scholarly journals Flexibility in Metal–Organic Frameworks: A Basic Understanding

Catalysts ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 512 ◽  
Author(s):  
Noor Aljammal ◽  
Christia Jabbour ◽  
Somboon Chaemchuen ◽  
Tatjána Juzsakova ◽  
Francis Verpoort
Keyword(s):  
Metal Organic Frameworks ◽  
Structural Flexibility ◽  
Logical Basis ◽  
Research Areas ◽  
Research Activities ◽  
Basic Understanding ◽  
Fundamental Understanding ◽  
Metal Organic ◽  
And Behavior ◽  
External Stimuli

Much has been written about the fundamental aspects of the metal–organic frameworks (MOFs). Still, details concerning the MOFs with structural flexibility are not comprehensively understood. However, a dramatic increase in research activities concerning rigid MOFs over the years has brought deeper levels of understanding for their properties and applications. Nonetheless, robustness and flexibility of such smart frameworks are intriguing for different research areas such as catalysis, adsorption, etc. This manuscript overviews the different aspects of framework flexibility. The review has touched lightly on several ideas and proposals, which have been demonstrated within the selected examples to provide a logical basis to obtain a fundamental understanding of their synthesis and behavior to external stimuli.

scholarly journals Temperature dependence of adsorption hysteresis in flexible metal organic frameworks

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Shamsur Rahman ◽  
Arash Arami-Niya ◽  
Xiaoxian Yang ◽  
Gongkui Xiao ◽  
Gang (Kevin) Li ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Capillary Condensation ◽  
Metal Organic Frameworks ◽  
Sorption Isotherms ◽  
Separation Performance ◽  
Process Simulations ◽  
Metal Organic ◽  
Flexible Metal ◽  
Pressure Swing ◽  
External Stimuli

Abstract“Breathing” and “gating” are striking phenomena exhibited by flexible metal-organic frameworks (MOFs) in which their pore structures transform upon external stimuli. These effects are often associated with eminent steps and hysteresis in sorption isotherms. Despite significant mechanistic studies, the accurate description of stepped isotherms and hysteresis remains a barrier to the promised applications of flexible MOFs in molecular sieving, storage and sensing. Here, we investigate the temperature dependence of structural transformations in three flexible MOFs and present a new isotherm model to consistently analyse the transition pressures and step widths. The transition pressure reduces exponentially with decreasing temperature as does the degree of hysteresis (c.f. capillary condensation). The MOF structural transition enthalpies range from +6 to +31 kJ·mol−1 revealing that the adsorption-triggered transition is entropically driven. Pressure swing adsorption process simulations based on flexible MOFs that utilise the model reveal how isotherm hysteresis can affect separation performance.

scholarly journals Cyclodextrins Modified/Coated Metal–Organic Frameworks

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1273 ◽  
Author(s):  
Huacheng Zhang ◽  
Zhaona Liu ◽  
Jian Shen
Keyword(s):  
Hybrid Materials ◽  
Metal Organic Frameworks ◽  
Supramolecular Interactions ◽  
Future Research ◽  
Covalent Bonds ◽  
Characterization Methods ◽  
Coated Metal ◽  
Metal Organic ◽  
Future Research Directions ◽  
External Stimuli

Recent progress about a novel organic–inorganic hybrid materials, namely cyclodextrins (CDs) modified/coated metal–organic frameworks (MOFs) is summarized by using a special categorization method focusing on the interactions between CDs and MOFs moieties, such as ligand–metal cations interactions, supramolecular interactions including host–guest interactions and hydrogen bonding, as well as covalent bonds. This review mainly focuses on the interactions between CDs and MOFs and the strategy of combining them together, diverse external stimuli responsiveness of CDs-modified/coated MOFs, as well as applications of these hybrid materials to drug delivery and release system, catalysis and detection materials. Additionally, due to the importance of investigating advanced chemical architectures and physiochemical properties of CDs-modified/coated MOFs, a separate section is involved in diverse characterization methods and instruments. Furthermore, this minireview also foresees future research directions in this rapidly developing field.

Tuning Packing, Structural Flexibility, and Porosity in 2D Metal–Organic Frameworks by Metal Node Choice

2019 ◽  
Vol 72 (10) ◽  
pp. 797 ◽  
Author(s):  
Witold M. Bloch ◽  
Christian J. Doonan ◽  
Christopher J. Sumby
Keyword(s):  
Structural Changes ◽  
Metal Organic Frameworks ◽  
Chemical Properties ◽  
Complete Removal ◽  
Structural Flexibility ◽  
X Ray Diffraction ◽  
Metal Centre ◽  
Metal Organic ◽  
Physical And Chemical ◽  
And Chemical Properties

