<i>p</i>-Xylene-Selective Metal–Organic Frameworks: A Case of Topology-Directed Selectivity

Vermoortele, Frederik; Maes, M.; Moghadam, Peyman Z.; Lennox, Matthew J.; Ragon, Florence; Boulhout, Mohammed; Biswas, Shyam; Laurier, Katrien G. M.; Beurroies, Isabelle; Denoyel, Renaud; Roeffaers, Maarten B. J.; Stock, Norbert; Düren, Tina; Serre, Christian; Vos, Dirk De

doi:10.1021/ja207287h

Cited by 157 publications

(136 citation statements)

References 13 publications

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“…[223][224][225]227] Due to pore morphology, and commensurate stacking, both MIL-125 and MAF-X8 have shown high p-xylene selectivity. [228] A flexible cerium tetradentate carboxylate MOF with restructuring driven by guest molecules, displaying molecular-level recognition for p-and mxylenes giving high selectivities, thereby adding to the increasing number of flexible MOFs that can be used for separations. [35,223,229] Stoddart et al recently reported a high selectivity of CD-MOFs (γ-CD) (see section 3.4), which exhibited high shape selectivity, for separation of aromatic hydrocarbons using alkali metal cations.…”

Section: Catalysis and Separationsmentioning

confidence: 99%

Biologically derived metal organic frameworks

Anderson

Stylianou

2017

Coordination Chemistry Reviews

120

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Metal organic frameworks (MOFs) are extended structures composed of a network of organic ligands and metal ions or clusters connected to each other via coordination bonds. The numerous choices of organic ligands and metal coordination geometries have led to the construction of porous MOFs with various compositions, network topologies, pore sizes and shapes and they possess high surface areas and low densities. The structures of MOFs can be tailor-tuned in such a way that any desired ligand or/and metal ion can be incorporated; this has given to researchers the advantage of designing MOFs for a targeted application. Within this review, we overview recent examples of a sub-class of MOFs namely biologically derived MOFs (bio-MOFs), made of multifunctional and commercially available biologically derived ligands (bio-ligands) such as: amino acids, peptides, nucleobases and saccharides and focus on their coordination chemistry with a variety of metals. Central to this review are four tables detailing the coordination modes of bio-ligands to metals, along with a visual representation of the bio-MOF that is subsequently formed. Through the detail analysis of these structures, we highlight the structural impact of these ligands on the structure, and their contribution to the MOFs properties and applications. Finally, we showcase the potential of bio-MOFs in several research areas such as CO2 capture, separation, catalysis, drug delivery and sensing.

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Section: Catalysis and Separationsmentioning

confidence: 99%

Biologically derived metal organic frameworks

Anderson

Stylianou

2017

Coordination Chemistry Reviews

120

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“…Both MOFs exhibit high o-xylene selectivity, separating the xylene regioisomers based on molecular packing and entropic differences. [21][22][23]25 More recently, 26,27 MIL-125 and MAF-X8 Figure 1. Representations of the solid-state structure of CD-MOF-1.…”

