Structural‐Deformation‐Energy‐Modulation Strategy in a Soft Porous Coordination Polymer with an Interpenetrated Framework

Abstract

To achieve unique molecular‐recognition patterns, a rational control of the flexibility of porous coordination polymers (PCPs) is highly sought, but it remains elusive. From a thermodynamic perspective, the competitive relationship between the structural deformation energy (Edef) of soft PCPs and the guest interaction is key for selective a guest‐triggered structural‐transformation behavior. Therefore, it is vital to investigate and control Edef to regulate this competition for flexibility control. Driven by these theoretical insights, we demonstrate an Edef‐modulation strategy via encoding inter‐framework hydrogen bonds into a soft PCP with an interpenetrated structure. As a proof of this concept, the enhanced Edef of PCP enables a selective gate‐opening behavior toward CHCl3 over CH2Cl2 by changing the adsorption‐energy landscape of the compounds. This study provides a new direction for the design of functional soft porous materials.

Supramolecular modification of a metal–organic framework increases sorption switching: insights into reversible structural deformation of ZIF-8

“…The relative areas of the hysteresis between adsorption and desorption isotherms were calculated using a partial integration function to compare the dissipated pressure during phase transitions. 58 The hysteresis area of the untreated sample (Fig. 4c) was approximately 20% higher than that of the Et 3 N-modied ZIF-8 nanocrystals (Fig.…”

“…In summary, an experimental method of comparing the structural-deformation and pressure-modulation mechanisms of soft, porous materials was developed by leveraging AFM nanoindentation and gas physisorption analysis. Observed differences in the thermodynamic pressure landscape 58 were related to the elastic modulus, a structural property of the material that gives its resistance to adsorption stress as a function of strain during reversible deformation. 69 The measured mechanical properties align with the idea that more rigid materials require higher pressure or energy to induce structural mobility.…”

Supramolecular Modification of a Metal-Organic Framework Increases Flexibility and Switchability: Experimental Insights into Structural Deformation of ZIF-8

“…The relative areas of the hysteresis between adsorption and desorption isotherms were calculated using a partial integration function 47 to compare the dissipated pressure during phase transitions. 48 The hysteresis area of the untreated sample (Figure 3c) was approximately 20% higher than that of the Et3Nmodified ZIF-8 nanocrystals (Figure 3d). A higher area of the hysteresis indicates more pressure or energy dissipated due to internal material deformation.…”

“…57 In summary, an experimental method of comparing the structural-deformation and pressure-modulation mechanisms of soft, porous materials was developed by leveraging AFM nanoindentation and gas physisorption analysis. Observed differences in the thermodynamic pressure landscape 48 were related to the elastic modulus, a structural property of the material that gives its resistance to adsorption stress as a function of strain during deformation. 59 The physical properties of unmodified and modified nanocrystals of ZIF-8 were directly linked to potential differences in the supramolecular structure of the framework via hydrogen bonds and point defects as determined by FTIR spectroscopy.…”

Guest‐selective gate‐opening by pore engineering of two‐dimensional Kagomè lattice porous coordination polymers

“…A long-sought goal for researchers has been to mimic the confined environments of proteins in which physical and chemical processes can be regulated [1][2][3][4]. Supramolecular chemistry has provided the possibility to design artificial porous materials called porous coordination polymers (PCPs), also known as metal-organic frameworks via the coordination of metal ions with organic ligands, which results in the for-that exhibit significant structural deformation during the uptake process [14][15][16][17][18][19][20]. For the former, pore surface engineering schemes have been developed for the separation of small hydrocarbons, which is an extremely complicated problem, owing to the close physicochemical properties exhibited by such small molecules [21].…”