Understanding the key features that determine structural flexibility in metal–organic frameworks (MOFs) is key to exploiting their dynamic physical and chemical properties. We have previously reported a 2D MOF material, CuL1, comprising five-coordinate metal nodes that displays exceptional CO2/N2 selectively (L1=bis(4-(4-carboxyphenyl)-1H-pyrazolyl)methane). Here we examine the effect of utilising six-coordinate metal centres (CoII and NiII) in the synthesis of isostructural MOFs from L1, namely CoL1 and NiL1. The octahedral geometry of the metal centre within the MOF analogues precludes an ideal eclipse of the 2D layers, resulting in an offset stacking, and in certain cases, the formation of 2-fold interpenetrated analogues β-CoL1 and β-NiL1. We used a combination of thermogravimetric analysis (TGA), and powder and single crystal X-ray diffraction (PXRD and SCXRD) to show that desolvation is accompanied by a structural change for NiL1, and complete removal of the coordinated H2O ligands results in a reduction in long-range order. The offset nature of the 2D layers in combination with the structural changes impedes the adsorption of meaningful quantities of gases (N2, CO2), highlighting the importance of a five-coordinate metal centre in achieving optimal pore accessibility for this family of flexible materials.

Stimuli-responsive structural changes in metal–organic frameworks

2020 ◽  
Vol 56 (66) ◽  
pp. 9416-9432 ◽  
Author(s):  
Zhanning Liu ◽  
Lu Zhang ◽  
Daofeng Sun
Keyword(s):  
Structural Changes ◽  
Metal Organic Frameworks ◽  
Stimuli Responsive ◽  
Feature Article ◽  
Metal Organic ◽  
External Stimuli

This feature article mainly summarizes how the structure of MOFs changes under external stimuli.

scholarly journals Control of structural flexibility of layered-pillared metal-organic frameworks anchored at surfaces

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Suttipong Wannapaiboon ◽  
Andreas Schneemann ◽  
Inke Hante ◽  
Min Tu ◽  
Konstantin Epp ◽  
...  
Keyword(s):  
Metal Organic Frameworks ◽  
Structural Flexibility ◽  
Metal Organic

scholarly journals Landscape of Research Areas for Zeolites and Metal-Organic Frameworks Using Computational Classification Based on Citation Networks

Materials ◽  
2017 ◽  
Vol 10 (12) ◽  
pp. 1428 ◽  
Author(s):  
Takaya Ogawa ◽  
Kenta Iyoki ◽  
Tomohiro Fukushima ◽  
Yuya Kajikawa
Keyword(s):  
Metal Organic Frameworks ◽  
Citation Networks ◽  
Research Areas ◽  
Metal Organic

scholarly journals Integration of Fluorescent Functionality into Pressure Amplifying Metal-Organic Frameworks

2021 ◽  
Author(s):  
Francesco Walenszus ◽  
Jack D. Evans ◽  
Volodymyr Bon ◽  
Friedrich Schwotzer ◽  
Irena Senkovska ◽  
...  
Keyword(s):  
Structural Changes ◽  
Gas Adsorption ◽  
Metal Organic Frameworks ◽  
Metal Exchange ◽  
Limited Information ◽  
X Ray Diffraction ◽  
Metal Organic ◽  
Synthetic Metal ◽  
External Stimuli ◽  
Highly Porous

The flexibility of soft porous crystals, i.e., their ability to respond to external stimuli with structural changes, is one of the most fascinating features of metal-organic frameworks. In addition to breathing and swelling phenomena of flexible MOFs, negative gas adsorption and pressure amplification is one of the more recent discoveries in this field, initially observed in the cubic DUT-49 framework. In recent years the structural contraction was monitored by physisorption, X‑ray diffraction, NMR and EPR techniques, providing only limited information about the electronic structure of the ligand. In this work we designed a new ligand with a fluorescent core in the linker backbone and synthesized three new MOFs, isoreticular to DUT-49, denoted as DUT‑140(M) (M - Cu, Co, Zn) crystalizing in space group. DUT‑140(Cu) can be desolvated and is highly porous with an accessible apparent surface area of 4870 m2g-1 and a pore volume of 2.59 cm3g-1. Furthermore, it shows flexibility and NGA upon adsorption of subcritical gases. DUT-140(Zn), synthesized using post-synthetic metal exchange, could only be studied with guests in the pores. In addition to the investigation of the adsorption behavior of DUT-140(Cu) spectroscopic and computational methods were used to study the light absorption properties.

scholarly journals Quantification of the mixed-valence and intervalence charge transfer properties of a cofacial metal–organic framework via single crystal electronic absorption spectroscopy

2020 ◽  
Vol 11 (20) ◽  
pp. 5213-5220
Author(s):  
Patrick W. Doheny ◽  
Jack K. Clegg ◽  
Floriana Tuna ◽  
David Collison ◽  
Cameron J. Kepert ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Mixed Valence ◽  
Three Dimensional ◽  
Fundamental Understanding ◽  
Intervalence Charge Transfer ◽  
Metal Organic ◽  
Transfer Properties ◽  
Transfer Mechanisms

Gaining a fundamental understanding of charge transfer mechanisms in three-dimensional Metal–Organic Frameworks (MOFs) is crucial to the development of electroactive and conductive porous materials.

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