Robust Biological Hydrogen‐Bonded Organic Framework with Post‐Functionalized Rhenium(I) Sites for Efficient Heterogeneous Visible‐Light‐Driven CO 2 Reduction

Macrocycle Self-Assembly Hydrogel for High-Efficient Oil-Water Separation

Supramolecular hydrogels involved macrocycles have been explored widely in recent years, but it remains challenging to develop hydrogel based on solitary macrocycle with super gelation capability. Here, the construction of lantern[33 ]arene-based hydrogel with low critical gelation concentration (0.05 wt%), which can be used for efficient oil-water separation, is reported. The lantern[33 ]arenes self-assemble into hydrogen-bonded organic nanoribbons, which intertwine into entangled fibers to form hydrogel. This hydrogel which exhibits reversible pH-responsiveness characteristics can be coated on stainless-steel mesh by in situ sol-gel transformation. The resultant mesh exhibits excellent oil-water separation efficiency (>99%) and flux (>6 × 104 L m-2 h-1 ). This lantern[33 ]arene-based hydrogel not only sheds additional light on the gelation mechanisms for supramolecular hydrogels, but also extends the application of macrocycle-based hydrogels as functional interfacial materials.

Recent Advances in Multifunctional Reticular Framework Nanoparticles: A Paradigm Shift in Materials Science Road to a Structured Future

Porous organic frameworks (POFs) have become a highly sought-after research domain that offers a promising avenue for developing cutting-edge nanostructured materials, both in their pristine state and when subjected to various chemical and structural modifications. Metal-organic frameworks, covalent organic frameworks, and hydrogen-bonded organic frameworks are examples of these emerging materials that have gained significant attention due to their unique properties, such as high crystallinity, intrinsic porosity, unique structural regularity, diverse functionality, design flexibility, and outstanding stability. This review provides an overview of the state-of-the-art research on base-stable POFs, emphasizing the distinct pros and cons of reticular framework nanoparticles compared to other types of nanocluster materials. Thereafter, the review highlights the unique opportunity to produce multifunctional tailoring nanoparticles to meet specific application requirements. It is recommended that this potential for creating customized nanoparticles should be the driving force behind future synthesis efforts to tap the full potential of this multifaceted material category.

Charge-Assisted Hydrogen-Bonded Organic Frameworks with Inorganic Ammonium Regulated Switchable Open Polar Sites

Surface open polar sites within the voids of porous molecular crystals define the localized physicochemical environment for critical functions such as gas separation and molecular recognition. This study presents a new charge-assisted hydrogen bonding (H-bonding) motif, by exploiting inorganic ammonium (NH₄ ⁺ ) cations as H-bond donors, to regulate the assembly of C₂ -symmetric carboxylic tectons for building robust H-bonded frameworks with permanent ultra-micropores and open oxygen sites. Diverse building blocks are bridged by tetrahedral NH₄ ⁺ to expand distinctive H-bonded networks with varied pore architectures. Particularly, the open polar oxygen sites can be switched by altering NH₄ ⁺ sources to tune the deprotonation of carboxyl-containing tectons. The activated porous PTBA·NH₄ ·DMF preserves the pore architecture and open polar oxygen sites, exhibiting remarkably selective sorption of CO₂ (107.8 cm³ g^-1 ,195 K) over N₂ (11.2 cm³ g^-1 , 77 K) and H₂ (1.4 cm³ g^-1 , 77 K).

A Flexible Hydrogen-Bonded Organic Framework Constructed from a Tetrabenzaldehyde with a Carbazole N-H Binding Site for the Highly Selective Recognition and Separation of Acetone

Rational design of hydrogen-bonded organic frameworks (HOFs) with multiple functionalities is highly sought after but challenging. Herein, we report a multifunctional HOF (HOF-FJU-2) built from 4,4',4'',4'''-(9H-carbazole-1,3,6,8-tetrayl)tetrabenzaldehyde molecule with tetrabenzaldeyde for their H bonding interactions and carbazole N-H site for its specific recognition of small molecules. The Lewis acid N-H sites allow HOF-FJU-2 facilely separate acetone from its mixture with another solvent like methanol with smaller pK_a value. The donor (D)-π-acceptor (A) aromatic nature of the organic building molecule endows this HOF with solvent dependent luminescent/chromic properties, so the column acetone/methanol separation on HOF-FJU-2 can be readily visualized.

Binary Solvent Regulated Architecture of Ultra-Microporous Hydrogen-Bonded Organic Frameworks with Tunable Polarization for Highly-Selective Gas Separation

A binary solvent synthetic strategy is proposed for the construction of C₂ -symmetric molecule-based hydrogen-bonded organic frameworks (HOFs) with permanent ultra-micropores and surface polarization derived from tunable coplanar open oxygen atoms. The activated HOFs BTBA-1 a and PTBA-1 a show highly selective separation of CO₂ /N₂ with a record high ideal adsorbed solution theory (IAST) selectivity >2000 under ambient temperature and pressure.

Hydrogen-Bonded Metal-Nucleobase Frameworks for Efficient Separation of Xenon and Krypton

Xe/Kr separation is an industrially important but challenging process owing to their inert properties and low concentrations in the air. Energy-effective adsorption-based separation is a promising technology. Herein, two isostructural hydrogen-bonded metal-nucleobase frameworks (HOF-ZJU-201 and HOF-ZJU-202) are capable of separating Xe/Kr under ambient conditions and strike an excellent balance between capacity and selectivity. The Xe capacity of HOF-ZJU-201a reaches 3.01 mmol g-1 at 298 K and 1.0 bar, while IAST selectivity and Henry's selectivity are 21.0 and 21.6, respectively. Direct breakthrough experiments confirmed the excellent separation performance, affording a Xe capacity of 25.8 mmol kg-1 from a Xe/Kr mixed-gas at dilute concentrations. Density functional theory calculations revealed that the selective binding arises from the enhanced polarization in the confined electric field produced by the electron-rich anions and the electron-deficient purine heterocyclic rings.

A Solid Transformation into Carboxyl Dimers Based on a Robust Hydrogen-Bonded Organic Framework for Propyne/Propylene Separation

Self-assembly of N,N,N',N'-tetrakis(4-carboxyphenyl)-1,4-phenylenediamine with the help of different solvents provides isostructural hydrogen-bonded organic frameworks (HOF-30). Single-crystal X-ray diffraction (SCXRD) analysis reveals HOF-30 possesses 3D ten-fold interpenetrated dia nets connected by two kinds of hydrogen bonds, namely solvent-bridged carboxyl dimers and carboxyl⋅⋅⋅carboxyl dimers. Degassing treatment for HOF-30 yields HOF-30a with 3D ten-fold interpenetrated dia nets but linked with sole carboxyl⋅⋅⋅carboxyl dimers. Reversible hydrogen-bond-to-hydrogen-bond transformation between solvent-bridged carboxyl dimers in HOF-30 and carboxyl⋅⋅⋅carboxyl dimers in HOF-30a has been unveiled by single-crystal and powder X-ray diffraction. In addition, HOF-30a enables the selective adsorption of propyne over propylene according to single-component sorption and breakthrough experiments. The preferred propyne location in HOF has also been identified by SCXRD test.