Revisiting molecular adsorption: unconventional uptake of polymer chains from solution into sub-nanoporous media

Oe, Noriyoshi; Hosono, Nobuhiko; Uemura, Takashi

doi:10.1039/d1sc03770f

Cited by 27 publications

(55 citation statements)

References 82 publications

(120 reference statements)

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“…The adsorption isotherm for PEG (M w = 2 kg/mol, hereafter referred to as PEG 2k) showed significant adsorption for both MOFs. 4 The maximum amount of adsorbed PEG 2k on these MOFs was comparable to their ideal capacity, indicating that spontaneous PEG insertion occurred simultaneously with a gradual replacement of pre-existing solvent molecules inside the MOFs. Thus, the polymer adsorption behavior showed an intriguingly high degree of solvent dependence.…”

Section: Adsorption Of Polymers On Mofs From the Solution Phasementioning

confidence: 85%

“…Large polymers can enter and diffuse from MOF nanochannels by uncoiling themselves although they would otherwise adopt selfentangled globular conformations with hydrodynamic sizes larger than MOF pore apertures (Figure 1). 4 In this Account, we demonstrate the potential of MOFs as versatile media for polymer adsorption and recognition. Introducing polymers into the regular and well-defined MOF structure addresses the challenge of polymer separation.…”

Section: ■ Introductionmentioning

confidence: 89%

“…34 Recently, we found that adsorption of PEG on subnanoporous MOFs occurred readily from the solution phase. 4 The solution-phase adsorption behavior of PEGs into two isostructural 1D channeled MOFs, [Zn 2 (1,4-bdc) 2 (ted)] n and [Zn 2 (1,4ndc) 2 (ted)] n , with subnanometer diameters (d = 0.75 and 0.57 nm, respectively) was investigated (Figures 1b and c). The adsorption isotherm for PEG (M w = 2 kg/mol, hereafter referred to as PEG 2k) showed significant adsorption for both MOFs.…”

Section: Adsorption Of Polymers On Mofs From the Solution Phasementioning

confidence: 99%

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Metal–Organic Frameworks as Versatile Media for Polymer Adsorption and Separation

Hosono

Uemura

2021

Acc. Chem. Res.

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Conspectus Molecular recognition is of paramount importance for modern chemical processes and has now been achieved for small molecules using well-established host–guest chemistry and adsorption-science principles. In contrast, technologies for recognizing polymer structure are relatively undeveloped. Conventional polymer separation methods, which are mostly limited in practice to size-exclusion chromatography and reprecipitation, find it difficult to recognize minute structural differences in polymer structures as such small structural alterations barely influence the polymer characteristics, including molecular size, polarity, and solubility. Therefore, most of the polymeric products being used today contain mixtures of polymers with different structures as it is challenging to completely control polymer structures during synthesis even with state-of-the-art substitution and polymerization techniques. In this context, development of novel techniques that can resolve the challenges of polymer recognition and separation is in great demand, as these techniques hold the promise of a new paradigm in polymer synthesis, impacting not only materials chemistry but also analytical and biological chemistry. In biological systems, precise recognition and translation of base monomer sequences of mRNA are achieved by threading them through small ribosome tunnels. This principle of introducing polymers into nanosized channels can possibly help us design powerful polymer recognition and separation technologies using metal–organic frameworks (MOFs) as ideal and highly designable recognition media. MOFs are porous materials comprising organic ligands and metal ions and have been extensively studied as porous beds for gas separation and storage. Recently, we found that MOFs can accommodate large polymeric chains in their nanopores. Polymer chains can spontaneously infiltrate MOFs from neat molten and solution phases by threading their terminals into MOF nanochannels. Polymer structures can be recognized and differentiated due to such insertion processes, resulting in the selective adsorption of polymers on MOFs. This enables the precise recognition of the polymer terminus structure, resulting in the perfect separation of a variety of terminal-functionalized polymers that are otherwise difficult to separate by conventional polymer separation methods. Furthermore, the MOFs can recognize polymer shapes, thus enabling the large-scale separation of high purity cyclic polymers from the complex crude mixtures of linear polymers, which are used as precursor materials in common cyclization reactions. In solution-phase adsorption, many factors, including molecular weight, terminal groups, polymer shape, polymer–MOF interaction, and coexisting solvent molecules, influence the selective adsorption behavior; this yields a new liquid chromatography-based polymer separation technology using an MOF as the stationary phase. MOF-packed columns, in which a novel separation mode based on polymer insertion into the MOF operates under a dynamic insert...

