Understanding the Diversity of the Metal-Organic Framework Ecosystem

By combining metal nodes and organic linkers one can make millions of different metal-organic frameworks (MOFs). At present over 90,000 MOFs have been synthesized and there are databases with over 500,000 predicted structures. This raises the question whether a new experimental or predicted structure adds new information. For MOF-chemists the chemical design space is a combination of pore geometry, metal nodes, organic linkers, and functional groups, but at present we do not have a formalism to quantify optimal coverage of chemical design space. In this work, we show how machine learning can be used to quantify similarities of MOFs. This quantification allows us to use techniques from ecology to analyse the chemical diversity of these materials in terms of diversity metrics. In particular, we show that this diversity analysis can identify biases in the databases, and how such bias can lead to incorrect conclusions. This formalism provides us with a simple and powerful practical guideline to see whether a set of new structures will have the potential for new insights, or constitute a relatively small variation of existing structures.

Download Full-text

Metal–organic frameworks for H2and CH4storage: insights on the pore geometry–sorption energetics relationship

IUCrJ ◽

10.1107/s2052252516019060 ◽

2017 ◽

Vol 4 (2) ◽

pp. 131-135 ◽

Cited By ~ 22

Author(s):

Mohamed H. Alkordi ◽

Youssef Belmabkhout ◽

Amy Cairns ◽

Mohamed Eddaoudi

Keyword(s):

Surface Area ◽

Binding Affinity ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Large Surface Area ◽

Pore Geometry ◽

Trade Off ◽

Storage Media ◽

Metal Organic ◽

Low Pressures

This study aims to assess the possibility of improving H2and CH4binding affinity to the aromatic walls of a designed new Metal–Organic Framework (MOF) through simultaneous dispersive interactions. It is suggested here that desirable H2and CH4storage media at low pressures require narrow uniform pores associated with large surface area, a trade-off that is challenging to achieve.

Download Full-text

Magnetic Ordering via Itinerant Ferromagnetism in a Metal-Organic Framework

10.26434/chemrxiv.12330866 ◽

2020 ◽

Author(s):

Jesse Park ◽

Brianna Collins ◽

Lucy Darago ◽

Tomce Runcevski ◽

Michael Aubrey ◽

...

Keyword(s):

Charge Transport ◽

Magnetic Order ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Magnetic Ordering ◽

Double Exchange ◽

Itinerant Ferromagnetism ◽

Organic Solids ◽

Metal Organic ◽

Organic Framework

Materials that combine magnetic order with other desirable physical attributes offer to revolutionize our energy landscape. Indeed, such materials could find transformative applications in spintronics, quantum sensing, low-density magnets, and gas separations. As a result, efforts to design multifunctional magnetic materials have recently moved beyond traditional solid-state materials to metal–organic solids. Among these, metal–organic frameworks in particular bear structures that offer intrinsic porosity, vast chemical and structural programmability, and tunability of electronic properties. Nevertheless, magnetic order within metal–organic frameworks has generally been limited to low temperatures, owing largely to challenges in creating strong magnetic exchange in extended metal–organic solids. Here, we employ the phenomenon of itinerant ferromagnetism to realize magnetic ordering at TC = 225 K in a mixed-valence chromium(II/III) triazolate compound, representing the highest ferromagnetic ordering temperature yet observed in a metal–organic framework. The itinerant ferromagnetism is shown to proceed via a double-exchange mechanism, the first such observation in any metal–organic material. Critically, this mechanism results in variable-temperature conductivity with barrierless charge transport below TC and a large negative magnetoresistance of 23% at 5 K. These observations suggest applications for double-exchange-based coordination solids in the emergent fields of magnetoelectrics and spintronics. Taken together, the insights gleaned from these results are expected to provide a blueprint for the design and synthesis of porous materials with synergistic high-temperature magnetic and charge transport properties.

Download Full-text

Engineering Porosity Through Defects in a Giant Pore Metal–Organic Framework

10.26434/chemrxiv.12847574.v1 ◽

2020 ◽

Author(s):

Adam Sapnik ◽

Duncan Johnstone ◽

Sean M. Collins ◽

Giorgio Divitini ◽

Alice Bumstead ◽

...

