Fluorine‐Boosted Kinetic and Selective Molecular Sieving of C6 Derivatives

Abstract

Porous molecular sorbents have excellent selectivity towards hydrocarbon separation with energy saving techniques. However, to realize commercialization, molecular sieving processes should be faster and more efficient compared to extended frameworks. In this work, we show that utilizing fluorine to improve the hydrophobic profile of leaning pillararenes affords a substantial kinetic selective adsorption of benzene over cyclohexane (20:1 for benzene). The crystal structure shows a porous macrocycle that acts as a perfect match for benzene in both the intrinsic and extrinsic cavities with strong interactions in the solid state. The fluorinated leaning pillararene surpasses all reported organic molecular sieves and is comparable to the extended metal organic frameworks that were previously employed for this separation such as UIO‐66. Most importantly, this sieving system outperformed the well‐known zeolitic imidazolate frameworks under low pressure, which opens the door to new generations of molecular sieves that can compete with extended frameworks for more sustainable hydrocarbon separation.

Uncovering tetrazoles as building blocks for constructing discrete and polymeric assemblies

“…The mixture of 41, 38, and 43 in a molar ratio of 3 : 2 : 9 resulted in a 3D dodecanuclear octahedral cage (47). This 3D architecture had a truncated octahedral geometry with twelve half-sandwich Ir units and four ligands (48); a Cl atom bridged between two Ir centres. The tetrazole ligand displayed a bidentate nature (via VI binding mode) (Fig.…”

“…On the other hand, discrete coordination assemblies, which are comprised of metal-organic cages (MOCs) and metallacycles (MCs), exhibit better solubility in polar and non-polar solvents. [46][47][48][49] These structures have diverse applications ranging from catalysis, [50][51][52][53][54][55][56][57] selective separation, [58][59][60][61][62] fluorescence tuning, [63][64][65][66][67][68] sensing, [69][70][71] to photochromism. 72,73 Most self-assembled coordination assemblies use pyridines, carboxylates and imidazoles as the primary linking motifs to the metal centres.…”

“…On the other hand, discrete coordination assemblies, which are comprised of metal–organic cages (MOCs) and metallacycles (MCs), exhibit better solubility in polar and non-polar solvents. 46–49 These structures have diverse applications ranging from catalysis, 50–57 selective separation, 58–62 fluorescence tuning, 63–68 sensing, 69–71 to photochromism. 72,73…”

Fluorinated Nonporous Adaptive Cages for the Efficient Removal of Perfluorooctanoic Acid from Aqueous Source Phases

“…Macrocycle-based crystalline materials, termed nonporous adaptive crystals (NACs), are a relatively new class of synthetic materials with appealing adsorption/separation properties . For example, the Huang group showed that pillararene-based NACs could be used to achieve the selective separation of 2-methylfuran from 2,5-dimethylfuran .…”

Mechanically Interlocked Water-Soluble Pd6 Host for the Selective Separation of Coal Tar-Based Planar Aromatic Molecules

“…Thus, intricate molecules can be created without the need of tedious multistep covalent synthesis. , Compared to purely organic catenated cages, metal–organic catenated cages generally exhibit better solubility in polar solvents, and multiple intriguing structures with different metal units and ligands have been synthesized. , Such catenated cages can also be water-soluble, thus mimicking the naturally occurring MIMs. However, most of the works with such systems are related to their synthesis, and while multiple applications of non-interlocked cages in catalysis, , sensing, , and separation , are known, the applications of catenated cages are rare. , …”