Section: ■ Introductionmentioning

confidence: 99%

Carbohydrate-Mediated Purification of Petrochemicals

et al. 2015

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Metal−organic frameworks (MOFs) are known to facilitate energy-efficient separations of important industrial chemical feedstocks. Here, we report how a class of green MOFsnamely CD-MOFsexhibits high shape selectivity toward aromatic hydrocarbons. CD-MOFs, which consist of an extended porous network of γ-cyclodextrins (γ-CDs) and alkali metal cations, can separate a wide range of benzenoid compounds as a result of their relative orientation and packing within the transverse channels formed from linking (γ-CD) 6 body-centered cuboids in three dimensions. Adsorption isotherms and liquid-phase chromatographic measurements indicate a retention order of ortho-> meta-> para-xylene. The persistence of this regioselectivity is also observed during the liquid-phase chromatography of the ethyltoluene and cymene regioisomers. In addition, molecular shape-sorting within CDMOFs facilitates the separation of the industrially relevant BTEX (benzene, toluene, ethylbenzene, and xylene isomers) mixture. The high resolution and large separation factors exhibited by CD-MOFs for benzene and these alkylaromatics provide an efficient, reliable, and green alternative to current isolation protocols. Furthermore, the isolation of the regioisomers of (i) ethyltoluene and (ii) cymene, together with the purification of (iii) cumene from its major impurities (benzene, n-propylbenzene, and diisopropylbenzene) highlight the specificity of the shape selectivity exhibited by CD-MOFs. Grand canonical Monte Carlo simulations and single component static vapor adsorption isotherms and kinetics reveal the origin of the shape selectivity and provide insight into the capability of CD-MOFs to serve as versatile separation platforms derived from renewable sources. ■ INTRODUCTIONWith the expanding global demand for petrochemical feedstocks, the development of novel, low-cost materials that reduce the impact of chemical processing on the environment is critically important. Improving the efficiency of the refinement and separation of aromatic hydrocarbons is of particular importance, given the large volumes on which these compounds are produced. The sustained interest in metal− organic frameworks 1 (MOFs) as adsorbents and sequestering agents for industrially important gases, 2−4 e.g., H 2 , CH 4 , CO 2 and N 2 , as well as for the liquid-phase separation of larger molecular compounds, which include (1) constitutional isomers, 5 (2) chiral compounds, 6 (3) aliphatic hydrocarbons, 3b,5b,7 and (4) pharmaceuticals, 8 is leading to MOFs being investigated as alternatives to zeolites 9 and activated carbon 10 as separation media. The improvements 5−7 in separation efficiencies using MOFs over traditional size-and shape-selective materials can be attributed primarily to (i) the physiochemical properties imbedded in their diverse building blocks, (ii) their higher surface areas, and (iii) their larger adsorption capacities, which reduce the amount of adsorbent required for industrial processes. 7a,11 Consequently, MOFs represent emergent materials f...

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“…In previous work, some of the authors showed that Metal-Organic Frameworks could be successfully used as selective adsorbents for the industrially relevant separations of paraxylene (pX) versus meta-xylene (mX) and ortho-xylene (oX) versus ethylbenzene (eB) [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Host–guest and guest–guest interactions between xylene isomers confined in the MIL-47(V) pore system

et al. 2012

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The porous MIL-47 material shows a selective adsorption behavior for para, ortho, and meta-isomers of xylenes, making the material a serious candidate for separation applications.The origin of the selectivity lies in the differences in interactions (energetic) and confining (entropic). This paper investigates the xylene-framework interactions and the xylene-xylene interactions with quantum mechanical calculations, using a dispersion corrected density functional and periodic boundary conditions to describe the crystal. First, the strength and geometrical characteristics of the optimal xylene-xylene interactions are quantified by studying the pure and mixed pairs in gas phase. An extended set of initial structures is created and optimized to sample as many relative orientations and distances as possible. Next, the pairs are brought in the pores of MIL-47. The interaction with the terephthalic linkers and other xylenes, increases the stacking energy in gas phase (-31.7 kJ/mol per pair) by roughly a factor four in the fully-loaded state (-58.3 kJ/mol per xylene). Our decomposition of the adsorption energy shows various trends in the contributing xylene-xylene interactions. The absence of a significant difference in energetics between the isomers indicates that entropic effects must be mainly responsible for the separation behavior.Corresponding authors: an.ghysels@ugent.be, veronique.vanspeybroeck@ugent.be 2

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p-Xylene-Selective Metal–Organic Frameworks: A Case of Topology-Directed Selectivity

Cited by 157 publications

References 13 publications

Biologically derived metal organic frameworks

Biologically derived metal organic frameworks

Carbohydrate-Mediated Purification of Petrochemicals

Host–guest and guest–guest interactions between xylene isomers confined in the MIL-47(V) pore system

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