Ultrathin Films of Porous Metal–Organic Polyhedra for Gas Separation

Andrés, Miguel A.; Carné‐Sánchez, Arnau; Sánchez‐Laínez, Javier; Roubeau, Olivier; Coronas, Joaquı́n; Maspoch, Daniel; Gascón, Ignacio

doi:10.1002/chem.201904141

Cited by 24 publications

(23 citation statements)

References 31 publications

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“…Inspired by the previous work on the processing of ultrathin films of MOPs using the Langmuir–Blodgett technique, we conduct studies on the structures of hairy MOPs (C 18 -MOP) at the air/water interface . The hairy MOPs (C 12 - and C 18 -MOPs) show similar surface pressure–area compression isotherms (π– A ), suggesting the same structural evolution process during the compression process (Figures S3 and S4 in the Supporting Information).…”

Section: Resultsmentioning

confidence: 93%

Solvated and Deformed Hairy Metal–Organic Polyhedron

et al. 2020

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Despite the fact that numerous studies have been conducted to explore the crystalline structures of various metal−organic polyhedrons (MOPs), the direct probing of solvated and deformed structures of MOPs is still rare but critical to the development of processing protocols and the understanding of their structure−property relationship for gas separation and ion transportation. Here, MOPs from the coordination of isophthalic acids and Cu 2+ are covalently functionalized with alkyl chains for studies in solutions and at the air/water interface, respectively. As suggested from small-angle scattering studies, the MOP structures in the solvated state remain intact while the grafted linear alkyl arms exhibit an extended conformation, allowing solvent molecules to penetrate into the cavity of MOPs. Meanwhile, under surface pressure at the water/air interface, the hairy MOP structures, as suggested by in situ neutron reflectivity studies, can be deformed and MOP cores are close together while the grafted chains are squeezed upward and downward toward liquid and air phases, respectively. This discovery provides the first direct evidence for the existence of an ion transportation active conformation of hairy MOPs.

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Section: Resultsmentioning

confidence: 93%

Solvated and Deformed Hairy Metal–Organic Polyhedron

et al. 2020

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“…In a different strategy to the homogeneous dispersion of coordination cages in polymers described above, André s et al 115 reported the deposition of cage-based thin films onto polymer membranes for gas separation. A Rh II 24L24 cuboctahedron functionalised with pendant aliphatic chains, analogous to Rh II 24L24 10 (Figure 2B), assembled at the air-water interface and formed homogenous monolayer films with 2-3 nm thickness through the Langmuir-Blodgett technique.…”

Section: Analogues Of Cu IImentioning

confidence: 99%

Metal–organic cages for molecular separations

et al. 2021

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Separation technology is central to industries as diverse as petroleum, pharmaceuticals, mining, and life sciences. Metal-organic cages, a class of molecular containers formed via coordination-driven self-assembly, show great promise as separation agents. Precise control of the shape, size, and functionalization of cage cavities enables them to selectively bind and distinguish a wide scope of physicochemically similar substances in solution. Extensive research has thus been performed involving separations of high value targets with coordination cages, ranging from gases and liquids to compounds dissolved in solution. Enantiopure capsules also show great potential for the separation of chiral molecules. The use of crystalline cages as absorbents, or the incorporation of cages into polymer membranes, could increase the selectivity and efficiency of separation processes. This review covers recent progress in using metal-organic cages to achieve separations, with discussion of the many methods of using them in this context. Challenges and potential future developments are also discussed.Compared to metal-organic frameworks (MOFs), a class of solid, porous coordination-based materials that have been widely used for separation, [29][30][31][32] an advantage of coordination cages is their tailorable solubilities. 33,34 Cages in solution, in contrast to solid MOFs, can deform or de-ligate so as to encapsulate a guest much larger than the cage pores. Cages can also be incorporated into polymers, [35][36][37][38] as fillers, to prepare mixed-matrix membranes for performing separations. [39][40][41][42] The solubility of these capsules in different solvents enables them, in contrast to MOFs, to form homogeneous mixtures with polymer matrices, avoiding agglomeration or precipitation of fillers during membrane formation, which may lead to poor separation performance.This review summarizes recent advances in using metal-organic cages for separations, with emphasis on their multiple modes of use, ranging from cages in solution and in the solid, to polymer membranes and separation columns with cages incorporated. Cages in solution for extractionCoordination cages have been explored as liquid-phase extractants to extract target molecules from an immiscible liquid phase (liquid-liquid extraction) or a solid phase (solid-liquid extraction).These strategies require binding affinities that are strong enough to pull target molecules from the initial phase into another. Cages bring guests into solvents in which the guests are not normally soluble; the cages are thus useful liquid-phase extractants. Successful application of this extraction strategy requires cages that are stable in different solvents. The high stability of a host-guest complex after extraction can impede extractant recycling and cargo recovery, however stimuli-responsive guest release can be used to overcome these challenges. [43][44][45][46][47] Liquid-liquid extractionThe Nitschke group recently reported Fe II 4L4 tetrahedron 1 (Figure 1A), prepared from an azaphosp...

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“…For this, Langmuir-Schaeffer (LS) or Langmuir Blodgett (LB) techniques were used to form dense monolayers of [Rh 24 (C 12 -bdc) 24 ] (C 12 -bdc = 5-dodecoxybenzene-1,3-dicarboxylate). 37 The hydrophobicity of the aliphatic chains aided the dispersion of the MOCs on the surface of water, leading to the formation of monolayers of ca. 2.5 nm in thickness.…”

Section: Soft Mattermentioning

confidence: 99%