and volume, thus triggering the gate opening. Our results are critical to understanding the gate opening in several other flexible frameworks and provide an opportunity to fine-tune hydrocarbon separation.

In Situ Electrochemically‐Bonded Self‐Adapting Polymeric Interface for Durable Aqueous Zinc Ion Batteries

“…[37] Additionally, the COO─Zn bond at 1629 cm −1 was also detected. [46] Collectively, these results affirm the successful transference of the SAP film from the separator to the Zn anode surface, accompanied by in situ electrochemical welding via the formation of Zn─O bonds between SAP interface and Zn anode during cycling (Figure 2e). This robust electrochemical interfacial interaction significantly improves interfacial compatibility between the SAP interface and Zn electrode during prolonged cycling, effectively mitigating parasitic reactions and Zn dendrites formation at the electrode/electrolyte interface.…”

Breathing Metal–Organic Frameworks Supported by an Arsenic-Bridged 4,4′-Bipyridine Ligand

“…While the central Zn(II) cation maintained its octahedral structure, its Zn−O bond lengths underwent significant alteration following solvent removal. 17 Additionally, some Zn(II) cations that coordinate with water molecules likely originate from ambient moisture. Consequently, the framework underwent adjustments to adapt to the vacant cavities caused by the flexibility of the nodes and hydration effects.…”

“…The Zn­(II) cations at the terminal ends shifted from their original tetrahedral structures to distorted trigonal bipyramidal structures after the solvent molecule removal. While the central Zn­(II) cation maintained its octahedral structure, its Zn–O bond lengths underwent significant alteration following solvent removal . Additionally, some Zn­(II) cations that coordinate with water molecules likely originate from ambient moisture.…”

Luminescent Metal–Organic Framework for the Selective Detection of Aldehydes

“…Calculations based on van der Waals density functional theory (vdW-DF1) – were performed as implemented in the VASP code, – which uses plane-waves and projected augmented wave pseudopotentials. The kinetic energy cutoff is selected to be 500 eV with tight convergence criteria for forces (0.01 eV/Å) and energy (10 –6 eV).…”