Keyword(s):

Distribution Function ◽

Ball Milling ◽

Local Structure ◽

Pair Distribution Function ◽

Function Analysis ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Defect Engineering ◽

Metal Organic ◽

Unsaturated Metal Sites

Defect engineering is a powerful tool that can be used to tailor the properties of metal–organic frameworks (MOFs). Here, we incorporate defects through ball milling to systematically vary the porosity of the giant pore MOF, MIL-100 (Fe). We show that milling leads to the breaking of metal–linker bonds, generating more coordinatively unsaturated metal sites, and ultimately causes amorphisation. Pair distribution function analysis shows the hierarchical local structure is partiallyretained, even in the amorphised material. We find that the solvent toluene stabilises the MIL-100 (Fe) framework against collapse and leads to a substantial rentention of porosity over the non-stabilised material.

Download Full-text

Metal-Organic Frameworks vs. Buffers: Case Study of UiO-66 Stability

10.26434/chemrxiv.12588269.v1 ◽

2020 ◽

Author(s):

Daniel Bůžek ◽

Slavomír Adamec ◽

Kamil Lang ◽

Jan Demel

Keyword(s):

Inductively Coupled Plasma ◽

Buffer Capacity ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Analytical Techniques ◽

Aqueous Dispersions ◽

Inductively Coupled ◽

Plasma Mass Spectrometry ◽

Metal Organic

<div>UiO-66 is a zirconium-based metal-organic framework (MOF) that has numerous applications. Our group recently determined that UiO-66 is not as inert in aqueous dispersions as previously reported in the literature. The present work therefore assessed the behaviour of UiO-66 in buffers: 2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS), 4-(2-hydroxyethyl)piperazine-1-ethane sulfonic acid (HEPES), N-ethylmorpholine (NEM) and phosphate buffer (PB), all of which are commonly used in many UiO-66 applications. High pressure liquid chromatography and inductively coupled plasma mass spectrometry were used to monitor degradation of the MOF. In each buffer, the terephthalate linker was released to some extent, with a more pronounced leaching effect in the saline forms of these buffers. The HEPES buffer was found to be the most benign, whereas NEM and PB should be avoided at any concentration as they were shown to rapidly degrade the UiO-66 framework. Low concentration TRIS buffers are also recommended, although these offer minimal buffer capacity to adjust pH. Regardless of the buffer used, rapid terephthalate release was observed, indicating that the UiO-66 was attacked immediately after mixing with the buffer. In addition, the dissolution of zirconium, observed in some cases, intensified the UiO-66 decomposition process. These results demonstrate that sensitive analytical techniques have to be used to monitor the release of MOF components so as to quantify the stabilities of these materials in liquid environments.</div>

Download Full-text

An Overview of Metal-organic Frameworks-based Acid/Base Catalysts for Biofuel Synthesis

Current Organic Chemistry ◽

10.2174/1385272824999200726230556 ◽

2020 ◽

Vol 24 (16) ◽

pp. 1876-1891

Author(s):

Qiuyun Zhang ◽

Yutao Zhang ◽

Jingsong Cheng ◽

Hu Li ◽

Peihua Ma

Keyword(s):

Alternative Fuels ◽

Heterogeneous Catalysts ◽

Supported Catalysts ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Flexible Structures ◽

Biodiesel Production ◽

Biodiesel Synthesis ◽

Metal Organic ◽

Organic Framework

Biofuel synthesis is of great significance for producing alternative fuels. Among the developed catalytic materials, the metal-organic framework-based hybrids used as acidic, basic, or supported catalysts play major roles in the biodiesel production. This paper presents a timely and comprehensive review of recent developments on the design and preparation of metal-organic frameworks-based catalysts used for biodiesel synthesis from various oil feedstocks, including MILs-based catalysts, ZIFs-based catalysts, UiO-based catalysts, Cu-BTC-based catalysts, and MOFs-derived porous catalysts. Due to their unique and flexible structures, excellent thermal and hydrothermal stability, and tunable host-guest interactions, as compared with other heterogeneous catalysts, metal-organic framework-based catalysts have good opportunities for application in the production of biodiesel at industrial scale.

Download Full-text

Exciton Coupling and Conformational Changes Impacting the Excited State Properties of Metal Organic Frameworks

Molecules ◽

10.3390/molecules25184230 ◽

2020 ◽

Vol 25 (18) ◽

pp. 4230

Author(s):

Andreas Windischbacher ◽

Luca Steiner ◽

Ritesh Haldar ◽

Christof Wöll ◽

Egbert Zojer ◽

...

