A database to compare possible MOFs for volumetric hydrogen storage, taking into account the cost of their building blocks

Physical adsorption at cryogenic temperature can increase the density of the stored hydrogen at a lower pressure than conventional compressed gas systems. This mechanism is also reversible and involves faster kinetics than chemical storage. Materials with certain structural and porous properties are necessary for volumetrically efficient hydrogen storage, including large specific surface areas, pore volumes, and appropriated bulk densities. Metal-organic frameworks (MOF) materials are remarkable candidates as adsorbents due to their porous properties and high crystallinity. Large databases like the MOF subset from the CSD or the CoRE-MOF can be used to find the best materials for this application, providing crystallographic information, composition, and porous properties. Herein, we created a database which includes crystallographic and porous properties, metallic and organic composition, and the minimum available cost for their linkers and corresponding suppliers for those for which it was publicly available. The database is also helpful for selecting structures with potential for industrial production and starting material for computational tools like machine learning or artificial intelligence approaches that relate the composition of MOFs with their performance in different applications. A user interface allows for creating customized selections of suitable MOF structures, looking for their porous and crystalline properties, gravimetric and volumetric total uptakes, and metallic and organic composition, as well as properties for the organic linkers like name, molecular mass, price, or presence of specific functional groups. This information was used to select potential structures from up to two metals and two linkers for the volumetric cryostorage of hydrogen

Structural variety of aluminium and gallium coordination polymers based on bis-pyridylethylene: from molecular complexes to ionic networks

A systematic structural study of the complexes formed by aluminium and gallium trihalides with 1,2-bis(4-pyridyl)ethylene (bpe) was performed. Quantum chemical computations revealed that the energy differences between the ionic and the molecular complexes expected in the MX3-bpe (M = Al, Ga; X = Cl, Br) system are very small. These computational findings indicate that this system is a rich source of compounds with diverse structural motifs. Indeed, eleven complexes, namely, [M2Cl4(bpe)(5)](2+)[M2Cl4-(bpe)(6)](2+)[MCl4](4)(-)*3bpe (M[double bond, length as m-dash]Al (1), M[double bond, length as m-dash]Ga (2)), [Al3Br8(bpe)(3)](+)[AlBr4](-) (3), [Al2Br4(bpe)(5)](2+)[AlBr4](2)(-)*bpe (4), [Ga2Br4(bpe)(7)](2+)[GaBr4](2)(-)*bpe (5), [GaCl3(bpe)](infinity) (6), [(MX3)(2)(bpe)] (MX3 = AlCl3 (7), AlBr3 (8), GaCl3 (9), GaBr3 (10a, 10b), and [(GaBr3)(2)(bpe)]*bpe (11) were synthesized in a solvent-free melt reaction of group 13 metal halides and bpe. The diversity of the complexes obtained shows the marked effect of different reagent ratios as well as Lewis acid on the product structures. Ionic coordination polymers (CPs) 1 and 2 exhibit isostructural unusual mixed one-dimensional-two-dimensional (1D-2D) networks. Interaction of bpe with excess AlBr3 yielded ionic 1D CP 3 while the same reaction in excess bpe produced ionic 2D CP 4. Reaction of GaBr3 and bpe in equimolar ratio yielded binuclear ionic complex 5 in a mixture with an adduct solvate 11. The only molecular CP 6 with 1D structure was isolated when the reaction between GaCl3 and bpe was carried out in both 1 : 1 and 1 : 2 stoichiometric ratios. In the case of the 2 : 1 ratio, irrespective of the Lewis acid, [(MX3)(2)(bpe)] adducts 7-10a and 10b were obtained. Remarkably, complex 10 crystallizes in two polymorphic modifications, 10a and 10b. The solid-state structures of complexes 1, 3-5, and 7-11 were determined for the first time

Coordination polymers and molecular complexes of group 13 metal halides with bis-pyridylethane: comparison with rigid N-containing ligands

A systematic structural study of novel complexes formed by aluminium and gallium trihalides with 1,2-bis(4-pyridyl)ethane (bpa) is performed. The complexes were synthesized using a solvent-free melt reaction approach and crystallized by sublimation in vacuum. Ionic coordination polymers (CPs) [MCl$_2$(bpa)$_2$]$^+$[MCl$_4$]$^−$,M = Al (1) or Ga (2), exhibit isostructural one-dimensional networks. Ionic CP 3 [AlBr$_2$(bpa)$_2$]$^+$Br$^−$ has a 1: 2 composition and possesses a cationic part analogous to 1 and 2, featuring a modulated structure, in which the entire polymer chain and/or the positions of the bromido ligands are displaced according to a harmonic law. In the ionic CP [Ga$_2$Br$_4$(bpa)$_5$]$^{2+}$[GaBr$_4$]$_2$$^−$bpa (4) featuring a 2 : 3 composition, the [Ga$_2$Br$_4$(bpa)$_5$]$^{2+}$ cation forms a 2D polymer framework, in which {GaBr$_2$}$^+$ nodes are linked by the $μ$-bpa spacers forming 1D chains that are further interconnected by $μ$-bpa ligands of every second metal center. In the case of the 2 : 1 ratio, irrespective of the Lewis acid, molecular complexes [(MX$_3$)$_2$(bpa)] (MX$_3$ = AlCl$_3$ (5), AlBr$_3$ (6), GaCl$_3$ (7), and GaBr$_3$ (8)) were obtained. Solid-state structures of complexes 1–8 were determined for the first time

Optimizing the Green Synthesis of ZIF‑8 by Reactive Extrusion Using <i>In Situ</i> Raman Spectroscopy

We report the scale-up of a batch solid synthesis of zeolitic imidazolate framework-8 (ZIF-8) for reactive extrusion. The crystalline product forms in the extruder directly under the mixture of solid 2-methylimidazole and basic zinc carbonate in the presence of a catalytic amount of liquid. The process parameters such as temperature, liquid type, feeding rate, and linker excess were optimized using the setup specifically designed for in situ Raman spectroscopy. Highly crystalline ZIF-8 with a Brunauer–Emmett–Teller (BET) surface area of 1816 m2 g–1 was quantitatively prepared at mild temperature using a catalytic amount of ethanol and a small excess of the linker. Finally, we developed a simple and comprehensive approach to evaluating the environmental friendliness and scalability of metal–organic framework (MOF) syntheses in view of their large-scale production

Lighting Up Industrial Mechanochemistry: Real-Time In Situ Monitoring of Reactive Extrusion Using Energy-Dispersive X-Ray Diffraction

Mechanochemistry is an environmentally friendly synthetic approach enabling the sustainable production of a wide range of chemicals while reducing or eliminating the need for solvents. Reactive extrusion aims to move mechanochemistry from its conventional gram-scale batch reactions, typically performed in laboratory ball mills, to a continuous large-scale process. Meeting this challenge requires the use of in situ monitoring techniques for gaining insights into reactive extrusion and its underlying processes. While the effectiveness of in situ Raman spectroscopy in providing molecular-level information has been demonstrated, our study uses energy-dispersive X-ray diffraction to monitor reactive extrusion in real-time at the crystalline level