Rotors, Motors, and Machines Inside Metal–Organic Frameworks

Martínez-Bulit, Pablo; Stirk, Alexander Joseph; Loeb, Stephen J.

doi:10.1016/j.trechm.2019.05.005

Cited by 68 publications

(58 citation statements)

References 77 publications

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“…Pillared pyrazine in a pillared layer PCP shows a rotational barrier of 7.7 kJ mol −1 , whereas 1,4‐benzenedicalboxylate (1,4‐bdc) in MIL‐53 yields barriers ranging from 30 to 50 kJ mol −1 . The local flexibility of rigid frameworks can be further engineered by integrating molecular machines . Incorporating interlocked rotaxanes, shuttles, motors, and dynamic binding sites in the framework backbone facilitates stimuli‐driven local softness in an otherwise rigid framework, for example, upon application of an electric field or light .…”

Section: Structural Softness Transitions and Dynamicsmentioning

confidence: 99%

Chemistry of Soft Porous Crystals: Structural Dynamics and Gas Adsorption Properties

2020

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In this Minireview, we discuss the fundamental chemistry of soft porous crystals (SPCs) by characterizing their common structural features and the resulting structural softness and transitions. In particular, we focus on the recently emerging properties based on metastable transitions and those arising from local dynamics. By comparing the resulting adsorption properties to those of commonly applied rigid adsorbents, we highlight the potential of SPCs to revolutionize adsorption‐based technologies, considering our current understanding of the thermodynamic and kinetic aspects. We provide brief outlines for the experimental and computational characterization of such phenomena and offer an outlook toward next‐generation SPCs likely to be discovered in the next decade.

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Section: Structural Softness Transitions and Dynamicsmentioning

confidence: 99%

Chemistry of Soft Porous Crystals: Structural Dynamics and Gas Adsorption Properties

2020

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“…The reader is referred also to other recent reviews on responsive porous materials [57][58][59][60][61][62] and molecular machines embedded in MOFs. 63 Figure 1 Illustration of three distinct modes of incorporation of a photoswitch in a solid material scaffold (a) as a guest in the pores, (b) pendant to the linker, (c) in the backbone of the linker.…”

Section: Molecular Photoswitchesmentioning

confidence: 99%

Photoresponsive porous materials

et al. 2021

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“…13 A vision towards robust, high-fidelity, fixedvolume MOFs that retain dynamic complexity and exhibit adsorption properties inaccessible to rigid materials is to graft dynamic, mechanically interlocked molecules onto rigid MOFs, treated as scaffolds. 7,[27][28][29] In contrast to MOFs with pliable struts and backbones which, subject to repeated dynamics, will rupture, mechanically interlocked molecules 30,31 can undergo repeated dynamics without breakage. In addition, as some mechanically interlocked molecules are influenced by light and electric field, 27 integrating mechanically interlocked components into MOF scaffolds may offer new routes to modulate gas adsorption with exotic (aside from the usual temperatureand pressure-swing) external stimuli.…”

Section: Introductionmentioning

confidence: 99%

“…In 2015, Loeb and coworkers 36 synthesized an RMS-MOF coined UWDM-4. 28 The struts of UWDM-4 serve as the axle for a [2]rotaxane, whose macrocyclic wheel was shown to rapidly shuttle between the two benzimidazole stations on its strut, unimpeded owing to the porosity of the MOF. 36 Fig.…”

Section: Introductionmentioning

confidence: 99%

Statistical Mechanical Model of Gas Adsorption in a Metal-Organic Framework Harboring a Rotaxane Molecular Shuttle

Carney¹,

Roundy²,

Simon³

2020

Preprint

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Metal-organic frameworks (MOFs) are modular and tunable nano-porous materials with applications in gas storage, separations, and sensing. Flexible/dynamic components that respond to adsorbed gas can give MOFs unique or enhanced adsorption properties. Here, we explore the adsorption properties that could be imparted to a MOF by a rotaxane molecular shuttle (RMS) in its pores. In the unit cell of an RMS-MOF, a macrocyclic wheel is mechanically interlocked with a strut of the MOF scaffold. The wheel shuttles between stations on the strut that are also gas adsorption sites. At a level of abstraction similar to the seminal Langmuir adsorption model, we pose and analyze a simple statistical mechanical model of gas adsorption in an RMS-MOF that accounts for (i) wheel/gas competition for sites on the strut and (ii) gas-induced changes in the configurational entropy of the shuttling wheel. We determine how the amount of gas adsorbed, position of the wheel, and differential energy of adsorption depend on temperature, pressure, and the interactions of the gas/wheel with the stations. Our model reveals that, compared to a rigid, Langmuir material, the chemistry of the RMS-MOF can be tuned to render gas adsorption more or less temperature-sensitive and to release more or less heat upon adsorption. The model also uncovers a non-monotonic relationship between the temperature and the position of the wheel if gas out-competes the wheel for its preferable station.

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Rotors, Motors, and Machines Inside Metal–Organic Frameworks

Cited by 68 publications

References 77 publications

Chemistry of Soft Porous Crystals: Structural Dynamics and Gas Adsorption Properties

Chemistry of Soft Porous Crystals: Structural Dynamics and Gas Adsorption Properties

Photoresponsive porous materials

Statistical Mechanical Model of Gas Adsorption in a Metal-Organic Framework Harboring a Rotaxane Molecular Shuttle

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