Keyword(s):

Conformational Changes ◽

Photophysical Properties ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Red Shift ◽

Light Emitting ◽

Light Emitting Devices ◽

Exciton Coupling ◽

Metal Organic ◽

Crystalline Metal

In recent years, the photophysical properties of crystalline metal-organic frameworks (MOFs) have become increasingly relevant for their potential application in light-emitting devices, photovoltaics, nonlinear optics and sensing. The availability of high-quality experimental data for such systems makes them ideally suited for a validation of quantum mechanical simulations, aiming at an in-depth atomistic understanding of photophysical phenomena. Here we present a computational DFT study of the absorption and emission characteristics of a Zn-based surface-anchored metal-organic framework (Zn-SURMOF-2) containing anthracenedibenzoic acid (ADB) as linker. Combining band-structure and cluster-based simulations on ADB chromophores in various conformations and aggregation states, we are able to provide a detailed explanation of the experimentally observed photophysical properties of Zn-ADB SURMOF-2: The unexpected (weak) red-shift of the absorption maxima upon incorporating ADB chromophores into SURMOF-2 can be explained by a combination of excitonic coupling effects with conformational changes of the chromophores already in their ground state. As far as the unusually large red-shift of the emission of Zn-ADB SURMOF-2 is concerned, based on our simulations, we attribute it to a modification of the exciton coupling compared to conventional H-aggregates, which results from a relative slip of the centers of neighboring chromophores upon incorporation in Zn-ADB SURMOF-2.

Download Full-text

Metal-organic-framework derived hollow manganese nickel selenide spheres confined with nanosheets on nickel foam for hybrid supercapacitors

Dalton Transactions ◽

10.1039/d1dt01215k ◽

2021 ◽

Author(s):

Bahareh ameri ◽

Akbar Mohammadi Zardkhoshoui ◽

Saied Saeed Hosseiny Davarani

Keyword(s):

Active Sites ◽

Nickel Foam ◽

Metal Organic Framework ◽

High Surface ◽

Metal Organic Frameworks ◽

High Surface Area ◽

Supercapacitive Performance ◽

Hybrid Supercapacitors ◽

Porous Networks ◽

Metal Organic

Metal-organic frameworks (MOFs) derived nanoarchitectures have special features, such as high surface area (SA), abundant active sites, exclusive porous networks, and remarkable supercapacitive performance when compared to traditional nanoarchitectures. Herein,...

Download Full-text

Synthesis, crystal structure, luminescence, and photocatalytic properties of a 2D Cu(II) metal-organic frameworks based on 3,5-di(1H-benzimidazol-1-yl)pyridine and 4,4′-oxybis(benzoate) ligands

Zeitschrift für Naturforschung B ◽

10.1515/znb-2020-0041 ◽

2020 ◽

Vol 75 (8) ◽

pp. 727-732

Author(s):

Chen Zhang ◽

Jian-Qing Tao

Keyword(s):

Crystal Structure ◽

Thermal Analysis ◽

Uv Light ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

X Ray Diffraction ◽

X Ray ◽

Uv Light Irradiation ◽

Photocatalytic Activities ◽

Metal Organic

AbstractA new Cu(II) metal-organic framework, [Cu(L)(OBA)·H2O]n (1) [H2OBA = 4,4′-oxybis(benzoic acid), L = 3,5-di(1H-benzimidazol-1-yl)pyridine] was hydrothermally synthesized and characterized through IR spectroscopy, elemental and thermal analysis and single-crystal X-ray diffraction. Complex 1 is a four-connected uni-nodal 2D net with a (44·62) topology which shows an emission centered at λ ∼393 nm upon excitation at λ = 245 nm. Moreover, complex 1 possesses high photocatalytic activities for the decomposition of Rhodamine B (RhB) under UV light irradiation.

Download Full-text

Crystal growth of the core and rotated epitaxial shell of a heterometallic metal-organic framework revealed with atomic force microscopy

Faraday Discussions ◽

10.1039/d1fd00033k ◽

2021 ◽

Author(s):

Fajar Inggit Pambudi ◽

Michael William Anderson ◽

Martin Attfield

Keyword(s):

Atomic Force Microscopy ◽

Crystal Growth ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Force Microscopy ◽

The Core ◽

Atomic Force ◽

Metal Organic ◽

Surface Crystal ◽

Organic Framework

Atomic force microscopy has been used to determine the surface crystal growth of two isostructural metal-organic frameworks, [Zn2(ndc)2(dabco)] (ndc = 1,4-naphthalene dicarboxylate, dabco = 4-diazabicyclo[2.2.2]octane) (1) and [Cu2(ndc)2(dabco)] (2) from...

Download Full-text