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Section: Adsorption Of Polymers On Mofs From the Solution Phasementioning

confidence: 85%

Section: ■ Introductionmentioning

confidence: 89%

Section: Adsorption Of Polymers On Mofs From the Solution Phasementioning

confidence: 99%

See 1 more Smart Citation

Metal–Organic Frameworks as Versatile Media for Polymer Adsorption and Separation

Hosono

Uemura

2021

Acc. Chem. Res.

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“…PEGs were used to explore the thermodynamics and kinetics of polymer insertion, which revealed an enthalpy-driven mechanism coupled with a dynamic insertion/rejection process at the solution/MOF interface. Isothermal adsorption study indicated a unique solvent dependency of PEG insertion, which is explained by PEG-MOF affinity, MOF-solvent affinity, and the solvation effect [ 131 ].…”

Section: Applications Of Zn-based Mofs For Gases Adsorption Imaging and Sensorsmentioning

confidence: 99%

“… ( a ) Zn–TDPAT emission spectra (kex at lower wavelength) at varied concentration levels and ( b ) various thermal values [ 131 ]. Reprinted with the permission of Ref.…”

Section: Figurementioning

confidence: 99%

Zinc-Based Metal-Organic Frameworks in Drug Delivery, Cell Imaging, and Sensing

Ali

Meng

2021

Molecules

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The design and structural frameworks for targeted drug delivery of medicinal compounds and improved cell imaging have been developed with several advantages. However, metal-organic frameworks (MOFs) are supplemented tremendously for medical uses with efficient efficacy. These MOFs are considered as an absolutely new class of porous materials, extensively used in drug delivery systems, cell imaging, and detecting the analytes, especially for cancer biomarkers, due to their excellent biocompatibility, easy functionalization, high storage capacity, and excellent biodegradability. While Zn-metal centers in MOFs have been found by enhanced efficient detection and improved drug delivery, these Zn-based MOFs have appeared to be safe as elucidated by different cytotoxicity assays for targeted drug delivery. On the other hand, the MOF-based heterogeneous catalyst is durable and can regenerate multiple times without losing activity. Therefore, as functional carriers for drug delivery, cell imaging, and chemosensory, MOFs’ chemical composition and flexible porous structure allowed engineering to improve their medical formulation and functionality. This review summarizes the methodology for fabricating ultrasensitive and selective Zn-MOF-based sensors, as well as their application in early cancer diagnosis and therapy. This review also offers a systematic approach to understanding the development of MOFs as efficient drug carriers and provides new insights on their applications and limitations in utility with possible solutions.

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Isolation of Polyethylene Glycol with Larger Molecular Weights via Metal–Organic Frameworks

Huang,

Ren,

Fan

et al. 2024

Macromol. Rapid Commun.

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Polymer products typically present as mixtures with a range of molecular weights, which notably influence the expression of their properties. In this study, a technique is proposed to separate polyethylene glycol (PEG) mixtures of varying molecular weights using metal–organic frameworks (MOFs), thereby narrowing down their molecular weight distribution. Due to the hydrogen bond interactions between PEG and ‐OH groups in the pores of NU‐1000, NU‐1000 can selectively adsorb PEG with larger molecular weights from PEG mixture. This separation method consistently yields with narrower molecular weight distribution across multiple cycles. This is the first application of MOFs in regulating the dispersity (Ð) of polymers in solution, providing a novel approach for separating and purifying mixed molecular weight polymers.

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Revisiting molecular adsorption: unconventional uptake of polymer chains from solution into sub-nanoporous media

Abstract: Self-entangled large polymeric coils in solution can go into sub-nanometer pores by spontaneous uncoiling, which has been considered unfavorable in conventional molecular adsorption models.

Cited by 27 publications

References 82 publications

Metal–Organic Frameworks as Versatile Media for Polymer Adsorption and Separation

Metal–Organic Frameworks as Versatile Media for Polymer Adsorption and Separation

Zinc-Based Metal-Organic Frameworks in Drug Delivery, Cell Imaging, and Sensing

Isolation of Polyethylene Glycol with Larger Molecular Weights via Metal–Organic Frameworks

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